What's the real effect of ISO equivalence?

I mean, with high-res digital, are you really going to get a grainy effect at higher ISOs than 100. I guess using a selected lower ISO prevents overexposure? Any thoughts on this subject would be appreciated.

Thanks!

Hi there,

Unfortunately there's no getting away from the fact that increasing the ISO equivalence is done by increasing the gain on the readout of the imager. When you increase the gain, you increase the noise, and the effect is worse than increasing the exposure time, i.e. for a given illumination, you get more noise with 1/2s at ISO 800 than you will with 4s at ISO 100.

I don't see why would think that high res imagers would suffer less from noise. The only thing that really reduces the amount of noise is using larger photosites (physical imager pixels). This means that "35mm/APS format" d-SLRs have better noise profiles than consumer digicams.

Hope that helps with your understanding of the noise issues.

Martyn

Pretty much what he said...:-)

No matter what size imager you use, when you up the ISO, you up your noise. How high you can go and still get "acceptable" results depends on the camera and what you are going to use the shot for.

I get good shots at ISO400 with my Fuji S2, but not with my Coolpix.

HTH

James Wiseman

Thanks all.