Omega/Peak Enlarging tool question

[Drew Wiley]

I use Anti-Newton glass on BOTH sides of the negative - on ALL my enlargers, all formats, both color and black and white work. No problem, ever. It's how I've done it all along - little prints, big prints, low contrast work, high contrast....It's all about using the correct type of AN glass for the degree of incidence and magnification. So I don't give a %^$##@!!! whether this is the conventional wisdom or not. It works! There's no loss in either detail or microtonality, no secondary artifacts or glass texture. But none of my enlargers are condenser style, so I can't comment on that.

[Robbie Bedell]

AN glass above or below the film?

What are “rings”?

The AN glass faces the top (shiny side) of the negative as it should be... It is slipped beneath the condenser. The 'AN ring', on a Focomat, is a round brass spacer insert that goes inside the assembly to compensate for the room the glass takes when the glass is slipped on the bottom of the condenser. It allows room for the neg. and carrier to slide into it's space. The whole glass and spacer idea is an accessory for the enlarger to correct for the actual anti-Newton Rings you correctly predicted. On Focomats Anti-Newton Rings can be very noticeable, yet some operators never have the problem! I have them, thus the need for the glass and ring.

[Robbie Bedell]

I use Anti-Newton glass on BOTH sides of the negative - on ALL my enlargers, all formats, both color and black and white work. No problem, ever. It's how I've done it all along - little prints, big prints, low contrast work, high contrast....It's all about using the correct type of AN glass for the degree of incidence and magnification. So I don't give a %^$##@!!! whether this is the conventional wisdom or not. It works! There's no loss in either detail or microtonality, no secondary artifacts or glass texture. But none of my enlargers are condenser style, so I can't comment on that.

Drew, I never thought of the AN glass on both sides! Perhaps I should try it..

[Bob Salomon]

The AN glass faces the top (shiny side) of the negative as it should be... It is slipped beneath the condenser. The 'AN ring', on a Focomat, is a round brass spacer insert that goes inside the assembly to compensate for the room the glass takes when the glass is slipped on the bottom of the condenser. It allows room for the neg. and carrier to slide into it's space. The whole glass and spacer idea is an accessory for the enlarger to correct for the actual anti-Newton Rings you correctly predicted. On Focomats Anti-Newton Rings can be very noticeable, yet some operators never have the problem! I have them, thus the need for the glass and ring.

I had the 2C and did have them.

[Bob Salomon]

Drew, I never thought of the AN glass on both sides! Perhaps I should try it..

Be careful! AN glass is produced two different ways, etched or sprayed.

It can act like a diffuser when it is against the emulsion side of the film.

[LabRat]

On smaller format roll film negs, bottom AN glass is not needed usually as the film has a natural crown curl that needs to be pressed downwards, but LF sheet formats can have a sag below that needs to be supported...

Lower AN surface tends to be not needed, as the film emulsion has a matte surface that resists ringing, but some smooth emulsions can ring, or extremes in humidity can allow rings to form...

Steve K

[Drew Wiley]

Nonsense, Steve. Why do you think that two different styles of slide projector lenses were made, one style engineered for optimal but imprecise focus once the slides heated up and "popped" convex, and a different series for slides mounted truly flat between two little sheets of AN glass in a special mount, like Gepe made. 35mm is the worst, or perhaps 120 film, which is thin and flimsy. Film doesn't just potentially pop one way or another, but might wrinkle during exposure. Even paper does to some degree (vac easels cure that when necessary). But I knew that Bob would respond to what I said earlier, and he has correctly noted how not all AN glass is created equal. There are not many choices today, but at one time I experimented with thirteen different types, in all kinds of applications and formats. Some of the best were made in Belgium, but still turn up as Durst or Omega anti-newton glass for their carriers. The recent Focal Point glass works fine for large format negs under diffusion sources, but I haven't tried it with small format negs. Anti-newton sprays also exist, available from the same outfits that sell scanner fluid; but I consider these a last resort. All of my contact frames, masking frames, pin registration glass etc also use high-quality anti-Newton glass, only thicker.

[LabRat]

Hey Drew, just read again...

Unmounted 35mm pops pretty reliably, as I understand much engineering took place to form the proper curl for in camera, and post processing optimum curl, but the base is convex, and pops up...

Happy New Year, y'all!!!

Steve K

[Bob Salomon]

Hey Drew, just read again...

Unmounted 35mm pops pretty reliably, as I understand much engineering took place to form the proper curl for in camera, and post processing optimum curl, but the base is convex, and pops up...

Happy New Year, y'all!!!

Steve K

Steve,

Do you really believe that all emulsions, in all thicknesses, from all manufacturers, in all mounts curl the same?

[LabRat]

Not all emulsions are the same, but a curl for 35mm was engineered so that when in camera, the pressure plate pressed the top of the curl down evenly and provided an even flatness... If you look along the edges of the film gate, there is a slight recess where most all of the film was flat, but a small edge past the perfs needed to not be pressed flat, as this would create an overall tension that could affect the rest of the flatness of the frame...

Color slides that were hot mounted were expected to have a crown so popping was minimal... When I hot mounted many E6 slides at a pro lab, the paper hot mounts allowed for this... The different thinner color films tended to somewhat alike, so if put in a projector, the auto focus feature hopefully did not have to do too much...

B/W films with thicker emulsions and bases were all over the place, but some more or less curl was there, but the final curl also had a lot to do with processing, wash times, drying, storage, etc...

The curling function seems to be going away these days, as many customers plan on scanning film very flat, but curled film is important for best film flatness...

Steve K