Atmospherics?

[Bill Ferris]

Since noise is a product of the total light energy used to make a photo, compositing multiple exposures of the same scene and composition increases the total light used to make the final composite. As a result, the final image is cleaner.

Compositing multiple exposures of the same static scene suffering from poor atmospheric seeing is likely to make the effects of that distortion even worse. If anything - provided the light level allows it - you could lean into the conditions, close the lens aperture and reduce the ISO enough to use a really slow shutter speed to capture the subject's movement with intentional blur. There would still be distortion from the unstable air but, if the blur is prominent enough, that might overwhelm the lack of resolution.

 

[Nimi]

Think of "atmospherics" as a small cloud between you and your subject. It's not noise, or artifact or anything like that. It's part of the scene.

 

[JAJohnson]

Think of "atmospherics" as a small cloud between you and your subject. It's not noise, or artifact or anything like that. It's part of the scene.

Well said.

 

[Jbear]

I think I'd rather just wait for a better opportunity than try number theory, topology, quantum mechanics, and a super-computer to have a slightly-less-garbage shot of something I've probably got a thousand other shots of. Of course if I happen across a triceratops grazing...I'm willing to put in the mental/technical elbow grease...but datz me.

 

[Not A Speck Of Cereal]

And third, not applicable to photography, sensing with different wavelengths would "ignore" the barrier atmospheric effects. I am not aware of a consumer camera that performs it in-body and I am not aware of commercially-available software for use in post processing.

If I'm understanding that properly, I've found that infrared can cut through atmospherics. I was able to take much better shots of a distant mountain through wildfire haze using an 850nm IR filter, compared to the same shot (at the same time/place using the very same lens) for a visible light spectrum shot on a non-IR camera.

Of course, that's of no interest to anyone here shooting wildlife with visible-light color-image cameras (850nm in landscape being only useful for black and white work).

Chris

 

[ARClark]

Think of "atmospherics" as a small cloud between you and your subject. It's not noise, or artifact or anything like that. It's part of the scene.

I view atmospherics differently. A cloud is visible, and whether to include it in one’s composition can be a conscious decision. Atmospherics from light refraction, short of obvious heat waves, are typically invisible to the naked eye, revealing themselves only after the shot is taken where they unexpectedly play havoc with fine detail.

 

[Not A Speck Of Cereal]

I view atmospherics differently. A cloud is visible, and whether to include it in one’s composition can be a conscious decision. Atmospherics from light refraction, short of obvious heat waves, are typically invisible to the naked eye, revealing themselves only after the shot is taken where they unexpectedly play havoc with fine detail.

I've always been able to see haze. I mean, at least, the effects of haze, but it's visible. You can't make a compositional decision about it, you either take the shot or not. Some don't like it, but of course haze gives us depth in a shot. If you need something more defined, make sure there's a feature subject somewhat closer than the haziest distance.

Chris

 

[Doug Herr]

If I'm understanding that properly, I've found that infrared can cut through atmospherics. ... 850nm IR filter...

I suspect the reason is you're using only a single wavelength. Atmospheric distortion will refract different wavelengths differently, just like the dispersion from glass lens elements. Examples are the prism effect on broad-spectrum light sources and the rainbow effect.

 

[Not A Speck Of Cereal]

I suspect the reason is you're using only a single wavelength. Atmospheric distortion will refract different wavelengths differently, just like the dispersion from glass lens elements. Examples are the prism effect on broad-spectrum light sources and the rainbow effect.

Yeah, sort of. The 850nm wavelength is a high-pass cut-off point, not a single band-pass, filtering everything below that and allowing all above that point.

720nm is considered the 'standard' wavelength filter for IR work, which allows a small amount of color / visible light (which is 380-780nm), while anything above the ~800nm is more or less monotone and used for black and while imaging (in art, different things in forensics).

But you're right that since the 850nm filter is so good at cutting through atmospheric haze, it must be that those atmospherics scatter the visible wavelengths better than the IR ones.

Chris

 

[Doug Herr]

Yeah, sort of. The 850nm wavelength is a high-pass cut-off point, not a single band-pass, filtering everything below that and allowing all above that point.

What wavelengths are recorded by the sensor?

... since the 850nm filter is so good at cutting through atmospheric haze, it must be that those atmospherics scatter the visible wavelengths better than the IR ones.

Refraction affects all wavelengths. When the camera is recording fewer wavelengths the effect of dispersion is less visible.

 

[Not A Speck Of Cereal]

What wavelengths are recorded by the sensor?

The sensor will record all of it (at least UV, visible light, and IR). For that reason, all standard cameras leave the factory with a hot-filter (IR-cut filter) over the sensor.

When someone does an IR conversion, they first remove that factory hot-filter. Then they might install an IR filter in it's place.

Rather than asking for an IR filter in place of the hot-filter, you can get a "full-spectrum" conversion. It's up to you to put the IR filter on the lens. The benefit here is that you can have different wavelength filters to put on the lens and have your choice of what kind of IR photography you will do from frame to frame, ranging from wild false-color imagery to stark, contrasty black and white.

But with a full-spectrum conversion, you can also shoot with no filter at all on the lens to get all of those wavelengths hitting the sensor. This can be beneficial for some things, such as astrophotography. Here's a page describing that. You can also get a H-Alpha band-pass filter to use with a full-spectrum camera.

Full-spectrum daytime photography isn't very interesting to me (not the reason I do IR).

On-topic: at any rate, I found that the 850nm really cuts through the haze, even wildfire smoke, which is more common these days.

Chris

 

[ARClark]

I’m not referring to haze, though that does bring up the fact that the term “atmospherics” is imprecise and could apply to a range of effects on photography. I’m referring to the effects produced by light moving through pockets or layers of air of varying temperature and density. The light can be bent imperceptibly to our eyes but show up as softening of fine details in images. I frequently encounter it when shooting birds, even at close distances if conditions are “right”.

 

[Doug Herr]

On-topic: at any rate, I found that the 850nm really cuts through the haze, even wildfire smoke, which is more common these days.

It's because you're limiting the spectrum. It's not because IR isn't refracted.

 

[Cameron T]

Yes. The movement of the molecules of air and differences in temperature (and thus refracting the light differently) is what causes it, and how they bend light. It doesn't matter what kind of molecules are between you and the thing you're taking a picture of. You see the same effect with thermal layers in the ocean and how they mess up sonar. It's a physics issue, not a particle type issue.

 

[bleirer]

I see that you are correct, that it is a separate issue from haze.

 

[cmc4214]

Yes absolutely...I know that and have for a long time. Not asking if it's real...My question is how can it affect one lens (same setting...same distance) more or less. Look at my analogy (at the end)...hopefully is helps clarify what I am asking.

A lens or hood can cause heat distortion if they are at a different temperature than the surrounding air, so could one assume that a denser/heavier lens/ hood might cause more distortion than a lighter one...just a guess.

 

[bleirer]

A lens or hood can cause heat distortion if they are at a different temperature than the surrounding air, so could one assume that a denser/heavier lens/ hood might cause more distortion than a lighter one...just a guess.

I would think it would take slightly longer for the heavier one to equalize with the air temperature, but it should be so slight we wouldn't notice the difference,

 

[rjselders]

Great topic. About wavelengths, do Didymium filters have a noticeable affect on seeing? I seem to recall rare earth filters discussed to improve images at one time.

Bob

 

[macwalter]

My take isatmospheric issues rear their ugly head in greater amounts the further the subject is away. It can be hard to determine just how bad on any given day or situation it will be. I was in Bosque this past December photographing snow geese and cranes to good effect when just a bit further out a gray ghost started hunting low over the field, no more than 50-100feet beyond. Not a single usable shot although the cranes and geese were fine. I was Using my 600pf without the tc and also with. I do find that a sharper lens can give you a bit more resolution further away and just maybe in some cases give you a hair better result. I can remember the old days spending hours in Africa trying to get a good shot of a couple rollers doing their thing way out in the field, I couldn’t get closer for obvious reasons. Needless to say I never got a single usable shot.

 

[fcotterill]

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