What causes this?

[DrMoab]

Every time I do a longer exposure at night I get a lot of light from the upper corners of my photos. Seems somewhere I heard that it can be caused from the sensor heating up. Is this true? Anything I can do to avoid it other than shortening the exposure, upping the ISO or opening the lens?

This is the Original.

I reduced the blacks down to nothing and took some red out and came up with this. I guess it's a way to work around it but I would like to know if there is something I can do before I process the photo to cure the problem.

 

[Michael Slade]

Usually if there is noise being generated by the chip heating up, it will be very uniform across the frame. That red color you are seeing in the corner of your image looks kind of weird to me. Yeah, it does have the general feel of noise, but the fact that it is localized doesn't sit quite right.

It could be lens flare from the moon, a glow from the moon, a reflection off of a low cloud, etc...

Is it in the same place in every frame? Does it occupy the same amount of the frame in each frame? Does it move around or change color?

Seems as though you've found an effective work-around for now.

 

[Wander]

My guess is that the auto focus assist beam is the red
bleed in the corner. That beam is usually to the right of the lens so the red glow would show up in that corner.

 

[DrMoab]

My guess is that the auto focus assist beam is the red
bleed in the corner. That beam is usually to the right of the lens so the red glow would show up in that corner.

Autofocus was turned off. I thought about this also but then remembered that everything was set to manual, including the focus.

Michael, yeah I haven't done a ton of super long exposures but it seems like the ones I do over about 15 minutes always end up with this coloration in the upper corners. If you look close you can see some on the upper left too.

 

[ruditron]

how long is your exposure?
are you using a remote to take the shots?

if your using infrared devices such as a remote the sensor will actually pick up The IR light and show as pink or red.

try switching to a timer or pop on an IR filter and see what happens

the white light in corners might be from light seeping in from the viewfinder... get a cap or just make one see if it helps

 

[Michael Slade]

Do some long exposures against a blank wall if you can. Dim the lights and make it super dark. Bracket some shots starting at 2, 4, 8, 12, 16 minutes against something dark and uniform like a black blanket or sheet.

I'm curious to see how long the exposures have to be before the noise starts to show up.

EDIT: Send me that RAW file if you can...

 

[DrMoab]

how long is your exposure?
are you using a remote to take the shots?

the white light in corners might be from light seeping in from the viewfinder... get a cap or just make one see if it helps

Exposure was around 25 min.

Hmmm, the viewfinder....I remember hearing something about this and if I remember Nikon sent me a little cap to go in front of it.

No IR. I got to camp and realized I left my remote laying on the kitchen table. I used a hat, a .177 cal pellet and a piece of electrical tape to make it work. How? Like this...

Place dark hat over lens. Set camera to bulb. Place pellet on shutter button and place electrical tape over pellet. Remove hat. Reverse procedure when finished LOL.

Rednecks have to improvise...always.

 

[DrMoab]

Send me that RAW file if you can...

Its sending now. I sent it to the email you have listed here...hope that is a good one.

 

[Michael Slade]

Its sending now. I sent it to the email you have listed here...hope that is a good one.

Very interesting file. As I increase the exposure to +400% I see the artifacting in the corners seems to increase as you move towards the end of the frame. The noise is not even but seems to be emanating radially from each of the top corners.

I have NO idea what this means, but it is interesting to note that there is a pattern to what is happening in the file. I am not sure that this is caused by external light entering the camera. This seems to be something that is happening inside and/or during processing of the file.

I will sleep on this one...

 

[Every Miles A Memory]

I dont know how to explain it, but all of my really long exposure shots have the same red bleed in the corners. Usually stronger in the upper corners?

I'm shooting Canon, so it must be something that happens to the sensor or maybe just gathering so much light that the human eye cant see or notice is the cause?

I've always noticed it, but I just adjust the Vingetting tool in CS3 and bring the corners back to what looks acceptable and go on with it

I'd be interested to hear what causes it though

 

[Lost Canadian]

Google 'DSLR Amp Noise.' It's a pretty common problem with older DSLR's. My old D200 suffered from it, but to a lesser extent.

 

[Michael Slade]

Canadians are so dang smart. Some guy even did a write-up on it.

Read it here.

Look familiar?

 

[DrMoab]

Very interesting. He is using a D80 and that is what I have.

I guess I will stay away from long exposure times.