I was at a party on Sat and I took some pictures with my new Sigma 50mm 1.4 Art Lens for Nikon.

On Sunday I noticed some artifacts on some of the images when I shot vertically like rainbows in the shadows and people's skin. I've never seen this before so I trying to determine if the cause is

  1. The D3s
  2. The Sigma lens - I hope not since I just bought this
  3. The B+W 77mm UV filter
  4. SB 800 Flash
  5. A combination???

I spent 3 hours yesterday trying to duplicate the CA, Moire or horizontal artifacts at my house but the environment is completely different so it' s like comparing apple and oranges.

How you seen these types of artifact before? What might cause it? Extraneous light, faulty lens, low pass filter??

I've seen CA, but not this bad if that's what it is. Certainly not the rainbows. Look at rainbow on the ladies left leg and in the shadows.

Please let me know what you think??

Had to severely crop the pic!!

Thanks enter image description here

  • Was the flash attached to your hot shoe, on a 'flip bracket', or even further off camera?
    – Michael C
    Dec 5, 2017 at 8:59
  • 3
    Since the rainbow is behind her, could she be nyan cat? :) Dec 5, 2017 at 16:04
  • My first thought was moire. The background looks like it has a very fine pattern to it, and moire can cause false colors when it interacts with the Bayer pattern in the camera. But moire is unlikely to produce a perfect rainbow, nor is it likely to be brighter in the shadows. Dec 6, 2017 at 0:01

5 Answers 5


Because that rainbow is partially obscured by your subject, I would tend to believe that it has nothing to do with any of your equipment. Rather, there was something in the room acting as a prism and diffracting light into a rainbow pattern that just happened to fall within the frame of what you were shooting. It might be that the source of the light was your flash, especially if the rainbow was not visible in your viewfinder before taking the shot, but the cause of the diffracted pattern is something other than your equipment.

  • Part 1 @twalberg Thanks for your reply. So you think the light from the flash bounced of some object in the room and caused the fringing effect?? That's a possibility. The rainbow effect had to be superimposed on the backdrop before I got there. Dec 5, 2017 at 3:28
  • Part II But how could the rainbow effect show up in the shadows between their bodies?? That means the light had to bounce off the ceiling somehow. The light that created the shadow between their bodies must have happened a fraction of a second “before” the light that created the fringe rainbow which is why we see the rainbow on top of the shadow. Since I was shooting vertically from left to right as the shadows indicate that’s probably what happened. What do you think??? Dec 5, 2017 at 3:28
  • What possibly could have reflected a Rainbow pattern in the snow?? ukclimbing.com/forums/t.php?t=634314 Dec 5, 2017 at 3:29
  • 1
    @SpencerJung The object(s) with the prismatic properties only need to be to camera right, there's no need for anything to bounce off the ceiling first. If your camera was rotated 90° counterclockwise, then the image was exposed from right to left. Your shutter curtains move from top to bottom, but the image is inverted on the sensor compared to the scene in front of you.
    – Michael C
    Dec 5, 2017 at 9:06
  • 2
    In the time it takes a typical DSLR's first shutter curtain to transit a sensor (≈1/300 seconds), light travels approximately 620 miles. For purposes of photography in a room that size, light is "instantaneous".
    – Michael C
    Dec 5, 2017 at 12:01

Your flash could have been reflecting off the subject's watch crystal and bouncing to camera right, then reflecting off something to camera right and back into the field of view.

The prismatic effect might be coming from the mineral crystal on the watch or from the source of the reflection at camera right.

On the other hand, the source of the prismatic effect may have nothing at all to do with your camera and flash and may have just been present in the scene at the time you took your picture(s).

P.S. - Please take the UV filter off that nice lens. It doesn't provide near as much protection as some folks think it does. In situations like the one in your example above, flat filters can cause issues of ghosting and other unwanted reflections.


This looks like shadow edge effects of an LED stage light. The kind that can produce different color mixes by varying the brightness of discrete LEDs. In that case it should be visible with the naked eye and show up in pictures no matter the camera orientation. It can be verified because the order of the colors on one side of the shadow edge will be the opposite of the other side. The top and bottom may not show any colors. (And top/bottom/left/right will depend on what orientation the light is mounted.) It happens because each discrete LED color focuses at a slightly different location. The light will appear white where all the LEDs are illuminating an area. There will be no light where none of them are. There will be color bands in between.


At first I was going to say it might be something to due with the texture of the banner behind the subjects, but then I noticed that the rainbow effect is also on her front leg in the highlights. It's also out in the bottom right corner away from the shadows.

That leads me to think it's an effect of the light not Chromatic Aberation. CA tends to stay near the edges/lines from what I understand of it.

I'd lean towards either the flash for investigation. Were you using any modifiers on it? Does that flash have a built in diffuser and was it on or maybe slightly off?


Thanks for your assistance. There seems to be a consensus that there were object(s) in the room that were reflecting/ projecting light onto the subject.

As long as it wasn't my equipment, I'm happy. :)

I will replace the filter though.

Thanks again!!!


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