Please elaborate on the above either here or even better start a separate thread.
I'm happy starting a separate thread, but I think it fits better here. After all, it's just a couple or three old farts discussing an esoteric subject.
My observations come from empirical data and I'm too stupid or overworked to figure out a way to confirm or infirm "scientifically." Of course, it could all be in my head or just the way my eyes works.
When I first started F-class about 12 years ago, I was not ready to commit big bucks for a rifle and the glass to complement it. I was using a heavily modified AR-15 on which I had installed a Weaver T-36. That scope has phenomenal tracking, but the optics, well, suck.
I shoot most of my matches in south Texas and we have "mirage," a lot of it. Between April and November, we may get one match in before the sun really starts to do its thing but after that one match, it's mirage time. Big time.
In my T-36, I would look at the aiming black on the target and it would be like looking at an amoeba doing a St-Vitus dance. The stupid thing was changing shape as I would look at it through the scope. Needless to say, the scores suffered from that dance. In time, I upgraded to a rebuilt .308 bolt and kept the T-36 on it. After a while, I decided to take the plunge and got a rifle built and bought a Nightforce NXS 12-42X56. I immediately notice that the amoeba had been tranquilized greatly, but it was still fluttering around the periphery. At least, it stayed round. I could definitely see the mirage waves in the scope and I played with some filters to see if that would have any effect. I found that a middle yellow filter would highlight the mirage somewhat, but by virtue of having another stop, the already darkish NXS at 40X got even darker. Not a good thing for this old geezer. I did notice that the mirage waves were much less pronounced with the NXS than with the T-36. Huge difference in IQ as well as price.
Then I looked through some March scopes and bought a March-X 5-50X56. Once again, when it came time to look at the target in mirage conditions, I noticed yet another marked improvement of the IQ. In heavy mirage, all I see is some fluttering around the edges and I can barely discern the waves. On the other hand, in my Kowa TSN-82SV, I have absolutely no problem discerning the mirage waves, speed and direction. My Kowa does not have ED glass, but my March certainly does.
As I have stated several times now on this site, I'm an avid long-time photographer and as you would expect, I subscribe to photography discussion sites. ED has been in camera lenses for several decades now. My photo equipment is all Nikon with Nikkor lenses and they all have ED glass now. A lot of photogs agree that ED glass increases the IQ of a lens especially in challenging (mirage) conditions. I postulate that also holds true with sports optics. A group of optics users that live and die by their optics is birders. The more extreme the birder, the better their optics. They are HUGE fans of ED, super-ED and fluorite glass. They love the glass for color rendition, chromatic aberration control and being able to see through tough conditions.
My (probably mistaken) belief is that ED glass (super-ED and fluorite glass) "tames" the sparkle of the mirage and deadens it. I see more and more people using modifier disks on their high-end rifle scopes to try to INCREASE the mirage by increasing the depth of field due to the reduction in the aperture. I think, they're just trying to compensate for having ED glass.
When I shoot individual, I use my Kowa to read the conditions, including the mirage and then I transition to my rifle with the March scope with ED glass always set at 40X, regardless of conditions and I don't see anywhere near as much mirage in there as I did with my non-ED NXS and my non-ED Kowa. The Kowa is running at 27X, so that will increase the depth of field but I can still discern far more mirage waves in my Kowa that I can hope to see in my March.
For me, I would rather see all the mirage in my spotting scope, make a call and then transition to my March scope with ED glass and surgically place the reticle where I want it on the target easily and take the shot. Then I can go back to my Kowa to observe the conditions and shortly see the results of my "surgical shot placement," mirage and all.
Could this be a figment or my imagination? Sure. But I do spend a lot of time using my spotting scope calling wind for the team and that's when it's important for me to get all that mirage. My Kowa delivers all that and still presents me with a sight picture that has an IQ decent enough to not give me a headache even after peering through it for hours, but boy do I see the mirage twitches in the spotting scope.
It could be my eyes and just the way things work out for my setup. I am not married to the hypothesis but for now, it's working for me. My recommendation is to use the best glass in the riflescope, including ED so as to facilitate the shot placement and great, non-ED, Super-ED or fluorite glass in the spotting scope so you can see the waves. For those not using a spotting scope get a high-end, non-ED glass riflescope or use an MD; or both.
That's my hypothesis; fire away.
ETA: IQ stands for Image Quality. Apologies for the photog lingo.
