Too many dead pixels? New Camera Body?

[hoffstriker]

At what point would you consider replacing old dslr body due to dead pixels? I'm currently using a 20d and found approx. a dozen with my last night shoot. Easily enough fixed in photoshop, but still a hassle. Basically, just curious as to every one's logic in this situation.

Thanks

[Clactonian]

That really is a can of worms Chris.
Do you only notice the dead pixels when taking night shots? Is this a new occurrence or was the camera like it when bought? Is there any other fault with the camera? Can you afford to buy another one? .... and so on.
If I were satisfied with the camera in every other respect and my income didn't depend on night shots, and I wasn't planning to spend a few hundred dollars on new kit any time soon, I would soldier on for a while.
I wonder how many of us are using cameras with a similar fault and have never noticed.

[hoffstriker]

I actually like the camera, but am not sure if it was this way when I bought it. I just started taking longer exposure pixs and just got adobe, prior all I had was Picassa and therefore probably just never noticed it before. The full situation is my wife is willing to buy me an anniversary present as long as it is under a grand. I was going to have her get me a 70-200 L, but the IS is just too expensive so now I am going to wait until next year for that. But, as opposed to simply getting a lens to get one at this time, the 50D is going for a relatively good price and just started running this concept through my head. Plus, everything I have right now for my 20D will work with the 50D. I am basically looking to continue to improve, and wonder if this will help. Plus, just started school and we all love new toys for school...lol
If the improvement is justifiable for larger enlargements, then I don't mind taking the plunge. If, however there is minimal quality improvement in addition to the lack of dead pixels, I'll simply find something else or save the offer to expedite the Canon 70-200 f/4 IS purchase.

Thanks Mike,

[Colin Southern]

Hi Chris,

See if they're still dead with a short exposure.

20 out of 8 million is only 2.5 in a million! I probably have that many (or more) on my 1Ds3 when doing extended exposure night shots) (although ACR kills most as soon as it opens the image).

Of course if you're looking for an excuse to get a new one then ... just do it ... you know you want to

[hoffstriker]

If you can talk Maggie into it with a reasonable argument (she trusts you more than me) it will be done o' acrobat of Adobe.......

[Colin Southern]

In all honesty Chris, the lens will make a bigger difference. The 50D is without a doubt nicer, but I still have 22 x 33" canvases hanging on my gallery wall that were shot with a 20D (and an L-Series lens!), and they look just fine.

[Glenn NK]

At what point would you consider replacing old dslr body due to dead pixels? I'm currently using a 20d and found approx. a dozen with my last night shoot. Easily enough fixed in photoshop, but still a hassle. Basically, just curious as to every one's logic in this situation.

Thanks

Chris:

Maybe you should try this first:

http://forums.dpreview.com/forums/re...1&changemode=1

It also made the rounds on another forum about three and four years ago.

Others have tried it and reported success - at least it has worked with Canon bodies. Of course there were skeptics - until they tried it.

Glenn

[revi]

If they only appear in long exposures, it sounds more like hot pixels (dead pixels would be black all the time, stuck pixels would give max. intensity all the time, all three types stay in the same position from one exposition to the next).

To correct for hot pixels, there's a technique called 'black frame subtraction': you take a picture with the same long exposure but with the lens cap in place (giving a black image with the hot pixels), then subtract this black image from the 'real' image. The beauty is that this can be done early in the process by a good raw developer, and some cameras (like Sony ) can even do it 'in camera' (at least for jpegs, not sure about RAWs, and the manual is silent about such 'details').

Remco

PS. I'm sorry, but the link Glenn posted looks more like a dust problem to me, the more so as the spots seemed to appear at any exposure (by definition hot pixels only show up at long exposures)

[hoffstriker]

Thanks Remco, I'll give that a whirl once CS5 shows up. Right now, I'm only using PSE2 show I have to shoot in JPEG & Raw until I have the ability to edit the RAW format. I am pretty sure my Canon won't do it in camera. Have you tried this procedure with Adobe?

[Glenn NK]

PS. I'm sorry, but the link Glenn posted looks more like a dust problem to me, the more so as the spots seemed to appear at any exposure (by definition hot pixels only show up at long exposures)

Actually is was not a dust problem - it was hot pixels. And a number of posters did report success with the method.

There were several threads on the topic, but I can't find them now.

Fortunately I've never had the problem, so couldn't attest to its effectiveness.

In any event, it's a very low cost procedure that can't possibly cause any damage.

Glenn

[hoffstriker]

Maybe I'm wrong and they are not dead pixels at all. Took this awhile back as a test (sorry cleaned up all the good ones). Tell me what you think.

http://www.flickr.com/photos/hoffstriker/5026425933/

[Glenn NK]

Hmmm, red and blue snowflakes. I thought that was what hot pixels did, but maybe I'm wrong. Have you tried the sensor clean without taking the lens off and keeping the lens cap on? Just curious.

Glenn

[hoffstriker]

The 20D does not have an automated sensor cleaning, so unfortunately that is not an option for me. There are also green snowflakes, but you would probably need the file and plus 200 at least.

[Glenn NK]

The 20D does not have an automated sensor cleaning, so unfortunately that is not an option for me. There are also green snowflakes, but you would probably need the file and plus 200 at least.

I think there is a misunderstanding. My 30D doesn't have automated sensor cleaning (none of the Canon bodies of that era did), and the 20D didn't either.

By sensor cleaning, I mean: Menu - "orange settings" which include Sensor Cleaning. This action flips the mirror up, and opens the shutter so that the sensor is exposed so it can be blown or swabbed.

BUT - many users claim that doing this several times actually removed the hot pixels from their images if they left the lens cap/ body cap on.

Glenn

[hoffstriker]

REALLY???


I'll give it a shot.

[Colin Southern]

Out of interest, I tried this with my 1Ds3 ... didn't make any difference.

One thing I do know, Canon are EXTREMELY secrative about such things ... so we're unlikely to ever get a straight answer from them.

Here's a test for somebody (20 brownie points up for grabs) ... a while back someone here posted a link to a site where a Canon repair tech was delivering "shoot-from-the-hip" answers to questions about these kinds of things. Can anyone find that post here?

[hoffstriker]

Well, it looks like there are less (barely) but I will try it tonight using only available moonlight. Then I will be able to tell better. Right now, the longest exposure I can use is 30 seconds.

http://www.flickr.com/photos/hoffstriker/5027682708/

[Glenn NK]

Try it a few times - lens cap on.

Glenn

[hoffstriker]

Been trying it all afternoon, with no luck, but thanks anyway....

[Glenn NK]

Well we tried. I feel for you. I suppose I've been lucky with my 30D - I've never seen a hot pixel.

Glenn