Nikon D70: Noise on long exp: bright top left corner

The attached image was taken at night, with the camera under thick blankets in a dark room. The lens cap was on and the eyepiece was covered. Exposure was 2 minutes at f2.8, ISO 1600. With lower ISO speeds, it just takes longer to appear. At ISO 200, it takes 4 minutes to be visible, at 8 minutes it's quite clear. In-camera noise reduction gets rid of it. I also tried it with no lens, to eliminate it as a source of the problem, with the same results.

So the question is (since the guy at the camera store was useless):

Is it just my camera, or is this a "feature" inherent to all D70s?

wow, nice experiment. thats kinda wierd, as there is no source of outside light, must be the camera. not sure though.

sorry i cant help you. maybe someone else here can.

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Originally Posted by aculharobed

The attached image was taken at night, with the camera under thick blankets in a dark room. The lens cap was on and the eyepiece was covered. Exposure was 2 minutes at f2.8, ISO 1600. With lower ISO speeds, it just takes longer to appear. At ISO 200, it takes 4 minutes to be visible, at 8 minutes it's quite clear. In-camera noise reduction gets rid of it. I also tried it with no lens, to eliminate it as a source of the problem, with the same results.

So the question is (since the guy at the camera store was useless):

Is it just my camera, or is this a "feature" inherent to all D70s?

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Looks like it's a "feature" on all D70's...

2 min @ f3.5, ISO 1600

It's probably caused by heat. Further proof that if you look for problems you're bound to find them :)

seems like not only D70 is like this, i have a D100 and i've tried @ ISO HI-1(3200) and HI-2(6400) mode. @ 3200, about 2 mins i get same result even with noise reduction on, @ 6400 i've tried 15sec and same fing but not as noticalbe, but 1600 or below with nosie reduction on fix the problem.

And now, for my next trick, I will put the camera in the freezer and see if it really is the heat. Wasn't such a good thing to have it tucked under the blankies, eh?

Try covering the viewfinder as well, just as a matter of experiment.

I know, others will boohaha about that suggestion, but humour me as well.

Heat coming off of the control circuit for the CCD. The higher the sensitivity, the sooner it will creep up. Only happens with CCDs, not CMOS. Freezing the sensor will help, but don't waste your time, it's an accepted and expected quality of CCD sensors. If you can't live with it, get a camera with a CMOS or turn on dark frame subtraction, which will double the time it takes to make the shot, but will remove the artifact.

Ok, forget the freezer bit. I don't have much hope of it making a change, anyway. But maybe I'll do it some day when I'm extremely bored.

What is it about CMOS vs. CCD that makes this difference? Does CMOS stay cool, or is it less sensitive to heat, or what?


Flashram_Peter_AUS, the viewfinder was covered. The whole camera was covered.

Has anyone tried this on other CCD based D-SLR's? What was the result? I guess I have to go and try it on mine.

Cheers.

Pete