Dead pixels on my 40D ?? :(

Ryan.S

Ryan.S

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Ryan S
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i have marked the two dots that im wondering if they are dead pixels... could anyone help me and confirm if they are or not?

all taken at a slow shutter speed

img6282xj3.jpg


update #1:
just done another pic now (above one taken a few months ago) and this is how it came out :(

img7197gh5.jpg


Cheers,
 
ignore this post
 
cameras suffer from 'hot pixels' at high ISO...I'm guessing this was 1600 or something?? Shouldn't be noticable at lower ISOs but annoying none the less...
 
this was only at 400 iso and is only really visible at slow shutter speeds.
on all my rally shots (usually taken at high shutter speeds and about 200 iso) i cant find anything ...

cheers,
 
thats an awful lot if Im honest!! May be worth seeing what Canon say..
 
how slow is slow? if they are 30 second+ exposures then I would expect results like that. If they are 1 second then I'd be concerned.
 
purpleclouds said:
cameras suffer from 'hot pixels' at high ISO...I'm guessing this was 1600 or something?? Shouldn't be noticable at lower ISOs but annoying none the less...
Click to expand...

it's more about shutter speed than ISO in my experience. the sensor gets physically hotter the longer the exposure which can results in these hot pixels.
 
ok, thanks for all the rapid responses :)

it was taken on bulb (trying to catch some lightning) so was about 20 sec exposure or something around there.

Thanks,
 
why dont we all take a 30 second exposure and see what we come up with i,ll do mine tonight and get back to you
 
olv said:
it's more about shutter speed than ISO in my experience. the sensor gets physically hotter the longer the exposure which can results in these hot pixels.
Click to expand...

Likewise though there is more current being passed through the pixels at higher ISO to make them more sensitive, and more current = more heat!

I do agree with you though...there is just a couple of a explanations! :)
 
that makes perfect sense then. i imagine a 30 second exposure at 3200 on my 10D will just result in a sea of blue dots.
 
get it to the shop mate just took several very long exposures with my d50 62 secs at f38 iso1600 only thing i could see was dust on my sensor(cleaning kit out already) ive heard of heat spots but thought you had to expose for 2-3 mins before they appear
 
I took a light trails type picture last year, and experienced something similar. I assumed at the time the red dots were as a result of sensor dust but obviously I was wrong.

I overexposed the picture anyway, so I wasn't too arsed!! :)
 
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