Mirage - Normal Glass vs ED Spotting Scope

[Pinkes]

Hi

I want to buy a spotting scope but after reading all the threads on the subject, I’m still undecided.
Opinions are that you need lesser glass to pick up mirage early, others believe you need ED glass (top tier glass) to pick up small change and then there is a lot of people believe that ED glass( top tier glass) “cuts” through mirage.

I know the best will be to compare but unfortunately, it is not possible.

So, my Q is which is true or better for ready mirage. Ave or Top glass?



Regards

 

[boltfluter]

Hi

I want to buy a spotting scope but after reading all the threads on the subject, I’m still undecided.
Opinions are that you need lesser glass to pick up mirage early, others believe you need ED glass (top tier glass) to pick up small change and then there is a lot of people believe that ED glass( top tier glass) “cuts” through mirage.

I know the best will be to compare but unfortunately, it is not possible.

So, my Q is which is true or better for ready mirage. Ave or Top glass?



Regards

I cannot think of one reason, to not purchase the best glass you can afford. Just my take on it.
Paul

 

[Mark M.]

Hi

I want to buy a spotting scope but after reading all the threads on the subject, I’m still undecided.
Opinions are that you need lesser glass to pick up mirage early, others believe you need ED glass (top tier glass) to pick up small change and then there is a lot of people believe that ED glass( top tier glass) “cuts” through mirage.

I know the best will be to compare but unfortunately, it is not possible.

So, my Q is which is true or better for ready mirage. Ave or Top glass?



Regards

I'll say this, once you experience true top notch glass, you won't go back to "normal glass", check out Tract Optics for the best for the money spent.
TRACT Optics ? Rifle Scopes, Binoculars & Spotting Scopes

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tractoptics.com

 

[Ranger188]

@Turbulent Turtle

 

[rwj]

So, my Q is which is true or better for ready mirage. Ave or Top glass?

IMHO, it doesn’t matter as mirage is caused by light being refracted as it passes thru air having differing density/humidity layers before arriving at the scope. There are definitely differences in glass quality/clarity as determined by your eyes.

 

[coldboreshot]

Get the best glass you can afford. High end glass by my experience, does provide the most minute nuances however, I have yet to see any spotting or rifle scope "cut-through" mirage. Such a misleading statement. Mirage is an optical intrrference caused by atmospheric conditions between you and the target. If there is such a device that displaces mirage, let me know.

 

[Turbulent Turtle]

Let me see if I can explain this simple terms.

When you are looking at the target line with your mark 1 eyeball, you really don't see shimmer. You can see it in extreme conditions, such as the tailpipe of a jet aircraft at full power. You can also see a mirage with your naked eye, looking down a long stretch of paved road and you think you see a lake or water up ahead. That is a mirage. There are also cases of inversion, where you see an object above ground down the road, another mirage.

For us shooters, what we call mirage is the distortion of the image in our optics caused by the shimmer out there and made worse by the use of optics. When we increase the magnification on an optic, we bend the light more and this causes increased color dispersion in the optic, which further exacerbates the effect of shimmer and messes with the IQ of the optics.

(Please note that "bending the light" is done by the objective lens group. As we increase the magnification, we are examining a smaller portion of the FFP and the defects in the IQ are made more apparent. When we decrease the magnification, the observed section grows, and the details shrink along with the distortion.)

Low end optics do not control the CA very well and as you further examine a smaller portion, the IQ worsens dramatically. I had a long-running thread on this site about my experiences and findings using different types of glass and mirage. ED glass does a decent job of controlling CA across the entire spectrum, and I found that I could stay at 40X all the time, regardless of "mirage" conditions. The IQ deteriorated, of course, but not as quickly as non-ED glass. When people had to wind down their scopes, the IQ was more usable. I could stay at 40X.

Next came Super ED glass which actually contains a great deal of fluorite in a glass matrix. The CA is extremely well controlled in riflescopes with Super ED glass (the March High Master and Majesta scopes are the only ones with Super ED glass currently). In my case, I found myself using 50X all the time with my March 10-60X56 HM. In the Majesta, there is more pixie dust in the formula, and a lot of people shoot it at or near 80X in "mirage" conditions, where lesser scopes are wound down to the 20-some X or less.

When it comes to spotting scopes, as I discussed in that long-running thread, I selected Kowa as my latest spotting scope because they are the only ones with pure fluorite crystal glass, which has the highest Abbe number and thus the lowest color dispersion. It's a tick above Super ED glass, but it's pricey, fragile, and subject to temperature variations. That's not a problem for spotting scopes, can't say the same for a riflescope which is all about shock. The Kowa 883 is excellent in "mirage" conditions.

The neat thing about ED, Super ED and CaF2 glass is that since the CA is better controlled, you are able to actually discern the slightest twinge of "mirage" which will show up as a wind river moving in one direction or another. The definition is so much better.

If you want the best spotting scope to discern mirage and still be able to see the movement, Kowa with their CaF2 glass is the way to go. I will also add that other top tier optics that do not use ED/Super ED/CaF2 glass, can control CA very well but only for 2 or 3 specific wavelengths.

I hope that explains it. I tried to keep it simple and didn't even talk about the circle of confusion.

 

[Krogen]

I hope that explains it. I tried to keep it simple and didn't even talk about the circle of confusion.

Nice post, thanks. I know about the circle of confusion regarding camera lenses, depth of field and aperture size. Amusingly, the "Circle of Confusion" exists with various members of our gun club. It means a whole 'nother thing and has nothing to do with optics!

I don't have the super high end Kowa glass, but moving up to better glass was highly beneficial. I replaced my TSN82-SV with a TSN663. It's physically smaller with a smaller objective, yet it's far better optically. I can imagine what even better glass would be like. A buddy has a Majesta and it is stunning - both in optical quality and price. I say buy the best glass you can justify (or rationalize).

 

[RCE1]

In my opinion as a photographer of many years as well as a target shooter and spotter, good quality optics can be just fine for most situations. By good quality, I mean I have Kowa TSN 82 spotting scopes with 27x wide angle eyepieces (that were pre-fluorite) and I feel no need to upgrade. Kowa was kind enough to refinish both of them under warranty when the "rubberized" green coating started to peel off. That really impressed me.

The exotic materials really show their merit in difficult conditions, with the light causing flare in the lenses or the quality of light lacks contrast, like at dawn and dusk or severe stormy weather. Of course, anyone who's been shooting competitively for a long enough time will attest that marginal and unusual lighting conditions aren't unusual at all.

 

[Turbulent Turtle]

I have a TSN-82 which I babied and used for many years. It has the LER 27X eyepiece and the 25-60X zoom eyepiece (or whatever the range is.) It now sits in a closet since I got the 883. The difference in IQ is stunning. I am also a long-time photographer, as many here know after perusing the thousands of pictures of the many Nationals and World comps I posted here. I am all about optics and quality in lenses.

Here is a link to a video I took with my Nikon D7500 through my Kowa 883 with a digiscoping adapter. Notice the wind river of the mirage. Notice the degradation of the IQ, yet the aiming point of the targets remain round and you can still see and identify the rings. I ran the magnification to 60X, because it would not go higher on the Kowa. Other scopes would present a dreadful image with everything jumbled up past 25X.

This is the kind of image you see in the Majesta at high magnification; not crystal clear, nothing that you will show in a photography contest, but definitely a shootable target.
https://www.facebook.com/share/v/15yKxnwKVx/

I will also state that it was very difficult to focus the setup properly, I was looking at the little display in the back of the camera at high noon on the line at Ben Avery.

 

[Turbulent Turtle]

Nice post, thanks. I know about the circle of confusion regarding camera lenses, depth of field and aperture size. Amusingly, the "Circle of Confusion" exists with various members of our gun club. It means a whole 'nother thing and has nothing to do with optics!

I don't have the super high end Kowa glass, but moving up to better glass was highly beneficial. I replaced my TSN82-SV with a TSN663. It's physically smaller with a smaller objective, yet it's far better optically. I can imagine what even better glass would be like. A buddy has a Majesta and it is stunning - both in optical quality and price. I say buy the best glass you can justify (or rationalize).

Yeah, I know photographers will understand CoC, but I just thought it was a fun word to throw in.

 

[ronemus]

Another factor is objective size - the larger the aperture the more apparent mirage is.

 

[Turbulent Turtle]

The bigger the objective, the more you bend the light. The more you bend the light...

 

[Fred Bohl]

The bigger the objective, the more you bend the light. The more you bend the light...

Not necessarily good optical engineers would not do that unless the sales department is in charge.

 

[Turbulent Turtle]

Not necessarily good optical engineers would not do that unless the sales department is in charge.

What Fred wrote above is very important and that's why the better (more $$$) scopes deal with the issue better than others.

 

[ELR LVR]

we bend the light more and this causes increased color dispersion in the optic,

Are you saying that the mirage we pick up down range is tied in with CA
IE: When we are seeing mirage, by increasing magnification...
..we are magnifying a slight amount of CA and thats why we are able to pick it up?
This would make sense to me, even if I may be understanding this incorrectly
------------------
What I do know is, once I stepped up to Schott glass (Kahles) I noticed how it would
"See through" any mirage, or I did not perceive any mirage when compared to other scopes that are also high quality but not in the same realm of glass. (such as B&L vs. Kahles)
Just trying to understand how a higher quality glass scope can see through the mirage.
With my Kahles I cannot use mirage as an indicator of wind
However, it is nice to be able to clearly see my image undistorted at long range though.

 

[jnr88]

I have a TSN-82 which I babied and used for many years. It has the LER 27X eyepiece and the 25-60X zoom eyepiece (or whatever the range is.) It now sits in a closet since I got the 883. The difference in IQ is stunning. I am also a long-time photographer, as many here know after perusing the thousands of pictures of the many Nationals and World comps I posted here. I am all about optics and quality in lenses.

Here is a link to a video I took with my Nikon D7500 through my Kowa 883 with a digiscoping adapter. Notice the wind river of the mirage. Notice the degradation of the IQ, yet the aiming point of the targets remain round and you can still see and identify the rings. I ran the magnification to 60X, because it would not go higher on the Kowa. Other scopes would present a dreadful image with everything jumbled up past 25X.

This is the kind of image you see in the Majesta at high magnification; not crystal clear, nothing that you will show in a photography contest, but definitely a shootable target.
https://www.facebook.com/share/v/15yKxnwKVx/

I will also state that it was very difficult to focus the setup properly, I was looking at the little display in the back of the camera at high noon on the line at Ben Avery.

Great post Mr. Turtle. Do you remember what the wind was doing?

 

[Turbulent Turtle]

The wind was blowing.

 

[jpjulian]

Are you saying that the mirage we pick up down range is tied in with CA
IE: When we are seeing mirage, by increasing magnification...
..we are magnifying a slight amount of CA and thats why we are able to pick it up?
This would make sense to me, even if I may be understanding this incorrectly
------------------
What I do know is, once I stepped up to Schott glass (Kahles) I noticed how it would
"See through" any mirage, or I did not perceive any mirage when compared to other scopes that are also high quality but not in the same realm of glass. (such as B&L vs. Kahles)
Just trying to understand how a higher quality glass scope can see through the mirage.
With my Kahles I cannot use mirage as an indicator of wind
However, it is nice to be able to clearly see my image undistorted at long range though.

If you have a target at say, 300 yards, and the next one is at 600, leave your focus at 300 when sighting at 600 and you should clearly see any visible mirage.