What do hot pixels look like

[jengwen]

I am trying to decide if my D60 has a hot pixel. I have heard them described as white dots, which is not what I have. I had a dot in the same spot on many (but possibly not all) photos. It is a slighly darker circle that is particularily noticable when it falls on a blue sky. I thought this was a spec of dust or just a problem with one of my lenses, but I am starting to think it is a problem with the camera. Can someone describe what hot pixels look like?

[Roger_Cavanagh]

Jengwen,

Hot pixels are white. A dead pixel would be black. I have not seen either (fingers crossed on my D30 :) ), but I think a pixel would be very regular in shape.

I'd try giving the sensor a good clean before deciding on a bad pixel. I don't think you can get Canon to do anything about it. I'm pretty sure the small print in the warranty would say some pixel faults are allowed.

Regards,

[hmhm]

"Hot pixels" are easiest to see in Photoshop (or equivalent)
viewing an image at "actual pixels" magnification. They'll
show up as tiny spots that are brighter and a different color
(typically purely red, green, or blue) from the surrounding area.
These can be easily shown by taking an exposure of total
darkness, e.g. with the lens cap on and the viewfinder blocked.
These are really pixels that consistently demonstrate greater
"noise" than other pixels. As you increase the exposure time,
noise levels will rise throughout the entire image, but you'll
find that a few pixels consistently get noisy faster than the
"norm" (at least on a D60, behavior seen on a D30 or D1 once
your exposures are long enough for the "noise reduction"
second exposure feature to kick in may be different).

If you've got a darkish, cloudy, semi-transparent, smudgy spot,
that's characteristic of dust on the sensor, which can be cleaned.
These can typically be "shown" by taking an exposure of a pure
white subject at the smallest aperture, e.g. shoot a white wall
at f/22.
-harry