Mysterious "White Pixel" on 20% of Digital Images

[BWiley]

I just returned from a photo trip to find that about 20% of my images have a very tiny white dot in the same place when enlarged with the Breezebrowser function "View Actual Image." It's like viewing the image in PhotoShop at 100%. When blown up, it appears that it is a single pixel that is white.

On this trip I shot waterfowl with my new Canon 1Ds and a 600mm IS lens, oftentimes with a 1.4 adapter attached. At first I thought the problem must just be a speck on the sensor, but that wouldn't be likely since the white dots happened intermittently. Also, a speck of dust on the lens wouldn't look like a single pixel. Could it be a problem with my microdrives? Any ideas would be appreciated, as I want to avoid this in the future.
Thanks,
Bill

[G3]

Sounds to me like you may have one bad pixel on your image sensor.

[drisley]

I have one hot pixel on my Rebel, but it only shows up at exposures longer than 1/20 second. Apparently this is VERY common with CMOS sensors. I read about one guy who returned 3 Rebels only to find that each new one had more hot pixels than the one he returned. Finally, he just kept the original.
It is very easy to remove with photoshop, and quite honestly, I dont notice it anymore (sometimes I wonder if it just disappeared). When I first noticed it, it was VERY hot in my apartment. Temperature definately affects hot pixels.
I've seen sample pictures from a few camera review websites that had more than one hot pixel.

[robertwgross]

I agree completely with G3.

I think you want to discuss this with Canon.

If it were a stuck pixel on the rear display, that would be different. But one stuck pixel on the sensor makes different degrees of problem for the user.

---Bob Gross---

[Jesper]

Just found a useful page about dead, hot and stuck pixels, but it's in Dutch, so probably not very useful to you....: http://home.hetnet.nl/~heuker2000/pixels/pixels.htm

I'll try to translate some of it:

A complaint that many owners of digital cameras of all brands have, especially if they're getting older, is that they get defect pixels on the sensor. There are three types of defects: dead, hot and stuck pixels.

Dead pixels: These pixels don't read information and are always off, they show up as black on the image.
Stuck pixels: These pixels are always on. They will show bright white on all images.
Hot pixels: These are pixels that show up red, orange or green at longer exposure times. When a hot pixel gets worse and also shows up at the shortest exposure time, it becomes a stuck pixel.

By the way, don't worry too much about it - almost every camera has a few defect pixels on the sensor. It's simply too difficult and too expensive for sensor manufacturers to make only 100% perfect sensors.

I once did a test for stuck and hot pixels with my 10D: put the lens cap on, switch lens to manual focus, set camera to manual exposure and shoot at f/22, 2 minutes. Repeat this with different ISO settings.

I noticed that at ISO 100, I have probably 4 or 5 hot pixels (red, green and blue), and the higher the ISO, the more hot pixels show up. That's to be expected - if you turn up the ISO, you turn up the "volume" (the signal from the sensor is amplified more) so you'll see defects earlier.

[drisley]

Yes, that is why I consider myself lucky having only 1 intermitant hot pixel. Most cmos sensors will have atleast 1, and often more than that.
That is how it is with the 10d and rebel and d60 anyway. I'm not sure if it's acceptable for a camera like the 1ds though.
I'm sure Canon can map out the offending pixel, but that may mean you will be without a camera for a while.
You could probably exchange it, but chances are very good you will get another camera with atleast 1 or more hot pixels. Atleast this is the advice given to me, and from what I've read, it seems to be true.

[BWiley]

Thanks for all the information. To expand further, most all of my shots were 1/200 or faster, many being 1/1000 or faster (I had to be ready for the cranes, egrets and herons to fly). All of the shots were taken in sunlight in the 70-85 degree temperature range, which may be a factor. A very few of the shots were taken at ISO 100 or 200 when the subject was stable; the rest ranging from 400-1000.

Based on your information, it definitely sounds like I have a "stuck" pixel. I probably wouldn't let it bother me, except for the $ I shelled out to buy the top-of-the-line 1Ds with my goal being high-resolution big glass photography. My ultimate objective is making prints and I'd rather not have to PS every final image that I choose to enlarge.

G3, drisley and bob gross, thanks for the tips. It still amazes me how in a few hours one can obtain good information on a most minute subject from experts all around the world. THANKS! Bill

[BWiley]

Jesper too. Thanks for your feedback.
Bill

[drisley]

Yes, if it is a stuck pixel, not just hot, I would have canon look at it. Especially since it is a big $$ camera.