Purple pixels... help?

[leinad]

I was taking some first-light 30sec unguided test shots out the back tonight with the 18-55IS EF-S, F/8(too high I think) @ ISO400 & ISO800; and I noticed in photoshop these purple pixels.

Can someone help explain what this is? With normal photos I dont see them. I didnt try shorter sec. exposures at the time, so Im wondering if this was because of the 30sec shots.
Anyone had this before? :help:

EDIT: I read I need to take darkframes to reduce hot pixel/noise. Can 350D's do this automatically? Would these be hot pixels?

[iceman]

You got it - they're hot pixels. They don't show up in normal point and shoot shots - they appear in long exposures and with higher ISO.

And you're right - that's what dark frames are for. Either use ICNR or separate darks.

[leinad]

Sorry Mike, what ICNR ?
Must dark frames be done after shooting or during shooting? Can you snap; take dark, snap; take dark..etc, etc or must darks be taken at the pc?

[Tandum]

In Camera Noise Reduction. Should be under custom functions in the menus. You take a shot and the camera takes another, of the same exposure time, with the shutter closed and does a dark subtration inside the camera.

[leinad]

Thanks! I'll have a thorough read through the manual tonight, and more on-line reading.


:D:D

[Omaroo]

Clone tool in Photoshop... ? It's not exactly a huge problem here... :)