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I've found that a few of my recent trip photos have this odd artifact/ghosting resulting in a blue/purple glow around the helmet(see below pic): Annoying hue

I've found this question which i think relates to what I'm experiencing, I undersand the bright spot in front of the head torch, but I don't understand why the area behind the helmet is lit up like this?

This particular photo was shot with a 5D MkIII, f/2.8, 1/40s, ISO-1250 with a Canon 24-70mm II.

This is the original image: enter image description here

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  • \$\begingroup\$ Could you post the original uncropped photo? This may be ghosting caused by internal reflections. If so, the ghosting is inverted and flipped along the vertical and horizontal center axes from the original bright light source. \$\endgroup\$
    – Michael C
    Commented May 20, 2013 at 12:40
  • \$\begingroup\$ @MichaelClark there you are. If you want me to upload the full high-res version let me know. You'll note that it looks like his entire body is glowing? \$\endgroup\$
    – NULLZ
    Commented May 20, 2013 at 12:49
  • \$\begingroup\$ Depending on what you have done with tone curves locally on the area of the rock outcropping, I'm guessing it is mostly ghosting from that. Is it also possible there was enough moisture and temperature differential in the cave to cause the lower part of the lens' front element to fog? \$\endgroup\$
    – Michael C
    Commented May 20, 2013 at 12:57
  • \$\begingroup\$ @MichaelClark I'm not sure i understand what you mean, I haven't touched anything other than cropping it at a fraction of the size \$\endgroup\$
    – NULLZ
    Commented May 20, 2013 at 12:59
  • \$\begingroup\$ OK. I was thinking the rock outcropping might have been a lot brighter relative to the rest of the picture and you may have selectively reduced the exposure/brightness in that one area during PP. If not, then the most likely source of the haze effect is either a lot of localized humidity in the air (like fog, in only some spots) between the helmet light and the camera or there was some fogging on the lower left portion of the lens' front element. \$\endgroup\$
    – Michael C
    Commented May 20, 2013 at 13:04

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If the index mark on your photo was at the center of the original image, the purplish blotch above and to the right of it is a ghosting of the bright light source the same distance to the lower left of it.

Ghosting is caused by the light from extremely bright sources (relative to the rest of the scene) reflecting off the front surface of a lens element or even the IR filter on the front of the imaging sensor and then bouncing back to the sensor from the rear surface of an element further forward in the optical path. The most likely culprit when using modern lenses with multi-coated elements designed for digital use is the back side of a screw on filter placed on the front element of the lens. Film was not as reflective as the front of a digital sensor assembly and lenses created during the film era often did not have anti-reflective coatings on the back of lens elements which can also lead to ghosting.

The more diffused glow in the lower left of the photo was probably caused by some form of localized moisture between the helmet light and the camera. It could have been patch of air supersaturated with moisture, similar to fog, or it might have been the lower left portion of the front element of your lens had a small spot of condensation on it.

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This looks like some form of lens flare to me, it could be caused by one of the coatings in the lens in effect "glowing" as it is struck by light at an angle.

I believe this is known as "veiling flare" or Haze

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Do you have a protective filter attached with your lens? Most of the time they are the most common factor of lens flare. Most Lens especially those expensive lens are multi-coated and cannot create flares at all.

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  • \$\begingroup\$ I don't know of a lens that CANNOT create a flare? \$\endgroup\$
    – Digital Lightcraft
    Commented May 20, 2013 at 10:42
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First just to say: This is great picture :)

I think that blue spot is definitely result of lens flare.
Really interesting area is around helmet. You were too close to the rock, and your light source (probably LED) was so strong, which caused light to reflect from rock, and then it reflected from your white helmet around the area, and together with dust particles, it created this blue effect.

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