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Dead/Hot pixels on a 5D
Old 06-21-2007, 05:58 AM   #1 (permalink)
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I just unpacked my brand new 5D, slapped on a lens, and ran outside to take some pictures of my kids.

I then ran back to my computer to see how great my new images are and discovered 3 distinct hot pixels:

1. Bright red spot smack in the middle of the images.
2. Pale blue spot on the bottom left of the images.
3. Pale green spot on the top right of the images.

I did the old "pixel test" by shooting with a lens cap on at iso 100 for 1s, and of course found the 3 nasty pixels glowing at me on a black image.

The question is:

Should I send the camera back to Samy's (that's who I bought if from) for an exchange, or should I just send it to cannon to have them swap out the sensor? I know that I should just get a new camera from Samy's, but I don't know how many 5Ds canon ships with dead pixels, and my concern is that I will have to go through several cameras before I find one without Dead/Hot pixels.

I have been through several nikon DSLRs in a past few years, and never came across any dead pixels. The reason I even knew what one looks like is from my old Video days, working with Sony Betacams.
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Re: Dead/Hot pixels on a 5D
Old 06-21-2007, 08:28 AM   #2 (permalink)
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I'm on my way to LA right now, but ship back to Samy's, they should take care of you. Call Bob there first, thanks, rg sends!
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Re: Dead/Hot pixels on a 5D
Old 06-21-2007, 08:43 AM   #3 (permalink)
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Rolando,

Bob is a pleasure to work with. Thank you for hooking me up with him. I got my all my hensel and all my canon stuff from him, and he took great care of me.
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Re: Dead/Hot pixels on a 5D
Old 06-21-2007, 11:59 AM   #4 (permalink)
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Much faster to go back to Samy's than Canon. I think the chances of getting another one with obvious dead pixels is quite low. Usually Canon has pretty rigorous quality control so I guess its possible that a dead pixel can happen after QA.

I wonder what causes a pixel to go dead (quantum fluxuation perhaps?)?

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Re: Dead/Hot pixels on a 5D
Old 06-21-2007, 09:54 PM   #5 (permalink)
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I'd try at least one swap-over with the supplier - you must have received the one bad unit in thousands. If you get another bad one, then think about sending it to Canon.

Just received my 1D Mark III - fingers crossed that I don't see any bad pixels on it!
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Re: Dead/Hot pixels on a 5D
Old 06-28-2007, 07:37 AM   #6 (permalink)
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This could be very usefull to other 5D owners!

I sent my 5D back to Samy's Camera, and had them cross-ship me a new one.

When I received the new camera, the first thing I did was the dead pixel test, and I found 3 bright red pixels glowing nastily at me. Obviously I was upset! I started goggling for information on dead pixels on the 5d, so see if this was a common problem, and I found out that it was. Many people were complaining that it took them 3 or 4 cameras to actually find one without dead pixels.

I was not ready to sent the camera back to get it swapped out again, so I started searching for more information. What I found was real cool:

I came across a post on some camera geek board, that told me to do this:

Remove the lens from the camera, and cap the body.
Put the camera in the sensor cleaning mode for 30 seconds.
Shut off the camera for 30 seconds.
Do the dead pixel test again.


It worked! It seems that when you do the sensor cleaning on the 5D it maps the dead pixels automatically.

BTW: The way I test for dead pixels it to take a picture with the lens cap and the view finder cap on at iso100 for 1 second. The pixels show up nice and bright on a black background.
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Re: Dead/Hot pixels on a 5D
Old 06-28-2007, 09:46 AM   #7 (permalink)
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Quote:
Originally Posted by ffppro View Post
[b][size=5]
It worked! It seems that when you do the sensor cleaning on the 5D it maps the dead pixels automatically.
This may be a dumb question, but doesn't that then leave you with x number of pixels in your finished image that have no information at all? From your description, it sounds just like what happens with hard drives, where it maps bad sectors so it won't write to them. On a hard drive that's not necessarily a bad thing (except for losing some storage space), but on an image sensor I'd think that having "holes" in the area for capturing your image isn't a good thing.
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Re: Dead/Hot pixels on a 5D
Old 06-28-2007, 03:07 PM   #8 (permalink)
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Quote:
Originally Posted by TheGoldy View Post
This may be a dumb question, but doesn't that then leave you with x number of pixels in your finished image that have no information at all? From your description, it sounds just like what happens with hard drives, where it maps bad sectors so it won't write to them. On a hard drive that's not necessarily a bad thing (except for losing some storage space), but on an image sensor I'd think that having "holes" in the area for capturing your image isn't a good thing.
On the hard drive you don't usually lose any storage space because there is extra space that is not normally used for storage that can be used for this mapping. And it is non-contiguous, in other words the data can be stored anywhere and doesn't have to be side by side.

Now on the camera, it may be a different thing, but short of a full disclosure by Canon on how they map the sensor pixels and how they actually work and exactly why a pixel might be dead, it may be difficult to know. My observation has always been that a dead pixel or two and a speck of dust or two on the sensor will have no effect on my photos. You will never be aware that one pixel is either missing or less than accurate. But if this is perceived as a real problem that effects our real world photos then we should just keep sending back the cameras for replacement and then Canon will get the word fast enough when they have to eat tens of thousands of cameras. I strongly suspect, however, that this is not a problem and never has been.

Cheers,
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Re: Dead/Hot pixels on a 5D
Old 06-28-2007, 03:45 PM   #9 (permalink)
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The first camera that I got had a bright red pixel in the middle of the sensor, and it was obvious in every picture that I took. This was a real problem.

The replacement camera's problem pixels were not obvious, and the only reason I noticed that they were there is because the first thing I did is check for dead pixels, because of the first camera.

I did some reading on pixel mapping, and the impression I am getting is that Canon, and other camera manufacturers map dead pixels on all cameras before they leave the factory.

What I am also reading (all this information is from various websites, so dont rely on it) is if you have serious pixel problem and you send your camera to Canon for repair, all they do is just map the dead pixels on your camera and then send it back.

I do know for a fact that after you do the sensor cleaning of the 5d, it will map the dead pixels automaticaly. I now this because I did it and it worked.
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Re: Dead/Hot pixels on a 5D
Old 06-28-2007, 05:14 PM   #10 (permalink)
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Quote:
Originally Posted by ffppro View Post
I did some reading on pixel mapping, and the impression I am getting is that Canon, and other camera manufacturers map dead pixels on all cameras before they leave the factory.

...

I do know for a fact that after you do the sensor cleaning of the 5d, it will map the dead pixels automaticaly. I now this because I did it and it worked.
When you take a photo now, does the pixel(s) show black or some other color? Or does Canon's internal software interpolate among the surrounding colors so that pixel itself is no longer an issue?

I am just curious.

Best regards,
Kevin
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