Introduction

I’ve stated on another thread that people get accustomed to their scopes and that everyone can have different opinions about the same scope. This post is a (feeble) attempt at trying to understand some of the reasons behind this conundrum. It’s a long one, so I suggest you get a drink and comfortable before reading.

In a perfect world, the image presented to the eye of the shooter would be viewed (or interpreted) the same way by everyone. In a perfect world. That would be so if everyone had the same eyes and same experiences. And of course, that’s not the case because we are not in a perfect world.

Light coming into a scope is composed of various wavelengths, where red is on the long side at 740nm and violet is at the short end at 380nm. The unit of measure is nm or nano-meter; it’s very small. Now, when the light goes through a lens, it is affected by the difference in the density of the material, between air and glass. This density change location is known as the air-glass boundary. Ordinary glass will cause the light coming into it to reflect back about 5% of the light coming in. It also happens on the other side when the light exits the glass into air. Each air-glass boundary reflects about 5% of the light at that point. You can see that in a optical system with many lenses, this 5% loss quickly accumulates to the point of making the image at the other end quite dark, because of the cumulative loss of light.

Wavelengths are reflected a little differently from each other and so some colors wash out a little bit faster than others. If you look through an old 60s or 70s optics, you will notice that the image, while capable of being quite good, is dull; the colors are washed out. In the pre-lens coating days, the optics maker would try to compensate for the massive loss of light by having very large objective lens. If you’re going to lose 50-70% of the light, you may as well start with more light and hope to have enough at the other end.

Furthermore, as lenses bend the light this creates an effect called chromatic aberration or CA for short. This is where the different wavelengths of light are each bent a little differently and the boundary between one color and the next one sort of blur together. This effect is color fringing and it results in a loss of sharpness in contrast. Contrast sharpness is extremely important for resolution of an object in the image; it’s easier to distinguish an object if the contrast with another color is very definite, very crisp.

The big lens that causes the most CA in a riflescope is the objective lens. You can see this if you just observe how big the objective lenses have to refract or bend the light so the image fits in the inner tube within a few inches. Scopes with low power do not bend the light anywhere near as much so CA is not much of an issue in those scopes.

One method to deal with the CA is to use a doublet lens group in the objective lens where behind the first lens is another one that fits it like a mirror image. This takes care of some of the CA, but not all of it.

Lens Coating
In the 1960s, optical companies such as Nikon, started playing with coating on lenses in an attempt to minimize the amount of light reflected at each air-glass boundary. There are a few methods of coating lenses and one of them is to have a material of some kind be vaporized in an enclosure where the lens also resides. The vapor is deposited on the glass and that layer or coat, is designed to reduce or eliminate the reflection of a specific wavelength at the air-glass boundary. One wavelength or a small range of wavelength. Early on, with a single layer, you could readily see that one color much more readily in the scope while the other colors lost their strength going through multiple lenses. So, for instance, if the coating your lens had was for blue, the image coming to your eye would be blue-tinted.

To help with the other colors, lens manufacturers would apply multiple coats in an effort to reduce or eliminate the reflection of as many wavelengths as possible. This is what multi-coating is about, and you can be sure that all multi-coatings are not the same. Some companies would only coat or multi-coat one or a few lenses, while others would multi-coat all the lenses in an optic, hence the term “fully multi-coated optics,” as opposed to “multi-coated optics.”

Now, even with multi-coats, the optics from one company can have a little tint towards one color, or rather, a little washout of another color because the multi-coating does not encompass that color as well as the other ones.

This is how astute users can differentiate some optics from others saying that brand XYZ has an image that’s warmer than others or colder than others. Warmer is toward the red side of the spectrum and cold is toward the blue or violet side. And of course, you can have similar in the middle of the spectrum on in one area and not the other.

ED glass
In the late 60s, Nikon (again) developed something called ED glass where ED stands for Extra-low Dispersion glass. This ED glass reduces CA by having the various colors focus more towards the same spot by bending various wavelengths just so and also eliminating some of the side bands of the various colors in the glass. In other words, ED glass robs a little bit more light compared to high refractive index glass, which is more pure and transparent but it focuses all the wavelengths to the same sport.

Then you have multi-coats on ED glass and that scrambles it a little more. So you can quickly see that glass manufacturers using different types of ED glass and different types and numbers of coating will make for different IQ coming to the eye, even if the contrast is higher than with non-ED lenses.

The eye
The way the mark 1 eyeball detects something through a riflescope is by the cones in the retina. There are three types of cones in a human eye: S, M, and L. The S cones or short cones are sensitive to blue, the M or medium cones are sensitive to green and the L or long cones are sensitive to red. (Mixing different levels of RGB cones (just like computer monitors pixels) makes up all the various colors for the brain.) These cones, their numbers and sensitivity will change from person to person and many of us have some form of color blindness that affects how our eye distinguishes the image being presented to it through the riflescope.

For instance, I am a severe protan which means that I have a form of red-green color blindness. My long rods (Red) are not missing, they just don’t detect enough red and they are too sensitive to orange, yellow and green. The net effect is that I have difficulty telling the difference between green, yellow, orange, brown, and red or various combinations. This is even worse in low light. Furthermore, red and black can sometimes be hard to tell apart, and the same for other combinations.

Another form of color blindness is deutan, which is another red-green color blindness but this time it’s because the green cones (Medium) are having an issue detecting enough green and they are too sensitive to yellow orange and red. This manifests itself in a fashion similar to that of a protan but the underlying cause is different. So if a scope has multi-coatings that favor green and hinders red, a protan and a deutan will experience different contrasts looking at the same object and of course, each would be different from a non-colorblind person.

There is yet another color blindness, tritan, and this is reduced blue (Short) sensitivity. This presents a different perception of the same image from the other two and from non-colorblind people. And of course, everybody can have some degree of color blindness that most often is not really detected but can come mildly in play looking through various multi-coated optics.

If you want to find out if you have some level of color blindness, there are test sites on the internet that you can use online.
Here is a good one: https://enchroma.com/pages/test


What we are used to
We just saw there is a rather large range of color perception out there. Thankfully, most people see colors pretty much the same way or else we would have chaos, but there are still gradations.
Now we get into conjecture on my part; get your hip boots on.
I believe that the brain which does the interpretation of the vision coming from the eyes does a lot of what I would call PP or post processing; just like a photographer does for a digital picture. The brain tries to understand what the heck this stuff coming at it represents and get a clear picture (pun intended) that it can view, understand, and recognize. The brain learns over time, it’s called training or adaptation. So at some point, your brain is used to seeing the image coming through your scope and it is able to deal with it more easily. Of course, it’s not going to be able to add color where color is missing and so on, but by extrapolation of things it is familiar with, the brain can fill in some of the blanks. So to speak.

So when you compare scopes by getting behind one and looking at the same target as you’ve been seeing for a long time though another scope, your brain may judge the new image to be more difficult to interpret compared to the usual one. Of course, if you’ve been using a cheap scope with low contrast and you are now looking through an expensive scope with much higher contrast, that might make it easier for your brain to interpret the image because of additional granular info and you will appreciate the better image. But if the glass is fairly equivalent between the scopes and the difference is more in the coatings and their applications, then things get dicier. Especially if you have some degree of color blindness. Your original scope might have suited your “affliction” better than the new one, or the other way around. And your brain may react differently to the change as it relies on its training or adaptation.

This is why I am extremely leery of any review or impression from anyone looking through various scopes in an attempt to compare them. The vast majority of people have no clue what to look for and no experience in detecting something.

That said, I believe that the presence of ED and Super-ED glass compared to regular glass is detectable as it will increase the contrast for all the colors, not just a few or combinations of some. Unless you are totally colorblind the colors will pop, meaning you can tell them apart more easily, even when they are next to one another. The next frontier is the coatings used and how they can influence different people in different ways. To really test or compare one riflescope to another, you need to spend enough time behind each one, certainly more than a quick peek or two. That short time may help differentiate stark contrast differences and also resolution, but it won’t cut it for coatings, unless of course you hit on a combination of coatings that to your eye, shows a visible blue or red tint.

Thankfully, the end
That’s enough conjecture for today, but you can probably see that I’ve been giving this some thought for a while now. I’m almost at the point where I will start asking whomever makes a judgement call comparing one optics to another, to reveal any color blindness or affliction. This could make for some interesting discussion.

Thank you for that excellent discussion. As always.

quote:

Originally posted by NikonUser:
This is why I am extremely leery of any review or impression from anyone looking through various scopes in an attempt to compare them. The vast majority of people have no clue what to look for and no experience in detecting something.

This comment in particular is something I have long believed. There is a lot of blithe advice and opinion expressed about various optics, and I often really wonder what bases of knowledge the people offering it have. What conditions have they used it under, what similar optics have they compared it to, etc.

And thanks for that color vision test link. I have “normal” color vision, but I had to stare at one chart for a time to be sure of what it was.

Yeah, I know that people who take tests instinctively try to do the best they can and will work hard to get what they think is a good score.

The thing of it is, a vision test is NOT one where you want to do your bestest, if you know what I mean.

I wear glasses and have worn them for over 15 years (no the same pair or even the same prescription.) When I was taking eye exams in my youth, I would try to do my very best to read everything, like it was important to me to appear not as myopic as I really was.

Soon enough I realized that was the stupid thing to do. I wanted glasses that made me see well, not just better than no glasses. If I'm going to be saddled with glasses I want them to be perfect for me; who gives a crap about the prescription in them.

When I started taking color vision tests, again I tried for the best results possible. I would stare at a chart for a long time trying to discern the number. I consider that deluding myself. Now when I take these tests, I purposefully do not force myself to do the best I can. I read an awful lot and I want a proper reading prescription. For the colors, if I see the number right away, bingo. If I take more than a few seconds, I pass. I want to know exactly what my vision issues are so I can be aware of them.

Thanks; very sound advice.

I'm several years removed from working at a High End Audio/Video shop. I set up many data grade CRT front projectors with video processors for home theaters. Also set up up a handful 3x3's, 3 screens wide, 3 screen high commonly seen at sporting good stores... getting 9 screens exactly the same is a challenge. Adjusted gray scale, gamma and color using meters. Didn't take long to calibrate my eye. Up until a few years ago had a CRT projector/processor in our home. I've spent countless hours adjusting these things. A quality projector set up properly has great depth or black level detail. Today I can't look at TV's and not find fault with gray scale and color temp. This experience no doubt plays a role in what I believe to be good optics. Also the lights I choose for our home and flashlight. For you flashlight guys the Malkoff/Nichia 219 95CRI is a fantastic head!

When looking through scopes, binos... I need to see depth (black level detail), true color and a complete lack of CA. CA is a big deal for me, hard for me to look past it, like an out of convergence projector. I've shot friends rifles that have scopes with lots of CA, how can you shoot this thing? Absolutely that CA is taking away resolution. Those scopes work for them. Scopes/binos that pass the above I find very easy/relaxing on my eyes to stay on for long periods of time, easier time seeing impacts in shadows, picking up my own trace, see mirage but not over power the image....

Normal color vision on the test linked.

I like scopes that don't break, adjust consistently, I can see better through, are easy to focus and have useful reticles.............dj

The explanation by NikonUser about the effects of different glass and coatings and how individuals can perceive colors differently is very informative. I know a little about optics, but I was completely unaware of the facts about our color vision as relates to various types and degrees of color blindness. I therefore understand much better why different shooters perceive the images through different scopes differently, and why that can be important for certain long range shooting disciplines.

I must remind myself, though, that top optical quality isn’t really that important for the types of shooting I’m able to pursue. When my targets are large, easy to see, and are no more than five to six hundred yards away, a scope that’s easy to adjust and tracks reliably is far more important than optical excellence. That’s why I say I’m not in the market for a $3000 sight, and although I could afford one such scope, I couldn’t afford to put similar sights on four or five rifles.

But perhaps I’ll change my mind one day, and that’s why I appreciate such information from the knowledgeable, and helpful, members here.

quote:

Originally posted by djpaintles:
I like scopes that don't break, adjust consistently, I can see better through, are easy to focus and have useful reticles.............dj

With a post like that, I suggest you change your screen name to djpointless.

Nikonuser,

Do you know of a way to get experience with seeing these effects without having to take a bunch of scopes outdoors in full spectrum sunlight? I know that different indoor lighting always tends to skew to some area of the spectrum depending on florescent, sodium, led, etc. not many sporting goods stores use full spectrum bulbs for store lighting.

I am of course making the assumption that full spectrum daylight is the starting point for learning how to see\look for the optical trade-offs incorporated into various scope designs.

Ken

I got the opportunity to attend several precision rifle schools between 2011 and 2012. I attended a Police Precision rifle school hosted by Las Vegas Metro PD, one at Greenside Training in Benson, AZ and Tiger Valleys Level 2 precision rifle school in Waco, TX.

During those schools I used several different rifles and scopes, and got to try out alot of other agencies guns and optics during lowlight conditions and different daytime lighting conditions.

One thing was certain. Everyone had different opinions about which scopes were better, and which weren't. When it comes to something as subjective as image quality, opinions were plentiful.

Like most everyone, I decided what I liked, based on my own experience.

During the lowlight drills, the more expensive scope brands stood out.

One of the night shoot drills that was most challenging involved a target with magazine clipped pics of people pasted on it, and your spotter being given a folder containing copies of the same pics. The instructor would call out a target from the folder, and the spotter had to describe the target to the shooter using things like hair color, eye color, facial features, etc.

I had the easiest time using IOR, Schmidt Bender and US Optics scopes. Nightforce and Leupold was popular and alot of guys did well with them, as well as a few other brands, but I had a tougher time picking out some colors with the Nightforce and Leupold scopes.

I ended up buying my personally owned scopes from US Optics, except for one fixed 10x IOR. I ended up selling the IOR and getting another USO when I decided to go all mil/mil. I also liked the image quality through Schmidt Bender and IOR, but I was concerned about IORs warranty and durability, and the USO with their LEO discount was alot cheaper than Schmidt Bender.

Based on my experience, the lower refractive index scopes with longer objectives bells seemed to give an image with the most natural color. The colors in the scope image most closely matched the colors seen by the naked eye, if that makes any sense. Some of the more compact scopes have great image quality, and great contrast, but the colors look more, artificial? If that makes sense. I liked the more neutral image from IOR, USO and Schmidt Bender. Refractive index may have had nothing to do with it, but it's the impression I got based on the models I got to use.

I have some mild red/green color-vision deficiency, so that probably has some effect on my perception of image quality through a rifle scope.

Most of the newer Schmidt Bender scopes seem to be going to short, compact designs these days. I havn't used one of those models, so I'm not sure how I'd like them.

Edited to add:
I just took the test Nikonuser linked, and apparently I have a mild case of Deutan colorblindness. I never knew that.

quote:

Originally posted by NikonUser:

quote:

Originally posted by djpaintles:
I like scopes that don't break, adjust consistently, I can see better through, are easy to focus and have useful reticles.............dj

With a post like that, I suggest you change your screen name to djpointless.

"Brevity is the soul of wit"


The point being it doesn't matter how great optically a scope is if it doesn't perform mechanically. It doesn't matter how bright a scope is if it lacks resolution. A brightly lit unresolved blob is still an unresolved blob.

Interesting article. No color blindness for me per the test Nikon linked. At my age, cheap optics just don't cut it. I like Leupold, Burris and Vortex scopes. I like the really great brands but can't afford them. So, my Vortex Razor is my favorite goto scope. Wish I could afford more than one of those scopes.

quote:

Originally posted by KenS:
Nikonuser,

Do you know of a way to get experience with seeing these effects without having to take a bunch of scopes outdoors in full spectrum sunlight? I know that different indoor lighting always tends to skew to some area of the spectrum depending on florescent, sodium, led, etc. not many sporting goods stores use full spectrum bulbs for store lighting.

I am of course making the assumption that full spectrum daylight is the starting point for learning how to see\look for the optical trade-offs incorporated into various scope designs.

Ken

I'm forever telling people that for proper comparison of scopes, it's better to do that outside, for exactly the reasons you stated; artificial lighting can be all over the place. Of course, if you're going to be using the scope mainly indoors, then check it out in that setting.

While at SHOT, lots of people stop by and look through the scopes to try to get an idea of the glass quality. It's funny to watch as many people don't even know which end of the scope to look through. We had all the scopes mounted on rifle stocks so people could somewhat approximate the proper use. I even brought with me my carbon fiber monopod on which I have a V bracket. I would adjust the height of the unit to accommodate the person and they would then rest the rifle stock atop the unit and try to peer through the scope. They would immediately reach for the knobs and I so wanted to smack their hands. I always had the zoom set to the lowest setting, the diopter to 0 and the side focus to about 30 yards, why would they need to fiddle with the elevation and the windage?

If the person was semi serious, then I would take the time to point out various things to focus on and zoom in or out and I would tell them a little bit about what to look for.

But you are totally correct; if you really want to see the scope in its element, you need to take it outside and look at targets, or game or plates, or whatever you focus on.

One of the gadgets that Deon brought to SHOT was a little gizmo that you attach to the eyepiece of a scope, and another on which you clamp the scope and then place atop a tripod. This transforms your riflescope into a spotting scope. With a reticle. It's fabulous. I grabbed one of the wheels that we had in the booth and attached it to the side focus knob of the 8-80X56 that we had rigged as a spotting scope. Then I added the fast lever for the zoom control. This became an instant hit. I can now bring my backup scope and use it on a tripod as a spotting scope with reticle and if I need to use it on my rifle for some reason (it is a backup scope,) I just unclamp the rings from the tripod adapter and clamps them on the rail on top of my rifle, and I'm off to the races.

I'm looking forward to getting a set of that in the next couple of months. It's awesome.

Off track from the original topic, but what is the device that allows a scope to be used as a spotting scope and where can I get one?

This is something that I will find immensely useful.

Thanks for all of these amazing articles on the topic of optics & long range shooting. I learn something new with almost every post made on these topics and can say I have applied a lot of it to my shooting as well.

For my application a scope has to have good enough glass to allow for low light shots at dusk. Illuminated reticle is a big plus for this kind of shooting, used on the lowest setting. Being able to get a good shot on an animal in the brush or in a tree line with a dark shadowed background dictates the need for the best glass you can afford to get.

Its impossible to recreate these conditions in a store or on a range. You have to get out there and see how each scope works for you in your environment. I can’t justify huge dollars on scopes, but my two primary hunting rifles wear scopes that were more expensive than the rifle.

Based on the use requirement above - 50mm works for me. I’ve run Nikon, Zeiss, Vortex, Leopold and a few others on these rifles before picking the two that I like best for each rifle. I changed scopes 3-4 times on each rifle before I got the right setup.

+

I am 66 year old shooter with dootan extreme according to that test. I have known this for 60 years. Recently I have been trying to shoot PRS competition locally and I have been struggling with being able to get a consistant sight pic. It is especially bad shooting prone, I wear glasses and am having a heck of a time finding my target. I started out with a Zeiss ConQuest 6X24 but it was a second focal plane in MOA, so I recently bought a Burris XTR II 5-25x50 34 tube FFP mil.
My first outing with the Burris was not very good I keep flopping back and forth with wearing glasss and than throughing them off nd trying to shoot without . Needless to say I am having a hard time deciding how I need to setup my scope. Are there any recommendations out there?

quote:

Originally posted by NikonUser:

One of the gadgets that Deon brought to SHOT was a little gizmo that you attach to the eyepiece of a scope, and another on which you clamp the scope and then place atop a tripod. This transforms your riflescope into a spotting scope. With a reticle. It's fabulous. I grabbed one of the wheels that we had in the booth and attached it to the side focus knob of the 8-80X56 that we had rigged as a spotting scope. Then I added the fast lever for the zoom control. This became an instant hit. I can now bring my backup scope and use it on a tripod as a spotting scope with reticle and if I need to use it on my rifle for some reason (it is a backup scope,) I just unclamp the rings from the tripod adapter and clamps them on the rail on top of my rifle, and I'm off to the races.

I appreciate that you clearly note that you do NOT use a Scope Mounted to your rifle as a spotting scope. You should NEVER use your rifle mounted scope as a spotting scope, it SERIOUSLY violates safety rules about not pointing your gun at things you don't want to shoot. Having a Backup sighted in scope in QR rings is an excellent idea.

Added note: This is WHILE HUNTING! Doing so in a competitive match is a completely different thing.

This message has been edited. Last edited by: djpaintles,

great discussion! I took the test and can see colors normal.

quote:

Originally posted by l33571:
Off track from the original topic, but what is the device that allows a scope to be used as a spotting scope and where can I get one?

This is something that I will find immensely useful.

Thanks for all of these amazing articles on the topic of optics & long range shooting. I learn something new with almost every post made on these topics and can say I have applied a lot of it to my shooting as well.

l33571: Thank you for the kind words; I really appreciate them. The gizmo that I was describing is one that March was showing as a concept at SHOT show. I got word earlier this week that they will be bringing it to market within a couple of months. I'll will announce it here when it's available and where to get one.