Optical quality: good glass, bad glass, it’s all the same, isn’t it?

No, it is not the same. Not Quite. All you have to do to confirm that is get a couple of scopes with widely differing price tags but similar configurations and look through them side by side for a few minutes, preferably under some sort of challenging light conditions (not inside a gun store). However, comparing a $100 scope to a $3000 one sure looks like a rigged election, and it is. For products that are closer in price the differences are often quite small. Some companies offer more for the money than others, but overall, you get what you pay for. I’ll cover that in more detail further on, but, for the time being, it is worthwhile to talk a little bit about optical quality and image quality. A lot goes into making a riflescope with good optical quality: system design has to be properly worked out, all of the optical components have to be shaped and polished to very high standards, coatings have to applied both correctly and consistently, etc. However, from an end user perspective, none of those details by themselves should be of any interest. Still, I see internet discussion all over the place on how a particular scope features glass X which must be totally superior to glass Y. These discussions are largely a testament to how successful marketing departments of large equipment makers in diverting their customers’ attention from what is actually important and toward the useless, but cool-sounding details. I am not saying that the materials used are unimportant. They are important. However, they are not directly important. Moreover, the choice of materials is driven by the overall system design and no matter how high the quality of a particular piece is, it has to be used correctly. On top of that, some other part of the optical system may be the limiting factor. For example, there are three separate optical systems inside a typical riflescopes, eyepiece, relay and objective. All three are equally important, but if the eyepiece is badly designed, for example, it makes no difference how phenomenally good the objective lens system may be and vice versa. On top of that, as end users of the product we really do not know enough of the technical details of what goes into a particular scope to be able to make any sense of whether they matter or not. Once in a while, during a candid conversation with a scope maker they mention something that is actually worthwhile, but then they usually ask to keep this information private (and I understand why). Bottom line is that, first and foremost, we should be looking at the overall image quality of the product. Otherwise, we run the risk of “focusing on the trees so much, that we lose sight of the forest”. When it comes right down to it, the only truly relevant question about the optical quality of a riflescope is the following: “will you be able to see your target well enough to comfortably make a shot at all possible lighting and environmental conditions you might encounter?” If the answer is “yes”, do you care about how the scope maker achieved this? Unless you have a lot of money to spend on a scope, the answer is likely to be “no”. Then you just have to look and see which scope within your budget gets you the closest to “yes”. How the scope maker achieves that is still not especially relevant.

On the other hand, looking at this from the standpoint of those trying to sell their products in a very competitive market place, I can see why the advertisement campaigns we see are designed the way they are. After all, if you make a mid-range riflescope that is not very different from a half-dozen of your competitors, how do you make it stand out? You have to zero in on some sort of a differentiating features that touch on both optical and mechanical qualities of the product. Mechanical features are fairly simple: different knob and other control designs are easy to photograph, describe and put into an ad. How do you sell good image quality? Every magazine ad for every scope company for a riflescope talks about how well you can see. You pretty much have to tout something: patented coating recipe, extra low-dispersion glass, “high definition” glass, etc. None of these things by themselves are of any importance and (by my estimate) nearly 100% of what you see in a typical advertisement is, at best, misleading and at worst, pure BS. However, all these tricks are necessary for attracting enough attention to a particular product to at least get you to consider it.

Going forward, I’ll discuss a few things I look at when I evaluate a riflescope’s optical quality. I am not going to spend much time on scientific definitions of those terms. I think it is more pertinent to look at how they effect a scope’s performance.