F Class John
NRA Life Member
Only shoot when the bouncing blob is at the top or the bottom, never both times....
f class at 600 yards and can’t see the target just a blob
- Thread starter kawsam62s
- Start date
Jeff Porter
Gold $$ Contributor
Exactly - Not mirage but I have done exactly this in rainy weather on a sling target. Bull was a non distinct gray blob but the corner of the buff target face on the soggy brown cardboard was sharp enough to aim at. Knowing the full sheet target is about a 72" square I aimed at upper left corner, Came down 6 moa and right 6 moa and hit the 10 ring... clicked it into the X ring from there.
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Do you mean 6 moa down and then 6 moa right?
Jeff Porter
Gold $$ Contributor
LOL yes - I will fix that.
Lol I was getting worried!
I've never understood such statements. Mirage is there... it's moisture in the air and it refracts the image which causes distortion. No glass sees through the moisture from between you and the target.
If you cannot see the mirage it is for one of two reasons, either the glass is of exceptionally poor quality, or the depth of field is exceedingly short... neither of which are advantageous. A short depth of field presents a superbly blurred image in heavy mirage just as bad glass does.
Good glass offers the clarity to read the mirage and the depth of field to see it well. Mirage is not your enemy, not having glass that enables you to read the mirage is the enemy.
For the last 3-4 years, I have been reporting my experiences with ED-glassed riflescopes in the Optics forum. I reported that my March-X 5-50X56 stayed at 40X, regardless of conditions, whereas I had to dial down in mirage conditions with my prior scope, the NF NXS-12-42X56.
I postulated that an effect of ED glass was to lessen the blending of the colors of the image due to the mirage. I also clearly stated that even ED glass was subject to IQ degradation due to mirage, but at a reduced rate compared to non-ED glass. March scopes were the first in the industry to use ED glass, and all March scope have ED glass except for the LPVOs with the 24mm objective, and another few select ones.
These few others use Super ED glass, which is even closer to pure fluorite crystal glass, without the issues of the latter. The March-X 10-60X56HM is one of those and I replaced my beloved 5-50X56 with the 10-60X56HM, two years ago. I have looked at both side by side and I detected the extra benefit to the IQ with the Super ED glass. It was not as much as going from non-ED glass to ED glass, but there was a benefit. Within a few months, I discovered that my 10-60X56HM was now always at 50X, regardless of conditions. To me, that represented a 25% improvement, from 40X to 50X, all the time.
I was at the Atterbury match discussed earlier, and I remember that day with the bad mirage. I stayed at 50X, of course, and went on to shoot a 197-10X at 1000-yards with my F-TR rifle shooting .308 Winchester. The mirage was there, for sure. The image of the target was solid, and the rings were "electrified" is the best word I can think of to describe what I was seeing. But I could place the target dot of the MTR-5 reticle exactly where I wanted it and got great results. I could clearly discern the mirage, its direction and strength and that helped a lot.
March is the only manufacturer offering Super ED glass in some of their scopes. The 10-60X56HM is the only SFP variable with that glass. There are 4 FFP scopes with the same glass: the Genesis 4-40X52 and 6-60X56, and the March-FX 4.5-28X52 and the 5-42X56. There are two fixed power scopes with Super ED glass: the 48X52 and the 40-60X52 EP.
I'll say it again, ED (and in March scopes only, Super ED) glass retards the IQ degradation due to conditions; it is NOT immune to mirage.
I postulated that an effect of ED glass was to lessen the blending of the colors of the image due to the mirage. I also clearly stated that even ED glass was subject to IQ degradation due to mirage, but at a reduced rate compared to non-ED glass. March scopes were the first in the industry to use ED glass, and all March scope have ED glass except for the LPVOs with the 24mm objective, and another few select ones.
These few others use Super ED glass, which is even closer to pure fluorite crystal glass, without the issues of the latter. The March-X 10-60X56HM is one of those and I replaced my beloved 5-50X56 with the 10-60X56HM, two years ago. I have looked at both side by side and I detected the extra benefit to the IQ with the Super ED glass. It was not as much as going from non-ED glass to ED glass, but there was a benefit. Within a few months, I discovered that my 10-60X56HM was now always at 50X, regardless of conditions. To me, that represented a 25% improvement, from 40X to 50X, all the time.
I was at the Atterbury match discussed earlier, and I remember that day with the bad mirage. I stayed at 50X, of course, and went on to shoot a 197-10X at 1000-yards with my F-TR rifle shooting .308 Winchester. The mirage was there, for sure. The image of the target was solid, and the rings were "electrified" is the best word I can think of to describe what I was seeing. But I could place the target dot of the MTR-5 reticle exactly where I wanted it and got great results. I could clearly discern the mirage, its direction and strength and that helped a lot.
March is the only manufacturer offering Super ED glass in some of their scopes. The 10-60X56HM is the only SFP variable with that glass. There are 4 FFP scopes with the same glass: the Genesis 4-40X52 and 6-60X56, and the March-FX 4.5-28X52 and the 5-42X56. There are two fixed power scopes with Super ED glass: the 48X52 and the 40-60X52 EP.
I'll say it again, ED (and in March scopes only, Super ED) glass retards the IQ degradation due to conditions; it is NOT immune to mirage.
jackieschmidt
Gold $$ Contributor
I have three March High Master 48x fixed, and my Nightforce 10x55 is as good if not a little better as far as resolution goes.
But I am judging this just out to 300 yards.
But I am judging this just out to 300 yards.
I don’t know why it works but it does. I’ve had scopes side by side and you can make out the lines fairly clearly in one and it’s just a black blob in the other. When there’s no mirage they both see clearly. Both scopes set to the same power as well.
Not to be pedantic but mirage is a result of temperature gradients (and thus density gradients) in the air through which the light is traveling from the target to the viewer. Humidity can exacerbate mirage but in and of itself is not causative. Your analogy of the light diffraction observed when viewing an underwater object from above the surface is excellent and occurs for the same reason...density changes between air and water. The same can be seen underwater at thermoclines and at interfaces between salt and fresh water when viewing under water.
I love it when Robin says "not to be pedantic," and then he loses himself in pedantry. So pedestrian.
Denys, I was lost way before I ever responded. LOLI love it when Robin says "not to be pedantic," and then he loses himself in pedantry. So pedestrian.
Yeah, that came across loud and clear. I look forward to seeing you at the next 1000-yard match in 2 weeks time.
MGYSGT
Silver $$ Contributor
Sounds like you need a barrel mirage shade
I'm not sure you are correct here.
My interpretation of mirage is that temperature changes cause the relative humidity in the air to change as temperature changes. That results in various refraction densities that distort and refract the image differently. We interpret this distortion as mirage.
I do not believe that in a zero moisture environment you would see mirage regardless of wind or temperature. For example, I have never seen mirage taken on a photograph from Mars where water in the air is pretty close to zero moisture.
So yes, I do believe that water vapor in the air is as you put it is causative. Heat alone is not the cause of mirage, both heat and moisture are required.
You reference similar disturbance under water at the thermo cline. I have seen this myself at around 66 feet in Lake Huron. The common elements again are heat and water. In this case the changes to the density of water is again the lens that causes the refraction.
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While I am no expert, I have been in the Mojave desert and seen mirage. So your statement that heat alone is not a cause of mirage does not seem to stand up. Although any moisture may had to this, from my observation it is not required, at least in any abundance.
So, what was the humidity level in the air in the dessert?
While it seems dry, I can reasonably assume there was still moisture in the air.
The hotter the air, the more water vapor it can hold, so I don't really see your point as counter to mine.
Big difference between the Mojave desert and Mars, just guessing... I have no idea how much water is in the air on Mars. I just don't recall ever seeing a photo with Mirage from Mars.
I did look around a bit on the internet and the descriptions I found of mirage only mentioned temperature as a factor, but I assume they simply ignored the presence of water in the air within the context of the statement.
I have a good friend who is a meteorologist. I'll try and catch up with him and ask his opinion.
What Is The Humidity Of The Mojave Desert? - Sciencing
The humidity of the Mojave Desert changes throughout the day and night and from season to season. Average daytime relative humidity ranges from 10 percent to 30 percent. Nighttime humidity can be as high as 50 percent. Humidity is higher before and after the Mojave's infrequent rainfalls; it...
sciencing.com
The humidity of the Mojave Desert changes throughout the day and night and from season to season. Average daytime relative humidity ranges from 10 percent to 30 percent. Nighttime humidity can be as high as 50 percent. Humidity is higher before and after the Mojave's infrequent rainfalls; it tends to rise at night and during cold weather and to drop during the day and in hot weather. These temperature-associated fluctuations are largely a function of how humidity is measured.
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Mirage is all about the refraction of light passing through different density air masses. The photons get ‘bent’ as they pass through the interface between the layers. The overwhelming variable in air density is temperature when pertaining to mirage. Humidity will play a minor role. Theoretically zero humidity air will exhibit mirage if differentially heated.
I spoke with my friend the meteorologist and this is what he said... keep in mind that I'm paraphrasing...
Hot air is less dense than cold air
Humid air is less dense than dry air
Molecular weight of water is 18
Molecular weight of Oxygen is 32
Molecular weight of Nitrogen 28
Dry air is roughly 30 percent nitrogen and 70 percent oxygen, so the average molecular weight of dry air is about the average of 32+32+28 = 30.6 (roughly)
The more water in the air the lower the molecular weight of moist air. He didn't say how to calculate the molecular weight of moist air, and I didn't ask.
Cool dry air mixing with hot humid air creates the maximum density deferential and therefore the maximum mirage.
Therefore absolutely moisture is a significant factor in mirage.
He did say that even in zero humidity there could be mirage if cold air mixes with warm air.
Hot air is less dense than cold air
Humid air is less dense than dry air
Molecular weight of water is 18
Molecular weight of Oxygen is 32
Molecular weight of Nitrogen 28
Dry air is roughly 30 percent nitrogen and 70 percent oxygen, so the average molecular weight of dry air is about the average of 32+32+28 = 30.6 (roughly)
The more water in the air the lower the molecular weight of moist air. He didn't say how to calculate the molecular weight of moist air, and I didn't ask.
Cool dry air mixing with hot humid air creates the maximum density deferential and therefore the maximum mirage.
Therefore absolutely moisture is a significant factor in mirage.
He did say that even in zero humidity there could be mirage if cold air mixes with warm air.
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