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[filmscanners] Re: film and scanning vs digital photography



On Jun 8, 2007, at 8:49 PM, "" <lotusm50@sprynet.com>
<lotusm50@sprynet.com> wrote:

> Hmmm.  Interesting and quite contrary to my own experience and others.

It depends, really. Like, I was scanning some old Ektachrome 400
today. The images were coming out at at 4374 x 6400 pixels. That's
about 28 megapixels and the scanner still wasn't clearly capturing
the grain structure. Looking at it closely you can see what looks
like noise, but is actually imperfectly resolved grain. Now,
Ektachrome wasn't the finest-grained kid on the block, but the grain
is fine enough that 28 megapixels isn't getting there. Of course,
some of it is undoubtedly me hitting the optical limits of my
Microtek scanner. That said, I've taken 5 1/2 megapixel images with
my old Olympus E-1 that give some of my Ektachrome slides a run for
their money when it comes to resolving detail. It's just that the
actual image on a slide doesn't begin to cover the amount of
information contained in the slide and if you want it all you have to
scan huge to get it. I just shot a couple of rolls of Efke 25 in my
Mamiya 7. Those 6x7 negatives contain WAY more than four times the
amount of information on those 35mm slides. I wouldn't be surprised
if it took 175 megapixels to properly resolve the grain structure.
And that's the real problem with comparing film and digital. 10-12
megapixels will certainly give you images every bit as detailed as
you're used to getting from film. Yet to capture the beauty of film's
grain you have to scan at a level of detail that's really kind of
impractical.

I had a test arrangement with a camera manufacturer last year to do a
telecine of some old 8mm film to HDV. They wanted to know how it
performed. They may have been thinking of looking into an HDV
telecine product, I don't know. Anyway, the results were mixed. The
720x1280 images from the camera captured all the detail that the lens
on the 8mm camera original delivered to the film. I'm fairly
confident of that. But the camera didn't even begin to resolve the
grain structure. In fact, after talking to their engineers I found
out that the mpeg encoder saw the grain as high frequency noise and
tried to suppress it. So I was seeing a kind of cross-hatch pattern
on individual frames that had replaced the grain structure. Now, when
the image was in motion you couldn't tell you weren't just looking at
grain, but pausing on a frame left an impression of some kind of jpeg
compression gone wrong or something. Obviously this wouldn't be the
case with uncompressed recording, but then the file sizes would be
immense and I'm pretty sure 720p doesn't even approach the level of
detail needed to resolve the 8mm grain structure.

So you've got kind of a mixed bag, IMO. You can replace film with
digital at a fairly low resolution, IMO. 6-10 megapixels will usually
yield comparable imagery, IMO. And yet to fully resolve the grain
structure of film takes WAY more resolution than you need to replace
it as a capture medium.

Robert Jackson
Santa Rosa, CA

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