Newton Rings

themoleman342 · Expire: 2013-01-24

I've read a bit about Newton Rings in the past few hours. I was having trouble with a set of black and white negatives. Not real black and white but rather Kodak's C-41 processing "B&W" film. I generally hate this film but shot it once in a while just for quick developing, or at least I did before I had my darkroom set up.

I thought the problem was pressure of the lid was not sufficient to hold the negative flat and the gap that resulted was causing them. But even with excess pressure the problem did not improve in the slightest. Someone had defined the issue as having to do with "two shiny surfaces coming into contact with each other." With most film there is a dull (emulsion) and shiny side. The canoscan recommends that the emulsion side be down. Now I understand why.

With Kodak's "B&W" film there is no discernible difference between the sides. Both are considerably "shiny." So essentially this film, no matter which way you face it, creates the "two shiny surfaces" issue.

This is probably old hat to many of you. But I figured I'd offer this advice: stay away from this film if you are scanning on a flatbed type setup or don't have an anti-newton ring apparatus. I know I'll never buy the film again.

~Marc

Katastrofo · Expire: 2013-11-19

The best way to tell is by reading what's in the borders of the film. If you
can make out the word 'Kodak' that's the shiny, or shinier side that should
be up.

Seele · Joined: 17 Apr 2009 Posts: 742 Location: Sydney Australia

The great photographer and technical man Andreas Feininger recommended the use of glassless carriers for 35mm negatives, as the negative base has enough stiffness to stay flat, if properly supported in a well-designed carrier. For larger formats, such as 4"X5" I use a custom carrier with glass only on top and that never created any problems for me.

But if you are stuck with just the glass carrier with glass both on top and below the negative, you can treat the glass surfaces to prevent Newton's Rings:

Find a small atomiser bottle; I use the ones which used to contain spectacle cleaning fluid, but you can see what you can get. Mix up a dilute solution of gum arabic using distilled water to ensure no particles in it and put it in the bottle. A concentrated gum arabic solution should be available from an art supply dealer, it is used as a binder for watercolour.

Take the glass pieces out of the carrier, clean them properly and let dry. Then place them on a flat support, say a sheet of clean paper, but do not lift them up from the paper surface, otherwise the coating would not be even.

From a reasonable distance, say half metre, lightly spray the solution in the air and let it coat the glass surfaces. Do not go overboard as if doing spray painting, a light coating is good. When dry, examine it under bright daylight, if you see a coloured mottling reflection, like a film of oil floating on water, then it is done. Replace glass carefully, then try again.

When the coating is worn out or rubbed, you can wash it off and repeat the process.

Orio · Expire: 2012-12-04

hi Marc,
the Canoscan advice tells it all - and it's not only valid for Canon scanner, it's a universally good advice. I do get Newton rings and also Moiré if I scan the strips with the emulsion side up. I did that for mistake in my scans of the BW film strips I posted yesterday - and if you look closely, you will see obvious Moiré in some of the images.

Luckily, the remedy is simple : just scan with the emulsion side down. Smile

Xpres · Expire: 2014-10-28

You can buy anti newton ring glass. I have pieces for my enlargers in different formats for when the negs need some support - quite often with 6x9 as you're not going to get critical sharpness with a curved neg in a glassless carrier.
I haven't tried it in a scanner yet, but a sandwich of glass under and ang over placed on the scan bed should do the trick - as longs as the lower glass is the right thickness so the head can focus.
I did put a piece of ground glass on some curly negs the other day which worked for sharpness but contained too much of the ground glass! I just turned the negs around against the curl which was OK for a web scan.

Farside · Expire: 2013-12-27

@ Seele.
Interesting gum arabic idea. Must bear that in mind.