Light-Like Anomaly During Long Exposure

[thermopylae_480]

When I take long exposures, of over 50 sec or more depending on ISO, I get an odd light-like pattern (below image). The pattern is always the same and gets more pronounced the longer the exposure. It doesn't matter what the location, or light level; it will appear in the same pattern even in a completely dark room with the lens cap on or even with the lens removed and only a body cap in place. You can imagine this is rather disappointing for night photography; I'm guessing there is something wrong with the camera's sensor, but was curious if anyone had any advice?

The camera is a Sony Alpha A100 DSLR.

http://img.techpowerup.org/090217/DSC02975.jpg

[Taallyn]

The image doesn't show up for me. However, what you are describing sounds like "amp noise". Basically a portion of the sensor is getting some kind of interference due to the longer exposure times. My camera supposedly has it, although I have not made any exposures long enough to cause it yet. I think it uses the same sensor as my camera does though. One way to combat it is to turn your camera's Long Exposure Noise Reduction on. I don't know Sony camera's at all so refer to your manual on how to do that. It should remove the amp noise from the image as it writes the data to the card.

[Steve Paxton]

I am having a hard time seeing what your referring to in the image as well. What you describe as to be somehow has to related to the sensor. I am not entirely sure either. Issues like this crop up in different ways when you get into long exposures.

Have you contacted Sony? I wonder if this is a known/document problem - maybe there is a firmware update?

[Taallyn]

I can see the image now. That definately looks like amp noise / amp glow to me. Turn your long exposure noise reduction on.