I've been considering either purchasing or making my own glass negative carrier (Beseler 23c, 35mm) to handle the hassles and small imperfection introduced by negative pop. I know that glass carriers are notorius for collecting dust. Even so, I still think the move to glass might be worth the effort, or perhaps I could follow Eddie Ephraum's example and use one piece of glass for the top of the carrier and leave the bottom bare. Any suggestions, pros, cons, shared experiences?

-- Christopher Hargens (ldmr@cruzio.com), October 05, 2000

Answers

I think dust problems from glass carriers are overstated. One has to put some effort into cleaning the glass and negative, but after that one is rewarded with flat negatives that stay clean. No dust can settle on the negative while you are printing. The outer glass surfaces don't matter as much, at least with a diffusion enlarger, because they are out of focus. I use StaticMaster brushes and canned air to clean the negatives and glass. Also windex and soft cloth on the glass.

-- Michael Briggs (MichaelBriggs@earthlink.net), October 05, 2000.

Searching photo.net, I read the following commment from Bill Kocsi: "I've used anti-newton glass plates for my 6x6 negatives and found them to be very useful. True, dust is a problem. I live in the Northeast and, in the summer anyway, have enough humidity in the air to make that a manageable problem. Drier climates will be more difficult. I am able to place two pieces of glass and the neg. in my Besseler carrier and place it in the enlarger without using tape. Just be careful--the glass is fragile. Speaking of glass, try using the anti-newton glass from WESS Plastics 6x6 slide holders (Model DVA- 001). They are great." -- I think I'll try using/adapting the 6x6s to my 35mm negative carrier.

-- Christopher Hargens (ldmr@cruzio.com), October 05, 2000.

My 23CII has always had a severe problem with negative pop. Adding the Beseler heat absorbing glass reduces the temperature rise of the negative by about 1/2, not nearly enough, but better than nothing. I also find that the negative carriers have probably been "grained" (a sanding operation) after being punched. This produces a rounded edge next to the frame, and makes the popping problem that much worse. The edges of the frame are actually floating! I've measured over .020" of negative movement (center of frame) as it warms up! Several things help- get a better heat absorbing glass. Be sure your carriers are flat and meet perfectly (compare against a flat surface and bend ever so gently). Reduce the voltage to the enlarger bulb- this gives more usable printing times and reduces the heat output somewhat (use a Variac). Finally (and what you really wanted to know), get two ordinary sheets of glass, about 5x7 inches and tape one edge to form a hinge. You may want to put a couple strips of thin tape inside so they don't close too tightly. A black paper mask on the outside will cut stray light. This works fine and dust isn't a major problem if you blow the thing out with a "Hurricane Blower" or canned air each time you use it. Remember that it's simply impossible to get the maximum sharpness from your enlarging lens without some sort of glass carrier. IMHO, a one sided glass carrier isn't sufficient.

-- Conrad Hoffman (choffman@rpa.net), October 05, 2000.

Michael -- I live in California, near the coast where's there's a fair amount of humidity. Dust isn't a great problem -- it's usually a problem when I get lazy and forget to clean the negative or leave it for too long in the carrier.

I agree with you, Conrad, about the severity of negative pop. (BTW, I'm glad to hear that my suspicions about the effect of the rounded edge are born out.) I have used a dimmer (may get a Variac when I get more money) to reduce voltage and gain more control over enlarging times, but, as you pointed out, negative pop still occurs. I may buy some heat-absorbing glass, but I think that a glass carrier would probably be best in any case. You suggest ordinary glass. Have you had any problems with Newton rings?

-- Christopher Hargens (ldmr@cruzio.com), October 06, 2000.

Wow, this is an interesting discussing. I have not used a glass carrier in almost ten years. The last time I used one, a Beseler in a 23C, I kept getting - what I think were - Newton rings. Sort of looked like oil slicks, and no matter what I did, could not get rid of them.

So, I do think they are quite a few variables in this whole business. Perhaps humidity, little irregularities in the glass, phase of the moon, direction of the wind, Saturn's position in the sky............

Popping negatives are no fun either - perhaps it's time to try glass again.

chris

-- Christian Harkness (chris.harkness@eudoramail.com), October 06, 2000.

I haven't had a problem with Newton rings, but I usually resort to the glass carrier for special formats, technical reproductions where I need maximum sharpness, lens tests, and prints I'm really serious about. In other words, I don't use the glass carrier for every single print I make, so I might just be lucky. On a positive note, if there's enough dust, it will prevent Newton rings :-)

-- Conrad Hoffman (choffman@rpa.net), October 06, 2000.

I am under the impression that some films are more susceptible to forming Newton Rings than others. Christian and Conrad (and anyone else), what film(s) were you using when you did (or did not) get Newton Rings?

-- Warren Weckesser (weckwg@math.lsa.umich.edu), October 06, 2000.

Never thought about it, but it makes sense that different surface finishes would make the film more less prone to Newton rings. Duller is better and the retouching surface on large format films should be great. Most of the negatives I need glass carriers for are old, and were probably 120 Verichrome Pan. I also used a lot of 35mm TMX- the popping seemed worse than usual, but Newton rings weren't a problem.

Another interesting data point- you can put a thermometer in the carrier and see very little temperature rise because of the reflectivity of the stainless shaft or the mercury. BUT- if you attach a very tiny thermocouple to a dense negative, you'll find that the temperature rises to 120 degrees F in about a minute. The first part of the rise is very steep, so it hits 100 in about 30 seconds or less. My guess is that dense negs pop worse because they heat faster and hotter. But maybe this is more than anybody wanted to know... I really need to get out and take pictures!

-- Conrad Hoffman (choffman@rpa.net), October 06, 2000.

Warren, its been so long. The negatives were 35mm and probably T-Max- 100 and Tri-X.

chris

-- Christian Harkness (chris.harkness@eudoramail.com), October 06, 2000.

I get Newton rings when using 35mm film in my glass carrier (Durst M601) and I think it's because of the thickness of the film. I don't get them with 120 roll film. After making a print that had them, I held the carrier up to the light and could see them easily... by sqeezing the carrier, they moved or disappeared (this is not an option during an exposure!). I have made some 35mm inserts (to replace the glass) out of mattboard which work fine.

-- Nigel Smith (nlandgl@eisa.net.au), October 07, 2000.

That's what happened with my 35mm negs. You can see the rings - just like an oil slick, when you press the carrier together & I never did NOT get that.

Now, are there folks out there using 35mm and glass carriers who never get Newton rings to begin with?

chris

-- Christian Harkness (chris.harkness@eudoramail.com), October 08, 2000.

I get newton rings a lot when using t-Max 400 35mm. I've read in places that you can get rid of them by using anti-newtonian glass. The problem is that i have an old durst condensing enlarger and the negative is sandwhiched between one of the condensing 'lenses' on top and a glass piece on the bottom. I could replace the bottom glass, but would that get rid of it (only having one of the two glass parts with A.N. glass)? Furthermore, does anyone know where i could get the glass? (I kinda doubt they'll have it at the local hardware store!)

thanx luke

-- luke field (mrbiglleswurth@hotmail.com), October 08, 2000.

Try the following URL -- http://www.fpointinc.com/data/Store/fp1glas.htm

-- Christopher Hargens (ldmr@cruzio.com), October 08, 2000.