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I am shooting on the Nikon D800. I suspect it has a sensor defect because there is a very uniform artifact, in my images. It looks unlike a light leak as it's always in the same position and has the same character.

My theory is that in both circumstances, the image data was too little or took too long to build on the sensor due to which this is some sensor read-out pattern that dominates over actual data.

Image one: Sunset + 10 Stop ND + f9.5 + ISO 100- Very very underexposed.

Shot Details: 638 seconds, ISO 100, f9.5. ND Filter enter image description here

Image two: Lens Cap on, f3.5, ISO 3200.

Shot Details: 30 seconds, ISO 3200, f3.5. No Filter enter image description here

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  • \$\begingroup\$ Do you get the same thing as an in-camera jpg, and as an externally processed RAW (NEF)? \$\endgroup\$
    – user10216038
    Aug 31, 2019 at 18:56

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To me, the transition is too hard (seemingly from one row to the next) to come from a light leak - it would really have to be limited right in front of the sensor to get that hard edge, and that seems highly unlikely, especially, since it seems to be perfectly vertical (so the edge is always in the same row).

So I too suspect it is a sensor defect.

One way to find out for certain is to recreate your second photo (lens cap on), but hide your camera under some opaque things (cardboard, black plastic bags, cushions,...) - try to wrap it up as good as possible from all sides. Use a remote cable shutter to make the photo, but first, see that the room the camera is in gets as dark as possible.

If the issue persists, then it is not a light leak.

You could also do the opposite: Use a very bright torch and try to hit the camera from all angles for several seconds.

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    \$\begingroup\$ Although not the case in this instance, putting the camera in a light-proof container does nothing for issues caused by the infrared emitter inside the lightbox of many Nikon bodies that is used to confirm mirror and shutter positions. \$\endgroup\$
    – Michael C
    Aug 8, 2019 at 16:35
  • \$\begingroup\$ Which is why my original comment above begins with, "Although not the case in this instance..." If someone has a Nikon camera with the IR emitter that has been "converted" to IR and they are trying to find the "light leak", your advice will do them no good at all. \$\endgroup\$
    – Michael C
    Aug 8, 2019 at 17:11
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    \$\begingroup\$ @MichaelC Mea culpa - I read that as "your answer is invalid in this instance, as..." Sorry! \$\endgroup\$
    – flolilo
    Aug 8, 2019 at 17:16
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That is a processing failure. Light leaks are never straight lines and never create two distinct halves. Send your camera in for repair. Include your reference image. You may want to reinstall the firmware and see if that eliminates it but that is a longshot.

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If you mean the visible vertical "edge" in the middle of the picture, I would ascribe that to a problem with the electronics. If there are several analog-to-digital converters working in parallel, then you would get these results if an ADC or amplifier is not calibrated properly.

You should be able to reproduce the problem by shooting a uniform area (grey chart) at high ISO (and I thing the exposure time would have little influence on the result, but the problem could get worse with higher ISO).

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Raw image or out-of-camera JPEG? That kind of stuff can happen when the processing software has a bug with the raw format of the particular camera (there is an annoyingly large variation of formats and their support).

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