5dmkii sensors- major hot pixels

maybe your friend had long exposure noise reduction turned on?

how long was the exposure for ?
 
scottthehat said:
looks normal, have you got long exposure noise reduction on.
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Err NO.. that's abysmal and yes you should have long exposure noise reduction on, it will then subtract a dark frame to get rid of any hot pixels.

Try the shot again with it turned on, if you are then still getting hot pixels showing through like that then take the camera back.
 
You've stacked 24 exposures of 30 seconds each.. how many hot pixels have are you getting on each individual exposure?
 
phildaintith said:
normal? out of all the canon cameras iv had this is way worse and compared to a friends 5dmkii he gets none...

and no i have never shot with noise reduction on
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depends on alot of thing sensor size, pixels,
and as said you will probaly be best to ask your friend if they have the long exposure noise reduction turned on as they probably have.
 
never has a problem with mine with single shots of 200s
mind you not sure if my noise reduction is on or off.
 
Sent my 5d2 back to Canon, the number of hot or stuck pixels where shocking. They replaced the sensor under warranty.

It now shows no pixel faults whatsoever.
 
Here is my 5Dmk2, 30 secs, ISO3200, lens cover on, no cover over the eyepiece, room temperature


IMG_4710.jpg by arad85, on Flickr
 
im gona take it in to be looked at as they still show majorly with noise reduction on. its still under the extended warrenty- only problem is its with jessops :/

does anyone know if the warrenty will be covered bysomeone like H. Lehmann Ltd who are a canon authorised repair centerthats not far from me? and will be a hell of a lot more useful than my local jessops store
 
BTW, that's with long exposure noise reduction switched to OFF and high ISO speed noise reduction switched to Standard (i.e. the default settings). Post one of yours with the same settings.

I believe all authorised repair centres will do warranty repairs, but obviously they'll have to get Canons OK first.
 
PS. You could always take a set of dark frames (i.e. say 10x30 secs at same ISO and temperature) and use these to remove noise. Very commonly done in astrophotography. You might even find the tools they use for that (e.g. DSS or startrails if memory serves me right) good for automating the stacking process...
 
Aliens, big red dotty aliens.
 
Seriously though, do the lens cap test. Long exposure, lens cap on, high iso.

See what you get.

Pixels will play up if you have a hot sensor and use it continuously, the higher the isso the more power you're putting through it.
 
Does taking 24 30-second exposures in very close succession have the potential to make problems with hot pixels more apparent - either in the later frames or when the whole batch is stacked together?
 
Oh and stacking images will reinforce hot pixels too....

I thought the ISO only controlled the readout amp, so is a localised effect....
 
When you record 10 minutes of video on a 5D2 the CF card almost catches fire.

The sensor gets very hot. Stress any component and the crack will start to show.
I was always led to believe that long exposures generated a lot of heat.
 
Gel said:
I was always led to believe that long exposures generated a lot of heat.
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Long exposures are different to high ISO (which is effectively gain on the acquired pixels). You linked high temps to high ISOs :)
 
Gel said:
When you record 10 minutes of video on a 5D2 the CF card almost catches fire.

The sensor gets very hot. Stress any component and the crack will start to show.
I was always led to believe that long exposures generated a lot of heat.
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yes but i generally use iso 200 for my night shoots when not stacking and they still show- i just thought its very odd how iv shot on my 40d for over a year using this long exposures and had no problems. surely a camera just over twice as expensive should not have that problem :S

yes sensors will get hot.

i took a complete black shot (with the cap on) a while back to test this and it still had them. iv done a little bit of looking closer at the shots and the jpeg versions have way more than the raw ones. and they are all ways in the same place.

when i called today they mentioned a remap whatever that is- i always thought that thats what you do to your car to squeeze more bhp out of it- can i get more bhp out of my camera too:cuckoo:
 
arad85 said:
Oh and stacking images will reinforce hot pixels too....

I thought the ISO only controlled the readout amp, so is a localised effect....
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but cranking the amp power will increase digital noise (high iso noise) and also they're all pretty darn close together in that box
 
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