I alway use glassless carriers.
“The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”
Michael, I use the non-glare glass from Tru Vue in my contact frame specifically to eliminate Newton's rings and have not seen any texture or gincreased graininess in my prints. I also use it in my 8x10 negative carrier for the top glass, and plain Tru Vue glass on the bottom with Kodak Portra negatives without rings on the underside. I considered getting their museum glass since it is supposed to be colorless, but I haven't seen the need in my color prints to spend the extra money.
This is the glass I was talking about earlier in the thread-
Thanks Greg and M. Lointain. Looking forward to trying the various types of Tru-Vue glass. I'll have a look at Edmondoptics after the Tru-Vue experiments. There were a few other sources I wanted to look into also (although at some point I'll have to stop I guess).
Michael, I've just had a carrier cut and beveled from a type of coated framing glass, available in EU, that serves the same purpose as TruVue. To my eye, the colour, shade etc are identical to Nielsen's coated framing glass, though I am not sure who supplies them in Europe. This glass is called ArtGlass Water White, made by GroGlass in Latvia, and widely available in EU from framing suppliers. According to their web site, they use "advanced magnetron vacuum sputtering process to deposit a molecular film less than a micron thick": http://www.groglass.com/en/products/...specifications
When I sandwich a sheet of TMax 100, I get a faint, different looking NR on the emulsion side only, and only when significant pressure has been applied. I have not printed enough with it yet to know if it helps in the longer run, and I will report here after I had a good go at it, but it seems that NR are still present with this type of coated framing glass, though smaller and different. Incidentally, it is very nice as framing glass.
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As I understand it, Newton's rings occur when two smooth surfaces come into contact with each other. The Trix is designed to accommodate retouching on either surface, it has a tooth or texture to hold the spotting dye or pigment as does the coated surface of the Anti Newton glass. On the top position in the carrier and facing down it comes into contact with the smooth back of the film, and doesn't allow complete contact with the film and prevents Newton's rings. In the cast of some Tmax emulsions or thin, under exposed emulsions, the emulsion side of the film is allowed to come into more complete contact with the smooth uncoated bottom glass plate and creates Newton rings on the bottom interface. The method of coating Anti Newton can very from spraying on a coating to sandblasting the glass or chemically etching the glass. We also used lithographer's powder lightly dusted on the top glass plate to make the film stand off from the top glass plate (lithographers powder was finely ground glass)! Rosinor powder, corn starch baby powder or talc can do the same thing, just lightly dust it on and you have a temporary AN surface.
Optically-coated picture framing glass works so-so in our admittedly foggy coastal climate here. A
practical substitute for a true antinewton textured glass is simply to use a sheet of three mil or five
mil frosted mylar (frosted both sides) between the upper glass and the back of the neg. Just inspect it first on the lightbox for dust or blemishes. You can get sheets of this in art stores. It only slows the speed of printing about a third of a stop. Anti-newton powders are available from the same outfits who sell scanner fluid, but be careful how you use these - there's a distinct technique, so
you'll want to practice on a scrap negative first. I don't like to use them unless every other option
fails - like, for example in a masking sandwich where I can't avoid base-to-base film registration.
But most of you will never encounter a situation like that.
Maybe a technician specialized in optic constructions, like this one:
would be able to propose a solution and cut some optical glass of the right dimension with a cost which should be - I imagine - much lower than asking Zeiss, Schneider, Schott etc. to do the work. It would also give some peace of mind in case of accidental breaking.
The reason why the glass sold with the enlarger is "simple glass" is the same why break pad of my bicycle are in rubber, or why the springs of my motorbike are simple (non-progressive): they are good enough and better that that certainly exists but raises the cost considerably. If cost is of secondary importance, "customising" can certainly improve the quality of most products. Changing the glass to the enlarger is something like putting light alloy wheels to a car. Big expense for relatively small performance gain, but gain there is, and if that small performance gain is important...
Does anyone here actually believe the glass has an effect on the printed piece that will improve the print, other than keeping the negative flat and free of newton rings??
If so I would love to see samples??
Bob - I've done a lot of work and experimenting with this stuff and I have seen no difference in print quality between the best glass I used (Schneider nano-MRC in a 35mm carrier), the presumably cheap glass that originally came with my Saunders carriers, the glass in my Inglis carrier, and everything in between (all sorts of sample glasses from Tru-Vue, samples from Schneider's cinema division, Schott). I'm talking about the piece below the negative and above the negative. The main difference I found was in the increased transmittance of the coated glasses (due mostly to less reflection), which actually made a small difference in exposure times. "On paper", one would assume coated glass to also result in slightly higher contrast due to the reduction of reflection and flare in the system. But I'm not sure I could see a difference.
Assuming the glass in the carrier is optical glass, optically flat, and free of blemishes, scratches etc it should be fine. The only real benefit of super-hard coatings like Schneider's MRC coating is resistance to dirt and especially scratching - ie very easy to clean the carrier glass and keep it free of even the finest scratches. Worth hundreds of extra dollars? Perhaps below the negative, perhaps not. The other nice thing about using custom glass - specifically above the negative in this case - is I could use thicker glass (say 3mm for example), which results in any dust settling on the glass being out of focus. Again, a very minor benefit at least for me since I don't have a lot of dust problems in the first place.
The primary reason for my experiments with coated glass was to attempt to reduce/eliminate the occurrences of Newton rings above the negative (and occasionally even below the negative with films like TMAX and Acros which have shiny emulsions) without having to use anti-Newton ring glass, which can occasionally cause texture problems. I also thought it might help make masking a little easier. In the end while some coatings appeared to reduce the occurrences of the rings, I found no conclusive evidence any of the various coatings and multicoatings made a real difference when it comes to Newton rings. In fact I found it even more useful to give the glass a quick wipe-down with alcohol just before sandwiching the negative.
The only sure solution to Newton rings when they occur is a surface with slight "tooth" such as that of good quality anti-Newton ring glass, anti-reflection framing glass (Tru-Vue, etc), Drew's mylar suggestion - provided it is very uniform, or my solution - a simple sheet of unexposed, fully fixed Tri-X 320 (TXP). Well, actually there is one more potential experiment - Nikon's Nano Crystal Coating - but Nikon told me to get lost when I asked them about it.
I've gone all over the map with this, including correspondance with John Sexton (who is always interested in anti-Newton strategies for the emulsion side of TMX) and John Wimberley. John Wimberley does use coated glass in his carrier and feels it is necessary and makes a difference.
The caveat here is I don't make huge prints. I don't enlarge 35mm to more than 8"x10", and even my prints from 4x5 film are on 8x10 or 11x14 paper. People making much bigger enlargements might want to experiment for themselves, but these are expensive experiments - especially with sheet film sizes.
Last edited by Michael R 1974; 11-08-2012 at 07:50 AM. Click to view previous post history.