Bad pixels on a new dSLR?

[iamzip]

I tried to post this over on dSLRExchange.com, but can't post there for some reason.

This thread was supposed to be about the great deal I just got on a Canon Rebel XT, but after shooting a few pics and examining them close up, I have unfortunately found a bad pixel (I don't know if it's dead, or hot, I don't know the difference). I found it first in one photo, then checked to see if it was in others, which it was. My first thought was to send it into Canon to have it repaired or replaced; I can't take it back to the store to exchange it because I got the last one they had on clearance. However, I was searching around on the interent and found a post somewhere in which the poster claimed that they didn't think a "perfect" sensor existed, and that just about every camera they had has had a bad pixel or two. I think this is wrong, I have owned two different point and shoot cameras with no bad pixels, I found a bad pixel on this one in about a day or two of ownership. What is everyone else's experience? This is my first dSLR.

 

[RF-Addict]

I have a program to check for dead/hot pixels - I just looked on the internet, but it is no longer available - no idea why. If you are interested, send me a PM or email through RFF and I will send you the program - it is very easy to use and will at least answer your question.

 

[tmfabian]

hot pixels are unavoidable. Just because you've never seen one before doesn't mean your camera didn't have them. Before a camera leaves the factory they map out hot pixels and the firmware clones over them, but eventually you will end up with a few as the sensor ages. You can send it back and have it re-mapped, or shoot in raw because ACR actually maps out hot pixels and takes care of them for you.

 

[Petroleum V. Nasby]

Are you sure it's a dead pixel?

You're probably looking at a piece of dirt on the sensor and you think it's a dead pixel.

Post a photo.

 

[Gaspar]

I have a few on my D200 but to be honest I rarely notice them and had actually forgotten about the whole matter untill I read this post. After all what't a couple of pixels in 11000.

 

[sojournerphoto]

As someone said LR/ACR maps them out automatically. DXo doesn't, so if I do a long (30 to 40 minute) exposure on my 5D I have a handful of red and blue dots to clone out. The difficulty with hot pixels is that they will show up in prints if you don't clean up the file before printing.

If it's just one spot I wouldn't worry too much, though you might get a warranty repair (which would probably just remap the camera's record of bad photosites)

Mike

 

[charjohncarter]

Here is software to check your pixels:

http://www.starzen.com/imaging/deadpixeltest.htm

 

[gnarayan]

I have unfortunately found a bad pixel (I don't know if it's dead, or hot, I don't know the difference). I found it first in one photo, then checked to see if it was in others, which it was.

IIRC, there is some trick to getting the Canon's to map out hot pixels on their own without sending it in to them. I think there is some mode that you take a long exposure with body cap on and it removes it. It was not just the standard dark frame subtraction - it was intended as some sort of sensor cleaning mode. I'd ask on the Canon forums on Fred Miranda or dpreview. Oly DSLRs do have built in pixel mapping. It is a nice feature and you can actually access the service menus and tell how many pixels have been mapped. So far zero and I've had mine for a year and a half so I think it is a bit unlucky to get one so quickly but really its 1 in 8 million so I'd not lose sleep over it.

 

[iamzip]

I don't think it's dust. I think I can recognize the difference between dust and a bad pixel, so unless it's a pixel shaped piece of white dust, I think it's a bad pixel.

I realize now that perhaps I should have included a third option, "bad pixels are common but since you've only had this camera a few days you should think about sending it back!" I don't know if that would get any votes, but maybe. I just bought it on Monday. Even operating under the assumption that all cameras have bad pixels that are just mapped out, I still shouldn't be seeing any bad pixels yet.

Can anyone shed light on what exactly hot pixels are anyway? I assume dead pixels are just pixels which simply don't work. Can hot pixels be fixed? Would a firmware upgrade do anything?

I have posted pics of what I am seeing. The first one is a strange red spot that I also noticed. the second is the bad pixel that I noticed. Both anomalies are right in the center of the crop. Upon closer examination there are a few other ones as well.

 

[Doug]

I tried to post this over on dSLRExchange.com, but can't post there for some reason.

Were you logged in? If not, you won't see the Quick Reply text box...

 

[Quinn Porter]

Many DSLRs are programmed to automatically "map out" hot, stuck, or dead pixels over time. When I bought my 5D it had a hot pixel that was gone after about a week. I'd call Canon and ask them what to expect.

 

[iamzip]

Many DSLRs are programmed to automatically "map out" hot, stuck, or dead pixels over time. When I bought my 5D it had a hot pixel that was gone after about a week. I'd call Canon and ask them what to expect.

I didn't know that. As I said this is my first dSLR. I think that's what I am going to do anyway, contact canon and see what their position is. What's that weird red blotch though?

As for posting on dslrexchange.com, yes I was logged in, but then it tells me I don't have permission to post.

 

[iamzip]

As I research info on hot pixels, I see that at higher ISOs and longer exposures, more hot pixels show. The crops above were both taken from the same picture, shot at 1/8 sec. and 1600 ISO, just FYI.

Here is a shrunken low res copy of the entire shot:

 

[cmedin]

Yeah, 'hot' pixels will show up on longer exposures. 'Stuck' ones will show up on every shot.