unshootable mirage

[kzin]

Shooting F class at Laurel MS one weekend and it was horrible. There was no way you could say you held the same spot twice. I came to the decision that if I ever had to shoot in mirage that bad again I was going to back off to 25 or less and dial.

It happened at Connaught last yr. I was shooting the Canadian Nats and the mirage was just abysmal. Dialed the whole match and held center. Shot the highest score I shot all weekend.

Good to know that other people do feel this way, not just my incompetence.

 

[DaveTooley]

I turn the power down some and slow down. Given a few more seconds your brain can average out the bumps and gyrations.

 

[dgeesaman]

Ok. Sightron scope. I don't know anything about those and since you didn't specify the exact model, I looked at the online specs for the SIIISS1050X60LR series. Since they didn't mention ED glass, I'm assuming the glass in those scopes is the regular kind.

My hypothesis, as described in my running thread, is that ED glass tames the mirage, reduces or eliminates the CAI. When I switched from regular glass to ED glass, the crazed amoeba covering the target got really placid.

The quality of the glass can not cancel the effect of the light being distorted as it reaches you from the target.

ED glass is a worthy upgrade for competition; I have no arguments there. But the mirage is occurring outside of the scope, and without some kind of wildly advanced digital solution, the best scope optics can only be expected to add to the the distortion as little as possible.

 

[Turbulent Turtle]

The quality of the glass can not cancel the effect of the light being distorted as it reaches you from the target.

ED glass is a worthy upgrade for competition; I have no arguments there. But the mirage is occurring outside of the scope, and without some kind of wildly advanced digital solution, the best scope optics can only be expected to add to the the distortion as little as possible.

I totally agree with that.

If you had read my other thread, you would have seen where I explain my hypothesis that non ED glass MAGNIFIES the effect of mirage and makes the image worse, whereas ED glass does not suffer anywhere near as much from the effect of mirage and present a better, more usable image. In other words, ED does not cure the distortion from the mirage, it doesn't make it worse like non-ED glass does.

 

[Turbulent Turtle]

As far as I know the SIII model differences are only in reticle design.

How does this relate to spotting scopes?
The other problem with mirage was that I never saw a bullet hole in paper all day.
Usually at 200 with a white target I can see them easily.

As I explained earlier, I know virtually nothing about Sightron scopes. At their website there are 3 different types of SIII scopes: The LR series, the Field Target series and the FFP series. Since you only gave the magnification range and not the full name, I had to infer a few things and that's why I picked the one I mentioned.

Spotting scopes will be affected by mirage also, but in competition, you want that. So, while my riflescope has Super-ED glass, my spotting scope has regular glass so as to show me the mirage in full force.

 

[dgeesaman]

I totally agree with that.

If you had read my other thread, you would have seen where I explain my hypothesis that non ED glass MAGNIFIES the effect of mirage and makes the image worse, whereas ED glass does not suffer anywhere near as much from the effect of mirage and present a better, more usable image.

I believe I read your other thread at some point but I did not make the correlation here.

In any case we agree.

David

 

[kzin]

As I explained earlier, I know virtually nothing about Sightron scopes. At their website there are 3 different types of SIII scopes: The LR series, the Field Target series and the FFP series. Since you only gave the magnification range and not the full name, I had to infer a few things and that's why I picked the one I mentioned.

Spotting scopes will be affected by mirage also, but in competition, you want that. So, while my riflescope has Super-ED glass, my spotting scope has regular glass so as to show me the mirage in full force.

Mine is LR fwiw at this point
I never knew or forgot the other two options exist, sorry.
Within LR there are multiple reticles which I assumed doesn't matter.

I'll go read your other thread at some point.
thanks for the input

 

[Turbulent Turtle]

I believe I read your other thread at some point but I did not make the correlation here.

In any case we agree.

David

Yes.

Being a simple man, I have to simplify things so that I can understand them. A method for doing that is to use an analogy. (Yes, I know, argument by analogy is a waste of time, but we're not arguing here. Analogies can be useful to explain things.)

I think of glass as the BC of the optics world. That works for coatings as well as glass type/quality. Keeping in the analogy, the objective size is the muzzle velocity. You let in more light (have a higher MV) with a bigger objective, but anything after that is going downhill. Once the mirage starts manifesting itself, the image gets progressively worse with the "low-BC" optics. The "high-BC" optics are also affected by the mirage, just not as much.

(Yeah, I know; it's lousy analogy but I think it gets the point across.)

 

[rjtfroggy]

I have a question, will a 4" sun shade help on a fixed power competition scope? (40 or 45 power) For 100-300 yard comps..

 

[Turbulent Turtle]

I have a question, will a 4" sun shade help on a fixed power competition scope? (40 or 45 power) For 100-300 yard comps..

I have a sunshade on most of my scopes for 2 reasons. 1- Protection for the objective lens. 2- Eliminate incident light for better IQ especially when aiming near the sun.

I remember a match at the 2016 Nationals in Lodi; late in the day, I was on the final relay and since the range is oriented east to west, the setting sun was in full bloom, so to speak. I was blinded. I crawled under a tarp that was also covering my spotting scope with its retractable sunshade extended all the way out. My riflescope also had its sunshade, which kept artifacts from showing up in the scope. The line of sight was very close to the sun; without a sunshade, it could have been pretty bad.

Another benefit is that I start my mirage shield just under the end of the sunshade.

ETA: A sunshade will do nothing for the mirage.

 

[WIB3]

Build a good tracking gun, trust your last sighter and let them fly. If your gun is tracking, no need to look thru the scope. Concentrate on shooting the gun and trust the professionals who made it. Don’t correct for the dancing patch for it will lie to you.

 

[Keith Glasscock]

Question:

How does a sunshade affect the reducing ring math from earlier in the thread? Does having the reducer farther from the objective change anything?

 

[WIB3]

There are times to trust your shooting ability and times to trust your smith. When the patch is dancing in your scope, shoot for group not got score.

 

[Turbulent Turtle]

Question:

How does a sunshade affect the reducing ring math from earlier in the thread? Does having the reducer farther from the objective change anything?

Excellent question. The answer is no, nothing changes. I have played with various color filters and the one time I tried the MD disk on mine, I placed it at the end of the sunshade. For the record, a medium yellow filter on my NF scope gave a little more contrast to view the mirage. Since switching from the NF NXS to a March, I've not taken the chance to try any filters. Maybe I need to do that, for data purposes. I have light yellow, medium yellow and I think a red somewhere.

 

[Scott Harris]

Shooting F class at Laurel MS one weekend and it was horrible. There was no way you could say you held the same spot twice. I came to the decision that if I ever had to shoot in mirage that bad again I was going to back off to 25 or less and dial.

It happened at Connaught last yr. I was shooting the Canadian Nats and the mirage was just abysmal. Dialed the whole match and held center. Shot the highest score I shot all weekend.

+1
I often go to about 15X in heavy mirage and use the reticle cross hairs to bracket the target and thereby center up. I always hold center.

 

[kvd]

Some March variable power scopes come with the aforementioned reducer but I've been lead to believe that with the power to reduce magnification, they really don't do much and are better used on fixed power scopes. Is that true?

There is a reason it is called mirage - because it is a mirage - an optical illusion. One more reason to not judge according to the seeing of the eyes. We know the truth that the target is stationary. For this reason, it is of vital importance to do everything possible to get the rifle to track perfectly and return to established POA every time. Having confidence that this is happening will then allow one to use the mirage to determine what the wind is doing down range. Perversely, when the boil is at its worst and straight up and down is the time to shoot because that is an indication of a calm in the wind. Don't let the mirage get the best of you and make it work for you.

My 2¢

 

[JFrank]

My question is;
When the mirage is running towards 10:00 and I hold center x why are my rounds hitting a 4:00 7 ring

 

[memilanuk]

Sounds like you're not looking at the dominant condition.

 

[Turbulent Turtle]

I have a thread running in the Optics section about mirage and glass. May I ask what scope you were using, make, model, etc?

Also, it's called "aperture", but what it really is, it's a way to cut down on the size of the objective lens in a way that will increase the depth of field and thus reduce the criticality of perfect focus that gets messed up by the mirage. If you make a hole in a cardboard sheet or a lens cap cover to be half the area of the objective lens, you will get the equivalent of 1 f-stop reduction. It will show more mirage because of the greater depth of field but it may reduce what I called the CAI, Crazed Amoeba Index; the pulsating center of the target viewed through a scope.

I did some quick calculations and if your objective lens is a 56mm, the diameter of the hole you need for 1 f-stop reduction is 39.6mm.

The formula is S = sqrt((O ^ 2) / 2)
Where S is the smaller objective diameter and O is the objective lens size (diameter) in millimeters.
If you want 2 f-stops reduction, change the 2 to a 4 in the division.

ETA: I corrected the definition in the formula above. Age is a terrible thing to have to deal with.

I am reposting the above to highlight the correction I made. The example calculation was correct and I used the proper term (diameter) in that line. However I mixed up diameter and radius in the explanation for the formula. I originally said, radius, but it's diameter. That's what happens when you drop the piece of Pi.

 

[JFrank]

Sounds like you're not looking at the dominant condition.

Humm, thanks man I’m going to ponder/study on that for sure cause it’s making me crazy