I've been on this venue a short while, and have learned a great deal about the mechanics of riflescopes. Optics wise, I'm in awe of the best lens makers, and the folks (some of which reside in this very forum) who make the best riflescopes.
While I've been on this forum, I've seen things blurted out in a discussion that are absolutely uninformed and ridiculous regarding these optics, which are indeed some incredible optics. The more you learn about the science of optics, the more you find out what you don't know.
It takes incredible skill/determination to come up w/a top tier optic, and the folks elsewhere and those that reside here should be celebrated and respected for what they've achieved.
Take a complicated optic w/an incredible amount of glass in it, that gets 90% to the rear end for example, I don't know if folks know how difficult that really is to do.
Optics are made of glass, the first thing light does when it hits the 1st lens element/the front glass of an optic, is that some of the light rays will reflect/bounce off the other way, which means it doesn't go through the optic, but in another direction, and of course that's not what you want, which is a % of light is already lost trying to get it through the front lens element/group and to the rear of the optic.
Not only that, light going through a piece of glass will disperse (abbe numbers tell you how much) so that the % that has dispersed/is also lost and doesn't get to the rear end.
Every time you add a piece of glass, or worse, a lens group to an optic, the same thing happens, and let's say the loss is 2% (just for the sake of argument), for every lens element/piece of glass you add to the system, by the time you've added several pieces of glass, those % for each piece of glass/lens group, will add up/combine, resulting in a big number, regarding the light lost that was supposed to reach the back end of an optic.
The folks that make top tier optics know this, and their genius, and that's exactly what it is, is their ability in getting this total % light loss down by eliminating as much light loss as they can through extremely expensive lens coatings and low dispersion glass.
Quite a bit of optics is hard to explain, but simple to understand, depriving some folks from realizing just what they're getting for their money.
"Chromatic Aberration (both lateral CA, and axial CA)", is incredibly complex sounding "macaroni" which says that the red/green/blue wavelengths that make up an object/an image, will travel through a piece of glass and hit different spots behind the glass, instead of them all hitting the same spot which they're supposed to do. When these wavelengths don't hit the same spot, you'll see lines of different colors surrounding the edges of the subject matter.
Said another way, the light that makes an image is made up of 3 different wavelengths, the red/green/blue wavelengths, when those wavelengths/colors pass through a piece of glass and don't hit at the same spot behind the glass, you get "fringing" w/the lines of different colors surrounding an object.
Aspherics/Aspheric lens elements, same thing, harder to explain than to understand, which is the outer rim of a glass element is ground into a shape that bends light at a certain angle, so that the light rays traveling through the outer rim of a glass element hit the same spot as the light rays traveling through the center of the same element.
Modern lens making/riflescopes/any optic involving glass, is based on "the angle of reflection equals the angle of incidence" law which anybody who shoots pool will understand. If you hit the 8 ball at a 45 degree angle to the side of the pool table, it will bounce off at the same angle.
Same thing w/light rays. That's what optics do (among other things), they bend light at angles. At an earlier point they did this by combining crown and flint glass into a group to send the light in a different direction. Now there's Schott glass/various combinations of different types of glass such as flourite and lanthinum glass et al where they attempt to do this while at the same time keeping dispersion down to a minimum.
When they describe how a particular glass bends light, they give a number called a "refractive index"
When they describe the way light disperses in the glass itself, instead of passing it along to the rear of an optic, they give it an "abbe number".
I mentioned all this because it begins to give an idea of what you're paying all your money for in getting one of these top tier optics.
One thing needs to be understood, it is impossible to get 100% of the light that enters from the front of an optic, through an optic to the rear end, but the folks behind these outfits (some of who reside here) are to be applauded as to the incredible performance of the optics they do produce and their ability to get the performance they do get out of their optics.
This is really hard to do, and there aren't a bunch of people on the planet that can do it.
When you get an idea of just what kind of performance they do achieve w/their optics, you'll be amazed.
When the gentleman behind one of the outfits like Zero Compromise is actually here on this forum, and starts talking, I for one, will just shut up and listen.
If I'm "preaching to the choir" or I'm going over "old ground", then please forgive me and disregard.
One thing: Over the years, I've never been asked this question by the young kids I've mentored in photography, which is a question I did ask of the folks who taught me. Which is...
"If glass is transparent, why should it affect light anyway?"
That question makes sense, except for the fact that it's not just that something is transparent, but its density matters. The density of the atmosphere, and the density of glass is different. so light will travel through air, on a line, until it hits the surface of a glass element w/a different density than air, and it will deflect at an angle. Density matters, not just that a medium is transparent.
If density didn't matter, lenses and scopes wouldn't work. The difference in density between air currents can create a lens in the atmosphere where you see something close up that's actually farther away.
