Newton rings when scanning 8x10" plates

[Carlos A. Schwartz]

I have two EPSON scanners (EXPRESSION 1680 and PERFECTION 4990) with guides to avoid direct contact between film and scanner. But that is not possible with 8x10" plates, so I get Newton rings. Is there a way to avoid that?
Thanks for the help.
Carlos A. Schwartz

[Richard Ide]

Hi Carlos

I don't know if this may work but maybe worth a try. I had a process camera with a glass sheet at the film plane and would get newton rings with some films. A very light dusting of corn starch would eliminate the problem. Use very little, so you can't see it.

Richard

[Brian Ellis]

I have the same scanner and when I scan 8x10 negatives I place the film emulsion side down (i.e. the opposite of Epson's recommendation to put the base side down) to prevent Newton ringts. The image will be reversed but that's easily fixed in the scanner software or if not there in Photoshop.

[John Berry ( Roadkill )]

I just got a 4990 myself. I do the 8X10 down as when I tried it up my sheets curled up. They might lay flat if I left them in there long enough to stabalise the temp thruout. Scanning 4X5 both ways I could see at high magnification that emulsion up was more APO if you will. I am also thinking about wet mounting.

[ronald moravec]

If you have polyethelene storage sleeves, use one layer over the glass. Or scan emulsion up and invert in Photoshop.

I have never tries this with a scanner, but it worked with an enlarger that was making Newton rings and the proper treated disc could not be obtained.

[julian_4860]

I used to use a 1680. I'd place the negs emulsion side down then place a piece of AN glass slightly larger then the neg over the top. Get it from any enlarger supplies shop that will cut you AN neg carriers

[Lars Åke Vinberg]

Remove the scanner glass.

[Alan Davenport]

Lars beat me to the answer. Removing the scanner's glass and inventing a way to support the plates would solve the problem. Of course it creates a new problem, one of supporting the 8x10 plates.

If you have many plates to scan, or if this will be a recurring process, you might try to find a sheet of aluminum the same size and thickness as the scanner glass, then cut out an opening just smaller than the 8x10 plates. Rest the plates over the opening and scan.

[paulr]

the solution is a lot simpler than removing the glass (although you'll get optical benefits from doing that also, with the risk of dust getting in and making you miserable).

The theoretical focal plane on epson scanners is 1mm above the scanner glass. The depth of field is enough that flat art placed on the glass is focussed pretty well, but you'll notice that epson's own holders put the film above the glass.

You just need to cut windows out of various thicknesses of shim stock (could even be construction paper), and try different combinations to find the scanner's actual focal plane. This is one of those areas where there's a fair amount of manufacturing inconsistency, so you can't assume the best results will be at exactly 1mm. But you'll almost always find things looking best some distance above the glass.

[julian_4860]

Hi Paul, the 1680 actually has adjustable focus so you select the right position for whether you are glass or holder mounting. Another technique I used for the1680 was to use a black card transparency mount to hold the neg and put the newton glass on top of that