Rifle Scopes Optics Testing and Evaluation

[Swamper]

I read Lowlight's reply at post #60 over on Tony Burke's thread about the scope comparison and didn't want to hijack that thread, but really what does constitute a Good Test of Scope Resolution for a LongRange scopesight?

How many variables are there that can be isolated and tested for? Actually, it is sort of like firing for zero from 500-1000 yds, so many constantly changing effects happening continually. Then there is the "Beauty is in the eye of the beholder" effect. How good is the tester's eyesight? Finally, there is the psychological effect of color and color-balance.

Lots to consider and test for beyond crisp image rendition, and although that seems to be the ultimate criteria; is it after all?

 

[Swamper]

Re: Optics Testing and Evaluation

Lowlight's post:

"As an FYI, in most cases resolution charts are simply eye charts for the user, except with a scope between the test target and the observer.

You can download them and print them off online but really there is no way to actually test it this way, although you can get an consensus on what the group "sees". Also, you have to confirm the power setting of each scope which , you can't go by the numbers on the power ring because the chances of them being correct are slim to none. So if the group sets all the scopes on 10X according to each scopes' magnification ring, odds are one might be 9X, one 10X, one 11X, etc... so in that case the 11X will always look better.

You can do it, but I would record what each person "Sees' and then compile the information that way. As well do your best to standardize the power setting when doing so.

But to look at things make sure you bring something colored, with reds, blues, and especially yellow, cause yellow is where they fall off. But you can do a near and far test and record a score each person gives each scope across the field, I would make it as blind as possible so the "favorites" don't get wished a little higher.

Glass in a scope to anyone but those with laboratory quality testing equipment will always be subjective at best."

 

[Swamper]

Re: Optics Testing and Evaluation

I have commented more than a few times that "a sniper's scopesight does not need to resolve the skin texture of a mole on a targets face at 1000yds", and that you sure don't need to be able to count the number of hairs growing from that mole or pock marks.

Yet, if you are testing for optic clarity and resolution, that is surely what it comes down to. If we were testing spotting scopes, that would be the whole enchilada. (Make mine with 2 fried eggs on top and some green chile, please!) Yet, these are riflescopes and need to also perform.

Probably the biggest factor, unless we have a 1000yd indoor facility with SunLight temperature balanced lighting in even distrubution, is the ever-changing position of the Sun and how it lights our target. The angle and condition of the light source (the Sun if outside) will impact much of our ability to discern fine detail.

Is the lighting diffused or direct? What time of day? In early morning, lots of moisture in the air which causes diffraction and diffuses the intensity, thus changing the perception of color and image clarity; especially at distance. There is some degree of geometric fall-off of clarity from this effect, the greater the distance.

So many variables...

 

[Lindy]

Re: Optics Testing and Evaluation

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Glass in a scope to anyone but those with laboratory quality testing equipment will always be subjective at best."</div></div>

Yep.

While you can look through several scopes, and pretty clearly rank them in terms of what you can see, I find it highly questionable that the ranking would really have any effect on whether they are usable for shooting. A pretty picture is...a pretty picture - unless it helps you shoot better.

One test I <span style="font-style: italic">have</span> done is to set up several scopes late in the afternoon, and observe through them all the way to full darkness to see differences in light-gathering ability. And that does have some effect.

But optical quality is behind ruggedness and reliability of adjustment systems on my priority list for scopes, assuming that they all have the feature set I'm interested in.

 

[J.Boyette]

Re: Optics Testing and Evaluation

A technique I have used to test diffrent optic's clarity on a even field is this.

Check the manufacturers scale of FOV, then go down range at what ever distance you want.

Setup a left and right markers for the field of view you want to test. " this is the same idea as going to a 10x, on a variable"

Now when you adjust all the riflescopes, the magnification setting might be diffrent, but all of them are using the same FOV, this is a controllable.

I have been known to take 10 diffrent stakes, paint them five diffrent colors and use that at 100yds to see how each optic did.

How I do this is simple, I put the two BLUE stakes closest to the target, a equal distance left and right of the target.

Adjust the riflescope so the left and right side of the FOV just touches the blue stakes.

This gives me the ability to have all the optics with a simple scale to keep them even in testing.

The next set of stakes are red or pink, but equality further apart.

Try it out.

John

 

[Lowlight]

Re: Optics Testing and Evaluation

John brings up some very good points. Setting up the FOV so you can manage the conditions better. As well you may see some differences there.

Another thing to look at is the eye relief and how forgiving or unforgiving one is compared the others. This seems to be something that we see a lot, people struggling to maintain that perfect image from edge to edge. I would test it from lowest to highest power as it will change, some more than others.

Unfortunately with the testings being done, you can't check the turrets, but for those looking too, I recommend testing them across 100% of what you will use. A 4" box test is a complete waste of time, you need to do a 40 inch box test and see how it tracks. As well you need to see how it tracks with varying amount of windage dialed in.

Last, and they can do this, is set up something to check the reticles, nothing crazy a thick barber pole type check will work. The reticle will either line up or it won't. pretty simple there, bring a laser and something like a 2X2 with 3.6" blocks painted on it or you can even use duct tape just measure them right.

Honestly in this day an age, glass is the last thing I really worry about as there isn't a scope out there i can think of that doesn't let me see the target. Now there are some who's glass doesn't hold up over use and time, the coatings break down faster than I would want, but there is no way to test a new scope because out of the box they all look great. But you can test how they react to lighting changes and shadows, as well as colors this does help a bit, and new they should be pretty close to each others, you'll notice differences in contrast and color, but overall they probably won't be that bad. But definitely consider putting something the shadows to see how they all perform, as I know during they test conducted they plan on letting the sun set which should help even the field out.

Honestly if you buying a scope solely based on your first impression or someone else is impression of the glass, you have your priorities messed up, glass should really be the last thing you consider. The turret system is 10X more important as well as a few other factors.

 

[Swamper]

Re: Optics Testing and Evaluation

Photographers have long tested their lenses for clarity and resolution. Look at a 3x3" barcode on a package if you want to test for c&r, but be sure to focus on them in daylight temperature adjusted lighting if you are doing so inside.

Probably don't need to test for clarity and resolution at great distance. The scopesight that has c&r at 35' should also have it at distance, otherwise it has lens coating issues.

I admit I have no training as an optics technician, so much of this is my conjecture, but unless a lens/scope is optimized for use at a specific distance, it is expected to perform from close-focus to distant.

It is almost curious that scopesights don't have adjustable iris lens caps or objectives to further optimize image clarity via depth of field. Of course that probably would introduce other distractions to a shooter. The shooter is not looking to record information, IE the position of a subject in 3 dimensions. The shooter needs only the his target image and reticle to deliver a bullet.

Is the scopesight which possesses wider depth of field range, "better"? Maybe. Probably if we were testing spotting scopes. Yet there are so many variables.

Is there a doctor in the house?
Anyone here an Opthalmic Surgeon? All the surgeons I ever knew were gun nuts. Gotta be one or two reading here? We can't even begin to evaluate how much the human eye-brain relationship comes into play.

Zeiss optics are esteemed by so many for their contrast resolution which effects, or maybe falsely induces the brain to see an object as "more sharp"?

If, actually, all is really ultimately subjective, when dealing with high-quality optics, then what is the point? The point is what really enables the rifleman=sniper to make his shot with most certainty and capability?

 

[Lowlight]

Re: Optics Testing and Evaluation

I have contacted a professor who does the lens testing on cameras, and while it is two different things I asked him about his very inexpensive software to test a camera lens in order to test a scope.

Bottom line, you can test and record a specific camera lens, and then test and record the image through a scope, however I would recommend a camera small enough to see through the scope properly. But it can be done using modern software to test it, under $200 in fact. But really what is the point, they all see beyond the human eye anyway. When you look at the line pairs they go beyond our eyes.

But cameras and rifle scopes, while they may appear to be similar, are very different and are being asked to perform a different task.

But I wrote a professor and he said it was basically a waste of time given the job requirement.

 

[Lowlight]

Re: Optics Testing and Evaluation

This is the software

http://www.imatest.com/home

This is who I emailed and contacted several years ago

http://www.normankoren.com/

 

[Rob01]

Re: Optics Testing and Evaluation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Honestly in this day an age, glass is the last thing I really worry about as there isn't a scope out there i can think of that doesn't let me see the target. </div></div>

That's the way I feel. I look at tracking to be my most important feature in a scope and test every scvope I get. Any highend scope will have good glass and allow you to see the target but if you dial on 10 mils and get 11.5 of actual travel then you are still missing no matter how good you can see the target.

 

[Swamper]

Re: Optics Testing and Evaluation

I really appreciate all the replies from three of the best on this board.

Seems like a carpenter's square, or to be sure a machinists precison square would be ideal for noting reticle squareness. I like my bushnell 74-3333 boresighter with collimator grid also.


I have always been an optics fanatic, but not to the Nth degree for riflescopes. Seeing T. Burkes pic of so many fine longrange optics was like WOW! What accomplished rifleman couldn't make great use of any one in that lineup? Yet, weight is about the main concern for me, so I am probably going to buy a Leupold 6.5-20 mk4 TMR to go on my .338/300 TRG 42 here very soon. That rifle has a 10x Ultra presently, and it is very robust and has great clarity. Probably don't need a new scope, but...

Always the pursuit of more capability.

Anyway, conditions have to be 90% of the equation. Not many are testing for resolution in full-facing sun, or rainy/drizzling overcast conditions, but those are the most likely when your ass is on the line.

I once had to spend 4-5 hours waist deep in a frozen swamp freeing a 6x6 atv that high centered in a hole. At least I didn't have to pry the axle up using my Sendero stock, but had there been no spruce to cut, would've tried the stock. I wonder if anybody tests rifle stocks for breakage? That would be one time for sure I would have wanted an AICS 1.5 stock. If you don't have a pry bar, better have AICS!

 

[IsleofGough]

Re: Optics Testing and Evaluation

Although I would agree that the quality of the optics may be less important than ruggedness, reliability, repeatability, etc., I would not minimize differences in today's optics. I can make out my bullet holes better in low contrast targets at 400 yards better with a S&B or PH than equivalent Leupold. I found that magnification alone may not matter, and with the USO SN3, I did not find much added resultion dialing from 12x to 17x. However, I can see the actual targets well with both. I wish I could be at the upcoming scope comparison in Texas, but am interested in what will be said here.

Lowlight - you picked a very knowleagable and well respected photographer to ask, and your conclusions may be valid. http://www.photodo.com/topic_140.html has a review of camera lenses, but even most photographers feel that lens resolution may not be the most important factor in purchase. BTW, Lowlight, I would be curious about how you get through the scope pictures. I've tried without much success using Nikon macro lenses.

 

[Lowlight]

Re: Optics Testing and Evaluation

Point and shoot cameras are the best, as well I have the Zeiss Digiscoping mount to line things up along with a Picatinney rail that is threaded for a tripod mount. So I can put the scope on the tripod and the line the camera up, macro is not the answer that will only zoom in on the reticle, you need a normal setting.

 

[IsleofGough]

Re: Optics Testing and Evaluation

Thanks

 

[clmayfield]

Re: Optics Testing and Evaluation

I guess I sparked the argument in the other thread. The thing about resolution is that it is testable and it is objective. If the lens has been focused to the shooter's eye, a seeing eye chart-like test will help to determine this. I pointed out the USAF chart, but I would do rolling E's or rolling c's randomized to see what resolves the best.

Does resolution matter? Well, I have been shooting the Sniper's Hide group target, which is very nice, with a big black dot and a ring around it. I have been shooting it with a 22LR and an NXS scope at 100 yards. The way that I know that I am within the borders of the target is that the shot disappears. I can't resolve the area between the dot and the ring. Given, mirage has a lot to do with this... but it would be nice to be able to see where the bullet impacted.

I guess you could argue that this is what a spotting scope is for, but if I am supposed to figure out where the bullet impacted and make adjustments accordingly, it seems like this type of resolution may be of some use in a rifle scope.

If this were a difference between Scope A and Scope B, and this difference were measurable, it seems like it would be good information to know. That was all I was curious about. When there is a method to actually measure the differences between two scopes, I don't see the harm in measuring that.

Further, the ability to discern a .3" hole at long distances isn't, in my opinion, a matter of determining how many angels can dance on the head of a pin... And maybe the answer is that they are all the same or that there are differences, but they are minor compared to other important differences.

To test resolution is not to throw all of these other things out the window. It is just a variable that is measurable to test. No harm done and it will put to rest a bunch of carping.

I just have an engineering mindset with testing... determine the variables/criteria you want to test... test them... and then make an evaluation based on the criteria. If you make up the criteria as you go along, you won't come up with definitive results.