7D with 2 bad pixels?

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dvollrath

Active member
I think my 7D has a bad pixel and I have to send it in. I just wanted to see if anyone thought otherwise based on these 2 screen grabs. (These are shot with 2 different lenses so I'm sure it's not caused by them). The weird thing is, these pixels don't always show up. They tend to show up more often in darker situations.

pixel1.jpg


pixel2.jpg
 
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Those look like 'hot' pixels. Areas of the sensor which are stuck on red (out of a possible red, green and blue)

But since downscaling on the 7D and 5D supposably bins lines of pixels, it's strange that just TWO dead pixels get through every time. They also look blurred horizontally.

What do stills look like?
 
commanderspike said:
Those look like 'hot' pixels. Areas of the sensor which are stuck on red (out of a possible red, green and blue)

But since downscaling on the 7D and 5D supposably bins lines of pixels, it's strange that just TWO dead pixels get through every time. They also look blurred horizontally.

What do stills look like?
Click to expand...

I've looked through some stills and in some of them, one of the pixels shows up. It's much smaller (I think actually just one pixel). I've only found one pixel in the photos I've taken, but it seems like there's a good chance that the other might be present as well.

Johnny Cola said:
Looks like low light images with a lot of gain. Does it look that pronounced at low ISO in bright light?
Click to expand...

It's more noticeable in low light images with gain, but I've seen it appear in lighter images shot at 100 iso as well.
 
hotpixel.jpg


I just found mine, looks purple here, but on another thing I shot, it's red. *sigh* the trouble of returning exchanging...
 
Could create a script/plugin that clone stamps each pixel out with the one directly next to/above it.

(I'm joking please don't kill me.)
 
There is a trick that is worth trying - take the lens off, put the cap on the body and put the cam into manual cleaning mode for a few minutes. Apparently this causes the camera to map bad pixels. If they are gone then fine otherwise send it back.

The trick didn't work for my pixel, but many people on photography forums have said this trick works. My pixel only showed up on stills.
 
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This is a big problem with Canon cameras. I sent mine back to Canon last week for a dead pixel. Should be getting it back tomorrow.
 
I had one of those on my 5D MK2. it's a known problem. Had the camera store send it back to Canon. They said that they had a few of them go. Camera came back, pixel was gone.
 
I also had similar problem. Just got mine last night, except my pixel is pure white and I could only notice it when shooting video in low light. It looks about 4 pixels blob on video.

So I went back and examined my photos and notice the while pixel is there as well, but only visible when you zoom in. Then I tried zooming in on the camera's live view, and sure enough that white dead pixel is there every time. I believe the video compression is oversampling that dead white pixel and burring it out to 4 pixels when it's being compressed.

Others who have red or green pixels may not be as bad since those colors may get sampled and blended in better with the surrounding colors, whereas a white pixel will dominate the sampling (in my limited sampling knowledge:)

I've submitted a return request with b&h photo to get an exchange, but was wondering if a dead pixel or two is pretty common and you just have to work around it, or I just got a bad lemon?
 
I've noticed my pixel becomes more visible with longer shutter speeds. Bringing up the ISO doesn't seem to do it, just a longer shutter opening. This occurs both in video and in photos. Anyone else have the same result?
 
I too have a group of Hot Pixels (Red), round the center of both my footage and photos.
They're always in view - Only really visible in low light though, and the manual cleaning technique didn't work either.
I think I'll have to live with it, 'cause I bought my 7D from the States and I live in SA, so it isn't worth the shipping expense to send it there and back.
I'll contact Canon in my country & see what they can do - I'll probably have to pay for the repair, anyone have an Idea of what it'll cost?
In the mean time, this plug-in takes care of it: http://www.revisionfx.com/products/refill/
 
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I exchanged my first 7D, dead pixels are unacceptable, period. They are easy to see, just shoot in low light and search around in the blacks as soon as you get your camera. Every camera comes with a warranty or a return/exchange policy. Use it. BTW the sensor cleaning fix didn't work for me after numerous attempts.
 
My understanding of it is that you of course have your CMOS Sensor which captures both stills and video image. And CMOS-- any CMOS carries a series of imperfections [Hot Pixels, Dead Pixels, "spots" of various colors, etc.]

This is not to be confused with Dirt/Dust on the CMOS which collects through constantly being exposed to open air environments and probably over time. Of course this would not appear as red spots.

The imperfections of the CMOS are basically unavoidable from production (So is my understanding.) Electrical adjustments are done to clear or better said to "hide" these imperfections using a system of mapping to find and cover up these spots so that they do not show up in captured stills/video. However, the mapping treatment does not always go perfectly thus leaving some pixels to remain. The number of pixels discovered is also based on ISO settings.

A way to test for dead pixels is to put a body cap over your camera and set your shutter speed anywhere from one second or longer (at least 5 secs for me) and take an exposure at various ISO speeds (1600, 3200, 800, etc) and then examine the photos in black.

Sensor cleaning can help remove some spots. But really you might need to send the camera in for repair. They may try to "remap" the CMOS in order to add the dead pixels left in view to the map of "hidden" spots. If you do send it in, it might be good to send in photos of the pixels to better help identify and remove the problem.
 
I went over to Samy's Camera today and was luckily able to exchange my 7D body for another one. In the store I tested both the new camera I have now, as well as another new 7D and both had hot pixels like the first camera I had. The camera I ended up going with had the least bad spots, with the worst offender near the top edge of the sensor, which I can live with for the time being. This seems to only be visible in the test below.

I tested all the cameras with the body cap on, ISO at 6400, and the shutter set to 15". I understand that with these settings, there's supposed to be a certain amount of noise in the image, but I'm looking for the offenders that aren't supposed to be there.

In actual dark video footage and stills, at 1/30 shutter and 6400 ISO, none of the bad pixels show up on the new camera, which I am very happy with. :)
 
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