Newton rings revisited. Arrgghh...

[austin granger]

Hello all.

I realize that the problem of newton rings has been discussed at length before (I think I've read about everything that pertains to it) but I'm posting this in the faint hope that maybe someone's come up with The Definitive Solution since the last go-round. Also, to tell you the truth it makes me feel good to be able to rant about a problem that many of you have undoubtedly encountered (or is it just me?) and can relate to. When I start spouting off about newton rings to my wife her eyes just glaze over... Anyway, here's my trouble:

I'm attempting to make 8x10 contact prints using a Bostick and Sullivan contact printing frame. I'm getting terrible newton rings forming between the glass and the negative. I can see the rings clearly when tilting the frame at a certain angle in ordinary room light. The rings get better when I place the negatives backwards, but obviously this is not going to be a good long term solution. Many have suggested getting AR glass, which I did (Tru-Vue Museum). Unfortunately, the rings are as bad as ever. It does not seem to matter what type of film I use. The rings are not generally visible in the final prints except in clear, uniform areas. But even in prints without clear, uniform areas, just knowing that those damn rings are lurking in there somewhere bugs me... (it's here that my wife grows concerned about my mental state).

In any case, what now? Has anyone tried frosted glass? I've read that with the anti-newton ring glass, a faint pattern can show up on the prints from the etched texture, but I'm wondering if ordinary frosted glass might be better. How about the sprays? While it makes me nervous to be spraying anything on my negatives, at this point I'm getting desperate. Maybe it's the printing frame itself; too much pressure? It seems kind of strange that something especially designed for contact printing would have such a problem...

Any help, or even commiseration, would be greatly appreciated. Arrghhh!

[Oren Grad]

I've never been able to use a spring-backed contact print frame without getting rings. I think the problem isn't too much pressure, it's that the pressure is uneven - the springs exert their force at specific points, and the felt-covered wooden back isn't nearly rigid enough to redistribute the pressure evenly.

I've had my best luck with a simple sandwich - a piece of ordinary glass on the bottom, the negative and paper in the middle, and a piece of quarter inch optical glass, larger than the paper, on top. I can usually get ring-free prints that way.

For negatives smaller than 8x10" printed on paper 8x10" and smaller, I just use the glass cover from a PrintFile contact printer (designed for proofing a roll of 35mm negatives in a PrintFile sheet) that I had sitting around. For 8x10" negatives printed on up to 11x14" paper, I use a 12x15" piece of quarter inch glass obtained from Focal Point (www.fpointinc.com).

I should say that in sheet film I mostly shoot HP5+, which has a very smooth base side and is very prone to Newton's rings. Among other films I've used, the old TXT as well as Bergger BPF 200 both have retouching surfaces and in my experience were pretty much ring-free.

[darter]

Hi Oren,

Where do you buy large sheets of optical quality glass?

Thanks,

Phil

[Oren Grad]

Phil -

As I mentioned, I got the 12x15" glass from Focal Point (www.fpointinc.com).

Unfortunately, when I spoke to them a few months back about getting a larger piece to use in my forthcoming ULF experiments, they said that quarter inch optical grade glass had become so expensive that they weren't stocking it in very large sizes any more. So I may be forced to try pestering a local glass supplier to find as clean as possible a piece of ordinary glass and cut it to size for me without messing it up.

If anyone has a reliable supplier for very clean quarter inch glass in largish (say, 18x22") sizes, I'd love to hear about it.

[Brian Ellis]

I bought my 16x20 or so contact printing frame from Doug Kennedy and have never had a Newton ring problem. The glass isn't anti-Newton ring, I suppose I don't get the rings because I print 8x10 negatives and put the negative near the center of the glass. Plus the clamps are very strong. I don't know if Doug is still in business, I bought my frame about ten years ago and I don't have any contact information but someone else here might know or you could Google.

[Oren Grad]

Brian -

Both of my contact printing frames - 8x10 and 11x14 - were also made by Doug Kennedy. They're beautifully built, but they cause ferocious Newton's rings for me. Perhaps using a very oversized frame helps to even out the pressure in the center.

Newton's rings are a real challenge to get rid of, because there are so many pesky little things that vary from one darkroom to another and can affect getting the pressure just right.

For people who, like me, want to use a film with a very smooth base and don't want to spray gunk on the negative, I'm not sure there's any solution, other than possibly a heavy-duty vacuum frame for those who can accommodate one in their darkrooms, that would be guaranteed to work. Maybe not even that.

Probably you just have to keep tinkering until you find a trick that works in your darkroom...

[Eric Woodbury]

Austin, I suspect you are right -- that if you put a diffusor in contact with the neg and between the neg and the light source the Newton rings will go away. In this case it would not be the texture that cures it, but the perfectly diffuse light source. Your might try white plexi instead of the glass in the contact frame. It will cost you a couple of stops, however, and it might be thicker than your glass. Also, it is hard to see through the plexi for dodge/burns.

[Oren Grad]

As a side note, sadly, the website for Doug's firm, www.greatbasinphoto.com, is down now, with not even a cached page left on Google. Perhaps he's gone out of business - I know that he'd already stopped making film holders a while back.

[wfwhitaker]

Austin,



Last weekend I was printing in a friend's darkroom with a Bostick & Sullivan contact frame. I was told that the B&S frames do not provide even pressure. My friend's set-up included two layers of mat board between the back and the paper to help even the pressure. You might try doing that as a possible solution which would be inexpensive.



Add my vote to the others' for Doug Kennedy's printing frames. I have a couple of them and they seem to work well in addition to being beautiful. The last contact info I had for Doug was up in Lake City in the northeastern corner of California. Try this link: http://e.neilsen.home.att.net/dougkennedy.htm



Best,
Will

[Jacques Augustowski]

get the glass from an old scanner, its optical glass
Jacques