Trouble taking darks

[Joe_Phoenicia]

I am using a ATIK 16 IC on a Televue 85 controlled through Maxim DL.  I have done a number of test darks (around twenty) with five minute exposures.  THe results always look uneven.  When I run a test recommended by Adam Block in Making Every Pixel Count (the calabration section of the disc), I get results almost identical to ones he identifies as bad darks.  I open the dark in Maxim apply the Kernel filter at median and the unevenness is even more pronounced.  I have a multitude of examples but am attaching only one and that is a JPEG file.

I have blocked every possible light source; have turned off any other electornics except for the camera and the computer and have even taken the camera and computer to another location but the results are the same.

Attached is the JPEG.

Any help will be appreciated.

Joe

[bwa]

Joe,

I've never seen a dark (off any camera) that is almost "white", i.e.: totally burned out.  There are two options: 1) You have a light leak somewhere, 2) Something is seriously wrong with your camera.

Try shooting your darks with the camera off the scope with the front camera cap in place.  Better yet, do this in a totally dark room.

bwa

[Lex]

Wow, this is really a strange light dark?!
Never saw this before... I you shoot your darks, why not going to higher exposures like 600s or more and then retry and combine them?

What if you look at one single dark? Does the same reproduce or not?