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02-22-2022, 01:50 PM   #1
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ANR glass "sandwich" for camera digitising of film negatives?

Is anyone using two pieces of ANR glass - one below the film, one above - for camera digitising of negatives to keep them absolutely flat? Below the film, I assume it shouldn't cause any problems because at worst it acts as an extremely mild diffuser... but above the film, doesn't it result in a (potential) loss of contrast and/or detail? Furthermore, isn't there the possibility that the texture of the etching or coating on the glass above the negative could be picked up in the digitised image (especially with smaller formats such as 35mm)?

I'm quite interested in this approach to achieve absolutely flat negatives when working with curvy film stock (especially 120), but given the price of good quality ANR glass, I'd rather know before-hand if it's likely to cause problems...

Thanks in advance, all


Last edited by BigMackCam; 02-22-2022 at 02:22 PM.
02-22-2022, 02:14 PM - 1 Like   #2
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I never used them when I was doing enlarging partly because of the diffusion issue but primarily because of dust problems and having to have the glasses spotless before sandwiching the film. It seemed the film was always dragging in some kind of debris and it would often stick to the glasses. An air blaster was a necessity. You can also introduce ghosting issues unless the glass has anti-reflection coatings on the non-Newton sides.

Keep in mind that your lens may have some field curvature and having the film slightly bowed could potentially contribute to even better sharpness (or the opposite depending on the direction of any warp). In any case, using a sufficiently high f-stop will mostly take care of any problems with warped film through increased DOF, and most likely, the smaller the film size, the less the warp.

Last edited by Bob 256; 02-22-2022 at 02:21 PM.
02-22-2022, 02:35 PM   #3
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QuoteOriginally posted by Bob 256 Quote
Keep in mind that your lens may have some field curvature and having the film slightly bowed could potentially contribute to even better sharpness (or the opposite depending on the direction of any warp). In any case, using a sufficiently high f-stop will mostly take care of any problems with warped film through increased DOF, and most likely, the smaller the film size, the less the warp.
I recall Popular/Modern Photography recommending using a standard (non-Macro) lens for slide duplication for this very reason. However if the slides were in glass mounts (which flattens the film out) that a macro lens might be better.

The drawback of using glass sandwiches is the possibility of Newton's Rings occurring.

Newton?s rings | optics | Britannica
02-22-2022, 02:39 PM   #4
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QuoteOriginally posted by Bob 256 Quote
I never used them when I was doing enlarging partly because of the diffusion issue but primarily because of dust problems and having to have the glasses spotless before sandwiching the film. It seemed the film was always dragging in some kind of debris and it would often stick to the glasses. An air blaster was a necessity. You can also introduce ghosting issues unless the glass has anti-reflection coatings on the non-Newton sides.

Keep in mind that your lens may have some field curvature and having the film slightly bowed could potentially contribute to even better sharpness (or the opposite depending on the direction of any warp). In any case, using a sufficiently high f-stop will mostly take care of any problems with warped film through increased DOF, and most likely, the smaller the film size, the less the warp.
Thanks, Bob - this is helpful.

I'm OK dealing with the dust issue. I have a fairly low-dust environment in my home office / hobby room... I very rarely have to dust any surfaces (I'm talking months in between, and even then it's minor), and thus far I've managed to keep my negatives largely dust free by using a rocket blower on each side of a strip before digitising, then again before placing back in its glassine sheet. Additionally, before each digitising session, I wipe down my copy stand, film holder, light panel etc. It usually looks clean anyway, but I figure it's worth a couple of minutes effort just to make sure

The ghosting issue makes absolute sense and was one of the concerns in the back of my mind. So if I do consider this, I really ought to look at anti-reflective coated ANR glass, at least for the top side... Is that even available?

Regarding field curvature, the Sigma 50/2.8 EX DG Macro and Pentax D FA100/2.8 WR Macro I'm using on my APS-C camera for 120 and 135 respectively seem impeccably behaved at f/8 in this respect.

My interest in flat negatives is really more to do with geometric distortion than DoF, and particularly with the first and last frames on heavily-curled strips. Flat storage in glassine sheets is taming my negatives somewhat but my Fomapan 200 120 strips, for example, still exhibit a certain amount of curvature. The thing is, I have several rolls of it left to shoot - and it's actually a really nice film I can see myself using beyond that...

02-22-2022, 02:41 PM   #5
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QuoteOriginally posted by Not a Number Quote
The drawback of using glass sandwiches is the possibility of Newton's Rings occurring.
That's why I'm specifically looking at the use of ANR glass top and bottom - but, hence, why I'm concerned about potential degradation from the top pane...

Last edited by BigMackCam; 02-22-2022 at 02:49 PM.
02-22-2022, 03:22 PM - 1 Like   #6
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Get some cheap anti-reflection glass used in picture frames to try things out and then buy the real ANR glass for the final setup. This anti-reflection glass has exactly the same structure as the ANR glass, it is only a bit coarser, visible when you inspect it with a loupe.
02-22-2022, 03:30 PM - 1 Like   #7
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AN glass is generally just used (and needed) on the base side and not the emulsion side. To minimize dust issues you may well succeed in not using clear glass layer on the em side while achieving good flatness. The other trick I oft used was a strip of mylar masking tape on one long side on the clear glass side to crate a touch separation.

02-22-2022, 04:05 PM - 2 Likes   #8
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QuoteOriginally posted by BigMackCam Quote
That's why I'm specifically looking at the use of ANR glass top and bottom - but, hence, why I'm concerned about potential degradation from the top pane...
You don't need to use ANR on both sides, only the side with the shiny plastic film base. The emulsion side of the film is too rough to form Newton's rings. See How to avoid Newton Rings when scanning films | ScanCorner
02-22-2022, 05:53 PM - 1 Like   #9
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You are not the only one who has thought of this, this company sells it specifically for scanning and tells you how to use it.
Using the 35 mm Anti Newton Ring Glass ANR Insert
02-23-2022, 03:41 AM - 1 Like   #10
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Before I owned my OpticFilm 120 I used a betterscanning insert with ANR glass on top with my Epson V500.
02-23-2022, 02:16 PM - 1 Like   #11
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Thanks, everyone. Through a combination of your kind responses and some further research and cost / benefit analysis, I am - for now, at least - shelving the idea of an ANR glass sandwich

Instead, I'll be trying the Lomography Digitalizer 35 and 120 film holders / masks. Since I cut all my negatives into strips to fit standard Hama glassine sheets, these should suit my way of working. They have a pretty good reputation for keeping film flat without the need for glass (albeit there's still the potential for a tiny amount of lateral "bow" with particularly stubborn films), and the method employed for doing so makes sense. There's a ready market for these holders with both flatbed and DSLR digitising users, it seems, so if I find they don't meet my expectations, I should be able to move them on at only a small loss

One thing I'm learning from all this is that there doesn't seem to be a single negative holder that satisfies all of the following:

(1) supports a variety of formats in 35mm (e.g. standard, panorama) and 120 (6x6, 645, 67, 6x9
(2) supports both cropped and "with border" framing
(3) allows easy loading and alignment of both continuous rolls, short strips and individual frames
(4) allows easy advancing to subsequent frames
(5) has zero feeding issues on entry and/or exit portions of the holder
(6) keeps negatives completely (or very nearly) flat, including the leading / trailing edge of those at the start and end of a trimmed strip or roll

I already own two negative holders... the EFH "Essential Film Holder" and the budget-oriented Pixl-latr. The EFH is mostly great, but falls short with first and last frames of curly negatives (especially 120); the Pixl-latr keeps negatives even flatter than the EFH, including first and last frames of curly stock, but is very fiddly in initial alignment and subsequent advancing of frames. Both are versatile in different ways, both have their uses and are good products at their respective price points, but neither is close to perfect in relation to my own requirements. The Digitaliza holders seem like they should be better suited to my needs - but we'll see. I think a comparison review might be warranted at some future juncture, once I've had a chance to try them

Last edited by BigMackCam; 02-23-2022 at 02:30 PM.
02-25-2022, 09:12 PM - 1 Like   #12
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Give it try and see how it works.

My Coolscan 9000ED has a medium format negative carrier made of ANR glass both top and bottom. But it has a small, builtin gap. That is, the glass did not press the negative completely flat with 100% contact on both surfaces of the glass/film. I would still get newton rings on occasion more so with curly film. And cleaning the six surfaces free of dust is a nightmare. The scanner came with a negative carrier with no glass too and I preferred to use that when I can but it sucked at getting a flat scan across the whole negative much of the time.
02-26-2022, 01:12 AM   #13
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QuoteOriginally posted by tuco Quote
Give it try and see how it works.

My Coolscan 9000ED has a medium format negative carrier made of ANR glass both top and bottom. But it has a small, builtin gap. That is, the glass did not press the negative completely flat with 100% contact on both surfaces of the glass/film. I would still get newton rings on occasion more so with curly film. And cleaning the six surfaces free of dust is a nightmare. The scanner came with a negative carrier with no glass too and I preferred to use that when I can but it sucked at getting a flat scan across the whole negative much of the time.
Interesting. Thanks for that.

My Digitaliza 135 and 120 holders should arrive today, so I'll see how I get on with those first. I'm beginning to think there's no single solution that's ideal for every eventuality. When film is relatively flat and in strips of several frames or more, the Essential Film Holder just can't be beaten for speed and versatility, IMHO. With curly film, the Pixl-latr is better - especially for frames at either end of a strip or roll - but I find alignment fiddly and advancing to subsequent frames is a much slower process - plus the large diffuser back sits against the negatives and needs to be kept dust free. The Digitaliza holders look like they should work well - but they're no good for continuous rolls, and again there are surfaces that temporarily contact the film that need to be free of dust, or else the negatives needs to blown or brushed clean after their removal. I have realistic expectations, so I'm not expecting the Digitalizas to be perfect. So long as they hold the negatives flatter, I'll be happy. Otherwise, I may have to consider the ANR glass option once more...

Last edited by BigMackCam; 02-26-2022 at 01:52 AM.
03-08-2022, 10:52 AM   #14
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I stopped using ANR glass in enlarger carriers sometime in the 1990s.
Glassless was more effective and easier to maintain and the results were comparable (110 ->6x7)
If you are doing LF then maybe
03-08-2022, 02:54 PM   #15
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QuoteOriginally posted by titrisol Quote
I stopped using ANR glass in enlarger carriers sometime in the 1990s.
Glassless was more effective and easier to maintain and the results were comparable (110 ->6x7)
Sadly, I'm finding that with badly curled or bowed film - especially the first and last shots on a strip, and especially with 120 - depth of field with DSLR digitising at f/8 and even narrower isn't sufficient to obtain consistently sharp results across the entire frame, and even when it's acceptable, geometric distortion is noticeable.

I now own three different film holders - the EFH Essential Film Holder, Pixl-latr and Lomography Digitaliza (versions for both 135 and 120) - and all have their advantages and disadvantages. None does exactly what I want, so I'm currently designing a holder of my own that meets my needs. Watch this space
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