Anti Newton Glass on a budget

[Sal Santamaura]

If I ever post again, I'll have to choose my words more wisely...

Because of a response in this thread? Don't even think about it. Your contribution was fine. Keep it up.

[Drew Wiley]

Depends on the climate, Michael. I tested various coated optical glass options too. It's generally just too foggy here for that to work suppressing rings. Maybe in a drier climate. But the bigger problem is that quite a few modern films are just plain slicker than their older counterparts. What did halfway work was my special Zeiss ANR glass which is neither etched nor multi-coated, but has some kind of strange hard washable polymer coating which hasn't discolored over time. It came in a strange size, and had to be cut with tempered glass equipment (which I have). So it's not atop float soda glass, but some kind of real optical. I suspect it was leftover from a special batch order for some scientific purpose unknown to me. I've never seen anything else like it. But even it didn't work with a seriously slick film like 8X10 Acros (I only used it in one of the 8x10 enlargers, plus a big contact printing frame.) I successfully replaced it with nice thick Scan Tech AN glass, which that video guy ridiculed as a waste of money.

Classic retouching tooth is a rare feature on black and white films today. Pity. But Kodak does apply a "scanning improvement" coating to their current pro color sheet films, which does help a little suppressing rings during contact and projection too. But I still need true AN glass in both sides of all my enlarger carriers, and in contact frames. Of course, in any projection application, ordinary non-reflective picture frame glass would produce a hazy image. In a contact, the etching pattern would be blatantly apparent. You name it, I've tested for it. Have to in this climate. But the fog helps in keeping static issues low.

Right now I'm on a drymounting marathon, trying to take advantage of the first fog-free dry weather here in almost an entire year. Its forecast back tomorrow, and then heavy rain next week. I can overlap a few days, but once the humidity builds up, drymounting becomes a tricky chore.

[Michael R]

I agree - I generally wouldn't recommend the BBAR-(multi)coated filter glass route as it is obviously a very expensive approach and is not guaranteed to work. Too many variables including the light source.

Depends on the climate, Michael. I tested various coated optical glass options too. It's generally just too foggy here for that to work suppressing rings. Maybe in a drier climate. But the bigger problem is that quite a few modern films are just plain slicker than their older counterparts. What did halfway work was my special Zeiss ANR glass which is neither etched nor multi-coated, but has some kind of strange hard washable polymer coating which hasn't discolored over time. It came in a strange size, and had to be cut with tempered glass equipment (which I have). So it's not atop float soda glass, but some kind of real optical. I suspect it was leftover from a special batch order for some scientific purpose unknown to me. I've never seen anything else like it. But even it didn't work with a seriously slick film like 8X10 Acros (I only used it in one of the 8x10 enlargers, plus a big contact printing frame.) I successfully replaced it with nice thick Scan Tech AN glass, which that video guy ridiculed as a waste of money.

Classic retouching tooth is a rare feature on black and white films today. Pity. But Kodak does apply a "scanning improvement" coating to their current pro color sheet films, which does help a little suppressing rings during contact and projection too. But I still need true AN glass in both sides of all my enlarger carriers, and in contact frames. Of course, in any projection application, ordinary non-reflective picture frame glass would produce a hazy image. In a contact, the etching pattern would be blatantly apparent. You name it, I've tested for it. Have to in this climate. But the fog helps in keeping static issues low.

Right now I'm on a drymounting marathon, trying to take advantage of the first fog-free dry weather here in almost an entire year. Its forecast back tomorrow, and then heavy rain next week. I can overlap a few days, but once the humidity builds up, drymounting becomes a tricky chore.

[Daniel Unkefer]

I've searched for years for real ANR glass, Kevin at KHB sells it! I bought an 8x10 sheet for 18x24cm contact printing. Finding real Durst ANR was a challenge and I'm still loooking.

http://store.khbphotografix.com/Gene...ton-Glass.html

He talked me OUT of using ANR glass, I was rebuilding a 5x7 E-3 glass carrier. BTW they did not have ANR when the E-3 was exclusively in use by the US Military. Glenn Evans machined some missing parts for me on that one. Regular Glass and Masking Tape to stretch the negative very tight. The Olde Fashioned Ways can be the best.

[Drew Wiley]

Real Durst or comparable Omega AN glass is a distinct benefit mainly when working with relatively small negs, especially thin 120 film. But the generic AN brands are fine for typical sheet film use. My later Condit 8x10 registration printing frame came with the same Belgian AN glass pattern as Durst used, but in full nominal quarter inch thickness, and suitable for drilling - important when registration pins must be precisely set into the glass itself. Mounting registration pins to tempered or optical glass is hell by comparison. I've done it more than once; but its a helluva lot more work and anxiety. I've never resorted to the Medieval Spanish Inquisition methods of stretching anything darkroom related.

[Rayt]

edit to add: I have negative supply 4x5 film holder with the acrylic ANR sheets. They are terrible. Not flat, collect dust like crazy and seem to scratch just by looking at them. So compared to that, this framing glass works way better.

I am about to buy the 4x5 holder from Negative Supply and there’s a choice between “Micro Etched Acrylic” and “ANR glass”. I assume the ANR glass option is real ANR? The glass ANR option costs a hundred buck more so I guess it’s worth it if your acrylic sheet isn’t flat.

[Deyoung]

Issues with the acrylic ANR sheets is what got me thinking about an alternative in the first place. When I bought the holder from negative supply the glass option was back ordered for a long time. So I got the acrylic. Been regretting it ever since.

[Eric Woodbury]

Michael R (and others of course), the third thing you must have is coherent light. It doesn't need to be very coherent, but it must have some coherency. Fully diffuse light will not make a newton ring.

Weird thing is that diffuse light loses it diffuse quality and gains enough coherency in a short distance. I wish I could put some numbers on this, but I can't. Probably a result of quantum nature of photons.

[LabRat]

I had a long talk with Mike Sparks at Focal Point glass years ago and he explained the process of ANR glass to me...

He explained that the fine etched surface minimizes the contact area that the film rests on, as it is overall supported, but only rides on the minute "peaks" of the glass, but the "valleys" have some spacing from the surface, not making contact...

The surfaces were ground or blasted with fine abrasive, but this tended to leave a slightly rough/sharp surface that worked well, but tended to hold dust/debris (like almost sticky) and harder to clean as the roughness of surface would start to shred tools to brush it and debris could cling to the bottom of the "valleys"...

Or surfaces could be chemically etched, but with the glass being uniformly smooth would tend to develop a "worm" like surface that could not be completely uniform... But the Euro master glass makers developed "secret" proportions of grind vs etch for uniform "peaks", but the etch would remove some of the roughness, but also smooth over the jagged surface making it easier to clean and increasing some transparency... But unfortunately hydrofluoric acid was used, and became banned for production use in most countries for environmental reasons...

There can be nano coatings today that could provide the tiny gap spacing and small contact area, but I haven't explored these glasses yet... I was having Newton's ring issues with 35mm film + Leitz Focomat contact condenser enlargers, but made a cover with a Gepe 6X6 slide mount cover glass sandwich between neg & condenser that worked well, but only problem was glass was only blasted, and could be hard to clean and hold dust...

Steve K

[Rayt]

Issues with the acrylic ANR sheets is what got me thinking about an alternative in the first place. When I bought the holder from negative supply the glass option was back ordered for a long time. So I got the acrylic. Been regretting it ever since.

Your experience was helpful to me so thanks for that. I ordered the NS Basic 4x5 holder with ANC glass and the estimated ship date is two months from now.