Dark Frames and Flat Frames

[Michael Heald]

Hello! I am a newbie at scanning and image manipulation. I've tried some astrophotography in the past, and in astrophotography, the best final images are captured with mutliple exposures, with the subtraction of dark frames, and the division by flat frames.

I've read that some software will autimatically take multiple scans and average them.

Since Dark Frames are designed to subtract digital noise by obtaining images that have had no light exposure and flat frames are designed to detect how different pixels may respond to light differently by exposing them to a light field that does not change across the field of view, would either of these two techniques be useful for scanning negatives? Or is the exposure generally short enough that noise is not an issue, and the optical train good enough that flats would not benefit the final product?

Thank you and best regards.

Mike

[David Swinnard]

I've often wondered the same thing... (an astronomy background and a photography foreground)

I'm just making the move into digital (film originals then scanned) and am curious to hear the more experienced folks comments.

[Kirk Gittings]

Some of the higher range Silverfast applications will do it, but be careful, multipass scanning on sub $1000.00 flatbeds is a risky buiness as registration is a problem. SF also has a pretty good registration program built into some applications, but it is no substitute for a higher priced scanner. The New Epsons may be better.

[Jonathan_6488]

I concur on the Silverfast. You can get it cheap on ebay though. You would be VERY surprised, Kirk, at just how good some of the older generation higher end scanners are - compared to Epsons. I'm talking here about Linotype-Hell, Heidelberg, Creo and Scitex flatbeds - many of which can be had for the eagle-eyed ebay visitor for less than $500. I have a Saphir 2 Ultra and a Umax Powerlook 1100 Ultra (same engine - different outfitting). Mine may only be 1200 lpi but to me - it's more about the tonal capture. (Don't underestimate the importance of the software for this!) It's great for the web. If I want to print something REALLY seriously I'll do an 8K line drum scan. Okay - I'm getting WAY off topic.

A question for the astros... I hear that Lumicon will no longer sell hypered tech pan. Will they hyper tech pan if YOU supply it? Any idea?

thanks
Jonathan