Minimizing Moire patterns when scanning large format negatives???

I'm a large format photographer using an Epson 4870 scanner to scan my 5x7
negatives. I've had a custom 5x7 carrier made to hold the negatives (similar
to the 4x5 transparency carrier that came with the scanner). In general,
this setup work quite well, but I'm getting moiré patterns, especially in
the middle of the negatives where there is a lot of single tonality area
(like open sky) mostly on B&W negatives.

Does anyone have a clue on how to minimize this moiré pattern problem? (and
no, I'd rather not send my negs out to be drum scanned... s)

Thanks,
Terry

In article kLccg.87426$TK1.68135@fed1read06,
Terry Smith wrote:
I'm a large format photographer using an Epson 4870 scanner to scan my 5x7
negatives. I've had a custom 5x7 carrier made to hold the negatives (similar
to the 4x5 transparency carrier that came with the scanner). In general,
this setup work quite well, but I'm getting moiré patterns, especially in

Those aren't "moire patterns", they're Newton's rings. They're caused by
interference between re-reflections of the image across the airspace between
an imperfectly flat negative and an imperfectly flat piece of glass (both
of which are more or less inevitable).

If you dare, the most effective way to address these when scanning is to
coat the negative with special oil. Then you'll just have to clean it --
and your scanner -- before you use it for anything else...

Oil immersion is still standard practice when doing high-resolution drum
scans, I believe.

--
Thor Lancelot Simon

"We cannot usually in social life pursue a single value or a single moral
aim, untroubled by the need to compromise with others." - H.L.A. Hart

(Thor Lancelot Simon) writes:
If you dare, the most effective way to address these when scanning is to
coat the negative with special oil. Then you'll just have to clean it --
and your scanner -- before you use it for anything else...

There's special glass mounts you can get that avoids it somehow, at
least for 35mm slides, I dunno about large format. Look for
"Anti-Newton" glass.

Hi Terry:

I agree with the others... I think what you are seeing are Newton's
rings, which do look somewhat like round moiré patterns.

I shoot 11x14 Ektachrome and scan it on an 11x17 Epson 836XL with the
transparency top.

At first I couldn't get quality scans because the film wasn't flat
across its long side. So I added another piece of glass on top of the film.

This has worked well except for the appearance of very tiny Newton's
rings... and it's a real pain in the neck.

After trying shifting the film, and trying thin paper "lifters" between
the glass, as well as trying the messy oil used with drum scanners, I
found that it is impossible to avoid at least a few rings

So, the best way for me to remove the rings, is with both the cloning
tool and the healing brush in Photoshop.

Jim



Terry Smith wrote:

I'm a large format photographer using an Epson 4870 scanner to scan my 5x7
negatives. I've had a custom 5x7 carrier made to hold the negatives (similar
to the 4x5 transparency carrier that came with the scanner). In general,
this setup work quite well, but I'm getting moiré patterns, especially in
the middle of the negatives where there is a lot of single tonality area
(like open sky) mostly on B&W negatives.

Does anyone have a clue on how to minimize this moiré pattern problem? (and
no, I'd rather not send my negs out to be drum scanned... s)

Thanks,
Terry

How do I keep the negative flat on the glass?


"rm" rm@hotmailDOTcom wrote in message
u...

"Terry Smith" wrote in message
news:kLccg.87426$TK1.68135@fed1read06...
I'm a large format photographer using an Epson 4870 scanner to scan my
5x7 negatives. I've had a custom 5x7 carrier made to hold the negatives
(similar to the 4x5 transparency carrier that came with the scanner). In
general, this setup work quite well, but I'm getting moiré patterns,
especially in the middle of the negatives where there is a lot of single
tonality area (like open sky) mostly on B&W negatives.

Does anyone have a clue on how to minimize this moiré pattern problem?
(and no, I'd rather not send my negs out to be drum scanned... s)

Try scanning the negs with emulsion to the glass, then flip the image in
software.

David, Thanks for the correction. I'm sure they are Newton's rings; I don't
know why I called them Moiré patterns...


"David J. Littleboy" wrote in message
...

"Terry Smith" wrote:
I'm a large format photographer using an Epson 4870 scanner to scan my
5x7 negatives. I've had a custom 5x7 carrier made to hold the negatives
(similar to the 4x5 transparency carrier that came with the scanner). In
general, this setup work quite well, but I'm getting moiré patterns,
especially in the middle of the negatives where there is a lot of single
tonality area (like open sky) mostly on B&W negatives.

Does anyone have a clue on how to minimize this moiré pattern problem?
(and no, I'd rather not send my negs out to be drum scanned... s)

Are you sure it's not Newton's rings? Is the film touching the glass? My
experience with the 2450 was that Newton's rings was a nasty problem, but
the 4800 ppi Epson scans I've seen would lead me to doubt that Moiré would
be an issue.

David J. Littleboy
Tokyo, Japan

In article ,
"David J. Littleboy" wrote:

"Terry Smith" wrote:
I'm a large format photographer using an Epson 4870 scanner to scan my 5x7
negatives. I've had a custom 5x7 carrier made to hold the negatives
(similar to the 4x5 transparency carrier that came with the scanner). In
general, this setup work quite well, but I'm getting moiré patterns,
especially in the middle of the negatives where there is a lot of single
tonality area (like open sky) mostly on B&W negatives.

Does anyone have a clue on how to minimize this moiré pattern problem?
(and no, I'd rather not send my negs out to be drum scanned... s)

Are you sure it's not Newton's rings? Is the film touching the glass? My
experience with the 2450 was that Newton's rings was a nasty problem, but
the 4800 ppi Epson scans I've seen would lead me to doubt that Moiré would
be an issue.

David J. Littleboy
Tokyo, Japan

Flipping the original and scanning from the emulsion side does wonders
with the 2450.
--
The sometimes insomniac.

www.gregblankphoto.com

In article qNlcg.87432$TK1.42357@fed1read06,
"Terry Smith" wrote:

How do I keep the negative flat on the glass?


"rm" rm@hotmailDOTcom wrote in message
u...

"Terry Smith" wrote in message
news:kLccg.87426$TK1.68135@fed1read06...
I'm a large format photographer using an Epson 4870 scanner to scan my
5x7 negatives. I've had a custom 5x7 carrier made to hold the negatives
(similar to the 4x5 transparency carrier that came with the scanner). In
general, this setup work quite well, but I'm getting moiré patterns,
especially in the middle of the negatives where there is a lot of single
tonality area (like open sky) mostly on B&W negatives.

Does anyone have a clue on how to minimize this moiré pattern problem?
(and no, I'd rather not send my negs out to be drum scanned... s)

Try scanning the negs with emulsion to the glass, then flip the image in
software.


The idea is not to have the original flat on the glass....the reason for
the Newton rings is somewhere the original is touching the glass.
--
The sometimes insomniac.

www.gregblankphoto.com

"Terry Smith" wrote:

David, Thanks for the correction. I'm sure they are Newton's rings; I
don't know why I called them Moiré patterns...

Then all you have to do is keep the film off the glass.

Which would be, I'd think, quite hard. Sigh. (In my experience, the emulsion
side down trick doesn't really work.)

David J. Littleboy
Tokyo, Japan

I had my custom 5x7 carrier made out of 4 ply flat black matte board.

Would a thicker matte board (or some other material) lessen the chance of
the film touching the glass? If so, how does the scanner know where to
focus???




"David J. Littleboy" wrote in message
...

"Terry Smith" wrote:

David, Thanks for the correction. I'm sure they are Newton's rings; I
don't know why I called them Moiré patterns...

Then all you have to do is keep the film off the glass.

Which would be, I'd think, quite hard. Sigh. (In my experience, the
emulsion side down trick doesn't really work.)

David J. Littleboy
Tokyo, Japan