Mirage - Normal Glass vs ED Spotting Scope

[AR Shooter]

ED (or HD) is better glass. Especially in lower light conditions. You'll likely never notice the difference until you do and you'll be glad you have ED glass. As stated above, get the best you can afford (says the user of a Kowa Prominar spotting scope - ED glass & all ED glass scopes).

A good quality spotting scope is a "lifetime" product (you'll own it forever). Get a good one.

 

[Turbulent Turtle]

ED (or HD) is better glass. Especially in lower light conditions. You'll likely never notice the difference until you do and you'll be glad you have ED glass. As stated above, get the best you can afford (says the user of a Kowa Prominar spotting scope - ED glass & all ED glass scopes).

A good quality spotting scope is a "lifetime" product (you'll own it forever). Get a good one.

Please note that HD glass is not the same as ED glass, for the purposes of this discussion.
HD glass is "High Definition" or "High Density" glass, and does not address chromatic aberration. ED (and Super ED) glass, is where ED means Extra low Dispersion.

I have found that when manufacturers really use ED glass, they will state that fact in their propaganda. March is the only one using Super ED. Their propaganda states all their other scopes use ED glass, except for the LPVOs, where ED glass is not needed.

Edited to add: ED is not necessarily "better glass". It is designed to address a specific issue (CA) and it's only a few lenses that are ED and Super ED glass. Super ED glass is very spendy ($$$).

 

[209jones]

I don't understand a pile of optics discussions, but, I can say that along about 1991, I had a double hole on a target I couldn't see at 200yds with a 15-45 B&L spotter, so, got mad and went to sa birding/optic store, end up with a Kowa 77. Took the target with me and stuck on a post 200 yds away (turned out to be quite conveniently on the entrance to Cdn Tire store) across the mall lot. Hot day, lots of mirage, it was pretty much no contest against 5 or 6 other spotters he had there. Seems to me it has flourite coated lenses, and that's always been an ad feature with Kowa since then, at least. Not that I intend to "upgrade" it, but do wonder what would be the difference in the lenses, from say the 1991 flourite coated lense to what is on them now? I have certainly never regretted buying that scope, although it was a case of handing him the c/card and saying "don't tell me the price" at the time (was 1000.00 Cdn).

 

[Turbulent Turtle]

The word is fluorite, not flourite. Also, fluorite glass is not a coating, it's the actual glass material. There are fluoride coatings, but that's not what we are talking about here. Notice the spelling: fluorite glass, fluoride coatings. Not the same thing.

Not sure about the Kowa 77 from 1991, but I think Kowa introduced their fluorite glass more recently and the 77 was XD glass until recently. I think that's their version of ED or even Super-ED glass.

 

[Krogen]

Some years ago an "eye-opener" to better sporting optics occurred while hunting rockchucks. I had a new set of Fujinon binoculars. I spotted a critter flattened out sunning itself on some basalt. Plain as day. Then I went to find him in my Leupold scope. I couldn't see him. Back to the binoculars and again he was plain as day. I still couldn't find him in my scope. The hapless critter lived another day.

I think this was largely due to binocular vision. Two eyes are better than one! Still, closing one eye and looking through the binocular gave a better image than the scope. That points out the second issue - optical quality. Fujinon lenses and optical mechanism were just better than Leupold.

 

[Turbulent Turtle]

This video might be of interest for the readers of this thread.

 

[CA_Shooter]

@Turbulent Turtle - on the topic of seeing mirage, is there a good way (other than looking through someone else's) to know if a pair of binos or even a monocular will be able to see mirage before buying?

If its possible for a monocular to see mirage, it would be 100% to see mirage for Wind calls

 

[Turbulent Turtle]

@Turbulent Turtle - on the topic of seeing mirage, is there a good way (other than looking through someone else's) to know if a pair of binos or even a monocular will be able to see mirage before buying?

If its possible for a monocular to see mirage, it would be 100% to see mirage for Wind calls

I have little experience with binoculars at a match. As for monoculars, I have been testing a Tracking Scope prototype from March, based on the 8-80X56 HM Majesta riflescope. With its Super-ED lenses, it detects the faintest of mirage. I'll have more to say about it soon.

 

[Turbulent Turtle]

I wish to add more to my reply above, now that I have had more time to cogitate and do some research.

My hypothesis about CA and mirage-scrambled IQ is simply that CA exacerbates the degradation of the IQ engendered by "mirage" in a riflescope or any other optics. The more the optical devices bens the light, the greater the CA to be controlled. CA control is achieved with ED and especially Super ED/CaF2 glass for all wavelengths, or by judicious use of disparate types of glass in optics, but only for 2 or 3 wavelengths.

That said, I have not done any research on binoculars and how they really work, ie, the exact light path. In the deep recesses of my aging memory, I remember the two types of binoculars: Porro-prism, with the emblematic zig-zag shape featuring the big objectives lenses set far apart, so prized by U-boat captains in old war movies, being chased by destroyer captains also using similar binos. Roof-Prism, which only really started taking off in the 1970-1980s with the introduction of the compact Schmidt–Pechan roof‑prism designs with modern phase‑correction coatings. I remember when these new models became popular and people started shedding their big-ash porro-prism binos for the "new" smallish roof-prism binos.

However, these somewhat-maligned porro-prism binos have advantages of the roof-prism models. They present a better stereoscopic view, because the objectives are farther apart and they have a less complicated (read this as better) optical path compared to the roof-prism models.

I have an ancient pair of porro-prism binos as well as a pair of new SIG roof prism binoculars. The porro-prism (PP) binos are from the 1960s, meaning the glass is not coated in any way. The image is dull, the colors washed out, but the 3D effect is excellent. The Sig roof-prism (RP) binos have fabulous IQ, but they don't have near the stereoscopic view of the old PP binos.

Kowa makes the Highlander binocular model, with CaF2 glass and a 30X magnification. That is an object of desire and at $5000+, one might want to justify the purchase by using them, a lot. They should be fantastic for discerning mirage, to say the least.

As I said earlier, I have not tried using binos to read mirage. I use my Kowa 883 and also, the March TS prototype with its Super ED glass. They both work beautifully for the purpose.

If one is intent of using binoculars for reading conditions, mirage, etc., I would look for roof-prism models with Super ED/CaF2 glass; they do exist and they are pricey, but not Kowa 88x or 99x pricey. But I would most certainly be more interested in a porro-prism model with Super ED/CaF2 glass, if such an animal does exist, beside the Kowa Highlander. A quick search shows a few specialized (read $$$$$) models from Nikon, Fujinon, etc.