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Here is a terrible example of my issue: Photo of a ship several miles away

Technical data: Canon EOS 70D + Canon EF 100–400 mm f/4–5.6 L IS, ISO 320, 400 mm, 1/500 sec, f/10.

Is this issue caused by air turbulences over the water? Thank you.

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    \$\begingroup\$ That's a nice mirage you've shot there. \$\endgroup\$
    – Ilmari Karonen
    Commented Sep 12, 2019 at 8:39
  • \$\begingroup\$ @IlmariKaronen: A superior mirage, right? \$\endgroup\$
    – Eric Duminil
    Commented Sep 12, 2019 at 9:28
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    \$\begingroup\$ Now try astrophotography! Problem multiplied tenfold... \$\endgroup\$
    – Lightness Races in Orbit
    Commented Sep 12, 2019 at 12:08
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    \$\begingroup\$ @LightnessRacesinOrbit: Why? Shouldn't there be less distortion when shooting close to the zenith? \$\endgroup\$
    – Eric Duminil
    Commented Sep 12, 2019 at 12:20
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    \$\begingroup\$ @EricDuminil I'm referring to various phenomena such as gravitational lensing, which you can do even less about than the distortion in this case :P Astronomy requires a lot of deduction from multiple observations to actually find out what's "going on". Ultimately, light comes to you and that's the light you have to work with \$\endgroup\$
    – Lightness Races in Orbit
    Commented Sep 12, 2019 at 12:33

4 Answers 4

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This distortion is due to the sun shining on the water. The sun's heat warms the surface causing warm air to rise. Likely some water vapor mixed in. What happens is, different layers of different density air alters the path of the light rays from the principle subject. There is little you can do to mitigate. A UV filter or polarizing filter might provide a smidgen of help but this is something we live with.

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  • \$\begingroup\$ Thank you. I have also tried this with a polariser, but this only helped me a bit with the contrast, but not with the distortions. \$\endgroup\$
    – Neppomuk
    Commented Sep 11, 2019 at 20:52
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    \$\begingroup\$ I'd be really interested in knowing how a UV filter or polarizing filter could help in any way. \$\endgroup\$
    – Eric Duminil
    Commented Sep 12, 2019 at 9:26
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    \$\begingroup\$ UV/Blue filter only helps with scatter, not refraction. Polarizers only remove light reflected at certain angles, again, don't help with refraction. There is no way to remove the effect of the atmospheric refraction other than to reduce the amount of turbulent atmosphere you are shooting through (ie: get closer/higher, shoot in different environmental conditions). \$\endgroup\$
    – J...
    Commented Sep 12, 2019 at 15:35
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    \$\begingroup\$ Atmospheric haze obscures due to scattering and polarization driven by minute dust and water particles present in the air. A polarizing, due to its ordination mitigates plus it darkens the sky which increases contrast and penetrates haze. Since light scatter is more predominant for the shorter wave lengths (UV – violet – blue), a UV absorbing filter mitigate haze \$\endgroup\$
    – Alan Marcus
    Commented Sep 12, 2019 at 16:07
  • \$\begingroup\$ @AlanMarcus: My polariser also removes UV, but the ship and the lighthouse are both red and should not be affected be refraction, should they? \$\endgroup\$
    – Neppomuk
    Commented Sep 12, 2019 at 21:55
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Shoot early in day to avoid heat waves. Or shoot from elevated position.

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  • \$\begingroup\$ Best to shoot in the dark, probably. Look, no distortion whatsoever! \$\endgroup\$
    – Peter - Reinstate Monica
    Commented Sep 13, 2019 at 7:53
  • \$\begingroup\$ That kind of "distortion" tends to ruin night shots even more and more incalculably.... :) \$\endgroup\$
    – rackandboneman
    Commented Sep 13, 2019 at 23:07
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If what you try to photograph is not moving, you can go for ND filter + tripod for long exposure time.

This will replace some distortion by blurring (averaging moving distortion). However, some distortion will remain.

Combine with Ross Duggan answer for better results.

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  • \$\begingroup\$ May target was a ship, and ships move. :) Replacing distortion with blurring isn't an alternative, either, as I have already chosen the maximum possible enlargement, but the target still does not fill up the complete scenery. \$\endgroup\$
    – Neppomuk
    Commented Sep 12, 2019 at 21:53
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    \$\begingroup\$ If the ship is moving, the result will be disappointing indeed. You can however go with slightly longer exposure time (1/10's) in order to get some averaging without the subject moving too much. Tripod might be needed if you are at maximum zoom. \$\endgroup\$
    – Kevin FONTAINE
    Commented Sep 13, 2019 at 8:08
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The mirage effect is not caused by the equipment but by the light taking these funny paths, including diffraction/reflection at layers of different optical density above the ground or water, before it reached your lens; consequently there is little you can do about it by modifying your equipment at this location, weather and time of day. (Well, actually, since reflected light is somewhat polarized you may see less reflection with a polarization filter.)

The thing is that in my opinion you should not do anything about the "distortion": It is a very interesting image. The resolution is a bit low; did you present a crop to us? If anything I'd try to improve the resolution so that the crop does not degrade the quality so much. Since the ship (and the mirage) is the interesting part, it would be nice if the quality permitted cropping even more (in the absence of a lens with even longer focal length).

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  • \$\begingroup\$ Nope, this was not a crop. And 400 mm is already the maximum length available to me. \$\endgroup\$
    – Neppomuk
    Commented Sep 13, 2019 at 20:29
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    \$\begingroup\$ @Neppomuk Thanks for the info. Yes, you mentioned the lens in your question. The image appears void of meta data and of much lower resolution than what the camera produces, that's why I asked. \$\endgroup\$
    – Peter - Reinstate Monica
    Commented Sep 15, 2019 at 16:48
  • \$\begingroup\$ Nope, I had to downsample the pic in order to upload it. :) \$\endgroup\$
    – Neppomuk
    Commented Dec 24, 2019 at 16:13

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