loss of dynamic range

[bkindred]

anyone know what's going on inside a film scanner (coolscan 4000) when the dynamic range begins to decrease? dark areas in scanned slides (kodachrome) are suddenly coming out black or nearly so. upping the analogue gain helps a little but the noise increase is unacceptable and overall quality is still sub-par. any thoughts about diagnostics i can run to pinpoint the source of the problem? is this a normal failure mode for film scanners?

[Trevor Ash]

anyone know what's going on inside a film scanner (coolscan 4000) when the dynamic range begins to decrease? dark areas in scanned slides (kodachrome) are suddenly coming out black or nearly so. upping the analogue gain helps a little but the noise increase is unacceptable and overall quality is still sub-par. any thoughts about diagnostics i can run to pinpoint the source of the problem? is this a normal failure mode for film scanners?

My first opinion is that there isn't a problem. But I know you're not posting because you don't there there is one. Can you post a sample scan that illustrates the problem? I'd like to see a shrunken down version at least 500x500 as well as a 100% crop at a shadow area that best has the problem.

There are many factors that could contribute including film type, development, exposure, etc. When you increase the analog gain, the noise WILL be increased....so if the dark area is too underexposed and the film/development didn't do the underexposure any justice then no scan will really come out as well as hoped.

Samples will help me understand just how big of a problem it is that you're describing.