Glass for neg carrier

[Noeyedear]

I need to get some glass for a neg carrier, is there anything special to ask for, Any advantage in getting the coated glass like the coating on a lens?

Kevin.

[ic-racer]

It should be optically flat. Many people use one piece of Anti-Newton ring glass and one piece of plain. Two plain pieces and two Anti-Newton pieces also work. I have 4 glass carriers with various combinations of the above.

[Peter De Smidt]

Coated glass can minimize Newton's rings. The down side is that it's usually very delicate. I use Anti-Newton glass for the top and optical glass for the bottom, but some negatives are very shiny on the emulsion side as well as the base side. Anti-Newton glass both above and below would be a good idea for these films. That's what Howard Bond uses, for example, with TMX and TMY negatives.

[nelson_chan]

http://www.fpointinc.com/glass.htm

they have good glass.

[Noeyedear]

Coated glass can minimize Newton's rings. The down side is that it's usually very delicate. I use Anti-Newton glass for the top and optical glass for the bottom, but some negatives are very shiny on the emulsion side as well as the base side. Anti-Newton glass both above and below would be a good idea for these films. That's what Howard Bond uses, for example, with TMX and TMY negatives.

Thank you for the replies.
What makes some glass anti newton ring and others not, Is there any downside to using anti Newton glass. Does it cure the dreaded rings or just lessen them?
Also does anyone oil mount there negs in the enlarger, if so how etc.


Kevin.

[Peter K]

If two smooth surfaces touch each other, like the base of the negative and the carrier glass, a very small wegde from air appears. A part of the light will be reflectet from both surfaces, film and glass. But if the wegde is as nearly as small as the wavelenght of light, the rays interfere like an oildrop on water and one can see the colors of thin leaflets called after Newton. If the glass carrier isn't smooth but has a certain formed surfaces the wedge cannot appear.

If the surface of the film is demaged by scratches etc. mounting gel as used with drum scanners fills the scratches and the negative looks smooth and clean. But one has to clean the negatives after enlargement like after a drum scan.

[Noeyedear]

So how would you oil mount and not get oil everywhere? I thought about removing the upper glass and use an acetate sheet over the neg with oil above and below the neg. I can see this would work for 5x4 on my 5x7 carrier, not so confident about a 5x7 neg in the 5x7 carrier. I suppose the only way to find out is give it a try.

Kevin.

[Dave Brown]

Can coating really minimize Newton's rings? I thought anti-Newton glass was etched rather than coated. At any rate, I use plain window glass and have had no problems thus far.

[Peter De Smidt]

According to Ron Wisner, yes, anti-reflection coatings will reduce the appearance of Newton's rings. Anti-Newton glass, by contrast, has a texture, and that texture keeps the rings from forming. Some course anti-Newton glass can have a visible effect on image sharpness. For example, anti-glare picture framing glazing, i.e. picture framing glass, has a fairly coarse texture. This will eliminate Newton's rings, but the texture sometimes effects the image, in my experience. High quality AN glass, i.e. one with a very fine texture, has no noticeable effect, either in my enlarger, or on my 5300 spi scanner.