Hot pixel problem - long exposures

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ThankHeavenForShed 7

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Hot/dead pixel problem - long exposures

I've just been playing around in the house with a new remote shutter release for my Sony a200. I've noticed what seems to be quite a severe hot pixel problem in most of the images I've taken which gets progressively worse the longer the shutter is open. I know that I can probably expect quite a bit of noise but this seems to go way beyond that and I'm certain it's never been anywhere near this bad before. I just took a test exposure of a minute and a half with the lens cap on and it looked like one of Smoker's astronomy shots because of all the white spots!

Should I be worried about this? Is there anything I can do to fix it? I like to do quite a bit of long exposure stuff and I'm also in the middle of a Masters thesis on how we learn photography which is heavily dependent on me having a fully-functional camera!
 
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You it's not overly clear on here but you can still see the problem. When I process the file in Bridge/Photoshop it cleans it up to a certain extent but not completely. And it looks horrendous on the camera's LCD screen.

Edit: I should also add that this has came on really quickly. Took a couple of shots - fine...started shooting again after a big bowl of cake and ice cream and the problem started!
 
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had a problem with it on my old a200 as well, however i noticed that if i shot on RAW and processed with LightRoom they would just magically dissapear once i clicked into the photo to process it, but if i shot in jpeg i would have to clone them out....strange.
 
clyde said:
had a problem with it on my old a200 as well, however i noticed that if i shot on RAW and processed with LightRoom they would just magically dissapear once i clicked into the photo to process it, but if i shot in jpeg i would have to clone them out....strange.
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Would suggest they are jpeg artefacts then?
 
Icarebecauseyoudo said:
Would suggest they are jpeg artefacts then?
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They happen when I shoot in RAW though. PS seems to automatically pick them up and process them out without me having to do anything (when I took test shots with the lens cap on it managed to take away all of them, but it's not able to pick them all up in a normal shot) but it's a right pain in the arse.
 
Apparently if you do very long exposures (10 mins or so) you can burn hot pixels into your sensor. That's what I read anyhow. Maybe you've damaged it previously and it's showing up now?

I get no hot pixels up to 4-5 minutes in low light, but longer than that and it does mental. That's at ISO 100.
 
not spavin said:
Apparently if you do very long exposures (10 mins or so) you can burn hot pixels into your sensor. That's what I read anyhow. Maybe you've damaged it previously and it's showing up now?

I get no hot pixels up to 4-5 minutes in low light, but longer than that and it does mental. That's at ISO 100.
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Hmmm. So if, for example, someone had left a camera firing away on bulb mode while they got a huge bowl of cake and ice cream and forgot about it for a few minutes, there's a possibility that hot pixels could've been burned on to the sensor? Hmmm. Interesting!

Is there any fix for this?
 
ThankHeavenForShed 7 said:
Hmmm. So if, for example, someone had left a camera firing away on bulb mode while they got a huge bowl of cake and ice cream and forgot about it for a few minutes, there's a possibility that hot pixels could've been burned on to the sensor? Hmmm. Interesting!

Is there any fix for this?
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That's what I've read. I did it myself - left the shutter open for well over half an hour, forgetting it was there. No permanent damage as far as I can see. It might be bollcoks about the damage - there's a lot of crap out there on photography forums.

If it's damaged then it might need replacing. However, if it's damaged then it should show up on normal photos I'd have thought.
 
Hot pixels are standard fare on long exposures. Take a dark frame - ie a shot taken at the same ISO, exposure length and ambient temperature with the lens cap on - and subtract it from the light frame (your picture) in Photoshop. Better still, take loads of dark frames and average them to produce a master dark which you then subtract in PS.

not spavin said:
That's what I've read. I did it myself - left the shutter open for well over half an hour, forgetting it was there. No permanent damage as far as I can see. It might be bollcoks about the damage - there's a lot of crap out there on photography forums.

If it's damaged then it might need replacing. However, if it's damaged then it should show up on normal photos I'd have thought.
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You can't knacker DSLRs with too much signal, once the well is full it stops converting photons. The risk is from heat. As long as you don't point it at the sun, you should be OK IMHO.
 
smoker said:
Hot pixels are standard fare on long exposures.
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Yeah, I do quite a lot of long exposures so I know it happens some times. There was just a sudden and very, very noticeable jump in the amount of them and their severity.
 
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