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Last weekend, I tried shooting a wide-angle shot of a sunrise on the beach:

sunrise

You'll notice that there is a haze/artifact around the sun in an otherwise cloudless sky. What causes this? How can I avoid it?

The image is a bracketed HDR shot (3 images at -2, 0, +2), taken with a Tokina 11-16mm f/2.8. The artifact appears in the original shots as well (most noticeably in the 0 exposure compensation shot).

EDIT:

As requested, here are the original bracketed shots (resized down a lot to limit file size)

original 0 EV original -2 EV original +2 EV

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    \$\begingroup\$ Just a note - shooting directly into the sun, especially 3 shots without moving, is an excellent way to permanently burn your sensor! (I did it to my old D70 years back, it showed up as slightly dark circles on for example a blue sky, and more-so on long exposures) \$\endgroup\$ Sep 3, 2013 at 9:08
  • \$\begingroup\$ Can you post the 3 unprocessed shots? I get a similar effect when I overcook an HDR but I learned to expect all sorts of unpredictable flaring and undesirable effects when shooting sun against a uniform sky. If you can see the result in the camera preview perhaps there is a way to combat it in the field bu trying different settings. What were the the other settings aside from the obviously closed aperture? If it was an HDR processing issue i would suggest using a different software - I get better colour uniformity in Photomatix but stronger sky effects in HDR Effex Pro... \$\endgroup\$ Sep 3, 2013 at 13:43
  • \$\begingroup\$ @Jakub: I've added the 3 original bracketed photos as requested. I used Photomatix in my HDR processing. Let me know if you get better results :) The settings I used were: 11mm, ISO 640, f/14. Shutter speeds varied between shots: 1/800, 1/3200, 1/200. \$\endgroup\$ Sep 4, 2013 at 2:39
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    \$\begingroup\$ No question, now. It's a UFO (Unidentifiable Fuzzy Objective) \$\endgroup\$
    – Stan
    Sep 4, 2013 at 2:44
  • \$\begingroup\$ @FinerRecliner - yeah, it visible in every shot. I am out of ideas - will leave it to the experts to decide. Almost look like there are a few clouds or haze. \$\endgroup\$ Sep 4, 2013 at 13:43

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I think there's two reasons for this.

  • One is the lens not being optimally clean, like others have suggested. The largest blob closest to the Sun seems to suggest that by not being in line with the rest of the lens flare and having a more pronounced light refraction than I'd personally expect. Another, less pronounced (i.e. out of focus, suggesting a separate flare) one closer to the Sun going in almost, but not quite 180° opposite direction to lens flare also suggests an additional source of refraction than can't be attributed to lens elements arrangement only. I've personally never seen Tokina 11-16/f2.8 lens produce two distinct flares from what seems about same focal length as the other, normal flare:

                    Tokina 11-16/f2.8 flare issue

  • Another reason could be compression artifacts from a HDR shot along the edges of the objects in your scene, and it just so happens the part around the Sun has most sensitive gradient making it more visible, but you didn't mention all the specifics to actually give an informed opinion on this one. The 18-star shape is in line with your lens, so I presume no additional filters were used? Anyway, I suggest you try similar shots with as low (slow) ASA as possible, and see if this artefacting disappears, or is less pronounced at various steps. If this problem disappears, then it was probably just less than optimal exposure that caused it.
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I looks to me like the haze left behind from lens cleaner that didn't do a perfect job. Clean the surface of the lens again to remove the residual scum.

BTW, Improperly used aerosol pressurized products such as "Dust-Off" leave behind a nasty, hard to remove coating of residual propellant.

Don't soak the lens. Use lens cleaning fluids sparingly.

EDIT: All that stuff is true. BUT, your particular problem has nothing to do with the lens. Your example shows a classic example of a dirty sensor. The symptom is the appearance of a dappled flare appearing in the blue sky near highlights. Save it as an example.

Remedy: Clean your sensor.

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It could be residue on the lens or it could be internal reflections within the lens that are resulting in distortions. If it is dirty lens, then cleaning might help or trying to remove whatever filter you have on. If you don't have a filter on and the lens is clean, then it's probably just internal reflection from the lens. A lens hood couldn't hurt, but it probably won't help other than with general haze. There is a good chance it is probably just something you'll have to live with if it is just a lens geometry issue.

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    \$\begingroup\$ A lens hood won't do anything when the source of the light causing the flare is within the lens' angle of view. \$\endgroup\$
    – Michael C
    Sep 3, 2013 at 19:46
  • \$\begingroup\$ @MichaelClark - yes, but depending on how harsh the sunlight is, it might or might not reduce the amount of light coming in from outside the field of view that could be causing the reflection. If you are aimed in the general direction of the sun, there is a lot of light coming at you from just about any angle, though it is admittedly only a long shot at helping. \$\endgroup\$
    – AJ Henderson
    Sep 3, 2013 at 20:25
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    \$\begingroup\$ Considering that the flare is centered around the Sun, it isn't being caused by any other light source or even a reflection of the Sun from something outside the frame. It is being caused by a small portion of the direct light from the Sun being refracted at high angles by a lens element and bouncing around inside the lens. \$\endgroup\$
    – Michael C
    Sep 3, 2013 at 22:01
  • \$\begingroup\$ I would be extremely worried if there was an object outside the field of view that was brighter than the sun! \$\endgroup\$
    – Matt Grum
    Sep 4, 2013 at 10:47
  • \$\begingroup\$ @MattGrum - wouldn't have to be brighter I don't think, just sufficiently bright and coming from the right angle to reflect, though Michael is correct that it is unlikely to just happen to center around the sun. It's 95% chance at least that a lens hood wouldn't make a bit of difference, I updated my answer to reflect it more clearly as a long shot that can't hurt, but probably won't help. I was just trying to list all the things I could think of that had any remote chance of having an impact on image quality in that situation. \$\endgroup\$
    – AJ Henderson
    Sep 4, 2013 at 13:11
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It looks like a greasy lens, or you are using a UV filter that you always leave on and it needs to be taken off and cleaned in all 3 surface (1 on lens, 2 on filter). Better yet, shoot without the UV filter.

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