Tuesday, 12 June 2007

Further thoughts on scanning resolution

I mentioned in the previous post that I ran a series of resolution tests at 1200dpi multiples. This was based on the received wisdom that I had on sticking to multiples of the scanners native resolution. I then discovered that the scan settings can be used to set an output size and resolution, the software doing the rest. I gave it a go.
I picked a given output size (55cm, IIRC for a 60cm print) at 300dpi. That led to an odd enlargement factor. tested the results - I couldn't really pick up any difference pixel peeping. maybe a slight degradation at 100%, certainly nothing that'll show up on print. This will simplify my workflow: get a general crop from the pre-scan, set the desired output & away I go.

The other thing I've been pondering comes from Paul Butzi's post on digital versus medium format. I responded that I reckoned MF could do better. This is based on the resolution testing I outlined below. If I can scan a 645 (56mm wide) film at 3600dpi, that would yield 670mm (26") image at 300dpi print. Larger at 4800dpi. I might imagine that this sort of enlargement would push optical enlargement (darkroom) but seems well within the bounds for scanning to digital today. I've seen some 5D and M8 files up close and they are very good, but not as much detail as I might get at those scan resolutions. Of course, if the film isn't up to it in terms of grain etc the point is moot (at ISo400 I'd reckon on digital winning, no problem). If I'm still getting extra detail at 3600dpi then that really opens the window of opportunity for enlarging film.

There are, of course, other factors relating to colour & contrast etc but for out and out resolution I think current scanner technology is keeping film in the hunt (if you've got the patience for the lengthened time required for film).

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