Preventing newton rings

[AndrewBurns]

I know that in theory something like ANR glass has a micro-rough surface which prevents newton rings, however I'm wondering if anybody has ever tried using adhesive anti-reflective matte films to do the same job? I'm speculating that matte anti-glare films for phones and computer screens works in the same way as ANR glass, by having a micro-rough texture to the surface to diffuse reflections, and so maybe that kind of film stuck onto normal glass could also prevent newton rings.

 

[DonW]

Interesting idea.

 

[wiltw]

Are you thinking of this as a means of scanning neg/slide on a flatbed scanner w/o Newton rings?
If so, I can see an inherent problem that the texture of the anti-reflective matte layer also is detected by the scan head and alters the quality of the scan. Additionally, that stuff is generally coated with a layer that would make it difficult to lift off a neg/slide after scanning! Distancing the neg/slde from the scan head is not an issue...the plastic film holder supplied with the scanner for 135 or medium format film scanning distances the film from the scanner glass.
I have some of that antireflection stuff from years ago...I'll try to get around to trying a scan of a slide with that layer between the slide and scanner glass and post comparison.
OTOH, I have never encountered a problem with scanning any negs or slides, and in the past that included scanning 4x5 transparenies on a Canon 8000F, and I cannot recall reading posts about such complaints of Newton rings while scanning.

 

[AndrewBurns]

Yeah I'm thinking about eliminating newton rings when the film is directly sandwiched between glass plates, not in the plastic carriers that come with the scanner. Most of the plastic carriers I've seen hold the film at the edges but the middle is free-hanging in air which avoids creating newton rings. The disadvantage of that is if you have very curly film the focus can be off in the un-supported section. Sandwiching the film between plates of glass makes it perfectly flat but unless you're using ANR glass you get newton rings.

My thought is that you could apply matte anti-reflective film to a piece of glass (not to the film itself), and if that would effectively make the glass into ANR glass. Yes I understand that the film would slightly reduce light transmission through the stack and if it had too much texture that could lower the quality of the scan, which is worth investigating. That said, ANR glass is (as I understand it) simply glass with a very fine etched surface, which would in theory also effect the quality of the scan, but I suppose the etching is fine enough to not make much difference.

I've ordered a matte anti-glare screen protector for a tablet and when it arrives I'll try sticking it onto a piece of glass and seeing if it eliminates newton rings and what effect it has on scan quality.

 

[gone]

To address the issues you mentioned, I went to taping my negs to the scanner's glass. That made it simple to tape one side down, then pull the other side taut and then tape it down. It took less time to tape a film strip than it takes to type this up. Have you tried scanning w/o any glass to hold the negs down? It may be that your scanner has enough DOF to not worry about the bowing in the middle of the film strip.

 

[YoIaMoNwater]

I know that in theory something like ANR glass has a micro-rough surface which prevents newton rings, however I'm wondering if anybody has ever tried using adhesive anti-reflective matte films to do the same job? I'm speculating that matte anti-glare films for phones and computer screens works in the same way as ANR glass, by having a micro-rough texture to the surface to diffuse reflections, and so maybe that kind of film stuck onto normal glass could also prevent newton rings.

Just curious, did you manage to try this?

 

[AndrewBurns]

No I haven't had the time to try it yet, but I have all of the things I need to give it a shot. I'll try to get to it today.

 

[YoIaMoNwater]

So I went ahead and gave this a try.

My normal scanning method is to layer a glass panel on top of the scanner, followed by the film with the emulsion side down, followed by another glass panel. This time, I applied the anti-reflective matte film on one side of the top glass panel and tried couple experiments.

For the tests below, pay attention to the skies/highlight areas in each frame and also at the end of the film where it is clear.

Trial 1 - glass panel, film emulsion DOWN, glass panel with anti-reflective matte film facing UP: newton rings

Trial 2 - glass panel, film emulsion DOWN, glass panel with anti-reflective matte film facing DOWN: newton rings

After a quick search online, someone suggested to avoid shiny surfaces touching shiny surfaces, so I gave the followings a try with just the glass panel with the anti-reflective matte film attached.

Trial 3 - glass panel with anti-reflective matte film facing UP, film emulsion DOWN: no newton rings within frames, but noticeable at end of the film where it’s clear

Trial 4 - glass panel with anti-reflective matte film facing UP, film emulsion UP: no newton rings within frames, but noticeable at end of the film where it’s clear

Trial 5 - film emulsion UP, glass panel with anti-reflective matte film facing DOWN: newton rings

Trial 6 - film emulsion UP, glass panel with anti-reflective matte film facing UP: newton rings

Trial 7 - film emulsion DOWN, glass panel with anti-reflective matte film facing DOWN: newton rings

Trial 8 - film emulsion DOWN, glass panel with anti-reflective matte film facing UP: newton rings

Seems like Trial 3 and Trial 4 were the best so thankfully the £12 I spent didn't go to waste. Kudos to @AndrewBurns with the idea for a quick and cheap way to deal with newton rings.

 

[Ko.Fe.]

All I have to do is too keep negatives in the book for couple of weeks.
It makes them flat. No n-rings on scans.

 

[David Lingham]

You could look at wet mounting. Google or Youtube "wet mount scanning".

 

[AndrewBurns]

So I went ahead and gave this a try.

My normal scanning method is to layer a glass panel on top of the scanner, followed by the film with the emulsion side down, followed by another glass panel. This time, I applied the anti-reflective matte film on one side of the top glass panel and tried couple experiments.

Awesome thanks for doing those! I don't actually have a flatbed (I DSLR scan) so I had tried a few times with some old glass plates I have to even make newton rings in the first place but was having no luck, I think my glass was too dirty to get really good flat contact. I'll try again today, but it does look like you've shown there's some merit to the idea which is promising!

And yeah, wet mounting would give better results again but it's more work and mess, and with some scanners not really practical.