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

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Subject: Re: [Leica] Re: Problem with M6 scratching film
From: Henry Ambrose <digphoto@nashville.net>
Date: Thu, 8 Apr 1999 22:54:03 -0500

>B. D. Colen wrote:
>
>> 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:
>>
>
>I have run into this problem a lot with CCD film scanners. Very faint 
>scratches
>on the base side of negatives or slides which never show up on prints 
>often show
>up very readily on scans. So, yes, it is an artifact of CCD scanning 
>technology.
>A real pain. Similarly, grain in black and white negs is grossly over 
>emphasized
>with CCD scanners.
>
>>
>> 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....
>
>Light scattering when enlarging, especially with a diffused light source 
>helps
>minimizes the problem, but, when scratches are deep enough to be a 
>problem, an
>easy solution is to rub a little "nose grease" into the scratch. Has 
>worked well
>for the last century. If you try this when scanning with a CCD scanner, 
>you will
>end up with a smeary mess in the general area of application. The only real
>solution is to use take the lines out with your favorite image manipulation
>software.
>
>
>
>Mike
>
>
Really, my camera scratches the film. 

I've scanned a lot of film. I understand what you're saying about small 
scuffs and scratches. I've scanned film from lots of cameras. Mine and 
others. None of my Nikons, past or present, do this. (course they don't 
make quite as nice pictures either). Yes I can take the marks out in 
Photoshop. (I do this work as part of my job) I do not want to spend my 
time retouching something that should not be there. The scratches or 
scuffs are inside the image area and I don't think from the pressure 
plate. 

Its going back to Leica tomorrow. 

We'll see what they do.

I'll report the results soon I hope!

Thanks to all for the responses!

Henry