Long exposures burning the sensor.

Ptyler22 · Jul 21, 2009

I have heard of people doing really long exposures and frying their sensors. How long could I do an exposure without risking overheating my sensor? and how long in between shots would I have to wait for it to cool down before I could do another? Any tips or help would be awesome!

KmH · Jul 21, 2009

Not enough info......so, it depends.

What camera (CMOS or CCD sensor), what ISO? What did your web search and TPF forum search turn up?

I've only seen sensor overheating related to long term use of Live View in high ambient temperture environments.

Ptyler22 · Jul 21, 2009

OK, sorry, I should have included more info.

Body Canon 40d
ISO 100
Outside temp 75F

I searched the forum and got lots of similar questions but none that are quite the same, they are mostly about 20 or 30 minute exposures, but I just want to know what the longest exposure I can safely do is.

KmH · Jul 21, 2009

Ptyler22 said:
OK, sorry, I should have included more info.

Body Canon 40d
ISO 100
Outside temp 75F

I searched the forum and got lots of similar questions but none that are quite the same, they are mostly about 20 or 30 minute exposures, but I just want to know what the longest exposure I can safely do is.

It's going to vary with ambient temp and how hard the the sensors driving circuits must work at high frequency against the high capacitive load of any shift registers.

Your 40D has a CMOS sensor which is better for thermal performance than CCD. The trouble is I don't know how Canon configures their electronics around their sensor.

Hopefully, a Canon guy will chime in.

Bravotwofive · Jul 21, 2009

If we have a Canon expert I would love to know the answer to this. Long exposures are a frequently used tool of mine. Some nights I can do upward of 50 or so, and relatively close together.

musicaleCA · Jul 21, 2009

Bravotwofive said:
If we have a Canon expert I would love to know the answer to this. Long exposures are a frequently used tool of mine. Some nights I can do upward of 50 or so, and relatively close together.

Do you mean 50 seconds, or 50 minutes?

(Or 50 exposures?)

Bravotwofive · Jul 21, 2009

50 Exposures at 30 seconds to 2 minutes within 4 hours.

Joves · Jul 21, 2009

Bravotwofive said:
50 Exposures at 30 seconds to 2 minutes within 4 hours.

Well those should be fine.

KmH · Jul 21, 2009

Something like star trails will take 15 minutes or more. I've done those with no apparent ill effects.

Big · Jul 21, 2009

Great question! I have been wondering this for my future photography!

ddeerreekk · Jul 21, 2009

Anybody know what the answer to this question would be, if using a Sony camera? I'm using a sony a350, I never even considered this to be an issue - i didn't know that could happen.

My camera is under extended warranty though and I'm sure it would be covered.

dwol · Jul 21, 2009

The past few nights I have done star trails for at least an hour for each image (only two images taken per night, about an hour between each one), last night I did a two hour exposure and the camera is still alive lol.

The temperature was around 20 degrees or 68 farenheit. Used a Canon 450D, ISO 100, F8. The camera body istelf was a little warm but nothing to worry about.

The image itself did have some minute black spots like noise which im assuming is from the heat of the sensor. But I have been taking photos today and there is no problem with the camera. Hope that helps.

Ptyler22 · Jul 22, 2009

dwol said:
The past few nights I have done star trails for at least an hour for each image (only two images taken per night, about an hour between each one), last night I did a two hour exposure and the camera is still alive lol.

The temperature was around 20 degrees or 68 farenheit. Used a Canon 450D, ISO 100, F8. The camera body istelf was a little warm but nothing to worry about.

The image itself did have some minute black spots like noise which im assuming is from the heat of the sensor. But I have been taking photos today and there is no problem with the camera. Hope that helps.

OK, great so somewhere around a 10 minute exposure should be no sweat. Thanks!

Garbz · Jul 23, 2009

Ptyler22 said:
How long could I do an exposure without risking overheating my sensor?

I have seen this happen but unfortunately there is no simple answer. Each sensor in each camera model is setup differently and generates a different amount of heat. I would go so far as to say high end full frame cameras would possibly be able to go indefinitely but I wouldn't try it based on my word.

The camera in question was a 350D which took a 40 minute startrail I think it was, and then never recovered. I took a hour long startrail one day and aside from the picture being garbage due to the purple thermal effect of a CCD that's heating up the camera survived. But my D200 was burning hot to the touch so I won't ever try one that long again.

Sensors generate heat when they are on, and DSLR sensors are not heatsinked. Sensors for telescopes and other dedicated long exposure equipment have large heatsinks or peltier units to keep them cool.

Bravotwofive said:
50 Exposures at 30 seconds to 2 minutes within 4 hours.

Not an issue because the camera would have time to cool between shots. Worst case your sensor was off and on for 100 minutes out of 240, I'd expect any camera to do this without even getting warm.

KmH said:
Something like star trails will take 15 minutes or more. I've done those with no apparent ill effects.

I would also say 15 min is not an issue. I'd be worried getting longer than half an hour though, but then again modern cameras *may* last longer still. The 350D is a bit old.

dwol said:
The temperature was around 20 degrees or 68 farenheit. Used a Canon 450D, ISO 100, F8. The camera body istelf was a little warm but nothing to worry about.

The 450D is plastic! The sensor is in the very middle of the camera away from the body! If your camera is warm I would say it IS something to be worried about. If it was an all metal camera with good heat transfer I say non issue, but some thick hardened plastics can almost have the heat transfer characteristics of styrofoam.

Do you have access to a laser temp meter? I'd be interested if you do this again if you quickly flip the camera into cleaning mode and take a reading on the sensor.

For those interested in doing startrails the best way to do it on a DSLR is by stacking images. I have taken a exposure made up of 120 30second exposures with a 5 second gap between each one totalling 70minutes. The camera wasn't anywhere near as warm as my one hour continuous shot, and the image had zero noise as this was averaged out due to the stacking process, not to mention no purple thermal effects.

IgsEMT · Jul 28, 2009

You could just call Canon tech support and ask them this question.
It'll probably be safer that way. But if you're a maverick and willing to push your toy, please report
:thumbsup: