Archived posting to the Leica Users Group, 1999/04/08

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Subject: Re: [Leica] Problem with M6 scratching film
From: "B. D. Colen" <bdcolen@earthlink.net>
Date: Thu, 08 Apr 1999 10:37:13 -0400

uAt 02:00 PM 4/8/99 +0200, you wrote:
>This is one of the most interesting threads on this list.  But is the
>problem with the camera or the scanner?  I would assume that *every* camera
>pressure plate or winding mechanism leaves its stamp on a roll of film,
>albeit microscopically, much like a rifle barrel carves its mark on a bullet
>or a typewriter key uniquely strikes a page.  In fact, I would guess that
>the FBI Crime Lab could identify the camera a roll of film came from if they
>had to.
>
>But if nothing can see the scratches except a scanner, then maybe they're
>scanning in too much "noise."   There should be a "Dolby" scratch filter for
>these things.
>

Now that everyone keeps mentioning it...I to am seeing faint horizontal
scan marks on scanned negatives - I NEVER observed this problem on any lab
produced prints....Could it be that this is an artifact of scanning
technology, which is to say:

The pressure plates on the Ms - and perhaps most other cameras - have
always produces faint scratches on the film, but simply projecting enlarger
light through the neg doesn't show them up. When scanning, however, the
resolution is such that these scratches show up....

I don't claim to know enough about the scanning technology, or optics for
that matter, to know if this is a possible explanation...but it makes some
sense to me...

I also find, by the way, that eliminating these "scratches" with Photo Shop
or its equivalent is a piece of cake - even if a time consuming piece of
cake... :-)

B. D.