Subtracting a dark frame

[peatoire]

Anyone know of a good link for subtracting a dark frame is PS for minimising noise for long exposures.
I've noticed that the cameras built in function is useless for exposures less than 30sec unless you're using 1600 iso.

[Juan Zas]

May be this page can help you:

http://www.terra.es/personal2/oscarcj/introeng.htm

Anyway, I think you must look into the Astronomical Photo area. They use this technique

[peatoire]

Thanks, will have a dig around

[possom]

Yo peatoire maybe these links will have some good info for you.
http://www.covingtoninnovations.com/dslr/Combining.html
http://www.mediachance.com/digicam/blackframe.htm
Hope they help.
John

[ATucker]

http://www.photo.net/learn/dark_noise/

[peatoire]

Thanks Possom & Tucker :-)