Colour negs more prone to Newton's Rings?

[perkeleellinen]

I've been printing B&W for the best part of a decade and have never had a problem with Newton's rings. I assumed I had anti-Newton glass in my neg carrier. I've just started colour printing and I'm getting loads of rings from a roll of Ektar.

So, are colour negs more prone to Newton's Rings?

Flat bed scan then digi P&S: there's at least 5 rings on this print.




Apologies for the colour balance, it's a test print that the digi systems have taken to 'correct' (wrongly).

[Ian Grant]

Never found colour films to be any worse, but I stopped using glass for the top with 35mm and use a plain mask in my Dursts, that way I just don't get newtons rings and I found it better for dust control too.

Ian

[perkeleellinen]

I could try that. Presumably your negs are sufficiently flat using this method.

[Tom Kershaw]

I've recently printed Kodak Ektar 100 and Portra negatives with glass negative carriers and suffered Newton Rings. Using the same carrier with ILFORD Delta negatives produces no Newton Rings.

Tom

[Ian Grant]

Just as flat as with Glass on top. I made my own mask back in 1975 when I was a penniless student, Durst wanted too much for a simple piece of painted aluminium

Ian

[Anon Ymous]

Perkeleellinen, I use a glassless negative carrier for my Opemus 6a and enlarge from 135 negs only. I don't know about larger negatives, but I never had a problem with flatness. I use a 75W bulb, so the generated heat is not that much to cause problems either. A 150W bulb might cause problems, but I don't know. As an added bonus (as Ian said) you only need to clean dust from the negatives, not the carrier.

[perkeleellinen]

Anon - I also have the Opemus 6a and enlarge only 135. Good to know you've had no issues with a glassless carrier. My current carrier is the metal one with adjustable masks. I've got a glassless insert somewhere around here (which I filed out in my youth!). Later today I'll try to replace the top glass with that.

[AgX]

Using matting agents in a back layer is described in literature, however a hint at this I found so far only in two data sheets:

…back layer of the film (designed to achieve optimum vacuum draw down)…

Back layer designed for best reduction of Newton rings.

respectively


(To avoid confusion: a back layer does not necessarily need to be based on gelatine or a swelling polymer it can also be made of a waterinsoluble polymer, a lacquer.)