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brikman
Guest
Has anyone here ever tryed a Polarizer lens filter on there scope to help with the Mirage i cant seem to find any info .
David Halblom
Flying Fish Fundamentals
In order to minimize Mirage, you need to kill the blue end of the light spectrum. I know I will get the numbers wrong, but a yellow 15 and a red 24 filter stacked will do the job. You cannot do it with just one filter.....BUT......... Why do you want to get rid of it? Mirage is another wind flag. Learn to use it to your advantage. Learn to understand what you are seeing thru your scope.
As for the filter #'s, I would go to my shooting trailer and give you the exact filters, except it is 400 miles away right now. I use the filters on my spotting scope when things turn to oatmeal so I can see bullet holes at 300 yards. But I would NEVER consider doing that on my rifle scope. I want to see the mirage in my rifle scope. If it is boiling, don't shoot. If it is running, how fast and where, as it is an indication that there is wind out there moving the heat around. the only time I would ignore mirage is if I were shooting a railgun that I knew was an absolute return to battery.
As for the filter #'s, I would go to my shooting trailer and give you the exact filters, except it is 400 miles away right now. I use the filters on my spotting scope when things turn to oatmeal so I can see bullet holes at 300 yards. But I would NEVER consider doing that on my rifle scope. I want to see the mirage in my rifle scope. If it is boiling, don't shoot. If it is running, how fast and where, as it is an indication that there is wind out there moving the heat around. the only time I would ignore mirage is if I were shooting a railgun that I knew was an absolute return to battery.
John Kielly
Shari's fan club
A polariser is unlikely to remove mirage, if that is your intention. Late in my prone rifle career, I changed to polarised prescription lenses in my shooting glasses to eliminate glare caused by non-parallel light reflected/refracted by the atmosphere. I could still see the mirage through my rifle scope, though maybe less assertively. By that, I mean that the displacement caused was still there, but it only looked like floss floating by, not cords.
Tim Oltersdorf
Active member
If you use that polarizing filter on your scope you will be sorry. It will allow you to inadvertently see the hidden extra universe dimensions theorized by string theory. They are filled with bizarre, evil beings who move targets, smack bullets in flight, twist powder measure knobs, fart in your face when you pull the trigger and generally play hob with your agg. Don't do it. You don't want to know. Tim
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abintx
Guest
Here's something I was taught and it always helps me when Mirage is present:
Mirage blurs the target, making it difficult to establish point of aim; it does not permanently displace the image. Mirage causes you to aim at the wrong spot.
Establish point of aim in the cool morning, and check it throughout the day; you'll see that it does not change.
With Mirage the target image will bounce around, but always snaps back to the same point.
I do my shooting when it snaps back which indicates that the mirage has temporarily let up or dissipated for the moment, and the target is clearly visible.
Mirage blurs the target, making it difficult to establish point of aim; it does not permanently displace the image. Mirage causes you to aim at the wrong spot.
Establish point of aim in the cool morning, and check it throughout the day; you'll see that it does not change.
With Mirage the target image will bounce around, but always snaps back to the same point.
I do my shooting when it snaps back which indicates that the mirage has temporarily let up or dissipated for the moment, and the target is clearly visible.
And here I though that smell last weekend was my crappy shooting, thanks for the revelation.
Boyd Allen
Active member
Years back, I tried a circular polarizing filter, just looking through it and the scope, not shooting. It increased contrast, but darkened the image too much to be useful. What type of shooting are you doing, and what scope are you using?
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Vibe
Guest
The only way I've figured out to really see how much the mirage is moving the target image is to use the same effect to move another light path. Mirage makes you shoot at the wrong spot by bending the path of the light carrying the image of the target to your scope. To see how much it's been moved - mount a laser on your scope and zero both at the target distance in zero mirage conditions. Any mirage that moves the image should also move the laser on the way down to the target. The POA/POI should then always be 1/2 way between where the bull looks to be and the laser spot.
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IndianaJames
Guest
HuskerP7M8
Member
Vibe,
I remember being involved in a discussion with you a couple of years ago concerning using a laser to measure or correct for mirage and it may have been on Mike’s smallbore forum. Anyway, at that time, I took 3 or 4 lasers I had laying around the house out to my tunnel one day to play with and was bitterly disappointed at how large beam divergence was and how poor resolution was in measuring both the spot diameter and determining a reference point for measuring movement relevant to the effects of mirage.
I spent a few minutes googling laser specs back then and again this morning before making this post and I’m not sure there’s a practical way to make this experiment workable. That being said, I’m not very knowledgeable about lasers and there may be a solution I’m not aware of.
Landy
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Vibe
Guest
True. there is an issue with the "standard" optics on many laser pointers, as well as the natural beam divergence just from traveling through air. As I recall reading somewhere, the best optics in the world still result in a laser "spot" projected from the Earth onto the Moon as being larger than a football field. But so long as the beam stays essentially round, it should still be able to indicate the off-center nature - particularly when compared to target bull rings. But then again, I'm sure the optics on your lasers were better than the few I've tried.
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mks
Guest
Vibe,
The laser idea is intriguing, but I must be missing something. If the laser travels the same optical path as the line of sight, and wavelength effects are neglected, because Snell's law is reversible, the laser would be refracted the same as the target image. In other words, if you line up the cross hairs and the laser on the bull without mirage, and then the mirage starts, the laser image and the target image would dance around in lock step, which doesn't help. If the laser is mounted to the side or above the scope, it will travel a different optical path, but with unknown differences from the line of sight, which also doesn't help.
Now since refraction is wavelength dependent, it is possible that by using lasers with two different wavelengths that one could calculate the refraction of the line of sight from the difference in refraction of the two laser images. I don't know for sure, it would take some digging into the equations to see if this would yield a solution.
Clever idea, regardless.
Keith
HuskerP7M8
Member
Vibe,
I’ve got a few hi-tech toys in my tunnel but lasers aren’t among them. These lasers were of the sort you’d purchase at an office supply store and used as pointers. But, I got the impression (possibly wrong) from looking at images with higher quality lasers that this may be a problem I don’t know how to work around within the limits of my knowledge or finances.
Landy
HuskerP7M8
Member
Keith,
I seem to remember that astronomical observatories use what is called AO (Adaptive Optics) in conjunction with lasers to correct for atmospheric distortions and it’s done with almost unimaginable accuracy, but that particular system won’t be installed in my tunnel anytime soon. LOL
Do you have any familiarity with that system? Or, is it completely irrelevant to this discussion?
Landy
I seem to remember that astronomical observatories use what is called AO (Adaptive Optics) in conjunction with lasers to correct for atmospheric distortions and it’s done with almost unimaginable accuracy, but that particular system won’t be installed in my tunnel anytime soon. LOL
Do you have any familiarity with that system? Or, is it completely irrelevant to this discussion?
Landy
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Vibe
Guest
Keith
The laser beam is making 2 trips - one down and one back. Mirage will affect it in both directions equally. This will cause the beam to hit the target in a different spot - coming back, you are correct and both will be bounced around equally. So far there is only one scope maker (VISM) that mounts a laser designator inside a rifle scope - it's a "sister company" to NcStar, but they only go up to 9x that I could find.
David
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mks
Guest
Vibe,
OK, let's see if I am getting this right: If the laser is rigidly mounted on the bench and is initially pointed at the bull, then after the mirage starts, all we have to do is shoot at the laser dot regardless of where the bull appears to be.
However, if the laser is fixed to the scope instead and initially (without mirage) aligned with the crosshairs, then because the optical paths are exactly the same, the laser always appears at the center of the crosshairs, even as the bull dances around. The laser doesn't help in this case. In fact, it provides nothing more than an illuminated dot at the center of the crosshairs.
The laser could be fixed in the scope by a gyroscope reference, I suppose.
Cheers,
Keith
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mks
Guest
Landy,
I'm no optics expert, but I think it depends on the size of the eddies of hot air. If they are large, AO would provide a really clear picture of the target, but it (the whole thing) would still bounce around. If they are small, then AO would make the target clear and steady, exactly what we want. AO, as I understand it, deforms a mirror or other optical element to smooth the wavefront, which is like averaging. If the average of the refracted image is the same as that of the real image, then the corrected image has the bull in the right place.
Keith
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Vibe
Guest
Your competitors will love you if you shoot that way. You will have the lowest score of the day.
If the laser always stayed in the center of the crosshairs - what would be the point? But since the mirage will throw where the laser spot hits the target away from the crosshairs - now you have some real feedback as to where the bullseye "really" is.
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mks
Guest
True, we haven't included THE WIND.
Exactly.
This is what I don't see. The laser travels a refracted path to the target. Because Snell's law is reversible, the light from the laser dot on the target retraces this same path in the opposite direction back to the scope, where the crosshairs are superimposed on it. Wherever you align the laser dot with respect to the crosshairs, it will remain there as long as the scope and laser alignment are the same. It is only the image of the bull that dances around. What am I missing here? Have you actually observed a different behavior? PM me if you want.
Thanks,
Keith
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IndianaJames
Guest
Keith,
The key here is the light from the target travels the path once. The light from the laser travels the path twice, doubling the displacement and making it visible relative to the crosshairs.
Jim
The key here is the light from the target travels the path once. The light from the laser travels the path twice, doubling the displacement and making it visible relative to the crosshairs.
Jim