How to avoid newton rings

I’ve been using NLP for a few weeks now and have been quite pleased with it. However, during my increasingly long scanning sessions, more and more newton rings have found their way into my scans.

My negatives are scanned on a copy stand, by placing them directly onto a Kaiser slimline plano light box (emulsion side up), with custom-made masks for the respective negative sizes (cut out of black ABS styrene sheets) on top that reveal little more than the frame I am scanning, one at a time. I blow onto the frame before each exposure with a rocket blower to remove dust as best as possible, and swipe the surface of the light box with a microfibre cleaning cloth after each film strip. Doing so helps keep my scans mostly dust-free but, unfortunately, it also means that the light box becomes charged electrostatically, making the negative stick to it. While this is great for film flatness (not that that’s an issue with this setup), it introduces a lot of newton rings.

I thought I was doing the right thing by placing an anti-newton ring glass panel between the light box and the negative (with the dull side facing the negative), but if anything, it’s only made matters worse. What might I be doing wrong here?

I think your best bet for avoiding Newton rings is to not have the film negative touching anything… using a film holder like a Digitaliza or Negative Supply MK1, I’ve never gotten Newton rings.

If you do use ANR glass, you need something to make sure that it is actually perfectly flat against the glass surface, like a piece of museum glass on top pressing it down, or use KAMI fluid to wet-mount it with optical Mylar on top.

Hope that helps!
-Nate

Thanks Nate. I’ve looked at the MK1, it sure is a great piece of engineering. But not only does it cost as much as it does, it only does 35mm – I scan equal amounts of medium format, and some large format sheets, too. I was close to buying the Digitaliza (well, 2 of them – 1 for each format), but then I read about film flatness issues with the 35mm version.

I took note of the museum glass hint, but after thinking this through again, I come up with another idea, and it’s working well so far: instead of placing the negative directly on the light box, and the mask on top of it, I am now putting the mask on the light box first, and have the negative sitting on top of that. This creates a big enough space between the surface of the light box and the negative to prevent newton rings. No glass on top also makes it easier to keep that surface free from dust.
I thought I’d need a second mask to keep the negative flat (i.e. sandwiching the negative with 2 masks), but the electrostatic charge of said mask (the same charge that I suspect was giving me newton rings in the previous setup described in my first message) means that the negative is more or less glued to the mask. Larger negatives and freshly developed film might curve towards the middle, and that’s where your museum glass suggestion will come in handy. Thanks!

I use an 8x10 ANR glass plate on top of the negatives… with the dull side facing the negatives. Works perfectly. I got mine from betterscanning: http://www.betterscanning.com/scanning/mainintro.html

Incidentally I have one of those lying around (Betterscanning on a Epson V850 is how I used to scan my negatives before I found out about the possibilities of camera scanning). I am currently scanning a rather curled negative of a freshly developed and dried film that had been on the spool for 30+ years… still seeing newton rings at the beginning of the film strip.

That aside: won’t the scans show the texture of the ANR glass if you shoot through it?

I shoot the negatives “right side up” so that the text and frame numbers read correctly. So the emulsion will be facing downward. Then the ANR glass on top has the matte side facing down towards the negative. I’m using a slimlite plano and a D810. This is perfect for me with no hint of the glass and I’m getting nearly 36 megapixel scans. I just remember to never have two shiny surfaces touching each other and I haven’t had any newton ring problems.