8x10 contact prints compared to 4x5 enlargements?

[Oren Grad]

I wonder why we don’t read of this more in the writings of photographers who did a lot of contact printing (Weston, for example). Unless maybe the bases of old films were less shiny or something.

Yes, maybe retouching directly on the negative was more commonly done, and sheet films of that era were more often coated on bases with a "tooth" to accommodate that. I imagine it shouldn't be too difficult to confirm or disprove that as a historical assertion.

[Michael Kadillak]

Can't dispute results and if Newton Rings are manifesting themselves in your contact printing regiment, something needs to be fixed as that condition is clearly unacceptable. I have contact printed with T Max 400, FP4+, Delta 100, Efke 25 and Foma 200 on glossy paper (Azo, Ilford warm tone and Classic) through 1/8" shop glass over 25+ years and never had a problem.

Learn something new just about every day.

[Tin Can]

Is there any correlation between high and low pressure contact

I use 2 high pressure and one low. the low seldom

I am still working on my 20X36" with only heavy plate glass on low pressure foam

My job was flat surface examination using Surface RA tool and FujiFilm pressure sensitive

Wow, we can now buy it from eBay

https://www.ebay.com/itm/26602707237...d91bf38e15628b

[bob carnie]

Drew’s eyes have built-in microscopes and also filtration to match various standard illuminants. True story.

Not to mention he has built in XY coordinate vision so he can record every position he has ever been in and enhanced densitometer fingertip BORG style fingers.

[Michael R]

Is there any correlation between high and low pressure contact

I use 2 high pressure and one low. the low seldom

I am still working on my 20X36" with only heavy plate glass on low pressure foam

My job was flat surface examination using Surface RA tool and FujiFilm pressure sensitive

Wow, we can now buy it from eBay

https://www.ebay.com/itm/26602707237...d91bf38e15628b

Strictly speaking, contact is contact, so it would not matter how much pressure there is if the two surfaces are perfectly flat. However as usual we aren’t dealing with perfect things/conditions, so in reality high pressure, for example, can either help or make the problem worse, depending on the surfaces, how evenly the pressure is applied (ie you don’t want to distort flatness etc.).

My first suggestion if Newton rings are a problem was always to try using a sheet of fixed out TXP 320 as a spacer (for glass negative carriers as well) as Sal mentioned a few posts earlier, before investing in more costly alternatives that may or may not work - although with the prices of Kodak films these days...

Oren raises an interesting question regarding old timey films. Before small and medium format was a thing, we know retouching negatives was very common and basically standard practice in studio settings and such. Perhaps in those days more films had somewhat “matte” base coatings for this purpose - like TXP still does. Maybe this was just enough to prevent a lot of potential Newton ring problems from popping up. Maybe not. I don’t know.

I went down the rat hole (as is my custom) with this and tried a slew of things and inquiries, and seem to have been able to prevent Newton rings with multicoated filter glass (you need reflection to have Newton rings), but obviously there is no perfect BBAR coating so this is by no means guaranteed to work - and it is prohibitively expensive. I did it because (a) I’m an idiot, (b) I only needed big enough for 35mm to 4x5 negative carriers. The state of the art, as it were, would be to use glass with a sub-wavelength (“nano-structured”) anti reflective surface. Basically a much finer grained scattering surface than ANR glass. The type of thing lens manufacturers have been using (Nikon Nano Crystal Coat etc.). However for the time being it’s a no-go because those surfaces need to be in sealed settings.

Anyway that’s much more than anyone ever wanted to read about Newton rings lol.

I always meant to ask Christopher Burkett how he handles Newton rings since he does so much masking. Maybe Drew knows.

[Alan9940]

Strictly speaking, contact is contact, so it would not matter how much pressure there is if the two surfaces are perfectly flat. However as usual we aren’t dealing with perfect things/conditions, so in reality high pressure, for example, can either help or make the problem worse, depending on the surfaces, how evenly the pressure is applied (ie you don’t want to distort flatness etc.).

My first suggestion if Newton rings are a problem was always to try using a sheet of fixed out TXP 320 as a spacer (for glass negative carriers as well) as Sal mentioned a few posts earlier, before investing in more costly alternatives that may or may not work - although with the prices of Kodak films these days...

Oren raises an interesting question regarding old timey films. Before small and medium format was a thing, we know retouching negatives was very common and basically standard practice in studio settings and such. Perhaps in those days more films had somewhat “matte” base coatings for this purpose - like TXP still does. Maybe this was just enough to prevent a lot of potential Newton ring problems from popping up. Maybe not. I don’t know.

I went down the rat hole (as is my custom) with this and tried a slew of things and inquiries, and seem to have been able to prevent Newton rings with multicoated filter glass (you need reflection to have Newton rings), but obviously there is no perfect BBAR coating so this is by no means guaranteed to work - and it is prohibitively expensive. I did it because (a) I’m an idiot, (b) I only needed big enough for 35mm to 4x5 negative carriers. The state of the art, as it were, would be to use glass with a sub-wavelength (“nano-structured”) anti reflective surface. Basically a much finer grained scattering surface than ANR glass. The type of thing lens manufacturers have been using (Nikon Nano Crystal Coat etc.).

Back in the 80's when I first started contact printing 8x10 negs, I had a terrible time with Newton Rings. Lots of theories as to what caused them--reflections, uneven pressure, humidity, etc--and I tried everything to resolve the issue. I always thought the issue was mainly caused by light refractions caused by minute unevenness of the two surfaces.

I don't remember how it all began, but I got into a conversation with Ron Wisner about this problem which resulted in my sending him a sheet of 1/4" plate glass that he sent off somewhere to have a single coating (same stuff used on lenses) applied to one surface. I don't remember it costing me much because I think he thought of it as a technical challenge to solve. Anyway, lot story short...got the coated glass, tried it, not a single Newton Ring since! Been using the same piece of glass for 40 years now.

So, you may be on to something with that coating idea.

[John Layton]

Michael I'm also an idiot...and although I sense that there are quite a few of us here on this forum - I wish there could be more of us in the general population.

[Oren Grad]

Following up on Michael R's points:

The primary problem isn't the amount of pressure, it's that the pressure is uneven. The wood-and-felt backs of printing frames don't come close to spreading evenly the high pressure that the springs exert at their few points of contact.

As I've posted elsewhere, the most effective solution in my darkroom has been to skip the printing frame and use a plain glass "sandwich" - a large, thin piece of glass goes on the enlarger baseboard, then the paper, then the negative, and on top a thicker, heavier piece of plain glass.

I've tinkered with Tru Vue AR coated glass in print frames, with equivocal results. What brought those experiments to an end was that it was quite expensive, and difficult to find pieces without small coating flaws that would show up in prints. The local pro frame shop where I was buying the stuff humored me at first, but after a few rounds of inspecting samples to find clean sections of larger pieces that could be cut for me to purchase it became apparent that it was becoming a nuisance for them. This was quite a few years ago; perhaps the manufacturing process has improved since then.

[bob carnie]

FWIW we are contact printing inkjet negatives to silver, and Pt Pd using a very thick glass plate , to date we have not seen any issues with newton rings. We place the paper emulsion up on the baseboard lay down the inkjet negative (emulsion down right reading) and then lay down the thick glass to create the contact.

[Michael R]

Back in the 80's when I first started contact printing 8x10 negs, I had a terrible time with Newton Rings. Lots of theories as to what caused them--reflections, uneven pressure, humidity, etc--and I tried everything to resolve the issue. I always thought the issue was mainly caused by light refractions caused by minute unevenness of the two surfaces.

I don't remember how it all began, but I got into a conversation with Ron Wisner about this problem which resulted in my sending him a sheet of 1/4" plate glass that he sent off somewhere to have a single coating (same stuff used on lenses) applied to one surface. I don't remember it costing me much because I think he thought of it as a technical challenge to solve. Anyway, lot story short...got the coated glass, tried it, not a single Newton Ring since! Been using the same piece of glass for 40 years now.

So, you may be on to something with that coating idea.

Without getting into the weeds, two things are required for the interference pattern to form:

1. Different amounts of space between the surfaces (for example some space vs no space (ie contact))
2. Specular reflection between the surfaces