Rifle Scopes Nightforce NXS vs ATACR glass

[odoylerules]

I’m looking at getting one of these scopes for my next build. 7-300wm-Defiant hunter action, proof barrel, MPA chassis.
This will primarily be a LR hunting rig, but I will be continually be testing my limits ringing steel and busting rocks to a mile+.
I’m leaning towards SFP for my needs.
The NXS is jumping out at me because it’s a half pound lighter than the similar power ATACR.
My main question...
Is the glass quality in the ATACR gonna be noticeable enough to be worth the extra weight?

 

[Lowlight]

It is noticeable as the ATACR glass has color added and the NXS series is pretty flat.

The resolution of the NXS is still very good, but color gives you that sense of pop.

 

[CSTactical]

What Frank said above, both are great options and you'd be served great with either. Feel free to call us at 916.670.1103 to discuss the Pros an Cons of each of these scopes.

 

[G101489]

I just upgraded from a NSX 5.5-22 to a 5-25 F1 ATACR. For ME, the color and resolution was much better. The CA on the NSX is very noticeable also. On the ATACR, I can't see any. Save the extra money for the ATACR.

 

[odoylerules]

This is a nice build. I definitely don’t want to skimp on glass. I was thinking about the weight savings mostly, but noticeably better glass is worth 7 oz.
My buddy tells me I should forget the NF and buy a Schmidt and Bender. Any opinions there?
thanks

 

[Denys]

The main difference between the ATACR and the NSX is that the ATACR uses ED glass, whereas the NXS does not. ED glass reduces chromatic aberration in a riflescope which makes the color separation better by reducing or eliminating color fringing. I went from an NXS to a March-X mainly because of the ED glass in the latter. I do not know if the S&B uses ED glass or whatever variation of it there are out there. I know very little of FFP scopes as I need higher magnification than they usually have and I don't use my riflescope for ranging. So SFP for me.

Whatever you're looking at buying to replace the dull NXS, make sure it has ED or SD glass or something along those lines. I do not know what is meant by "color added."

 

[TheOE800]

Whatever you're looking at buying to replace the dull NXS, make sure it has ED or SD glass or something along those lines. I do not know what is meant by "color added."

I took that to mean either the depth of color ("pop") or the tone. Every NXS I've had was very blue toned vs. my eye.

 

[Denys]

Right, that would be due to whatever lens coating mix they use. Up until recently, Nightforce has never struck me has being up to date on lens coating and that accounts for the rather dismal light transmission of their NXS and others. This changed with the ATACR and a couple of more recent offerings. ED glass makes a big difference.

 

[hk dave]

This is a nice build. I definitely don’t want to skimp on glass. I was thinking about the weight savings mostly, but noticeably better glass is worth 7 oz.
My buddy tells me I should forget the NF and buy a Schmidt and Bender. Any opinions there?
thanks

You're not going to see a difference between a S&B PMII 5-25 and a NF ATACR F1 5-25. I have compared both exhaustively... it's seriously splitting hairs.

 

[5RWill]

You're not going to see a difference between a S&B PMII 5-25 and a NF ATACR F1 5-25. I have compared both exhaustively... it's seriously splitting hairs.

While i don't disagree for the price you can have a S&B with an H59 cheaper than you can an ATACR F1 with an H59 from EuroOptic. I want an ATACR pretty bad but haven't had the time to make any money for one, that and it's pretty hard to find deals on them like you can with Vortex or Kahles. S&Bs are on sale right now at EuroOptic is the only reason i bring it up. If i had the money i'd snag a PMII with an H59 for almost 400$ cheaper than an ATACR 5-25 with the same reticle. I think the regular reticle PMIIs are 2500$ or so at EuroOptic right now also.

Still would love an ATACR 4-16 for a hunting rig.

 

[Denys]

You're not going to see a difference between a S&B PMII 5-25 and a NF ATACR F1 5-25. I have compared both exhaustively... it's seriously splitting hairs.

That would indicate that S&B also uses ED glass, and it may well be sourced from the same place as the one used in the ATACR.

 

[G101489]

Ill also throw this in there. I personally think the ATACR F1 trumps the S&B.

Better turrets / Better spacing

Shorter by about an inch

No third knob for illumination

 

[TheOE800]

Ill also throw this in there. I personally think the ATACR F1 trumps the S&B.

Better turrets / Better spacing

Shorter by about an inch

No third knob for illumination

Honestly, at the level of ATACR vs Kahles K-series vs Vortex Razor vs Minox ZP5 vs S&B PMII...the MAIN differences are going to come down to reticles and turrets, and weight if we're talking about the Razor G2 specifically. Glass should be the last concern.

 

[Crews]

I’ve had both, and to this poor boy there wasn’t enough difference in glass quality to deliver a noticeable difference in the field. I’m not nearly as educated as most commenters here, but I chose to keep the NXS and spend the difference on more ammo and range time.


Sent from my iPhone using Tapatalk

 

[koshkin]

ATACR has noticeably better image quality than the NXS with most of the difference coming down to greatly improved contrast. One of the ways it is manifested is better color pop, but there are others. Attributing that to only coatings or to ED glass is not quite correct. There is a lot more that goes into that and the whole optical system of the ATACR is entirely redesigned compared to the NXS.

On ATACR and S&B using glass from the same source: you can't make that conclusion based on the fact that both are nice scopes. Several companies make exotic glass and any number of them may be used. From the little that I know about where they are made, I doubt they use the same glass supplier, although anything is possible.

ILya

 

[Denys]

ATACR has noticeably better image quality than the NXS with most of the difference coming down to greatly improved contrast. One of the ways it is manifested is better color pop, but there are others. Attributing that to only coatings or to ED glass is not quite correct. There is a lot more that goes into that and the whole optical system of the ATACR is entirely redesigned compared to the NXS.

Do tell. How does one improve the contrast and get better IQ by not using ED glass or better coatings? I'm here to learn.

On ATACR and S&B using glass from the same source: you can't make that conclusion based on the fact that both are nice scopes. Several companies make exotic glass and any number of them may be used. From the little that I know about where they are made, I doubt they use the same glass supplier, although anything is possible.

ILya

I don't know that anyone stated that the glass on the ATACR and S&B came from the same source. I did say that it might be possible. In this day and age of globalization and specialization and economies of scale and so on, glass sourcing is very convoluted and you may be surprised who gets what glass and from where. This also seems to be an ever changing story as well. Indeed, most riflescope makers, and many camera lens makers, will not reveal their suppliers and the suppliers are usually quiet about to whom they sell. In the end, it's the performance of the product that counts.

 

[koshkin]

Do tell. How does one improve the contrast and get better IQ by not using ED glass or better coatings? I'm here to learn.

That is not what I said. You are making a straw man argument. I said that you can not attribute the improvement to only coatings and ED glass.

However, a more sophisticated optical design, with better corrected aberrations and better stray light control will absolutely improve contrast in particular and image quality overall. Simply using ED glass does not guarantee anything as evidenced by a plethora of scopes that use ED glass and produce crappy image quality.

Before ED glass became commonly available and comparatively inexpensive, plenty of excellent optical designs were utilized. If you want an example, many slightly older Kahles and Zeiss designs deliver spectacular image quality without any ED glass in them. There is this myth propagating around that you must always have ED glass. That is simply not true. ED glass helps, but the designer needs to know how to use it and the rest of the system needs to be done well.

Typically, when a manufacturer says "ED glass", that means that there is one ED element in the objective lens system. All the other lenses are usually not of ED variety, nor do they need to be. For example, I see more and more scopes with high erector ratios that are screwed by what is happening inside the erector optical system. In those situations, it does not matter how amazing the objective lens assembly is. It all get screwed up further down the line.

Then, there are some with eyepieces that are not great. In other words, it really varies.

ED glass is sufficiently available nowadays, that you really can not make any conclusions based on a scope having them. It was an indication of quality when it just showed up because so few companies used it. Now, it has become almost irrelevant.

ILya

 

[Denys]

Talk about straw man arguments. We are not talking about just any cheap no-name or any other name riflescopes here; we are comparing the Nightforce NXS to the ATACR.

My contention is that the main difference in IQ between the NXS and the ATACR is due to the use of ED glass and the better lens coating in the latter. I don’t understand why you are talking about other manufacturers and what they may or may not do.

And I would hope that everyone knows that only a few lens elements are ED glass in a riflescope, just like they are in a camera lens.

 

[koshkin]

You may contend it, but I do not think that is true.

There is very little in common between NXS and ATACR designs best I can tell, although coatings are likely the same or very similar. Coatings are often quietly improved during the lifetime of the product, and I have a suspicion that they were changed during the lifecycle of NXS scopes. Late model NXS scopes as I recall, seemed to have notably better coatings than earlier ones I have seen.
As far as ED elements go, in a riflescope, it is typically only one ED element, not a few. Usually, it is the second element in the objective lens assembly. I suspect that is the case with the ATACR.

To claim that the only difference between ATACR and NXS optical system is coatings and a single ED element is to belittle the amount of design effort it took to make the ATACR and the optically similar BEAST. ATACR is a modern world class optical design that is notably more advanced than the NXS. NXS was a great scope for its time with great emphasis on mechanical durability. ATACR is much more than NXS with an extra ED lens element. It is really a major step up in terms of image quality.

ILya

 

[TheOE800]

Something had to have changed over the lifecycle of the NXS, otherwise I wouldn't think my ~2014 production was great while folks still rocking late 90s production are rubbish in this day and age.

 

[koshkin]

Something had to have changed over the lifecycle of the NXS, otherwise I wouldn't think my ~2014 production was great while folks still rocking late 90s production are rubbish in this day and age.

I could be wrong, but to the best of my knowledge, there were two changes that happened during the production run of the NXS: coatings went through an improvement process and centering spec got tighter.

ILya

 

[Tazman]

I have all the versions from NXS to the new F1 and what I don't like is the continued size and weight increase of these things. I have been doing carbon barrels and stocks on the new builds and the scope negates the gains! I do think the glass has improved a little but not in conjunction with the price and weight IMHO.

 

[High H2o]

I have both, and both are great scopes. When I first got my NXS, I was blown away with all it could do, compared to the scopes I have had in the past. I felt that same way when I got my Atacr. BLOWN AWAY. There is that much of a difference between the NXS and Atacr, imho. 1/2 lb? who among us couldn't stand to lose 1/2lb? I go Elk hunting in CO every year, going up and down canyons with a .338 lapua with an Atacr on it. When I see Elk through it... i can almost smell'em...

 

[Undrgrndprdcts]

Does anybody have a good idea of a safe date for when the last of the improvements on the NXS line were completed? For example scopes after "this date" will be the best ones produced.

 

[Denys]

You may contend it, but I do not think that is true.

There is very little in common between NXS and ATACR designs best I can tell, although coatings are likely the same or very similar. Coatings are often quietly improved during the lifetime of the product, and I have a suspicion that they were changed during the lifecycle of NXS scopes. Late model NXS scopes as I recall, seemed to have notably better coatings than earlier ones I have seen.
As far as ED elements go, in a riflescope, it is typically only one ED element, not a few. Usually, it is the second element in the objective lens assembly. I suspect that is the case with the ATACR.

I have no problem believing that coating can improve during the lifecycle of a product. It only makes sense as a coating change will not impact mechanical aspects of a riflescope.

To claim that the only difference between ATACR and NXS optical system is coatings and a single ED element is to belittle the amount of design effort it took to make the ATACR and the optically similar BEAST. ATACR is a modern world class optical design that is notably more advanced than the NXS. NXS was a great scope for its time with great emphasis on mechanical durability. ATACR is much more than NXS with an extra ED lens element. It is really a major step up in terms of image quality.

ILya

I very much like my 2012 NXS 12-42X56, but its IQ is quite inferior to my March-X 5-50X56, running at the same magnification and in similar conditions. The big difference between the two scopes is the use of ED glass in the March-X. I would suggest that to simply dismiss ED glass, saying that everybody does it now, is (pardon the pun) shortsighted. There is a reason why ED glass was invented by Nikon and others and is now finding its way into sports optics. ED glass approaches the qualities of fluorite glass in optics, without its drawbacks such as fragility, high cost and susceptibility to the weather (hot and cold). I doubt we will see fluorite glass in riflescopes but ED glass and even more recently Super ED glass have had a large effect on optics. Camera lenses have been using ED glass for a few decades already and most knowledgeable photographers would not consider an non-ED lens nowadays. You can get fluorite glass in camera lenses but the prices of these lenses is eye-watering; enter ED and now Super ED. (It is funny though, as the need for ED glass in photography has actually diminished since you can cure the chromatic aberration issues in PP nowadays, but photographers would rather not even introduce it in the picture at all. On the other hand, ED and Super ED glass do have a great impact on sports optics because it's real time, no PP for that.)

Before the advent of lens coating, you could still have great glass, but you needed huge objectives to get any amount of illuminance to the film or the eye in less than great lighting. Lens coating was special at first, but over time it became ubiquitous and nobody wants to buy uncoated optics. There are still improvements being made in coatings but each one is incremental now, compared to the early benefits. I have an old binoculars from the late 60s/early 70s, pre lens coating days, that I keep just to compare to what we have now.

Reengineering the optical system will improve the eyebox, the zooming range and the fidelity of the tracking and so on, but ED glass is what makes the colors pop and lens coating is what increases the light transmission for various wavelengths.

All my camera lenses have ED glass and all my sports optics will also, except for my team spotting scope, but that's a different story for another day.

 

[koshkin]

I have no problem believing that coating can improve during the lifecycle of a product. It only makes sense as a coating change will not impact mechanical aspects of a riflescope.

I very much like my 2012 NXS 12-42X56, but its IQ is quite inferior to my March-X 5-50X56, running at the same magnification and in similar conditions. The big difference between the two scopes is the use of ED glass in the March-X. I would suggest that to simply dismiss ED glass, saying that everybody does it now, is (pardon the pun) shortsighted. There is a reason why ED glass was invented by Nikon and others and is now finding its way into sports optics. ED glass approaches the qualities of fluorite glass in optics, without its drawbacks such as fragility, high cost and susceptibility to the weather (hot and cold). I doubt we will see fluorite glass in riflescopes but ED glass and even more recently Super ED glass have had a large effect on optics. Camera lenses have been using ED glass for a few decades already and most knowledgeable photographers would not consider an non-ED lens nowadays. You can get fluorite glass in camera lenses but the prices of these lenses is eye-watering; enter ED and now Super ED. (It is funny though, as the need for ED glass in photography has actually diminished since you can cure the chromatic aberration issues in PP nowadays, but photographers would rather not even introduce it in the picture at all. On the other hand, ED and Super ED glass do have a great impact on sports optics because it's real time, no PP for that.)

Before the advent of lens coating, you could still have great glass, but you needed huge objectives to get any amount of illuminance to the film or the eye in less than great lighting. Lens coating was special at first, but over time it became ubiquitous and nobody wants to buy uncoated optics. There are still improvements being made in coatings but each one is incremental now, compared to the early benefits. I have an old binoculars from the late 60s/early 70s, pre lens coating days, that I keep just to compare to what we have now.

Reengineering the optical system will improve the eyebox, the zooming range and the fidelity of the tracking and so on, but ED glass is what makes the colors pop and lens coating is what increases the light transmission for various wavelengths.

All my camera lenses have ED glass and all my sports optics will also, except for my team spotting scope, but that's a different story for another day.

I am beginning to have flashbacks of talking to Phillip with his Schott glass obsession.

I will give it another shot and then, I will bow out. You keep on repeating the same thing that is just patently incorrect. I build electro-optical devices for a living. I have a degree in applied physics and I have worked the entirety of my professional career with optical devices and beyond telling you that you are wrong, the only other thing I can suggest is that you go take an optics class or read some sort of an introductory optics textbook. If you want to have a discussion about this, you really need to understand what ED glass is and what it does.

Almost everything you said is flat out wrong, especially your take on what reengineering an optical system will do. Some historical references are correct. Some of what you said about coatings is correct, but other stuff you do not seem to understand. Arguable, the most important benefit we got from coatings is not so much light transmission, but rather the improvement in flare,scatter, etc.

ED glass was not invented by Nikon. Fluorite glass has been used in at least one riflescope I can think of. Drawing parallels between camera lenses and riflescopes is meaningless. They are very different types of optical devices. If you really want to compare, in terms of function, a camera lens does more or less the same thing as the objective lens assembly of a riflescopes. Most importantly though, a camera lens creates an image on film or an image sensor, while a riflescope is a DVO. That puts VERY different requirements onto an imaging system. I learned a lot about this the hard way when I used to make image sensors fro broadcast and cinema cameras (among other things, we provided imagers for the cameras that won an Oscar for Cinematography for Slumdog Millionaire).

March X is a much more sophisticated design than the NXS that is also built to much higher tolerances. There is a lot more to it than simply use of ED glass. You repeating ad nauseum that it is all about ED glass will not make it so.

Choosing a scope strictly based on presence of ED glass will make you choose Bushnell Legend Ultra HD over Kahles K312i. K312 does not have any ED glass in it. Bushnell Legend does.

Anyhow, I think I will bow out of this argument now. It has gone widely off track and bottom line is that we all agree that ATACR is a better scope than the NXS, other than being heavier.

ILya

 

[crossgun]

koshkin, thank you sir for sharing your knowledge and professional approach. Great read

 

[918v]

Is the recent trend of cheap scopes advertising ED glass but failing to deliver HD image quality an attempt by the manufacturers to improve image quality by going with better glass but skimping on coatings? Is ED glass cheaper than good coatings?

 

[koshkin]

Is the recent trend of cheap scopes advertising ED glass but failing to deliver HD image quality an attempt by the manufacturers to improve image quality by going with better glass but skimping on coatings? Is ED glass cheaper than good coatings?

Most of them have pretty decent coatings and perfectly legitimate ED glass. However, putting it together into a high quality product requires good engineering, good design, and good manufacturing. All of those cost money.

ILya

 

[Denys]

I thought I was done with this discussion, but that was not to be.

I am beginning to have flashbacks of talking to Phillip with his Schott glass obsession.

I don't know who Phillip is but you are starting to make me look for a shot glass of something strong.

I will give it another shot and then, I will bow out. You keep on repeating the same thing that is just patently incorrect. I build electro-optical devices for a living. I have a degree in applied physics and I have worked the entirety of my professional career with optical devices and beyond telling you that you are wrong, the only other thing I can suggest is that you go take an optics class or read some sort of an introductory optics textbook. If you want to have a discussion about this, you really need to understand what ED glass is and what it does.

Almost everything you said is flat out wrong, especially your take on what reengineering an optical system will do. Some historical references are correct. Some of what you said about coatings is correct, but other stuff you do not seem to understand. Arguable, the most important benefit we got from coatings is not so much light transmission, but rather the improvement in flare,scatter, etc.

I didn't get into the weeds about coatings, I just wanted to cover a couple of their benefits, which in this case are light transmission and when applied correctly, color correction.

ED glass was not invented by Nikon.

Ok, you say Nikon has nothing to do with ED glass. So who invented it, pray tell?

Fluorite glass has been used in at least one riflescope I can think of.

Ok, please be specific here. Which one is it? We are all here to learn, me especially.

Drawing parallels between camera lenses and riflescopes is meaningless. They are very different types of optical devices. If you really want to compare, in terms of function, a camera lens does more or less the same thing as the objective lens assembly of a riflescopes.

Finally something we can agree on. The front assembly focuses the image of the objective at the front on the erector tube and from that point forward the rest of the riflescope is used to inspect a portion of that image. It is called an afocal system. It should be noted that first focal point is critical to the image we get out of the eyepiece because the rest of the system will not generate more light or more detail.

Most importantly though, a camera lens creates an image on film or an image sensor, while a riflescope is a DVO. That puts VERY different requirements onto an imaging system. I learned a lot about this the hard way when I used to make image sensors fro broadcast and cinema cameras (among other things, we provided imagers for the cameras that won an Oscar for Cinematography for Slumdog Millionaire)

March X is a much more sophisticated design than the NXS that is also built to much higher tolerances. There is a lot more to it than simply use of ED glass. You repeating ad nauseum that it is all about ED glass will not make it so.

Choosing a scope strictly based on presence of ED glass will make you choose Bushnell Legend Ultra HD over Kahles K312i. K312 does not have any ED glass in it. Bushnell Legend does.

Again, you are making a straw dog argument. The question of this thread is "what makes the ATACR better than the NXS?" I pointed out that NF incorporated ED glass and better lens coating.

Now you are arguing that ED glass has little or nothing to do with the better IQ of the ATACR. I wonder why the hell NF even bothered to add ED glass if they were not going to get any benefit out of it. I don't remember saying that any scope with ED glass will have better IQ that any scope without it, as you seemed to indicate. But I will say that any scope with ED glass will have better IQ than the same scope without ED glass, all else being equal. Just like any scope with multicoated lenses will have better IQ than the same scope without multicoated lenses.

Anyhow, I think I will bow out of this argument now.

We'll see.

It has gone widely off track and bottom line is that we all agree that ATACR is a better scope than the NXS, other than being heavier.

ILya

I'll take the high road.

 

[hk dave]

I thought I was done with this discussion, but that was not to be.


I don't know who Phillip is but you are starting to make me look for a shot glass of something strong.


I didn't get into the weeds about coatings, I just wanted to cover a couple of their benefits, which in this case are light transmission and when applied correctly, color correction.


Ok, you say Nikon has nothing to do with ED glass. So who invented it, pray tell?


Ok, please be specific here. Which one is it? We are all here to learn, me especially.


Finally something we can agree on. The front assembly focuses the image of the objective at the front on the erector tube and from that point forward the rest of the riflescope is used to inspect a portion of that image. It is called an afocal system. It should be noted that first focal point is critical to the image we get out of the eyepiece because the rest of the system will not generate more light or more detail.



Again, you are making a straw dog argument. The question of this thread is "what makes the ATACR better than the NXS?" I pointed out that NF incorporated ED glass and better lens coating.

Now you are arguing that ED glass has little or nothing to do with the better IQ of the ATACR. I wonder why the hell NF even bothered to add ED glass if they were not going to get any benefit out of it. I don't remember saying that any scope with ED glass will have better IQ that any scope without it, as you seemed to indicate. But I will say that any scope with ED glass will have better IQ than the same scope without ED glass, all else being equal. Just like any scope with multicoated lenses will have better IQ than the same scope without multicoated lenses.



We'll see.



I'll take the high road.

By responding as you did and then saying you will take the high road, you essentially didn’t.

​

 

[Denys]

By responding as you did and then saying you will take the high road, you essentially didn'’t.

There was nothing derogatory or flippant in my post. My comment about me taking the high road was in response to the final comment from my interlocutor.

 

[koshkin]

I thought I was done with this discussion, but that was not to be.


I don't know who Phillip is but you are starting to make me look for a shot glass of something strong.


I didn't get into the weeds about coatings, I just wanted to cover a couple of their benefits, which in this case are light transmission and when applied correctly, color correction.


Ok, you say Nikon has nothing to do with ED glass. So who invented it, pray tell?


Ok, please be specific here. Which one is it? We are all here to learn, me especially.


Finally something we can agree on. The front assembly focuses the image of the objective at the front on the erector tube and from that point forward the rest of the riflescope is used to inspect a portion of that image. It is called an afocal system. It should be noted that first focal point is critical to the image we get out of the eyepiece because the rest of the system will not generate more light or more detail.



Again, you are making a straw dog argument. The question of this thread is "what makes the ATACR better than the NXS?" I pointed out that NF incorporated ED glass and better lens coating.

Now you are arguing that ED glass has little or nothing to do with the better IQ of the ATACR. I wonder why the hell NF even bothered to add ED glass if they were not going to get any benefit out of it. I don't remember saying that any scope with ED glass will have better IQ that any scope without it, as you seemed to indicate. But I will say that any scope with ED glass will have better IQ than the same scope without ED glass, all else being equal. Just like any scope with multicoated lenses will have better IQ than the same scope without multicoated lenses.



We'll see.



I'll take the high road.

If you ever make it out to California, I'll be happy to buy you a drink. I am a single malt man myself, but I enjoy a good bourbon occasionally.
I apologize for mentioning Phillip. That would drive you into the bottle. Almost did that to me.

I am not sure who was the first to use low dispersion glass, but it seems to have been started by Leitz in Germany some time in the 30s in their long focal length optics. There were several versions of it, some producing tinted glass (those yellowish radioactive Eastern block binoculars we see occasionally have glass doped with thorium dioxide, which results in low dispersion). Lantanium glass, I think, was first reliably made through work by George Morey at Carnegie institution in the 20s and 30s. That effort was primarily for improving the quality of gunsights and observation devices for the US military. I could have sworn that Kodak did work on that during WW2 for some aerial observation optics, but I would need to do some searching to confirm that.

Either way, Nikon was one of the first if not the first to use ED glass in their photographic lenses, but they by no means invented it or really had anything to do with it other than have the patience and workmanship to use it in consumer devices. I do not know who was the first to use ED glass in commercial riflescopes. I know Zeiss/Hensodlt was the first to use fluorite in a riflescope (in the 6-24x72 Hensoldt) and fluorite glass (in some Hensodlt scopes and Zeiss FL line).

On coatings, I re-iterate: for DVO systems, lack of reflection is more important than high transmission for image fidelity.

On ED glass: my argument is that the changes in the ATACR are far more significant than just adding ED glass. That is why it has better contrast, wider FOV, better off-center performance, better stray light baffling, etc. ED glass is important, but there is a lot more to it than that.

No here is the exact of your sentence, and I am sorry to use the word, but there is really not better way of saying this. This is just ignorant: "But I will say that any scope with ED glass will have better IQ than the same scope without ED glass, all else being equal" This is a fundamentally incoherent thing to say. It is impossible to simply add an ED element to a system and not have to re-design the rest of it. Optics do not work that way. You can't swap out components willy-nilly and expect everything to just get better.

Either way, with the ATACR, the FOV got wider and various aberrations (not just CA got better). It is not all abotu ED glass.

Coatings are different. You can change the coatings without changing anything else. You can not do that with lens elements.

ILya

 

[Denys]

Thank you for the invite. I used to do single malt Scotch but I'm really just a gin guy.

For the general public, fluorite glass is naturally low dispersion and that has been known for a long time. The problem is that it is difficult to make, especially in larger lenses (making it expensive) and is "fragile" compared to glass. I still believe that Nikon and others came up with ED glass in the 1960s and that allowed Nikon to use more ED glass in their lenses, compared to say, Canon, which used more fluorite glass. In the high $ camera lenses we actually see Nikon and Canon offerings using ED, Super ED and fluorite glass nowadays.

You're absolutely correct and thank you for correcting me, when you pointed out my error with the use of "all else being equal." My point was more about equal levels of quality in assembly, but definitely, "all else being equal" is nonsense here.

Thank you for pointing out the Hensoldt 6-24X72. I knew about that riflescope, because of the 72mm objective, but did not know that it had fluorite glass. EuroOptics shows the MSRP of that scope to be an eye-watering price of$12,000 but they have it on sale for $5,000. I cannot find anything about it at the Zeiss website, they only talk about Victory, Conquest and Terra riflescopes anymore. I downloaded the manual for that scope at EuroOptics. It's dated 2010, almost 8 years ago. A ctrl-f search of the manual for the word fluorite returns nothing. Clicking on their link for support returns nothing, unreachable, somehow it changes it to www.cassidian.com, which I believe is part of Airbus .. A ctrl-f search of that page does not turn up Zeiss, Hensoldt but optroni does: Jena-Optroniks. The names Jena and Zeiss are linked. The Euro Optics site says Hensoldt is part of Airbus. Over at Airbus, a search reveals that Airbus sold Hensoldt to KKR in March of this year. KKR website finally shows Hensoldt at www.hensoldt.net. Wow, that was easy, and fun. Circle down to the sights and then you get to the riflescope and the 6-24X72 is there. A ctrl-f search for fluorite brings up nothing,

They offer that scope in 72mm and 56mm. This is the write up they have about it.

The lens diameter considerably influences

the optical capabilities of a telescopic sight. With increasing magnification, the brightness of the sene diminishes. This factor plays a key role in the military, in particular, where long ranges are common. Under adverse weather conditions such as precipitation, twilight and haze, high magnification often leads to unwanted results.

Thereforce, we have limited our 6 x to 24 x telescopic sights to a magnification range that is both beneficial and noticeable to the user and combined it with a choice of a 56 mm or 72 mm lens.

Our 6 - 24 x 56 is the right telescopic sight when extremely precise adjustability and very high magnification are required.

The spelling mistakes are theirs. I will also point out that their statements lay waste to a certain gunwriter's assertion that the objective lens size has nothing to do with the amount of light going to the eye. (It's another story.)

So, I cannot confirm your assertion of the use of fluorite glass in a riflescope, and this one is rare and very expensive.

It's also an SFP, in case someone cares.

 

[koshkin]

It is not an assertion. It is a fact I got from Hensoldt back when they were still part of Zeiss. Since then, the brand has gone through serious changes and was recently spun out as a separate company. 6-24x72 used fluorite crystal, not the glass. 6-24x56 was an older design that didn't use it. Zeiss FL scopes used fluorite glass. I recall 4-16x50 being particularly impressive. Hensoldt 4-16x56 may also used fluorite glass, but I never got direct confirmation if that.

ILya

 

[tbeckstrand]

Thank you for the invite. I used to do single malt Scotch but I'm really just a gin guy.

For the general public, fluorite glass is naturally low dispersion and that has been known for a long time. The problem is that it is difficult to make, especially in larger lenses (making it expensive) and is "fragile" compared to glass. I still believe that Nikon and others came up with ED glass in the 1960s and that allowed Nikon to use more ED glass in their lenses, compared to say, Canon, which used more fluorite glass. In the high $ camera lenses we actually see Nikon and Canon offerings using ED, Super ED and fluorite glass nowadays.

You're absolutely correct and thank you for correcting me, when you pointed out my error with the use of "all else being equal." My point was more about equal levels of quality in assembly, but definitely, "all else being equal" is nonsense here.

Thank you for pointing out the Hensoldt 6-24X72. I knew about that riflescope, because of the 72mm objective, but did not know that it had fluorite glass. EuroOptics shows the MSRP of that scope to be an eye-watering price of$12,000 but they have it on sale for $5,000. I cannot find anything about it at the Zeiss website, they only talk about Victory, Conquest and Terra riflescopes anymore. I downloaded the manual for that scope at EuroOptics. It's dated 2010, almost 8 years ago. A ctrl-f search of the manual for the word fluorite returns nothing. Clicking on their link for support returns nothing, unreachable, somehow it changes it to www.cassidian.com, which I believe is part of Airbus .. A ctrl-f search of that page does not turn up Zeiss, Hensoldt but optroni does: Jena-Optroniks. The names Jena and Zeiss are linked. The Euro Optics site says Hensoldt is part of Airbus. Over at Airbus, a search reveals that Airbus sold Hensoldt to KKR in March of this year. KKR website finally shows Hensoldt at www.hensoldt.net. Wow, that was easy, and fun. Circle down to the sights and then you get to the riflescope and the 6-24X72 is there. A ctrl-f search for fluorite brings up nothing,

They offer that scope in 72mm and 56mm. This is the write up they have about it.


The spelling mistakes are theirs. I will also point out that their statements lay waste to a certain gunwriter's assertion that the objective lens size has nothing to do with the amount of light going to the eye. (It's another story.)

So, I cannot confirm your assertion of the use of fluorite glass in a riflescope, and this one is rare and very expensive.

It's also an SFP, in case someone cares.

I'm pretty sure I'm the gun writer you're talking about. What issues do you have with my statement that objective lenses do not gather more light, they dictate the size of the exit pupil?

 

[Denys]

It is not an assertion. It is a fact I got from Hensoldt back when they were still part of Zeiss. Since then, the brand has gone through serious changes and was recently spun out as a separate company. 6-24x72 used fluorite crystal, not the glass. 6-24x56 was an older design that didn't use it. Zeiss FL scopes used fluorite glass. I recall 4-16x50 being particularly impressive. Hensoldt 4-16x56 may also used fluorite glass, but I never got direct confirmation if that.

ILya

Understood, I just would have liked to have seen that confirmed at their website.

 

[Denys]

I'm pretty sure I'm the gun writer you're talking about. What issues do you have with my statement that objective lenses do not gather more light, they dictate the size of the exit pupil?

I suspect you are.

When I saw that sentence it went against all that I know about and have worked with in photography for the last 45 years. I just can't get my mind past "larger objective lenses do not gather more light." Yet, photographers pay top dollar for telephoto lenses with humongous objective lenses to be able to action pictures using higher shutter speeds to "stop" the action. In the triumvirate of shutter speed, f-stop and ISO rating, if you bring in more light with a larger objective, you can use a faster shutter speed and still maintain a decent ISO. The only way to transmit more light is to use bigger lenses.

You will notice that opening line from the Hensoldt website that I quoted above which says "The lens diameter considerably influences the optical capabilities of a telescopic sight. With increasing magnification, the brightness of the scene diminishes." That's why the have 56mm and especially 72mm objectives.

Larger objectives (let in/transmit/gather) more light. However you describe the action of the light coming into the scope, the size of the objective lens dictates how much light gets in.

 

[koshkin]

That is probably a terminology issue. Lenses do not gather light. It is a terrible term and I wish it would fall out of favor. Lenses transmit whatever light is incident on them (minus absorption, scattering and reflection).

"Increasing optical capabilities" and "gathering light" are two very different things. Let in, transmit and gather all mean different things and the terms are not interchangeable.

ILya

 

[Denys]

That is probably a terminology issue. Lenses do not gather light. It is a terrible term and I wish it would fall out of favor. Lenses transmit whatever light is incident on them (minus absorption, scattering and reflection).

"Increasing optical capabilities" and "gathering light" are two very different things. Let in, transmit and gather all mean different things and the terms are not interchangeable.

ILya

I will try to send an email to Hensoldt to see if I can get some details on the construction of that 6-24X56 or 72. You have really intrigued me and I want to know for sure.

If it really is using fluorite glass, then I need to correct my understanding of this and stop making the mistake thinking fluorite is not used in riflescopes.

Unfortunately, even if it is using fluorite, the top end magnification is too small for my needs. At my age, all I can compete in is F-class, invented for old people by an old shooter, and 24X is not nearly enough magnification for me.

 

[koshkin]

https://www.zeiss.com/sports-optics...t-archive/victory-fl-diavari-riflescopes.html

 

[308pirate]

Gotta love amateurs arguing with pros.

I don't know shit about optics but I do have professional knowledge and working experience with the heat treatment of low alloy steels and precipitation hardening stainless. Which is why I no longer get involved in any gun forum discussion of salt bath nitriding or similar "coatings". The derp is endless

 

[tbeckstrand]

I suspect you are.

When I saw that sentence it went against all that I know about and have worked with in photography for the last 45 years. I just can't get my mind past "larger objective lenses do not gather more light." Yet, photographers pay top dollar for telephoto lenses with humongous objective lenses to be able to action pictures using higher shutter speeds to "stop" the action. In the triumvirate of shutter speed, f-stop and ISO rating, if you bring in more light with a larger objective, you can use a faster shutter speed and still maintain a decent ISO. The only way to transmit more light is to use bigger lenses.

You will notice that opening line from the Hensoldt website that I quoted above which says "The lens diameter considerably influences the optical capabilities of a telescopic sight. With increasing magnification, the brightness of the scene diminishes." That's why the have 56mm and especially 72mm objectives.

Larger objectives (let in/transmit/gather) more light. However you describe the action of the light coming into the scope, the size of the objective lens dictates how much light gets in.

You are not alone. Lots of photographers wrote in and disagreed with my column in Guns & Ammo. What many have a hard time understanding is the only similarity between rifle scopes and camera lenses is they are both tubes filled with glass elements. Like Ilya mentioned above, a scope stops behaving like a camera lens at the objective lens.

"Gathering more light" is a myth. When matters of image brightness are concerned, objective lens diameter controls exit pupil diameter. Bigger objective lenses do mean bigger exit pupils, but dialing down magnification also makes the exit pupil bigger and is the best way to brighten any image.

The drawback of buying a big objective lens on the belief that it "gathers more light" is that bigger objective lenses, left uncorrected, also come with increased aberration and decreased image quality. The bigger an objective lens becomes, the harder it is to get a good image from it. On scopes costing more than $2000 the manufacturer has the tools needed to create a great image off a large objective lens, so don't worry about it. Scopes between $1000 and $2000 vary by manufacturer. When I shop for a scope costing less than $1000 I buy as small an objective lens as I can find in an effort to get good image quality. Under $1,000 the manufacturer cannot afford to correct aberration enough to get good image quality off the largest objective lenses.

My follow-up article in Guns & Ammo has a test that illustrates that bigger objective lenses do not gather more light. I took the 7-35x ATACR (which is an amazing scope and worth every penny), ran it up to 35x with an unobstructed 56mm objective lens, and used a light meter to measure lux (light output) at the ocular lens (what our eye looks at when peering through a scope). I then calculated the size the objective lens would need to be to generate the same size exit pupil at 7x. I put a cap over the objective lens with a 11.2mm hole in it, used gaffers tape to seal any cracks, and again measured lux at the ocular lens. If bigger lenses gather more light the 56mm objective lens would have yielded more light at the ocular than the 11.2mm lens. That was not the case. Both objective lens sizes measured the exact same lux at the ocular because the exit pupil was the same size. We repeated this test 3 times on two different days and the result was always the same.

Leaving the 56mm objective lens unobstructed and dialing from 35x down to 7x yielded a 1,950% increase in light measured at the ocular lens. Yes, that is an almost two-thousand percent increase in light measured at the eye's end of the scope by simply running from max magnification down to min magnification. If you want to brighten an image in any scope, dial down the magnification.

The impetus of my original column in Guns & Ammo was my desire to protect the consumer with limited finances from getting hustled into believing he needs to buy something he doesn't really need. Buying a bigger objective lens on the belief that it is vital for a bright image is incorrect. Any scope can have a brighter image if you just turn down the magnification by 10-percent.

 

[koshkin]

You are not alone. Lots of photographers wrote in and disagreed with my column in Guns & Ammo. What many have a hard time understanding is the only similarity between rifle scopes and camera lenses is they are both tubes filled with glass elements. Like Ilya mentioned above, a scope stops behaving like a camera lens at the objective lens.

"Gathering more light" is a myth. When matters of image brightness are concerned, objective lens diameter controls exit pupil diameter. Bigger objective lenses do mean bigger exit pupils, but dialing down magnification also makes the exit pupil bigger and is the best way to brighten any image.

The drawback of buying a big objective lens on the belief that it "gathers more light" is that bigger objective lenses, left uncorrected, also come with increased aberration and decreased image quality. The bigger an objective lens becomes, the harder it is to get a good image from it. On scopes costing more than $2000 the manufacturer has the tools needed to create a great image off a large objective lens, so don't worry about it. Scopes between $1000 and $2000 vary by manufacturer. When I shop for a scope costing less than $1000 I buy as small an objective lens as I can find in an effort to get good image quality. Under $1,000 the manufacturer cannot afford to correct aberration enough to get good image quality off the largest objective lenses.

My follow-up article in Guns & Ammo has a test that illustrates that bigger objective lenses do not gather more light. I took the 7-35x ATACR (which is an amazing scope and worth every penny), ran it up to 35x with an unobstructed 56mm objective lens, and used a light meter to measure lux (light output) at the ocular lens (what our eye looks at when peering through a scope). I then calculated the size the objective lens would need to be to generate the same size exit pupil at 7x. I put a cap over the objective lens with a 11.2mm hole in it, used gaffers tape to seal any cracks, and again measured lux at the ocular lens. If bigger lenses gather more light the 56mm objective lens would have yielded more light at the ocular than the 11.2mm lens. That was not the case. Both objective lens sizes measured the exact same lux at the ocular because the exit pupil was the same size. We repeated this test 3 times on two different days and the result was always the same.

Leaving the 56mm objective lens unobstructed and dialing from 35x down to 7x yielded a 1,950% increase in light measured at the ocular lens. Yes, that is an almost two-thousand percent increase in light measured at the eye's end of the scope by simply running from max magnification down to min magnification. If you want to brighten an image in any scope, dial down the magnification.

The impetus of my original column in Guns & Ammo was my desire to protect the consumer with limited finances from getting hustled into believing he needs to buy something he doesn't really need. Buying a bigger objective lens on the belief that it is vital for a bright image is incorrect. Any scope can have a brighter image if you just turn down the magnification by 10-percent.

I apologize if I am barging into the argument you are having with Denys, but this is an interesting discussion. I wrote a lengthy piece on the fundamentals of riflescopes and I touched on it there. As I am working on a revision of that, I think this is worth re-visiting.

Some of this is correct and some of it isn't. Perhaps, it is more accurate to say that this is a bit of an oversimplification with bits of half truths and misunderstanding mixed in. As a disclaimer, I have not seen your article in G&A, since I stopped reading gun magazine articles on optics a little while back. The sheer incompetence of most people who seem to feel competent to write about optics in gun magazines gives me high blood pressure. I will try to find your article and see if it makes any sense. If it does, you are definitely going against the norm and I'll be the first to apologize.

With modern manufacturing techniques and for the typical objective sizes used in riflescopes, what makes you pick up aberrations is not so much the sheer size of the objective, but rather the f-number of the objective lens system: the ratio of the focal length to the lens diameter. It is much easier to make a well corrected optical system that is comparatively long for its diameter. That is one of the reasons those very compact S&Bs and Hensoldts are so impressive. Their optical performance is amazing, but even more amazing considering how short they are. IF you are on a budget, do not look for the shortest scope.

Your test with an objective lens constriction does a couple of things: you change the F/# of the system, so the aberrations come down a little. However, with most quality scopes (and definitely with the Nightforce), that is a fairly minor effect. Two other factors play a much larger role: with a high F/#, depth of field and depth of focus both increase, so small focus variations go away and it is much easier to get a sharper image. Also, you are blocking of the bulk of stray light that comes in from just outside the field of view. Target shooters have been doing this for years and many target scopes come with an aperture reducer for this exact purpose (Golden Eagle I recently tested does).

As far as your lux test goes, if you havn't published it yet, please don't. Unless you are looking for a comedic effect, of course.

Lux is a measure of illuminance, which is lumens per square meter. Effectively, the best way to think about lux is energy density: how much energy you get per area. For as long as you are looking at the same area, changing magnification and effective objective will yield exactly the same energy density (barring variations in the scene you are looking at). However, if you keep magnification the same and increase the objective lens diameter, you will get the same energy density, but in a larger area, so there will more light (lumens), but the same energy density (lux). Whether your eye can use it all, is a separate issue.

Last point, how well you see detail also depends on the magnification and image fidelity, not just how much actual light you get. Simply measuring the lux output of a scope tells you very little about how well you can see.

ILya

 

[tbeckstrand]

I apologize if I am barging into the argument you are having with Denys, but this is an interesting discussion. I wrote a lengthy piece on the fundamentals of riflescopes and I touched on it there. As I am working on a revision of that, I think this is worth re-visiting.

Some of this is correct and some of it isn't. Perhaps, it is more accurate to say that this is a bit of an oversimplification with bits of half truths and misunderstanding mixed in. As a disclaimer, I have not seen your article in G&A, since I stopped reading gun magazine articles on optics a little while back. The sheer incompetence of most people who seem to feel competent to write about optics in gun magazines gives me high blood pressure. I will try to find your article and see if it makes any sense. If it does, you are definitely going against the norm and I'll be the first to apologize.

With modern manufacturing techniques and for the typical objective sizes used in riflescopes, what makes you pick up aberrations is not so much the sheer size of the objective, but rather the f-number of the objective lens system: the ratio of the focal length to the lens diameter. It is much easier to make a well corrected optical system that is comparatively long for its diameter. That is one of the reasons those very compact S&Bs and Hensoldts are so impressive. Their optical performance is amazing, but even more amazing considering how short they are. IF you are on a budget, do not look for the shortest scope.

Your test with an objective lens constriction does a couple of things: you change the F/# of the system, so the aberrations come down a little. However, with most quality scopes (and definitely with the Nightforce), that is a fairly minor effect. Two other factors play a much larger role: with a high F/#, depth of field and depth of focus both increase, so small focus variations go away and it is much easier to get a sharper image. Also, you are blocking of the bulk of stray light that comes in from just outside the field of view. Target shooters have been doing this for years and many target scopes come with an aperture reducer for this exact purpose (Golden Eagle I recently tested does).

As far as your lux test goes, if you havn't published it yet, please don't. Unless you are looking for a comedic effect, of course.

Lux is a measure of illuminance, which is lumens per square meter. Effectively, the best way to think about lux is energy density: how much energy you get per area. For as long as you are looking at the same area, changing magnification and effective objective will yield exactly the same energy density (barring variations in the scene you are looking at). However, if you keep magnification the same and increase the objective lens diameter, you will get the same energy density, but in a larger area, so there will more light (lumens), but the same energy density (lux). Whether your eye can use it all, is a separate issue.

Last point, how well you see detail also depends on the magnification and image fidelity, not just how much actual light you get. Simply measuring the lux output of a scope tells you very little about how well you can see.

ILya

Op,

I've hijacked your thread and wanted to apologize. To answer your original question, the weight penalty of the ATACR is definitely worth the performance gained. If your personal finances allow it, I'd buy the ATACR.

Ilya,

What you identified as an oversimplification was deliberate. My goal in writing both the response you quoted and the original article in Guns & Ammo is not to cover the many contributions and characteristics of an objective lens. My purpose was and is to correct the inaccurate belief that the best way to get a brighter image (that most will equate with a better image) is to purchase a scope with a bigger objective lens. The shooter's eye sees the exit pupil and its size is adjustable on a variable powered scope. The size of the objective lens should have very little influence in what scope a shooter chooses, but that is not the case.

I don't understand your issue with the test I developed. It illustrates exactly what you described and it's a valuable lesson for all the photographers interested in an increased understanding of rifle scopes. "For as long as you are looking at the same area, changing magnification and effective objective will yield exactly the same energy density." Yes! If exit pupils are the same size, the eye will perceive the same brightness. "However, if you keep magnification the same and increase the objective lens diameter, you will get the same energy density, but in a larger area, so there will be more light, but the same energy density." Yes! As the exit pupil gets bigger the shooter perceives a brighter image (to a point).

The best most contemporary example of why I'm beating this drum is Bushnell's soon-to-be-released XRS-II. It teams a top end magnification of 30x with a 50mm objective lens. People have already started complaining about that decision. It's true the scope will have a smaller exit pupil at maximum magnification than if Bushnell had put a 56m objective lens on it. However, it is a beautiful scope to look through due in part to the smaller objective lens and larger f-number. As you stated, it is easier to correct aberration with either a longer focal length or a smaller objective lens.

What I write about optics has been and will continue to be vetted by the optical engineering departments at Nightforce, Leupold, and occasionally Vortex. I've sat through enough discussions with optical engineers to know that they sometimes disagree. While I am no optical engineer, this means that you and I will likely agree on most things and disagree on a few things. That's ok. I value your input and opinion and think you perform a valuable service in this forum.

 

[koshkin]

Op,

I've hijacked your thread and wanted to apologize. To answer your original question, the weight penalty of the ATACR is definitely worth the performance gained. If your personal finances allow it, I'd buy the ATACR.

Ilya,

What you identified as an oversimplification was deliberate. My goal in writing both the response you quoted and the original article in Guns & Ammo is not to cover the many contributions and characteristics of an objective lens. My purpose was and is to correct the inaccurate belief that the best way to get a brighter image (that most will equate with a better image) is to purchase a scope with a bigger objective lens. The shooter's eye sees the exit pupil and its size is adjustable on a variable powered scope. The size of the objective lens should have very little influence in what scope a shooter chooses, but that is not the case.

I don't understand your issue with the test I developed. It illustrates exactly what you described and it's a valuable lesson for all the photographers interested in an increased understanding of rifle scopes. "For as long as you are looking at the same area, changing magnification and effective objective will yield exactly the same energy density." Yes! If exit pupils are the same size, the eye will perceive the same brightness. "However, if you keep magnification the same and increase the objective lens diameter, you will get the same energy density, but in a larger area, so there will be more light, but the same energy density." Yes! As the exit pupil gets bigger the shooter perceives a brighter image (to a point).

The best most contemporary example of why I'm beating this drum is Bushnell's soon-to-be-released XRS-II. It teams a top end magnification of 30x with a 50mm objective lens. People have already started complaining about that decision. It's true the scope will have a smaller exit pupil at maximum magnification than if Bushnell had put a 56m objective lens on it. However, it is a beautiful scope to look through due in part to the smaller objective lens and larger f-number. As you stated, it is easier to correct aberration with either a longer focal length or a smaller objective lens.

What I write about optics has been and will continue to be vetted by the optical engineering departments at Nightforce, Leupold, and occasionally Vortex. I've sat through enough discussions with optical engineers to know that they sometimes disagree. While I am no optical engineer, this means that you and I will likely agree on most things and disagree on a few things. That's ok. I value your input and opinion and think you perform a valuable service in this forum.

I apologize if what I am about to say comes of as inconsiderate and I am by no means attempting to be rude. Sometimes, it is best to call a spade a spade.

You'd be amazed at how many things optical engineers from all sorts of companies will politely nod through in order to avoid pissing off a gunwriter or a customer, or simply to avoid getting themselves into a protracted explanation of something to a lay person who is not going to put in the effort to understand any of it. You are not the first gunwriter (or a customer within industry) who thinks asking questions from people who have a vested interest in flattering you is productive. Nor the last. I've been on both sides of this phenomenon.

My favourite example of that is probably another gun writer who set-up a blatantly stupid image quality test in his backyard. Then he asked some marketing folks from a couple of optical companies whether that is a good test. Of course, they said it is. If they said no, they either risk offending a guy who clearly think he knows what he is doing or they risk getting themselves into a lengthy tutorial on how to set-up a proper scope test. The gunwriter in question, while generally a rather reasonable guy, can't tell his ass from an elbow as far as optics go. However, after twenty years of scope manufacturers flattering his "brilliance", he is convinced he understands optics.

I am sure you are more circumspect than that, but you see my point. If you want a clear and detailed answer, ask someone who does not care about hurting your feelings. Sitting through meetings with optical engineers without doing some extensive homework on the subject will generally qualify you to bullshit convincingly to an audience that knows less than you do. Until someone in the audience does some homework. Then, instead of being convincing bullshit, it is just bullshit.

Now, onto some specifics, I think you misunderstand how a human eye perceives brightness. A lot of it comes from image fidelity. Equating illuminance with perceived image brightness is terribly misleading and generally wrong. It does not do anything to illustrate your point on objective size. I reiterate: PERCEIVED image brightness.

Perhaps, I do not understand what you are trying to prove. A 56mm objective at the same magnification, will get you a larger exit pupil than a 50mm objective. Given similar image fidelity, a 56mm scope will look brighter at magnifications high enough to keep exit pupil, rather than the eye pupil as a limiting factor. If you are trying to make an argument that XRS-II will have better image quality than competing 56mm designs because it was easier to build, you have to be specific which competing design it is better than. I do not think you can make a blanket statement like that. If there are similarly priced scopes that deliver similar image quality with a larger objective lens, Bushnell will lose some sales to them.

Building a scope is a compromise. If Bushnell wanted to use a larger objective without too many additional complications, they would have to make the scope a little longer and a little heavier. They chose to go with a smaller objective and a smaller overall scope. That is a perfectly reasonable choice. Beyond that, not having seen XRS II, I really can't comment.

When the original 3.5-21x50 Bushnell HDMR came out, they made it too short. Because of that, there was a lot of sample-to sample variation, sicne it really looked like they struggled to keep the tolerances. The one I owned was superb. Others I have seen varied. I did not test the original XRS thoroughly because when I looked at it briefly, it was apparent the optical system there could not quite maintain image quality all the way to 30x, so I passed on it. I am sure XRS II will be better.

Personally, I valued light weight and compactness, so I am not terribly obsesses with objective lens sizes. However, I also do not shoot at longish ranges in the middle of the night a whole lot. If I did, you bet that at least one of my rifles would have the rather excellent 6-24x72 Hensoldt. At 24x, this is far and away the best low light scope on the market (outside of intensified or thermal sights).

ILya

 

[Wiley Coyyote]

This has been a very interesting thread. I am certainly not a optical physicist but as a serious amateur astronomer who spen much time at Cerro Tololo in the Atacama desert in Chile using professional astronomy equipment I have some familiarity with optics of both reflector and refractor systems. As much as we need to give credence to the objective parameters of a system it often comes down to what do you see in the field when using it IMO. To me this is not only true for astronomy optics but rifle scopes.

A couple months ago i had for several days a NXS 5.5-22 x56 and a Hensoldt 6-24 X 56 at the same time. Comparing the scopes on at least a dozen if not more occassions with both set at the same, but varying magnifications and at varying conditions (dawn, dusk, light glare, mirage, etc); try as i might (as I really wanted the Hensoldt) to convince myself I was getting better optical performance from the Hensoldt over the NXS, I failed. To my eyes and to a couple other observers it was a toss up. Both were great, but I could not pronounce one superior over the other.

Since we are dealing with not just observational devices but targeting devices other factors come in to play such as reticles, knobs, and of course reliability. In the end it was the NXS that I thought was the better scope for me.

 

[RHutch]

The Zeiss Victory FL 4-16x50, 6-24x56 and 72 were labeled with FL glass. Does FL glass = flourite glass?
dont know but I did own the 4-16 and 6-24x72 and the glass was spectacular.

 

[koshkin]

The Zeiss Victory FL 4-16x50, 6-24x56 and 72 were labeled with FL glass. Does FL glass = flourite glass?
dont know but I did own the 4-16 and 6-24x72 and the glass was spectacular.

In the case of 4-16x50 and 6-24x56 it was fluorite glass. For the 6-24x72, it was fluorite crystal.

ILya

 

[koshkin]

This has been a very interesting thread. I am certainly not a optical physicist but as a serious amateur astronomer who spen much time at Cerro Tololo in the Atacama desert in Chile using professional astronomy equipment I have some familiarity with optics of both reflector and refractor systems. As much as we need to give credence to the objective parameters of a system it often comes down to what do you see in the field when using it IMO. To me this is not only true for astronomy optics but rifle scopes.

A couple months ago i had for several days a NXS 5.5-22 x56 and a Hensoldt 6-24 X 56 at the same time. Comparing the scopes on at least a dozen if not more occassions with both set at the same, but varying magnifications and at varying conditions (dawn, dusk, light glare, mirage, etc); try as i might (as I really wanted the Hensoldt) to convince myself I was getting better optical performance from the Hensoldt over the NXS, I failed. To my eyes and to a couple other observers it was a toss up. Both were great, but I could not pronounce one superior over the other.

Since we are dealing with not just observational devices but targeting devices other factors come in to play such as reticles, knobs, and of course reliability. In the end it was the NXS that I thought was the better scope for me.

The 6-24x56 Hensoldt was a significantly older design that probably preceded the NXS chronologically speaking. I never quite could get a straight from anyone how long it has been around, but it was notably weaker optically than the much newer 4-16x56 and 6-24x72.

Still, it sounds like you got a particularly nice NXS and a somewhat average Hensoldt. There is enough sample variation to account for that. Besides, newere NXS scopes ar emuch improved.

ILya