# 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!


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## 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.


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## 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.


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## KmH (Jul 21, 2009)

Ptyler22 said:


> OK, sorry, I should have included more info.
> 
> Body Canon 40d
> ISO 100
> ...


 
It's going to vary with ambient temp and how hard the the sensors 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.


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## 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.


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## 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?)


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## Bravotwofive (Jul 21, 2009)

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


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## Joves (Jul 21, 2009)

Bravotwofive said:


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


 Well those should be fine.


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## KmH (Jul 21, 2009)

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


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## Big (Jul 21, 2009)

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


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## 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.


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## 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.


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## 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!


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## 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.


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## 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:


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## Garbz (Jul 29, 2009)

IgsEMT said:


> 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:



You're assuming that you'll call tech support you'll end up with an engineer and not some dork behind a helpdesk in New Delhi.

Search this very forum and you'll find cases of people who have been told some very stupid things from a helpdesk.

It's hard enough to speak to an engineer of an engineering company when you're a multi-million dollar client of theirs, good luck


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## Moglex (Jul 29, 2009)

Does anyone know why (or, indeed, if) the camera manufacturers don't do the obvious and include a temperature sensor that will shut down the exposure if the sensor temperature nears critical?

A lot of times you have problems early in the life of a technology and the danger enters folk-law even though the engineers have found and implemented a way to prevent the danger years back.

Take as a prime example the amount of contradictory nonsense talked about batteries of various types.


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## Garbz (Jul 29, 2009)

One reason is they probably get too few failures to even care. Many camera models wouldn't last more than half an hour to an hour battery wise let alone doing the exposure. And then that's not something the camera is capable of. To get more than 30 seconds on any camera I believe you need to buy a remote.

I don't think it makes economic sense to include the extra part and programming in every camera when far less than 0.1% of them would fail due to this "issue" if it is still in fact an issue. I mean it's not exactly a big problem, I haven't seen anyone on this board who has first hand experience, I have second hand experience with a 350D which isn't a new camera either, and the rest is just talk.


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## IgsEMT (Jul 29, 2009)

> You're assuming that you'll call tech support you'll end up with an engineer and not some dork behind a helpdesk in New Delhi.


Not assuming, but hoping... I had to contact Nikon and Canon tech support in the past and surprisingly we actually had a fluent conversation rather then hearing "one moment sir, let me look it up"


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## Moglex (Jul 30, 2009)

IgsEMT said:


> > You're assuming that you'll call tech support you'll end up with an engineer and not some dork behind a helpdesk in New Delhi.
> 
> 
> Not assuming, but hoping... I had to contact Nikon and Canon tech support in the past and surprisingly we actually had a fluent conversation rather then hearing "one moment sir, let me look it up"



I wonder if they route P&S enquiries to a different department to enquiries about top of the range DSLR's.


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## Sw1tchFX (Jul 30, 2009)

I've done 5 minute to 1 hour long exposures off my D700 and they've been great, and the camera still works awesome too! The hour one one was noisy as hell and ran my battery down, but it still worked. I don't know if i'd do another hour long shot though. 30-45 minutes might be tops. 15 minutes though...cake. 







My D70 has trouble, I can't do a 5 minute exposure without Long Exposure NR, and that's about as long as i'd want to go too on that body.


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## Garbz (Jul 30, 2009)

Funny enough I saw a post on some hacking forms where someone built a peltier cooling unit for his camera. He does cool 3 hour exposures of the sky using image stacking. 30x5min exposures with a few second gaps between each. The peltier unit cools the camera down to negative temperatures and dramatically increases his signal to noise ratio too.

A novel idea that may work even better on metal bodies. If I had a telescope I'd be all over that hack


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## musicaleCA (Jul 30, 2009)

Link please? I might be able to scrounge a telescope from somewhere...*ponders* In any case I want it in my bookmarks for later.


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## Jaszek (Jul 30, 2009)

Yestarday I was doing star trails with 5 minute exposures for 1 hour and 10 minutes with 5 sec. break in between. that was my second star trail and so far nor problems with my XSI.


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## Garbz (Jul 31, 2009)

Yeah your 5 second break does wonders. 

musicaleCA: Peltier Cooling of Modified Canon Digital Rebel XSi (450D) - Version III -by Gary Honis Beware this guy looks like he has absolutely nuts gear


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## ocular (Jul 31, 2009)

Too be honest I've never heard of this, but if you shooting at night (it's naturally cooler right ? ) But in a hot summer day with filters and a slow aperture ? Must be a cannon thing... :hug::


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## KmH (Jul 31, 2009)

ocular said:


> Too be honest I've never heard of this, but if you shooting at night (it's naturally cooler right ? ) But in a hot summer day with filters and a slow aperture ? Must be a cannon thing... :hug::


Do you mean the kind that go BOOM and launch a projectile? Or, you just have poor spelling and proofreading skills?    Canon :mrgreen:


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## Garbz (Aug 1, 2009)

ocular said:


> Too be honest I've never heard of this, but if you shooting at night (it's naturally cooler right ? ) But in a hot summer day with filters and a slow aperture ? Must be a cannon thing... :hug::



Define cooler. It often has 25 degrees C here during the night.  Remember this is a story from Australia. So your mileage probably varies a lot if you live in Alaska


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## ocular (Aug 1, 2009)

lol guys. Seriously never heard of this before, never happened to me or anyone I know, guess I'll keep asking though.


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## Joves (Aug 2, 2009)

Garbz said:


> Yeah your 5 second break does wonders.
> 
> musicaleCA: Peltier Cooling of Modified Canon Digital Rebel XSi (450D) - Version III -by Gary Honis Beware this guy looks like he has absolutely nuts gear


 Now that is a nice setup. I now wish I still had my D80 to do that with.


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