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TWDesigns
03-17-2005, 11:00 PM
I purcahsed a canon rebel xt and noticed 4-6 hot pixels at iso 100 with a 3 and 10sec exposures delay. About 90hps at 30sec / 1600iso, all taken in low light areas.

Is this about normal?

Norm in Fujino
03-18-2005, 12:23 AM
That sounds like a lot for a new camera, but I dunno what other users are finding.

TWDesigns
03-18-2005, 05:50 AM
It's a digital rebel xt if that helps.. It's my first SLR so I have no idea whats a good limit to have, if any. After hours of searching I never really could find any good posts. They all either were freaking out about 1 pixel or they said all cameras have "some" so Im just curious as to what "some" would be.

D70FAN
03-18-2005, 08:38 AM
I purcahsed a canon rebel xt and noticed 4-6 hot pixels at iso 100 with a 3 and 10sec exposures delay. About 90hps at 30sec / 1600iso, all taken in low light areas.

Is this about normal?

How about posting a couple of samples? Are these hot pixels or stuck/dead pixels?

Hot pixels are random, stuck/dead pixels show up in the same place every shot. The first is fairly common, the later may be a problem.

TWDesigns
03-18-2005, 09:01 AM
Doh, Didn't know hot pixels were random. A few come up in the same spot every time at the longer exposures.

I will get some samples and post but I know for sure at least 2 are in the same spot each time.

D70FAN
03-18-2005, 09:07 AM
Doh, Didn't know hot pixels were random. A few come up in the same spot every time at the longer exposures.

I will get some samples and post but I know for sure at least 2 are in the same spot each time.

Do the constant pixels show up in every shot? Or just long exposures?

TWDesigns
03-18-2005, 09:10 AM
From what i can tell i see them in the same spots at 1+ secs on all iso's. Im stallling my software to check them now.

TWDesigns
03-18-2005, 10:45 AM
Im just going to exchane it and pray i guess.

I took about 5 shots from iso 100 and 1600 at less than 1sec and compared each image. The spots are in all of them in the same exact place so Im thinking they are stuck pixels maybe. Other spots appear but are random depending on what settings i snap the photos at.

Here are 2 that were close together. Theres more further up but I didn't want to post that big of an image.

tests (http://www.tommywhite.com/uploads/tests/index.html)

Also thats blown up x2 since i reduced the quality for web so that you can see it better. Just by looking at the raw image soon as its opened you can spot those dots above and the others right away because they are bright, on dark backgruonds. Also on brighter bg's but you have to look harder.

petejackson
03-25-2005, 08:18 AM
I purcahsed a canon rebel xt and noticed 4-6 hot pixels at iso 100 with a 3 and 10sec exposures delay. About 90hps at 30sec / 1600iso, all taken in low light areas.

Is this about normal?

Hot Pixels don't have to be random. The main quality of a hot pixel is that it shows up at longer exposure times, due to charge leakage. But here's my experience:

I also have a Canon Digital Rebel XT. Mine shows 2 hot pixels at 8 seconds outside in the dark. They appear in the same place every time, but do not appear in photos with a slower shutter speed. At about 15 seconds, I pick up an extra hot pixel. At 30 seconds, I have about 4-6 hot pixels. Over 2 minutes, and I only noticed 1 hot pixel. All of these shots were taken at ISO 100.

You results at ISO 1600 are likely to be inconclusive because of sensor noise. Move down to ISO 100 and put the lens cap on to test for hot pixels.

It sounds like your camera has a few more hot pixels than most, but remember that you could end up in a worse situation if you exchange the camera. If it's going to annoy you to see all those hot pixels and you take a lot of night shots, then go ahead and roll the dice.

gary_hendricks
03-25-2005, 08:44 AM
Sounds normal for a new DSLR ...

ecos 606
03-27-2005, 07:27 AM
Hello,
I am new to digital photography. I am thinking of buying a digital rebel XT or the digital rebel but am waiting for reviews from CNET and JEFF. Could you please explain what hot pixels are?. I am assuming it is undesirable.
Thanks
ecos 606

Bluedog
03-27-2005, 07:39 AM
Click this link to read about "Hot Pixels" (http://www.mediachance.com/digicam/hotpixels.htm)