dead pixels 'common'? (5d2)

[matt_m__toronto_]

<p>i've noticed what looks like a white pixel in the same poistion on a few photos...well any photo that has a dark area where said pixel exists. i'm new to digital photography, so i don't know if this is something that digital shooters just deal with and correct in post, or if i have a lemon.</p>

<p>thanks for any info.</p>

[alfonso_valdes]

<p>I've had a few on my 40D and I found a procedure that works. WIth a capped lens in the camera, go through the manual sensor cleaning menu. This will move the mirror up as if you were cleaning the sensor, only you're not and in fact you have a capped lens on. Leave it for 30s or so, then turn off the camera. This has cleared up my hot pixels twice, and no, I have no idea why it should work and people in this forum have said id would not work on this camera. But it's worth a shot.<br>

It is annoying as hell and I have not gotten an answer from Canon as to why these occur.<br>

The only other solution is to send the camera to Canon and have them remap the pixels. Not sure exactly what that does either.<br>

On the other hand, I have not noticed any for a while (I'm at about 6,000 clicks, and probably no stuck pixels for 3000 lpus, so maybe the camera outgrew the problem).</p>

[christopher hartt dallas]

<p>Yes, dead pixels are common. And the more you pack on a sensor, the more dead pixels you will have.<br>

I've wondered if this is how Canon is dealing with mollifying the Ds3 owners - by putting lesser quality sensors on the 5D2? I've had a chance to look at several 5D2's now, and there seems to be many times more dead pixels on those sensors than on those of our Ds3's.<br>

Several associates of mine have done (minimal) research, but so far there doesn't seem to be any specs about the "dead pixel" tolerance of the various sensors.</p>

[PuppyDigs]

<p>All my cameras--10D, 20D, 40D, 50D & 5D--had a few but I rarely noticed save a pixel peep session. Most only appeared at high ISO. None were visible in my 8x12 and 12x18 prints so I didn't worry about them. It's pretty much par for the course in digiland. If they're bad enough to be seen in a medium to large print, I'd ask Canon service to map it out.</p>

<p>Now for a real shock, shine a penlight down your lenses and peep in the other side. Plenty of dust, factory installed and user installed. MAybe even a hair or two. The anal retentive go bananas over dust. Some guys will exchange the lens 3 or 4 times trying to get a clean one only to have it suck in more dust with a few zoom and focus cycles.</p>

[matt_m__toronto_]

<p>thanks for the replies. i'm used to dust in the lens, but the white pixel had me question what is acceptable. all my years of shooting film and scanning, i've grown used to hair and dust that i would need to patch up. was just not sure what is acceptable in terms of digital 'patching up' . ... as this pixel is noticeable without any 'peeping' or zooming into the image.</p>

[bobatkins]

<p>Sensors may have many more "dead" or "stuck" pixels than you actually see. I think most of them are "mapped out" by the manufacturer (Canon, Nikon etc.) and filled in with interpolated data. I'm told that Canon can "remap" bad pixels to remove them from the image, but I don't know how willing they are to do that for just one or two pixels.</p>

<p>

BTW a white pixel would be a "hot" pixel, not a dead pixel. Dead pixels are black (no response to light) whereas "hot" pixels are oversensitive and can show up as white, red, blue, green etc. depending on their location in the bayer matrix

[matt_m__toronto_]

<p>ok, so the answer is that noticeable 'hot pixels', are accepted in digital photography...even when the file is not enlarged?</p>

[roger_smith4]

<p>Lightroom seems to get rid of these automatically for me using a 20D.</p>

[martijn_houtman]

<p>Mine seem to be mapped out as well (30D) with LR. A friend of mine just bought the 5DII, and he has 3 noticeable hot pixels. I think it is actually pretty common, especially with a high pixel count such as this. However, in his LR imports, the hot pixels are very distracting, as they do not get corrected automagically. I wonder if this can be fixed by the internal dust subtraction option (not sure about the exact name) or by using "black frames" in your RAW converter, or even internally in the camera.</p>