Test for hot pixels

I was recently taking some photos in ISO 1600, and noticed a lot of white/green/red specks in the pictures. I've looked at a lot of ISO 1600 samples on the internet, and none have these. Is there a standard test I can carry out and compare results with other cameras?

Thanks

Can you tell us anything else abot the shooting conditions and camera settings (and what camera). I never get that and I do shoot in 1600 from time to time.

Around 1/4 second ISO 1600 with 350d.

Put the lens cap on, switch it to mf, and shoot at desired iso (1600 in this case). Go for a reasonably long shutter time. If you've got hotpixels they will show...

FYI - I got worried cos i had two on my 350d. Came here and asked, apparently its quite common to have a few.

okay, ive done the test above with a 30 second exposure and i see some white pixels when zoomed right in on the camera, hard to tell how many, should i be concerned, is this something else for me to worry about?

What you're seeing is sensor noise, more common at high ISO settings, with long exposures, and in dark areas of your photos. If your camera has the "noise reduction" custom function and you take long-exposure shots, turn it on.It'll double the time needed for a shot, but it'll seriously reduce the problem. There are also noise-reduction programs available,like Noise Ninja or NeatImage,as wellas noise reduction functions in most recent photo editors.

A few hot pixels (and these will occur reliably at the same place in long exposures of a given duration) are nothing to worry about. A salt-and-pepper image suggests a problem that warrants exchanging the camera if it's new enough or sending it in to Canon for service if it's outside the exchange period. When you're deciding whether it's "a few", remember we're talking at least 6 million total pixels and consider how long the exposure was that showed the hot pixels relative to what exposure you normally use. If you practically never take shots of over a second, don't worry about what turns up on a 30 sec. test.

ive just down a test at 1600 for 1 sec and i can see one or two when zooming in about 5 times, again i dont think there is cause for concern.

Mine doesn't have 1 or 2 - it has hundreds if not thousands. I'll post a sample pic later tonight.

A piece of software for testing dead pixels is available at: www.starzen.com/imagin​g/deadpixeltest
It works brilliantly and is a must to use every time you buy a new camera.

I would only worry if you see hot pixels at near normal ISO/shutter speeds. Then you can call them stuck (dead) pixels. ie if you see them at ISO 200 at 0.1 sec I would be concerned. If there is only a one or two under this condition, send the camera back to Canon and they will map out the stuck pixels. If it is much worse than this they will replace your sensor.
Instead of 1/4 sec ISO 1600 have you considered ISO 400 at 1 sec exposure (or ISO 200 at 2 sec). It depends upon what you are trying to capture, but this will usually give much better noise performance. If you really need ISO 1600 and ISO 3200 frequently you should consider purchasing Neat Image or Noise Ninja if the grain bothers you.
Mike K

Saudidave wrote:
A piece of software for testing dead pixels is available at: www.starzen.com/imagin​g/deadpixeltest
It works brilliantly and is a must to use every time you buy a new camera.

Got a page not found with this link.

red hot sheep wrote:
Mine doesn't have 1 or 2 - it has hundreds if not thousands. I'll post a sample pic later tonight.

Hundreds if not thousands of them? holy crap, I would like to see a sample.