From: Judy Seigel (jseigel@panix.com)
Date: 02/01/00-02:17:38 PM Z
On Tue, 1 Feb 2000, Tom Ferguson wrote:
> ... Many scanners (including mine) have holders that
> elevate the film a few mm above the glass. Unfortunately with large format
> film, the center often sags just enough to get a few rings in the center of
> your picture ;-(
I was wondering if any of you scan experts know if difference in focus
is an issue when elevating/not elevating. For instance I have put slides
in the mount on the scanner bed, also a holder comes with for 4x5s, but
I've also scanned a large negative with no holder directly on the glass...
not noticing focus or Newton problems with any, but not looking for them
either.
I've found that the copy machine seems to have a depth of field so that
small differences (eg a pasted-on cardboard) come in equally sharp. On the
other hand, when I've *scanned* 3-dimensional objects I've found that they
get out of focus within a relatively short distance.
Presumably the scanner is configured to be sharp for opaque copy directly
on the glass and, unless works differently for negatives in holders, has
that amount of leeway, but, as noted it goes off before a great distance
is reached. I also note that I had trouble with a quite curly fiberbased
print until I weighted the scanner cover -- not so much sharpness as I
recall, as tone, which was woozy.....
Any input on these issues gratefully received. (We the damned of scanner
hell need any help we can get... And PS to faithful friends & readers:
The THIRD scanner replacement was also defective !)
PS to Tom: Beseler I believe has a glassless negative holder that grabs a
large-format negative with pins of some sort around the edges and holds it
tight. It's fairly thick, but I wonder if something of the sort could be
configured to hold your large neg flat.
Judy
>
> You rarely see this problem scanning prints due to the fact that paper
> (printers or photo) is rougher (less glossy) than film.
>
> On my Umax Powerlook, I find a lot less newton rings with the emulsion down
> towards the glass. I assume that this side is less smooth, and thus less
> rings. In the original software I had to flip the image (as the scan was
> backwards). In Umax's newest drive it is already set for me (confused the
> heck out of me for the first week!).
>
> Hope that helps.
> --
> Tom Ferguson
> http://www.pipeline.com/~tomf2468/index.html
>
>
> > From: Dave & Erin <dfisher@nstar.net>
> >
> > My name is Erin and I am a grad student and I scan a lot of my negs. The
> > moire pattern is common when scanning negatives. At school I am using a
> > Linotype scanner and it came with a liquid solution that you put some on the
> > scanner and then lay your negs down and it prevents the moire pattern.<SNIP>
> >
> >> From: Kathryn Garrison <Kathryn.Garrison@Colorado.EDU>
> >>
> >> I'm hoping someone has the answer to this, I have a negative with some kind
> >> of damage to it... not sure what. Although I'm not able to see it through
> >> the loupe or projected from my enlarger, when I scan the negative there's a
> >> distinctive moire' pattern.
> >>
> >> I'd like to have a scan of this negative! Does anyone have a suggestion? I
> >> recall that oil is sometimes used with microscopes to improve the image,
> >> would I be further damaging the negative if I did that? Kathryn
>
>
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