Do you get more noise shooting at higher ISO's. I shot b/w for years at 400 and immediately set my 990 to it and left it there.

-- bill (this_old_house@pobox.com), June 19, 2000

Answers

Most people feel that you do get more noise, since they supposedly(it sounds reasonable) jack up the amplification on the CCD to get more low light performance. Whenever you amplify a signal you invariably amplify any noise that may be induced into or even created by the amplifier, associated components, or from other signals present in the camera. In some cases, it's highly prefferable to raise the voltage range across a sensor rather than incease the gain of an amplifier. By doing so, you minimize the effects of very low voltage noise in ratio to the signal level or simply put, raise the signal to noise ratio. Whether this can be, or is, done with CCDs, I can't say.

This is not to say that the effects will necessarily be so pronounced that you see them. But, bear in mind that the normal ISO for the camera is likely the best mode to image in, since it probably represents the mode in which the most care was taken to provide the best image. Chances are you won't notice any noise or abnormalities until you get into fairly low light, although some people complain of color shifts and other problems in the higher ISO modes on some units. At least I seem to recall that was the complaint that I read, possibly in this forum?

If it was me, I'd consider trying a few tests at different ISO's to see if there was a noticeable difference. Probably the best way to see any effects of noise would be to jack the magnification up to 5 or 600% when viewing the images. Perhaps a little levels manipulation would help the noise to stand out?

-- Gerald M. Payne (gmp@francomm.com), June 19, 2000.