Rifle Scopes Is there an OBJECTIVE rating scale for measuring optics clarity and resolution?

[Notso]

I've been recently pouring over threads on SH and reading some of the excellent reviews on the various scopes. But one thing has been niggling at me during the whole process..... almost ALL of the scope reviews can only give "subjective" feelings about optics resolution, clarity, color, etc. Things like reticle tracking, turret clicks, return to zero, etc are all measurable quantities. Is there anyway to objectively measure optics resolution? I come from (in a sort of roundabout way) military optical sensor background and we have fairly objective ways to accurately measure sensor and image resolution. We called it the National Imagery Interpretability Rating Scale (NIIRS) IMINT - NIIRS National Image Interpretability Rating Scales

"Through a process referred to as "rating" an image, the NIIRS is used by imagery analysts to assign a number which indicates the interpretability of a given image. The NIIRS concept provides a means to directly relate the quality of an image to the interpretation tasks for which it may be used. Although the NIIRS has been primarily applied in the evaluation of aerial imagery, it provides a systematic approach to measuring the quality of photographic or digital imagery, the performance of image capture devices, and the effects of image processing algorithms."

Is there anything similar in the world of photographic equipment, rifle scopes, spotting scopes and such? Just curious.....

 

[Papa Zero Three]

BLUF/Short answer to your question: No.

There is a thread or two on this very subject floating around the forum here. Lowlight and a few others in the optics industry listed the difficulties and reasons why there isn't one or a way to establish one that would be efficient/effective in giving a quantitative and qualitative baseline or standard on which to rate them. It's a harder nut to crack than most apparently.

 

[hamstur]

Here's the thread from October: http://www.snipershide.com/shooting...235-objective-testing-rifle-scope-optics.html

 

[Notso]

OK, cool. Thanks for the answers. I didn't see those earlier threads. The search function leaves a lot to be desired here.

 

[NevadaZielmeister]

Here's the thread from October: http://www.snipershide.com/shooting...235-objective-testing-rifle-scope-optics.html

Yes, that is a great thread.. (he he he). You might also want to review the sticky as well: http://www.snipershide.com/shooting/snipers-hide-rifle-scopes/215325-finnaccuracy-optics-test.html

I have tried to test my scope outdoors and this was a difficult test. There is a bit of subjectivity to the testing for resolution and clarity. However, through this test, I was able to find a flaw in the adjustment of my scope and now that that is corrected, I will try the test again.

 

[JL]

Yes, that is a great thread.. (he he he). You might also want to review the sticky as well: http://www.snipershide.com/shooting/snipers-hide-rifle-scopes/215325-finnaccuracy-optics-test.html

I have tried to test my scope outdoors and this was a difficult test. There is a bit of subjectivity to the testing for resolution and clarity. However, through this test, I was able to find a flaw in the adjustment of my scope and now that that is corrected, I will try the test again.

It is very hard to make even reasonable objective test when human eye and changing outdoor environment are involved.
With our (FinnAccuracy) test, we tried to minimize this variation by adding detailed instructions how procedure should be done.

Optical magnifier added to on scope ocular would basically solve eye difference issues, but not many have those available.

 

[Paulus]

I dont mean this to sound flippant, but i've always been told to and always tried to get time looking through the optics i was considering purchasing. I've always been told to let my eyes be the judge of what is best, as seeing is believing. Not quite the answer you're looking for and much harder to get time on many different optics but its the solution i adopted on advice from some knowledgeable folks. it worked for me. I spent time behind several i was considering and it made my choice clear. in fact, i went away from one i was pretty sold on and went a completely different route. had i not let my eyes do the choosing i probably would have made a purchase and ended up selling what i purchased.

-Paulus

 

[glock24]

Although still subjective, I appreciate the amount of effort gone into the below test method for comparing binoculars. Perhaps something similar could exist for riflescopes;

How do we test binoculars? - Description of test methods and categories. - allbinos.com

 

[TrapperT]

Unfortunately objective testing is reserved for those who have the tools to do so. You can subjectively test a scope and say that this scope seems to have less edge distortion than brand x and that chromatic aberration is better in brand z and resolution is better in brand y and the color is better in brand a. But without actual data, you are guessing at best. A trained optical engineer will pick up things very fast whereas a person who has little experience with regards to optical design/properties will have a heard time picking up the subtleties. You can look at the 1951 USAF resolution target, but it still becomes a subjective test. Equipment to do what you are talking about runs around $45,000. Most optics companies will have this (but you would be surprised how many don't). Then there is other equipment that will characterize the actual pieces of glass. So for the general public, the only thing to do is look through the optics you want to buy and compare. But in order to do a fair comparison, you need to have the optics side by side. If you don't, it will be very hard to pick up on the differences. But optical qualities is one thing, mechanics are another...

 

[918v]

To my knowledge, Zeiss is the only scope manufacturer who gives out resolution data. The Hensoldt 3-12 has a min resolution of 3.75 arc seconds, the 4-16 and 6-24x56 have a min resolution of 3 arc seconds, and the 6-24x72 has a min resolution of 2.5 arc seconds. In contrast, the Hubble telescope has a resolution of .05 arc seconds. My understanding is that 1 arc second is about 1mm at 100m.

I wish all optics came with resolution data.

 

[Papa Zero Three]

Another thing to keep in mind is that even if there was a way to do this objectively, you would need a large sample of the same optic(s) from the same Mfgr to compare them all to ensure the results weren't for just that specific optic being tested but the product lot/batch the mfgr was producing.

 

[JL]

To my knowledge, Zeiss is the only scope manufacturer who gives out resolution data. The Hensoldt 3-12 has a min resolution of 3.75 arc seconds, the 4-16 and 6-24x56 have a min resolution of 3 arc seconds, and the 6-24x72 has a min resolution of 2.5 arc seconds. In contrast, the Hubble telescope has a resolution of .05 arc seconds. My understanding is that 1 arc second is about 1mm at 100m.

I wish all optics came with resolution data.

actually, 3 arcs would be pretty bad.
Most if not all premium 6-24 and 5-25 scopes can do under 2- B/W test chart, without additional magnifiers.

 

[918v]

I thought 2 arc is the theoretical diffraction limit for 56mm scopes.

 

[LanceS4803]

I dont mean this to sound flippant, but i've always been told to and always tried to get time looking through the optics i was considering purchasing.

Very true.
I had done a lot of research about a particular set of Steiner binoculars, for hunting. Tried them at a trade show and was happy, until the vendor asked if I wanted to look at the next step up. I immediately noticed the difference and decided to go with them, until I was asked to take a look at another set. This new set was like night and day. The difference in color and clarity is amazing, even within the same brand.
I ended up spending far more than I planned that day...

 

[mdmp5]

Although subjective, I was only really able to notice the difference in good glass when looking through it in crappy weather, like rain or fog.

 

[HitEmHard]

Good stuff here. I learned the most about optics and optic quality when out in the field and peering through other people's gear. Helps objectivity when you aren't in a store or thinking about price etc. On a side note does anyone need a practically new shakeweight?

 

[918v]

actually, 3 arcs would be pretty bad.
Most if not all premium 6-24 and 5-25 scopes can do under 2- B/W test chart, without additional magnifiers.

JL:

I read on your website you are working on a database for scope performance. Do you have data for Hensoldt and S&B?

 

[JL]

JL:

I read on your website you are working on a database for scope performance. Do you have data for Hensoldt and S&B?

Yes- and actually we're updating whole pages soon. We will see if we manage to get DB running same time. Likely not, unfortunately. We have measured lots of scopes during years, but I feel bit uncomfortable sharing our own results.
Dont want to end up situation explaining why there are differences and what is normal- both to manufacturers and upset end users...

theoretical resolution depends greatly about wavelengt. Also test chart background color makes huge difference in minimum seen resolution. If you want to try it with your own scope, , just download FinnAccuracy testcharts and excel file- excel will calculate resolution as arc secs automatically based on test pattern numbers you see.

 

[Deadshot2]

Print out this chart and use it to check/compare

Even if it prints some lines a little fuzzy just see if the scope can resolve it as "fuzzy" or merely a solid line/blob.

There are other "resolution charts" like this available all over the net but this one was featured in a scope evaluation article on Accurateshooter.com. I have one similar that I hang at 100 yards and then view the image not only in the center of the scope but move the view around so I can see if he resolution near the periphery of the lenses is also good. Also good idea to check scope at all levels of magnification unless a fixed power.

 

[NevadaZielmeister]

Print out this chart and use it to check/compare

Even if it prints some lines a little fuzzy just see if the scope can resolve it as "fuzzy" or merely a solid line/blob.

There are other "resolution charts" like this available all over the net but this one was featured in a scope evaluation article on Accurateshooter.com. I have one similar that I hang at 100 yards and then view the image not only in the center of the scope but move the view around so I can see if he resolution near the periphery of the lenses is also good. Also good idea to check scope at all levels of magnification unless a fixed power.

I am sorry Deadshot. But these resolution charts do not address the difference in colors, which makes a BIG difference. For all practical applications, your targets are never black and white, so these charts are not very valid. The charts created by Finn Accuracy available here http://www.snipershide.com/shooting/snipers-hide-rifle-scopes/215325-finnaccuracy-optics-test.html are the best charts I have ever seen.

The great thing is that when I used the Finn Accuracy charts, it helped me correct an issue I had with my scope. I would recommend them. Then, when you run this test and post your results, others can benefit. I plan to post mine when the weather improves and I have more time this summer.

 

[Deadshot2]

We don't disagree. I did mention that others were available but the one I posted was featured in an "article" I had recently read.

For all too many people, a scope evaluation is conducted in the store by merely looking at something at the other end of the store or at an object they can see through the window. The rest of their decision making process is then focused on "Features", "Name", and "Price". Often too much focus on the latter. Quality and Price do not always go hand in hand.

 

[918v]

Yes- and actually we're updating whole pages soon. We will see if we manage to get DB running same time. Likely not, unfortunately. We have measured lots of scopes during years, but I feel bit uncomfortable sharing our own results.
Dont want to end up situation explaining why there are differences and what is normal- both to manufacturers and upset end users...

theoretical resolution depends greatly about wavelengt. Also test chart background color makes huge difference in minimum seen resolution. If you want to try it with your own scope, , just download FinnAccuracy testcharts and excel file- excel will calculate resolution as arc secs automatically based on test pattern numbers you see.

Maybe that's why Zeiss lists 3 arc seconds minimum to address the worst possible scenario, like black on a blue background.

 

[E. Bryant]

There are objective measurements that can be performed on complex optical systems; other industries have been doing them for years. But I see the following issues:

1) Objective testing requires expensive equipment and time. Subjective testing simply requires a keyboard, a front porch, some big words, and strong opinions.

2) Interpreting and evaluating the results of objective testing is likely to be highly subjective. How should resolution, contrast, color accuracy, et al be balanced against one another? There is no single right answer.

3) Objective measurement is likely to be met with significant resistance from both manufacturers and consumers. The number of sacred cows to be slayed would likely supply McDonald's beef demand for several days.

 

[Deadshot2]

2) Interpreting and evaluating the results of objective testing is likely to be highly subjective. How should resolution, contrast, color accuracy, et al be balanced against one another? There is no single right answer.

.

Isn't the "objective" to be able to see and hit a target not being able to see how many holes there are in it's shirt buttons or bumps on the antlers?

 

[918v]

Isn't the "objective" to be able to see...

Yes, but see what?

Turbo54 made a very interesting comment in another thread:

"That all said, I have a Premier Heritage 5-25 and a March 3-24, and have compared them side by side a number of times. Both have excellent, but decidedly different glass.

When looking at Orange 1" Birchwood Casey target dots on white paper @ 200 yards the difference becomes evident to my shooting partner and I...

The Premier is tuned for better contrast, whereas the March is tuned for better resolution.

We could easily make out the black "cross" in the target spots with the Premier but not so much the March.

However, we could make out the 6mm bullet hole in the orange with the March, but not so much the Premier."



So which one would you take hunting? Me, I would take the Premier. The reason is the March would prolly not be able to identify my target which would blend well with the foliage.

 

[JL]

Maybe that's why Zeiss lists 3 arc seconds minimum to address the worst possible scenario, like black on a blue background.

If I may ask, what is source for this?
I have been in Zeiss Wezlar plant, and seen production line including final inspection- just curious.

The Premier is tuned for better contrast, whereas the March is tuned for better resolution.

welcome to the wonderful world of test charts now you start to see why I constantly end up having very long conversations with customers asking simple "which scope has best glass" - question...

Our test method is not able or even ment to offer final truths- but it is fine method for DIY optical benchmarking.
it is simplified alright for practical reasons- but I do know as an fact that method shows image quality differences on identical same serial range premium scopes.

Final score weight relies heavily on resolution side with different colors- especially black and white.
But, ambient light changes would mess up contrast test and effect color resolution too- that's why it was done so.
if charts are used for various scopes on same test session, then results are naturally directly comparable - in those conditions.

 

[918v]

If I may ask, what is source for this?

My source is page 6 of the Hensoldt pamphlet:

http://www.finnaccuracy.com/data_files/hensoldt/53_0680e_ZF3_12x56_4_12x56_FF.pdf

 

[tipper]

let your eyes be the judge of what is best, Your shooting glasses will also make a difference .

 

[JL]

My source is page 6 of the Hensoldt pamphlet:

http://www.finnaccuracy.com/data_files/hensoldt/53_0680e_ZF3_12x56_4_12x56_FF.pdf

Oops, forgot that sheet..

but as previous gent described it- absolute resolution is important and gives good idea about excepted practical performance, but is still only one part of felt overall image quality. Eye works bit like taste- image looks always different depending who's looking it.

 

[918v]

The problem is that you can dress up the image, put some makeup on it, and get the observer drunk. That's what Leupold does. Image looks nice but the scope can't resolve shit.

 

[918v]

In case anybody cares, I got an email from Kahles Austria this AM.

The K312 resolves a minimum of 2.28 arc seconds. I guess their standards are pretty high.