Newton Rings on Emulsion side, how to deal?

[DREW WILEY]

It takes some patience to find new or otherwise unblemished Durst or Omega AN glass, but is worth the effort. It hasn't been made for quite awhile.

 

[koraks]

I'm not sure what quality problems you envisage with good framing glass with an AR coating

Maybe I'll rig up a test one of these days and share the results.
How did it work for you?

 

[Mark J]

I cheated because I work for an optical company. I had my Meopta under-glass Vac coated !
However I've had both single-coated and later multi-coated framing glass used on prints up to 16x20", and been impressed by its quality close up.
You could probably get an 8x10 piece for $20, and have a few squares of the right size ( I forget what the OP's format was ) cut by the framer.
After that, a bit of DIY would be needed to clean up the edges with a flat grindstone. You'd just need to protect all of the used area with masking tape while you are grinding the edges. I offer it as a worthwhile project if you are not afraid of a little bit of DIY.

 

[Patrick Robert James]

Corn starch always worked fine for me. No need to get complicated.

Also, I used a coated glass in my Leica Focomat 1c on the bottom for a long time. I got the glass at Edmonds Scientific I think. That worked well too, but I never had any issues with newton rings on 35mm.

The only film I really ever had any trouble with was Acros 120. Drove me nuts for a while but then I started using the corn starch. I just open the top of the package, give it a quick squeeze to puff out a bit then wave the neg through the "cloud" although there wasn't much of a cloud. Very little gets on the neg that way. Works like a charm. Never showed up in the images either.

 

[Hilo]

For me this thread is not an easy read. Don't get me wrong, I appreciate the original post and likewise everyone's posts trying to help. Perhaps I get confused because there's also talk about AN glass and scanning. This I have no experience with. Or color printing. This I also have no experience with.

But after over 40 years of enlarging profesionally, myself doing up to and including 50x60cm, using Leitz and Durst enlargers (up to 4x5) and using professional b/w printers for larger formats, I never ever experienced any Newton rings on the emulsion side. I wonder if we're missing out on something that's too simple for words?

Do we agree the emulsion side is the matte side of the film, that lays face down in the neg holder and can be in contact with non AN glass, without a problem?
I ask, because it is new to me that Newton rings can exist on the emulsion side of a negative. Clearly the original poster will not agree with this, but should he ( and perhaps a few others) be the only one then this problem could be due to something we're not thinking off.

There are basically two ways to make sure the negative does not move and we do not get Newton rings:

(1) by using a negative holder with a bottom glass and an upper glass. The upper glass AN treated on its bottom side that presses flat (making contact with) the glossy side of negative. No Newton rings.

(2) we use an 'open' negative holder whereby the negative gets pressed flat on the sides outside the image. This holder can have a non AN treated bottom glass, because Newton rings normally do not exist then. Or this holder can have no glass at all.

There is a third way that excludes a sandwiching negative holder, whereby the condenser presses down the negative. On the bottom of the condenser an AN treated glass is attached. Or the bottom glass of the condenser itself was AN treated. I think about the Leitz Focomat Ic and the last versions of the Leitz Valoy II.

Sorry to be so long. What I do not take into account is that certain film brands could have something to do with yes/no Newton rings. I began with Trix-X and Ilford FP4, since Tmax came on the market, I have only used their 400ASA film, together with the slower Ilford FP4.

The OP speaks about Newton glass causing less sharpness or a deteriation in the corners. This is the first time I hear that. Sorry, but if that were so, this would certainly have come up before.

What I have noticed is that between the various round AN glasses for the Leitz Focomat Ic there exist differences between them. Some clearly have a finer or less treatment. My old friend, a Leitz repairer his entire work life and now gone, said Leitz must have changed something in the production. He then asked if my prints were different, I said they weren't. His eyes smiled: "then you must find something else to worry about".

 

[brbo]

Do we agree the emulsion side is the matte side of the film, that lays face down in the neg holder and can be in contact with non AN glass, without a problem?
I ask, because it is new to me that Newton rings can exist on the emulsion side of a negative. Clearly the original poster will not agree with this, but should he ( and perhaps a few others) be the only one then this problem could be due to something we're not thinking off.

The problem is real and not tied to "doing something wrong". It presents itself under certain conditions. Documented so many times by so many people that by now it really is counter productive to question its existence.

The OP speaks about Newton glass causing less sharpness or a deteriation in the corners. This is the first time I hear that. Sorry, but if that were so, this would certainly have come up before.

Yes, you are right, it would and has come up before.

 

[Hilo]

The problem is real and not tied to "doing something wrong". It presents itself under certain conditions. Documented so many times by so many people that by now it really is counter productive to question its existence.



Yes, you are right, it would and has come up before.

View attachment 358863

In other words folks who use, for example, Leitz Focomats Ic, IIc and Valoy II should not use the AN carriers with the condensers Leitz designed for these enlargers?

 

[Don_ih]

In other words folks who use, for example, Leitz Focomats Ic, IIc and Valoy II should not use the AN carriers with the condensers Leitz designed for these enlargers?

I think it would probably be more of a problem in a 4x5 condenser enlarger, like an Omega, where the bulb is of much smaller diameter than the condenser. The distortion is caused by the angle of light hitting the glass - that would be much closer to perpendicular in a Focomat with 35mm than in an Omega with a 4x5. (Assuming the Omega also has the standard light.)

 

[koraks]

I never ever experienced any Newton rings on the emulsion side.

You may not have worked with TMAX films or Kodak color films. They easily form newton rings on the emulsion side, which is actually not very matte at all (that's the issue!)

 

[Hilo]

Don, that makes sense. I use the normal sized bulbs up to 6x9 (the IIc) and the old very large bulbs for the 4x5 Durst.

Koraks, I use Tmax 400 films since they came out, for these sizes. Just never had these problems.

 

[brbo]

In other words folks who use, for example, Leitz Focomats Ic, IIc and Valoy II should not use the AN carriers with the condensers Leitz designed for these enlargers?

I’d say that all condensers work in a similar way. My Philips PCS150 is not one of those that you now think are only ones “affected” and I’ve experienced problems on the edges. And that’s with ANR on top, problem is even a bit worse when you need to use ANR on emulsion side.

I can’t help to think that you still think that people are making this stuff up, so I don’t see much point in trying to discuss this any further…

 

[Mark J]

The potential for AN glass ( above) to cause problems with condenser illumination is not one that I'd considered. I'm just about to commission a Durst 138S with condenser head. Luckily I have both AN glass and two pieces of AR-coated glass for the full 5x7" neg carrier, so it looks like I'll be trying out both options in some early tests.

 

[Don_ih]

I can’t help to think that you still think that people are making this stuff up

I'm pretty sure he's just trying to clarify what's happening since it's not something he's experienced.

Tmax 400, at least the version from 20 years ago, is not shiny on the emulsion side. I have a sheet of it hanging up right now. It may be different, now. Tmax 100 is.

 

[DREW WILEY]

Hilo - without AN glass on BOTH sides, I ALWAYS get Newton rings. And it is simply impossible to get consistently in focus prints without glass on both sides. People have different standards of what is acceptable or not. My focus standards are high. And most modern thin emulsion films tend to be slick on both sides, and no longer have a traditional retouching tooth surface layer. Then add a foggy climate like I live in, and rings are a constant threat. Do you think Durst would have made AN glass for carriers which cost far more by themselves than any amateur enlarger if there wasn't a real reason for that? And if it wasn't still in demand, why is everyone scrambling to find the last of it? I've got it in all three of my 8X10 enlargers, as well as for all my 5x7 carriers. I have to.

Mark, it's easy to convert even a condenser head back and forth between diffusion instead. But you've done your homework already, and wisely have different carrier glass options as needed.

 

[koraks]

Koraks, I use Tmax 400 films since they came out, for these sizes. Just never had these problems.

I've not shot 400 in quite a while and never in sheet film. 100 I shot mostly in 4x5 and 35mm and it's very shiny on both sides. So are Kodak's color films. The new Harman Phoenix is also super smooth/glossy on the emulsion side. All of these films easily produce Newton rings on the emulsion side as well as the backside. Count yourself lucky you've never witnessed it. Saves you a lot of trouble and money!

 

[Hilo]

I've not shot 400 in quite a while and never in sheet film. 100 I shot mostly in 4x5 and 35mm and it's very shiny on both sides. So are Kodak's color films. The new Harman Phoenix is also super smooth/glossy on the emulsion side. All of these films easily produce Newton rings on the emulsion side as well as the backside. Count yourself lucky you've never witnessed it. Saves you a lot of trouble and money!

Saving the OP a lot of trouble and money was precisely the reason why I wrote, but rather clumsy - I admit.

Since this Newton bottom glass parameter was unknown to me, I was hoping for a simple cure for these problems. With analog photography this is often the case.

 

[Fatih Ayoglu]

Hi there,
So I’ve done 2 tests, printing the same negative with ANR glass at the bottom and again printing the same negative with a glassless carrier. No NR issue at all (well not surprising for glassless one)
I too did not have any NR with BW films from Ilford or Foma and also no NR with Fuji 400H. But this P160 has given me NR issue whatever and however I put the negative on the glass, always at the top edge where I’ve sticked the scrap film for pins.
Now I’ve ordered a new NR glass from Knight Optical as I need 2 NR glass for top and bottom.

Regarding NR glass might cause sharpness issue, is because NR is at the bottom, between paper and the emulsion, very close to emulsion which will show any imperfection. That’s at least my thought, might not be correct.

 

[Oren Grad]

Regarding NR glass might cause sharpness issue, is because NR is at the bottom, between paper and the emulsion, very close to emulsion which will show any imperfection. That’s at least my thought, might not be correct.

It is correct. You don't want to use a textured anti-Newton glass on the bottom.

You are on the right track. What you need to try is indeed antireflection coated glass. I've done experiments in the past with Tru-Vue AR glass, which is sold for framing purposes. The challenge at the time was that it was difficult to find pieces that were entirely free of small surface defects that wouldn't matter for framing purposes but could be a problem in the optical path of an enlarger. After a while the pro framing shop I was working with was clearly getting annoyed with my wanting to sift through their glass stock to find ultra-clean sections for them to cut for me - and I can't blame them, my use was not what they were stocking it for. But perhaps Tru-Vue's production process has improved over the years since.

At any rate, here's hoping the glass from Knight Optical will work for you - good luck!

 

[DREW WILEY]

To repeat, I ALWAYS use actual AN glass on the bottom as well as the top, for every size negative, and I can certainly print at least as precise as anyone else on any forum or any pro lab anywhere. If you do it correctly, it will not affect sharpness whatsoever. A lot has to do with the angle of incidence of light in relation to the specific texture itself, along with the degree of magnification. Unfortunately, it's not a one shoe fits all proposition, even though nowadays you're lucky to find a shoe at all in that respect.

True-Vue is NOT an enlarger-worthy AN glass, nor is any other picture frame glass. But if you can get scraps sized and edged cheaply, why not try it at least? More expensive multi-coated optical flats have been sold as an alleged substitute for AN glass with questionable success. Nothing of that nature ever worked for me. I did buy a surplus batch of a strange film-coated Zeiss glass with no specific product number on it - presumably left over from a custom scientific run - which did work work for all but the slickest of sheet films like Acros in particular. I have no idea what that coating was, except that it was not dichroic or vacuum deposited, and was surprisingly tough.