Rifle Scopes SWFA 5-20 vs. Burris XTRII 5-25 or 4-20

[SLG]

I've read whatever I could find on these scopes, but not much info directly comparing them.

I'm very curious what people with experience on both (or all 3) think about how they stack up. Ruggedness, tracking and glass being the 3 biggies. Then controls and reticle choices, then weight or size. Thanks in advance!

 

[just browsing]

Glass on the SWFA is the best of the bunch hands down. The 5-20s will compete - clarity wise - with scopes costing a lot more. They are practically bomb proof and track very consistently.

That being said, the XTR2s are also excellent optics. For what they lack in glass quality, they do make up for with their feature sets. Zero stop, reticle selection, control manipulation, etc. are all things that you will forego with the SWFA. The Burris are also known for being durable (probably to a lesser extent than the SWFA) and tracking very well.

Really comes down to application. If it’s a dedicated ELR or hunting optic, I am going SWFA all day. If it’s a match optic or something that you could use some of the other features with, you might consider the Burris. Either way you’re not going to go wrong as both of them are very proven options.

 

[patriot07]

I agree that, to my eyes, the glass on the SWFA is significantly better, and it's built tough with very reliable tracking and decent turrets. The XTR is a tough scope as well with more features than the SWFA, but glass quality is probably it's weakest area. It's maybe the worst glass in its price range IMHO (with some Bushnell options giving it a run for its money), but it makes up for that by having good features, decent reticle, and good build quality.

If you need the extra features or hate the mil quad reticle, get the XTR II. If you don't need zero stop or illumination and the mil quad reticle is palatable, then the SWFA is clearly superior IMHO.

On the XTR II, I am not a big fan of the 5-25. Maybe it was the one I looked through, but the glass was nearly unusable at 25x - very hazy and blurry. The 4-20 and 3-15 seem to be much better in this regard, but all of them are still inferior to the SWFA glass-wise, and not by a small margin.

 

[wigwamitus]

Never touched a SWFA, but have three xtr2.

I've used the xtr2 5-25x scr-mil mostly on .300WM(24)

It works in ice and snow and rain and humping thru the woods. It is a bit heavy and long compared to some others. I shoot from tripod and prone. Day and Night with thermal and NV clipons. And from 50yds to 1400yds. Use 220gr Otm Barnes Precision.

The zero stop is not tool-less, but it can be done in the field. I have never detected a tracking problem. I can see holes in white paper from 500yds. If mirage is bad, I do have to crank down the magnification, but that is even more true on the Night Force 7-35x T3 I also have.

The diopter and parallax are easy to adjust. The parallax is not 100% removable at 50yds, but it is at 100yds. Somewhere in between is the actual minimum distance parallax can be removed. The eyebox is generous, more so than two L&S scope I have.

The CA (chromatic aberation) is definitively noticeable, but it has not prevented me from hitting any target.

I like this reticle, the SCR-MIL

The illumination gives you a "T" to shoot with on low power and I can even see the sub-tensions well enough to hold with.

For a rifle that will be routinely going over 1000yds, I like the 5-25x. For a rifle never going over 1000yds I like the 3-15x. The 4-20x is of course somewhere in between. But it also depends on your target sizes. For 1/2 dots at 100yds, 15x is not quite enough.


I have been using xtr2 scopes for 2.5 years and never had a problem. Other scopes I've had, got to experience the customer service. Not the xtr2 scopes.

The price right now is around $900 even seeing a little less. I am jealous. I paid $1,100 for mine

 

[TimK]

As others have stated, the glass battle goes easily to the SWFA. I make a zero stop for it, so that shortcoming goes away.

That said, I own no SWFA 5-20's (neighbor has one) and two XTR II's. For me, the glass is good enough at the price point, they track great and seem to be reliable. It's the reticle that sways me. I think the SCR is one of the best reticles ever designed for those who exclusively dial for elevation. I have four scopes with it, and I wish NF had something as good.

IIRC, the field of view at 20x is wider on the 4-20 than the 5-25 set at 20X. One of mine is a 5-25, and I wish it was a 4-20.

 

[SLG]

As others have stated, the glass battle goes easily to the SWFA. I make a zero stop for it, so that shortcoming goes away.

Tim,

I thought they voided the warranty on that scope? Do you know what the issue is?

 

[SLG]

Curious to hear what Tim says on this, but I just got off the phone with SWFA (my scope's illum stopped working), and they said that the use of the shims does not void the warranty.

 

[Hoyt7mm]

I had a 3-15 XTR and still have the SWFA 5-20. As stated above, there is no comparison glass wise. SWFA wins hands down. Both scopes track great from my experience, although I am a fan of the SWFA turrets more than the XTR. XTR does have a zero stop that is very easy to set and pretty bomb proof if that makes a difference. Both have good reticles imo. SWFA is almost a touch thick, but I found the XTR to be too thin for my taste. Winner? SWFA

 

[TimK]

SLG, this is the first time I've heard that the zero stops would NOT void the warranty on the 5-20. I'm guessing the person you spoke to is confused. They don't void the warranty on all the other SWFA scopes, but I'm 99% certain they do on the 5-20.

Back to topic, if this matters to you, Burris is a huge supporter of the shooting sports. I paid for my 3-15, but I won the 5-25. I like to support those who support us.

 

[SLG]

SLG, this is the first time I've heard that the zero stops would NOT void the warranty on the 5-20. I'm guessing the person you spoke to is confused. They don't void the warranty on all the other SWFA scopes, but I'm 99% certain they do on the 5-20.

Back to topic, if this matters to you, Burris is a huge supporter of the shooting sports. I paid for my 3-15, but I won the 5-25. I like to support those who support us.

Maybe give them a call again and check? I spoke to a guy there, specifically about the 5-20, as I have to send it back to them. If you want his name, PM me. If it does still void the warranty, do you know why? Maybe they changed their minds?

I only support those who make what I want to buy and use. I'm sure that's true of you as well.

 

[wigwamitus]

the glass battle goes easily to the SWFA

glass is pretty nice on the Burris scopes I own

I wonder if it is time to drill in to "glass" ... what do we mean when we say "glass is good" or "glass is better' ??

==

So what about RESOLUTION. So when I got my NF 7-35x t3, there was a review in this sub-forum that influenced me. That guy was doing 100yds USAF eye charts and the NF 7-35x won by two eye charts? So that is RESOLUTION?
So does that mean NF had the BEST glass in the review?
Two other aspects were mentioned.
CA (Chromatic Aberration) ... this seemed to be a bit more subjective, but the reviewer and several commenters stated they did not think CA would prevent anyone from hitting a target, so perhaps this is a less important aspect, though it is an aspect.
POP. POP was the other aspect and presumably the TT and the MINOX were top dogs on POP and the NF was behind on POP. I'm not real sure what POP is, but since I've never looked thru a TT or a MINOX, I guess I would not know!!!

So what is "GLASS" ... is that
RESOLUTION
CHROMATIC ABERRATION
POP

Anything else?

For me, resolution is #1 probably because it can be more easily, objectively measured by me ... and for that .. while I think the NF resolution is clearly superior to the xtr2, I do not think that resolution prevents me from hitting the targets I want to hit. IPSC-D steel out to 1200yds (with .300WM(24)) or NATO-E steel out to 1400yds or 3/4 inch dots at 100yds. What it does enable is using lower power magnification with the NF so I can shoot out to 1,000 yards with no dial shooting with the T-3 and still see the target really well. With the xtr2, I will be dialing for that target and so can use higher magnification to make up for the reduction in resolution. At least that's how my brain is thinking about this.

==

 

[Quarter Horse]

SLG

What does your 5-20 have to go back for? If your calling to ask about the zero stop shims ask for Skylar or owners. If Tim's zero stops are approved for the 5-20, I'm going to get in line for three sets.

 

[SLG]

SLG

What does your 5-20 have to go back for? If your calling to ask about the zero stop shims ask for Skylar or owners. If Tim's zero stops are approved for the 5-20, I'm going to get in line for three sets.

The illum stopped working. great scope otherwise.

 

[wigwamitus]

... I'm not sure what you consider lower magnification, or why you would intentionally choose to stay on lower magnification for longer range shots when you can better see your target on higher magnification. Even in matches if I have a near to far target layout I'll use my cat tail to adjust up. It never occurred to me to intentionally shoot longer targets on unnecessarily low magnification ranges ...

Oh, this is simple, I'm sure I just did not express my self clearly

GUN: 7.62(22)
Cartridge: 7.62x51 175 SMK (M118LR LC)
Scope: NF 7-35x T3
Zero: 100yds

Distance Elevation hold Max Magnification to see sufficient reticle to hold, plus a little more to get it off the bottom edge
750yds 6 mils 25x
875yds 8 mils 20x
985yds 10 mils 17x
1035 11 mils 15x

Now that's as far as I can get with this setup on the t3 reticle. In fact the wind dots stop at 10 mils, but they can be easily extrapolated to 11 mils, and I shot that.

==
To go further requires dialing up 5 mils, but then the wind dots loose half their value. Which can be done, but I am trying to illustrate how with no dial shooting and use of wind dots, you dial down your magnification to a point. And with the higher resolution of the NF this is not an issue.
Of course with the xtr2 5-25x scr-mil, I just dial up and so do not have to reduce magnification. So that enables the xtr2 to compensate with magnification what the NF does with resolution.

Does this ^^ explain why magnification might be reduced for greater distances with no-dial shooting?

==
I have been in situations where I could not resolve my target.

01 - Mirage - in worst cases, even as low as 20x I could not see the target ... I had to reduce the magnification, once that was done, I could see the target.

02 - NV/Thermal clipons - too much magnification makes the image fuzzy, can't resolve the image, need to reduce the power. This point varies with gear and conditions.

There are probably others, but those are the first two that come to mind.

==
But you are saying that for you, the most important aspect of "good glass" is resolution, correct? Am I getting that part right??

 

[notorious]

If SWFA did a small tweak to the reticle and added zero stop I would buy more. It’s a very good scope just itching to break into “great” territory.

They are an absolute steal for what they go for in the buy/well section.

 

[patriot07]

If SWFA did a small tweak to the reticle and added zero stop I would buy more. It’s a very good scope just itching to break into “great” territory.

They are an absolute steal for what they go for in the buy/well section.

Add zero stop, add .2 mil hash marks to the first 2 mils of windage, make the center 2 mils of windage and elevation bars .03 mils instead of .05 mils, and add a center floating dot. I’d pay $2k in a heartbeat and never consider anything else. Leave the rest of the reticle alone for low-power aiming.

 

[SLG]

I asked them about improving their reticles earlier today. A very non committal "people are looking into it" is what I got back. Reminded me of Raiders of the Lost Ark. Great people every time I've dealt with them, but I have to wonder about the disco era reticle.

 

[spaniel]

Interesting. Own both. Perhaps anecdotal but I really can't agree with the sentiments giving glass props to SWFA. I like the SWFA but get what I pay for and like the Burris better.

 

[TimK]

So the thing about better glass for me is not about seeing the target, it's about all the other little details before and after the shot. Through really good glass, I'll see grass moving, dust in the air, even insects or general debris moving in the breeze. Before he shot, I get a better idea of what the wind is doing at the target. After the shot, I have an improved chance of spotting my impact precisely.

It doesn't often play a key role in making a hit, but to say that great glass plays no role in making a hit is, in my experience, too much. I'm not suggesting that anyone here is making that claim, but I've heard it made in other circumstances.

If I have to choose between a great reticle and great glass, I'll choose a great reticle. My only gripe with the SWFA is the clunky reticle. Usable? Absolutely. Great? Not by a fair margin.

As to shooting at reduced power...well suggesting that it has no value tells me something about that shooter's style of shooting. In a fast paced competition environment with compromised shooting positions, field of view is key the spotting impacts, be they hits or misses. Most of my competition rifles wear 5-25 scopes, and they rarely get dialed past 17x except for load development or positions that are super stable.

 

[patriot07]

Interesting. Own both. Perhaps anecdotal but I really can't agree with the sentiments giving glass props to SWFA. I like the SWFA but get what I pay for and like the Burris better.

The Burris is cheaper?

 

[MarinePMI]

So the thing about better glass for me is not about seeing the target, it's about all the other little details before and after the shot. Through really good glass, I'll see grass moving, dust in the air, even insects or general debris moving in the breeze. Before he shot, I get a better idea of what the wind is doing at the target. After the shot, I have an improved chance of spotting my impact precisely.

It doesn't often play a key role in making a hit, but to say that great glass plays no role in making a hit is, in my experience, too much. I'm not suggesting that anyone here is making that claim, but I've heard it made in other circumstances.

This. ^^^^

I have both, SWFA's (non-HD and HD) and have an XTR II 5-25 (first one replaced by Burris). The glass in the SWFA is noticeably better (you'd have to be blind not to see the difference), and concurred by multiple people. As stated above, shit glass will not incur a miss per se, but does limit seeing other things, like mirage, blowing grass around the target, and target ID at lower mag.

It really depends on what the OP intends to do with the rifle/scope. PRS/NRL style comps? The XTR is probably a better decision. Hunting/Varminting? SWFA would make more sense, since eye fatigue is a factor (and crappy glass just wears on you as the day gets long).

Both track well and are robust in their reliability. It just comes down to what is most important to you, the OP.

IF you (the OP) do go with the XTR, I'd recommend the 4-20x version. Personally, I think the 5-25x version is just pushing the optical design and lenses past it's limits.

 

[MarinePMI]

,,,And yes, if SWFA came out with the exact same scope but with a Christmas tree style reticle of some sort, they'd be eating up the market again.

 

[D_TROS]

Interesting. Own both. Perhaps anecdotal but I really can't agree with the sentiments giving glass props to SWFA. I like the SWFA but get what I pay for and like the Burris better.

I also owned both. Sold the SWFA due to I like the rect better in the XTR2, like the Knobs way better on the XTR2 and the lines line up perfectly as well as click feel, zero stop.

The glass was close enough to a push as to not matter. Everyone going off on a tangent like we are comparing tangent glass to tasco glass is laughable at best. Neither scope is shit glass and neither is TOL. Pick the scope with the rect you prefer and you will be gtg.

This. ^^^^

Both track well and are robust in their reliability. It just comes down to what is most important to you, the OP.

IF you (the OP) do go with the XTR, I'd recommend the 4-20x version. Personally, I think the 5-25x version is just pushing the optical design and lenses past it's limits.

I def agree the 4-20 is a better design. It has better eye box and better FOV and better clarity at 20x than the 5-25. I sold my 5-25 for another 4-20.
Ive also never got eye fatigue from either but I am seeing that mentioned.

as mentioned get the one with better features and be happy happy for only spending $1k and getting at that awesomeness in a scope.


Regards,
DT

 

[koshkin]

And yes, I do seem to think resolution is my hot spot. I just want to see the target as clear as I can to shoot it. I don't care if it's bright or not, and I don't care what color it is. I can see where I impact on a plate, and see enough clarity on mirage and movement to make an educated decision (guess ) .

Not to call you out, but.. what you just told me with that statement is that all else being equal you prefer scopes where the optical compromise leans toward lower resolution, better contrast and slightly warmer colors than normal.

Clarity is not something you see and is really a meaningless term as far as riflescopes are concerned. However, based on years of watching people use that term, after some digging, it usually turns out that they like contrast and warm colors.

ILya

 

[wigwamitus]

... Clarity is not something you see and is really a meaningless term ...

So you don't buy off on the idea of using USAF 1951 chart at 100yds for "resolution" comparisons between scopes (as has been done on some reviews on this site) ??

Why not??

 

[MarinePMI]

I'd think eye charts would measure acuity (it's a black and white chart), not necessarily clarity...but I have no where near the background that ILya does on these things...

 

[koshkin]

So you don't buy off on the idea of using USAF 1951 chart at 100yds for "resolution" comparisons between scopes (as has been done on some reviews on this site) ??

Why not??

Resolution charts are a part of the story only and resolution and contrast can not be de-coupled entirely.

ILya

 

[D_TROS]

@koshkin have you done any optical tests of these 2 scopes? any other tests?

thanks for your imput!


DT

 

[koshkin]

You are probably right. What's most likely going on here is I'm simply not aware of the proper semantics.

I don't know what the proper term would be for what I like to see when I look through a scope.

I need it to be bright enough, and clear enough, to make out what it is. I want to eliminate as much blurriness as possible. I don't care about CA, or what color it is. But I need clearly defined edges as a reference point for my holds.

While hunting, I just need enough light and a clear enough picture to tell elk rump from shrub and black bear from burnt stump. Seeing horns is easy even with cheap glass.

You may not think you care what color it is, but your eyes and your brain defiitely do.

Color is closely tied to how we perceive detail.

Chromatic aberration is tied to color and to how the optical system renders edges.

All these things that you say you do not care about are needed to differentiate between objects that are of somewhat similar colors like your examples above.

ILya

 

[koshkin]

@koshkin have you done any optical tests of these 2 scopes? any other tests?

thanks for your imput!


DT

I have a fair amount of mileage with both. SWFA is better optically. Both are robust mechanically. XTR II has a zero stop.

Reticles are in the eye of the beholder. I dislike Horus reticle and I am not too crazy about SCR, but it works. Same for Mil-quad. It is not the newest reticle, but I am quite used to it.

Still, given a choice, I prefer Christmas tree style reticles which neither of these offers (to forewarn the next obvious question, Horus is a mosquito-net style reticle which, to me, is distinctly different from the Christmas-tree style designs).

ILya

 

[wigwamitus]

... Resolution charts are a part of the story only and resolution and contrast can not be de-coupled entirely ...

Oh boy, I guess it is "complicated" !!!

 

[MarinePMI]

Hence my comment about Target ID being problematic with lesser grade glass. We have our local matches every month, and two months ago I thought it'd be sneaky to camo an IPSC target that was placed in tall grass and cactus. Most shooter's couldn't find the target in the morning light (8:30am, so not twilight or anything). The shooters who could were all running high end glass. Even the spotters were having issues...except the Hendsoldt 45. Eventually the sun got high enough to silhouette the target.

Glass does matter for certain applications. As you said, PRS tends to have large white targets...but as matches get more challenging, I think you're going to see more of the dirty (or purposely obscured/camo'ed) targets. Same for hunting. An elk or bear is fairly large, a brown prairie dog sitting in a brown hole with just the top of the head exposed at 400yds, showing a single black eyeball is a pretty small target.

JMTCW...

 

[SLG]

Wait a second. PRS, an equipment race? Say it isn't so!

 

[PBWalsh]

Got in a used SS 5-20 from a member here, very excited to mount it up later this year and test it out!

 

[MarinePMI]

Target obscuration is an interesting point.. Will it evolve at matches or will it be one toe over the line..

I saw a snippet of that trend last year in Craig Colorado for the Mile High NRL match. A 700'something target was hidden in the shade and partially obscured by tree branches. Lots of shooters complained about it and for day two, seeing as how they were using that same target again, they went and trimmed away all the branches. It was much easier to find and see on day two.

I think an MD has to be very careful in using targets of this nature. The most obvious being, this shouldn't be an equipment race. The guy without deep pockets should be allowed to come out with what they have and still be able to see the targets. The challenge should always be, first and foremost, hitting the target. Not seeing it. As soon as you start sending away shooters disgruntled by the fact that they couldn't find or see the targets because they were unable or unwilling to shell out 2k at minimum for a scope, you're going to start pumping the brakes on the growth of this sport.

And at the match in Craig, RO's were having trouble spotting impacts. The target was hard for them to see as well. A branch cut across the bottom of the plate hiding dust splash off the plate. And audio feedback was crap. If that plate would have rang like a bell or had a flasher on it, problem solved. But it had neither. So an MD can handicap his own RO's by trying to get too creative.

And I only hunt BIG game Marine. If I have to start trying to shoot a prairie dog in the eye at 400 yards, it would very quickly reveal how talentless I am

Oh, I hear you on the gear race thing. That being said, a good match has to have a couple curve balls thrown in it. Shooters can bitch all they want, target ID is a part of the sport, and it certainly keeps some egos in check. But as Frank mentioned once in one of his pod casts, setting up a match is a balance of confidence building stages, and stages that just drive you nuts (some set up for failure, some set up for other near impossible or trick shots; i.e. defilade shots, loop holes, etc.). It's all part of the sport. Obviously they can't all be hard or impossible, but not having them (difficult stages) also limits how much we push people to be innovative and let their ingenuity show as they push to think outside the box. Plus, @hic28 , @NoLegs24 and I enjoy being a little mischievous in how we lay out the match CoF's for our shooters (but there's always a lesson in the stages for the shooters to take back home with them to work on).

 

[notorious]

Got in a used SS 5-20 from a member here, very excited to mount it up later this year and test it out!

Enjoy. They are nice. If it doesn’t have a cat tail you might look into it. The mag ring on mine was insanely tight.

 

[koshkin]

Oh boy, I guess it is "complicated" !!!

No, it really isn't.

The basic point I am trying to make is that it is an optical system. Keyword: "system". When you are talking about the optics of a riflescope, all the different aspects of the image are not independent of each other. If contrast is very poor, resolution does not matter. If resolution is very poor, great contrast will not help you.

If there is severe CA, it is an indication of color management issues. Poorly handled CA, also often goes hand in hand with lower contrast. Flare control issues together with CA, really blur the edges of whatever you are trying to see. And the edges get screwy in different ways depending on where behind the eyepiece you are.

And so on and so forth. A blanket statement along the lines of "I do not care about CA" is pointless. CA is a symptom, not the problem itself. Same for a bunch of other image characteristics.

ILya

 

[PBWalsh]

Yeah it came with one and a sunshade. Parallax knob is stiff, but if I’m shooting a stage, I see myself setting it at an average mark and running it. For static shooting, I’ll find a more perfect setting.

 

[SLG]

"Wait a second. PRS, an equipment race? Say it isn't so!"

Haha, I know! Huh!

Me shooting stage 11 at Dog Valley. It's pretty much every pump pillow from the entire squad... I call it the Tactical La Z Boy.

That setup screams for a tripod. At 1400-1800 for a nice RRS setup, there is no equipment race going on. None.?

Cool set up though, and a great pic. Are you tiny, or are those the biggest pump pillows ive ever seen?

 

[wigwamitus]

..
No, it really isn't.

The basic point I am trying to make is that it is an optical system. Keyword: "system". When you are talking about the optics of a riflescope, all the different aspects of the image are not independent of each other. If contrast is very poor, resolution does not matter. If resolution is very poor, great contrast will not help you.

If there is severe CA, it is an indication of color management issues. Poorly handled CA, also often goes hand in hand with lower contrast. Flare control issues together with CA, really blur the edges of whatever you are trying to see. And the edges get screwy in different ways depending on where behind the eyepiece you are.

And so on and so forth. A blanket statement along the lines of "I do not care about CA" is pointless. CA is a symptom, not the problem itself. Same for a bunch of other image characteristics.

ILya

Excellent! So if "contrast" is another key aspect of "image" (or "good glass") the how can we most easily measure it ??

 

[SLG]

Different companies may define things differently, idk, but basically, a scope is a compromise between resolution, color rendition and light transmission. It is a balance, and though they can be close, especially with HD or ED glass, you have to favor one over the others. That is why a paper punching short range competition scope is different than the scope needed for a hunter or sniper. Which is also different than that needed for something like PRS. There can be a lot of overlap of course, but there are a milion variationsmon that balance, so finding one that is best for you should be easy, but also challenging given the scope, so to speak.

So, a scope with great resolution, but lesser light transmission and color rendition, would not be a good choice for low light shooting, as an example.

 

[TommyTwoGuns]

No, it really isn't.

The basic point I am trying to make is that it is an optical system. Keyword: "system". When you are talking about the optics of a riflescope, all the different aspects of the image are not independent of each other. If contrast is very poor, resolution does not matter. If resolution is very poor, great contrast will not help you.

If there is severe CA, it is an indication of color management issues. Poorly handled CA, also often goes hand in hand with lower contrast. Flare control issues together with CA, really blur the edges of whatever you are trying to see. And the edges get screwy in different ways depending on where behind the eyepiece you are.

And so on and so forth. A blanket statement along the lines of "I do not care about CA" is pointless. CA is a symptom, not the problem itself. Same for a bunch of other image characteristics.

ILya

Good points.

First thing I would note is that we all know the term color blind but don't always have a good handle on what it means. Not to mention that there is really no standard for how we view not only color but other factors as well.

In another life I was a serious photographer and there is a term photographers use; they will say an image pops. Lots of factors go into pop. But one thing I would point out is back in the day photographers used a black and white "resolution chart". As time passed this changed and a color resolution chart evolved that was much better than a black and white chart to determine how a digital sensor (or color film for luddites) captured an image.

Digital images allowed a much better way to measure images. In the old days of black and white there was something called a knife test, a knife was placed on a white paper and photographed and the gray between the black of the knife and the white of the paper was noted. Digital images allowed a different measurement. The number of pixles of gray between the blackest black and the whitest white was measured. Even with top quality digital cameras there were maybe 6-10 pixles that were not pure black or white (an exception was the Sigma digital cameras that used the foveon sensor and got it down to 3-4 pixles but suffered from poor light performance). This test was often called a rolloff test, as in rolling off a knife edge.

Anyone who has seen CA will understand how it affects rolloff and reduces the amount of pop in an image. You can also see how a color blindness in the deep violet area might reduce the amount of CA someone saw.

Another real consideration in pop is what is called depth of field. When you set the parallax to 10 yards thing at 500 yards are out of focus, in fact depending on the depth of field things at 30 yards (or even closer) may be out of focus. So stuff in focus will pop in comparison to the out of focus stuff.

This is just a long winded post so I can ask if anyone has seen depth of focus data on scopes? Sorry for the long post but I have no adult supervision and way too much time on my hands.

 

[wigwamitus]

I really appreciate the efforts to explain !!! "What does GOOD GLASS mean exactly?"

 

[SLG]

Depth of field is not a typical measurement given by scope makers, but it can be very important for field shooting. My ATACR 4-16 has an extremely generous depth of field, perhaps the best I've personally seen. NF can give you this info if you ask, I'm not sure if other companies can or do or not.

 

[TommyTwoGuns]

Depth of field is not a typical measurement given by scope makers, but it can be very important for field shooting. My ATACR 4-16 has an extremely generous depth of field, perhaps the best I've personally seen. NF can give you this info if you ask, I'm not sure if other companies can or do or not.

A big DOF can help in picking up targets but a shallow DOF means if the target is in the DOF it will pop better. Most photographers want what is called a fast lens because it has a shallow DOF which allows them to get the subject/target in focus to make it pop. Of course this takes time which may allow the target to get away, or out of the field of view. But for shooting paper or steel when you have a second or so to change the parallax you may be able to see the target better. Horses for courses.

 

[wigwamitus]

... Depth of field is not a typical measurement given by scope makers ...

I can measure DOF.

I am interested in attributes we can measure.

I think we can (at least sort of) measure "resolution" with the USAF 1951 eye chart.

Not sure how to measure contrast yet. Dark Lord implies contrast is important, so we need to learn how to measure that.

Don't know how to measure POP. Not sure how important POP is.

 

[MarinePMI]

"POP" is a subjective term, so I'm not sure how you could measure it, since everyone's eyes are different in what they can resolve. That being said, there are ways to measure attributes, but as Ilya mentioned, they are all interrelated.

Without getting into sensitive areas, I can tell you as a former photo interpreter/imagery analyst, that images have several factors to determine the overall useability of an image (often referred to as a NIIRS, National Imagery Interpretation Rating (pronounced "nears") ). This is a combination of things such as ground sampling distance ("GSD") and other resolution measurements (what could physically be resolved by the human eye). GSD is a measurement whereby if two objects on a certain size were placed apart, at the same distance as their size, and could be resolved as two distinct objects it was given a GSD of "x" (whatever the size of the object was). So, in the case of something that was 36" length, 36" wide and 36" tall was placed 36" from another object the same size, the GSD was 36". This measured "resolution", but not necessarily usability or clarity. Contrast, haze, edge detection and sharpness all greatly impacted usability. This was due (in part) to environmentals and a host of other geometric factors. So, in the case of something 36" of size, while I could (in one image) just see a 36" blob next to another 36" blob, in another image with the same GSD, I might have enough contrast to determine attributes of the object and define it as a start cart specifically related to a Mig-25E (for example). The image with higher contrast would have a higher NIIRS rating, since it's attributes (other than GSD) allow me to identify with greater accuracy than the similarly rated GSD image.

Conversely, I may have an image that has a smaller GSD, but has so much haze, that I cannot identify (with confidence) that same object as a start cart (and never mind the variant of it).

All of this is to say, there can be measurements made across various attributes of an image (a product of an optical sensor), but it is the sum of these measurements that determine things like clarity, resolution, or "POP". And, while these measurements can be aggregated to a specific sum, that sum, is one of many within a matrix of sums, that a apply differently to the task at hand. An image with haze can be pretty useless when identifying a variant of equipment, but that same hazy image, with strong edge detection characteristics may be exactly what I need to see the edge of a shadow of a large aircraft (like an IL-76 Candid) and determine (based on the shadow edge) that the nose has been modified, and it is actually a homegrown A-50 Mainstay variant (IL-76 based airborne early warning with a chin mounted sensor suite).

Within the monochromatic spectrum (IIRC) there are 256 shades that span from white to black within a softcopy image. The human eye can only define roughly 36 shades (it varies slightly by individual). Think about that for a second. IIRC, black has 26 different shades, but for the most part, humans see all 26 as "black". I would image (and perhaps ILya can enlighten us), that optical design and lens coatings are what alter or emphasize certain shades of color, redistributing those colors into more widely spaced wavelengths that the human eye can then resolve or see. In softcopy form, this is done via a histogram, and manually changing the distribution of those shades (this is how you can make "black" shadows suddenly become a series of grays that show an aircraft (for example) hidden in the shadows. I'd think when scopes are made, they are "hardcoding" a histogram of sorts into the scope design. This hardcoded histogram (via optics, coatings etc) predetermine how "normal" or "average" light is bent/refracted, so that some wavelengths normally not visible or hard discern are shifted to a higher contrast wavelength to be more easily viewable.

I would argue that these same principles apply to scopes: Not all attributes are equal (rather a series of sliding scales), resolution does not equate to clarity , and specific intended use determines usability.

I would suppose my background is what makes me so critical of some scopes, as spending hours upon hours staring at images tends to have biased me to certain aberrations that irritate the shit out me.

JMTCW...

 

[TommyTwoGuns]

I can measure DOF.

I am interested in attributes we can measure.

I think we can (at least sort of) measure "resolution" with the USAF 1951 eye chart.

Not sure how to measure contrast yet. Dark Lord implies contrast is important, so we need to learn how to measure that.

Don't know how to measure POP. Not sure how important POP is.

I would tend to use a camera resolution chart. Easy to find a file online you can download for free and print out. The first thing I look at is how well the "cross" made up of multiple lines in the upper left hand corner shows up. The 'cross' is composed of black lines that start out thick and wind up thin, same for the white spaces between the lines. Where the black lines and white spaces turn to gray mush is the resolution limit of the lens/scope. Those thick to thin lines also tend to show things like moire and Nyquist limit (indicating the need for an anti-aliasing filter). Here is a link to start you off in one measurement of resolution, but it is only a start. One reason there are duplicate parts of the chart is the whole field of view is measured, not just a part of it.

There are ways to measure contrast, but that is way above my pay grade.

I would define pop as a combination of all these factors (and probably more); Dark Lord's 'optical system' measured if you will. But a real problem with that is that not everyone has the same eye sight, stuff like 20/20 and color blindness for starters. So measuring pop is somewhat subjective. But there are great photographs that almost everyone would agree are great no matter how good their vision is.

 

[SLG]

This came up in a PM to me, but I thought I'd mention it here. The writer was apologizing for "polluting" "my" thread, with all this talk not directly related to the original question. I greatly appreciate his concern, but in my case it is completely unwarranted. First of all, this isn't my thread. It is ours, owned and hosted by SH. Second, I view these threads as conversations, and conversations with real people, tend to wander as topics become somewhat related. Third, this is all interesting stuff, and I'm learning about people and things, some of which is directly related to the bigger issues this thread is about. In addition, the guy writing me is a regular contributor here, with really good content, and is not a troll in any way. And finally, I've never understood people who get all upset and complain about off topic posts in their threads. I realize there is a sensible limit to that, but mostly I think those people must be fairly hard to talk to and deal with in real life. Plus, I hate whining. Its not like someone is talking your ear off in person and you can't get away. Rant off, and sorry if that was off topic?

 

[TommyTwoGuns]

Some random thoughts about DOF and pop. As a rule the DOF gets smaller as magnification gets higher.

As you change the parallax you change where the focal point in the depth of field is. Things in focus will be sharp and pop while things out of focus will be blurry and fade into the back ground. If there is any CA in the blurry portion of the FOV things will fade even more. In the image below the left side is what a deep DOF looks like while the right side is a shallow DOF. Most folks would think the flower on the right side pops out of the image. Related to shooting which image in the scope would be easier to put the cross hairs on. While contrast can be measured in an optical sense a shallow DOF will make a target seem to have more contrast (and easier to see and put the cross hairs on. Just my two cents but developing your skill set to set the parallax to make the target pop is something I think is important. And having a scope that makes getting the right parallax setting easy is a good thing.

No question for me the right side of the image above would be easier for me to put the cross hairs on and it also pops more. On the other hand if I was trying to hit something in the background the left side would be my first choice. Thing is it is probably worth the few seconds it would take to change the parallax setting to get what ever you are shooting at in as sharp as focus as possible.