Possibly Anti Newton glass ruining print, What am I doing wrong here?

[Casperrobo]

Is it the anti newton glass that is causing the light rough patterned area at the bottom of these two prints? I used a glass negative carrier in my new Meopta Opemus Six and this was my first time using it. There is a chance I could have put these emulsion side up (the wrong way).

 

[pentaxuser]

If the neg is 35mm or even MF try it between two plain glasses or just the one plain glass and open neg carrier insert and see what the difference is. Alternatively try a loupe on the neg and see if there is anything there.

I suppose it might be your AN glass that is at fault but unless it is damaged AN glass shouldn't do this. If it did then no-one would buy them or use them.

pentaxuser

 

[L Gebhardt]

I've seen issues when using textured AN glass as the lower glass. They make anti-reflective glass which solves the newton ring issue in a different way. I'm hoping to try some soon.

 

[cliveh]

Use a glassless carrier. The fewer air to glass surfaces the better. Keep it simple.

 

[DREW WILEY]

Sure looks like it. Different types of AN glass sometimes have to be used for drastically different applications per incident angle of illumination,
degree of diffusion, specific focal length and type of enlarger lens. All this can get a bit complicated, and there just aren't many sources for
AN glass anymore. There are several things you can try. First, have a well diffused source. Second, only use the AN glass on the slippery top
side of the film, not against the emulsion - use plain optical glass there (unfortunately, certain films are pretty slick on both sides, so that last bit of advice doesn't work every single time). You enlarging area should not be overly humid - that increased the risk of rings. Use a fast, somewhat longer than "normal" enlarging lens on a perfectly leveled and adjusted enlarger. That way you can use a relatively fast stop for as
shallow a depth of field as possible. And you need a good grain magnifier, so that only the film grain itself is in focus, not what's before and
behind it. I'd consider the "glassless" route to be the "nuclear option" to be avoided if at all possible. But some people prefer it.

 

[pentaxuser]

Let us know what you discover about the cause of the problem. Thanks

pentaxuser

 

[Casperrobo]

Thanks for the comments!

I'll try and reprint them sometime make sure I get the emulsion side down and try and nail the focus. I should probably invest in a proper grain magnifier.
The newton glass is obviously quite rough, it's probably pretty cheap.

I'm a bit apprehensive about glassless carriers because when I've tried to not use glass my negatives always bend and look sharp in some areas and soft in others but I will give it a try.

 

[MartinP]

The Meopta Opemus carrier with double-glass works perfectly adequately (I've used several different ones for years) and you should have no problem with the anti-Newton rings insert, if it is the original from Meopta. Something else is going wrong then - trying to visually focus on the baseboard is also not so very good for finding sharpness and indeed the examples do not appear particularly sharp, so I would recommend a magnifier (the small Paterson one is cheap-and-cheerful). Presumably the variation in lighting in your examples is down to the copy you made of the prints, rather than actually present on them?

Just to check a sharpness problem, are you sure that the lens carrier is properly seated in the mount? The edge of the lens mounting-ring should be parallel to the lens-mount casting, rather than at some irregular angle which might happen if either the locking-screw or one of the locating lugs is 'missed' by the edge of the ring. Another lighting gotcha would be if the double-condensers are not correctly placed in their mount (eg. perhaps not tightened up and then shifted when you moved the enlarger), and yet another - are you using the 'correct' enlarger bulb instead of a normal house-lamp? That can make a big difference.

An approximate (but pretty good, better than with my eyesight anyway) focus can be obtained from the built-in focus-aid by sliding the neg-carrier slightly forwards, observing the two light lines on the easel, and adjusting them to be one line. This depends on the neg-carrier being used in the same enlarger for which the focus-aid was adjusted in the factory, and that may not be the case after so many years.

 

[Jim Noel]

AN glass is meant to be used as the upper glass only. Unless some dampness is involved this will not happen when properly oriented. Newton rings do not form between glass and the emulsion of the film.

 

[Sal Santamaura]

...Newton rings do not form between glass and the emulsion of the film.

That's true for most films, but not all. Both Acros and TMAX 100 have emulsions with sufficient gloss to reliably form rings against plain lower glass, even under moderate humidity conditions.

 

[mnemosyne]

That's true for most films, but not all. Both Acros and TMAX 100 have emulsions with sufficient gloss to reliably form rings against plain lower glass, even under moderate humidity conditions.

Similar experiences here with Ektar ...

 

[ic-racer]

Condenser or diffuser? Is the AN glass on top, bottom or both?

 

[Casperrobo]

Think it's a condenser, it has a great big condenser lens in it under the lamp and AN glass is on top only

 

[ic-racer]

Thin negatives can make this (and dust) more noticeable. A denser negative acts like Dolby noise reduction in terms of dust and imperfections of glass or the film base.

 

[JW PHOTO]

I've seen issues when using textured AN glass as the lower glass. They make anti-reflective glass which solves the newton ring issue in a different way. I'm hoping to try some soon.

Could you elaborate on that a little? I read somewhere about using anti-reflective glass (like used in picture frames) in the same manner as anti-newton glass. Is this what you are talking about? Oh, and I've never had my anti-newton glass carrier interfere with my printing or scanning at all. John W

 

[MartinP]

Generally speaking, the emulsion side of the film is rough enough to prevent newtons-rings and the emulsion is on the bottom of the neg-carrier. This means that the anti-NR glass only needs to be on top so the possible visibility of the pattern is much reduced, if not totally eliminated.

I suspect that the internet-chat about picture-framing glass in negative-carriers reducing newtons-rings is the usual ignorance and mis-information. It may well be that the highest quality picture-framing glass is a practical way to find decent quality flat glass, if the alternative would be standard window glass - but that is the best one could say about it for this purpose.

 

[L Gebhardt]

Newton's rings are interference patterns from light reflected between two surfaces (http://en.wikipedia.org/wiki/Newton's_rings). They will only form when the two surfaces are smooth and reflective. The emulsion side of the film is usually rough enough to prevent them from forming, so you can use clear glass. But some films have very smooth emulsion layers and you can get rings forming on the top and bottom. I've seen issues with Fuji Acros in 4x5 and 120, and I believe on TMX as well.

You can break up Newton's rings by either scattering the light or by preventing the reflections. Most anti-newton glass I have used has been slightly textured. Some people use the textured AN glass both top and bottom, but I have found I can see the texture in the prints if it's used on the bottom, and for small formats sometimes even if I use it for the top glass. The other way is to use smooth glass, but reduce the reflections to such a degree that the rings are invisible (I imagine they still faintly form). The same thin film coatings that are used on camera lenses can be applied to flat glass.

I recently purchased a glass pin registered carrier for my Durst 138. It came with coated glass for both the top and bottom. I made a few prints over the weekend and saw no evidence of Newton's rings. I'll need much more experience before I'm confident the AR glass works.

I'm looking to get a few replacement sheets of AR glass since the ones I have have small scuffs in the coatings, and I may break them accidentally. I'm looking at getting some http://www.tru-vue.com/Commercial/vista-ar-glass/, which may work well. My concern is the reflectance seems to go up in the blue wavelengths, so it may not work as well as we would need for high contrast on VC papers (blue light, and high contrast will accentuate the rings).

Another option is to use an AN spray on the film or the glass. It's just small particles that rough up the smooth texture. Works well enough and that's how I printed the last sheet of Acros in the glass carrier.

 

[darkosaric]

Before, when I used Meopta Magnifax - this is the way that I removed Newton rings: make the negative sits between two cardboard that are sizes little bigger than negative, and then glass will press those papers, not the negative. Paper will hold the negative flat, and negative will not touch the glass surface.
Now I have V35 that had anti Newton glass on top, and nothing below - best solution, and Meopta axomat with glassless carrier - not bad solution, but I print at f5.6 or f8 to be double sure to compensate possible lack of negative flatness.

 

[L Gebhardt]

The anti-reflection thing doesn't really work in my experience. I've tried all the tru-vue types, a few others, and even a carrier made from Schneider multi-coated filters.

That's a shame. I guess I should get a piece of textured top glass for when I find the AR glass doesn't work. I imagine the AR bottom glass will still be better than plain glass.