7D Long Exposure (Stars)

prodigy2k7 · Jun 11, 2011

Having a hard time finding out how long I can keep my shutter open before damage is done (Obviously I dont want to damage my sensor!). I did 2 minutes and I got scared to go any further lol... What do you think is a safe upper limit for max shutter time for being open?

My result in bulb mode:
Half Dome, Yosemite National Park, California
Shot in RAW, with my 50mm F/1.4 @ F/1.4 (I didnt want to go over 2 minutes shutter) for ~120 seconds. Processed in LR with some white balance adjustments (hard to tell if its even near correct), and some noise reduction.

Any tips/suggestions? I forgot to read-up before I did this and didn't have internet access

o hey tyler · Jun 11, 2011

Try stopping down the lens a bit and doing multiple, shorter exposures and layering them together. There's a program for it, but I can't remember what it's called.

edit: It's called Startrails. I knew it wasn't too original.

Garbz · Jun 12, 2011

You can safely go above 2min. You can probably safely go 10-20min. I've once gone for an hour on my old camera but the entire camera was hot to the touch and the image was a purple mess so it wasn't worth the risk. The only time I've heard of sensor damage was about 3-4 years ago on a Canon, so I'm not sure if it's still a credible risk. Certainly sensors still generate a buttload of heat when running.

The technique to get really long exposures involves stacking. I've done startrails for 3 hours using a 25 second on, 10 seconds off stack and it came out wonderfully (save for the fact that I was close to a city). Stacking also allows you to take advantage of various algorithms such as "Max value" stacking which will allow you to cut through haze and light pollution as each frame won't be any lighter than any other so only a single frame contributes to the light polution, but all contribute to the stars moving