glass carrier, reduced contrast.

markbau · Nov 25, 2019

Last night I printed an old 35mm neg in a glassless carrier and then printed the same neg in a glass carrier. The print from the glass carrier is approx 1/2 a grade lower in contrast than the glassless, anyone else had this happen? Needless to say the glass was seriously clean.

voceumana · Nov 25, 2019

Perhaps the glass surfaces caused some internal reflections to increase flare. To be honest, I have never felt the need for glass carriers with 35mm film--the base is stiff, tend, by nature, to curve in one direction only, and a glassless carrier seems to clamp the film adequately.

Kino · Nov 25, 2019

The glass probably blocks a small percentage of wavelengths of light to which your paper is sensitive .

I assume this is Multigrade RC paper, correct? It is probably scattering some small portion of the blue spectrum, if I were to guess.

Probably will just have to print a bit harder when using this (a) glass carrier...

MattKing · Nov 25, 2019

Depending on the carrier, you might also be introducing some reflection based flare into the light path.
Is it a black carrier, a white carrier, a metallic carrier. or ....?

markbau · Nov 25, 2019

It’s a black framed LPL glass neg carrier. I agree, the glass must be absorbing a bit of a particular wavelength.

I was getting some softness on one side of the print when using the glass less carrier which was fixed by using the glass carrier. I suspect there may be a problem (slightly warped) with my 35mm glassless carrier.

eddie · Nov 26, 2019

I assume you're using a 4x5 glass carrier. Are you masking the 35mm negative in the carrier? If not, that could be the cause of your problem. You'd have a lot of extraneous light bouncing around below the negative.

Hilo · Nov 26, 2019

eddie said:
I assume you're using a 4x5 glass carrier. Are you masking the 35mm negative in the carrier? If not, that could be the cause of your problem. You'd have a lot of extraneous light bouncing around below the negative.

This is what comes to mind first.

Something else: if your glass carrier has an Anti Newton glass on top, this could also be part of the reason. For 135mm I have two negative carriers for the Focomat IIc, with (AN) glasses or glassless. It makes a difference. I have never found that a problem, because it is simple to correct . . . in fact I like this parameter as it gives me extra possibilities.

guangong · Nov 26, 2019

A Leitz Focomat glassless carrier presses 35 mm neg against Newton glass sitting below condenser lens. I only used glass carrier with odd sized negatives smaller than 35mm, and never with glassless carriers, so I wouldn’t have noticed any difference.
But markbau made an keen observation observation. Such are the reasons I follow the threads on APUG.

Ian C · Nov 26, 2019

If you’re enlarging a 35 mm negative in a larger-format glass carrier, the area outside of the negative might let relatively bright non-image light fall onto the easel and baseboard. That light might strike some nearby surface and be reflected onto the paper during the exposure resulting in some moderate fogging. If so, that might lower the contrast.

This wouldn’t happen with the metal carrier, whose opening masks the edge of the image rectangle on film. The 6 x 7 cm LPL glass carrier has a built-in adjustable masking-blade set to prevent unwanted spill light around the edges of negatives smaller than 6 x 7 cm.

If the glass carrier doesn’t have a masking-blade set, you can fashion a black paper mask easily enough. See posts 18 & 21 in the following thread for notes on making and using such a mask:

https://www.photrio.com/forum/threads/faulty-lens-on-agfa-enlarger.170968/

Mainecoonmaniac · Nov 26, 2019

I haven't used an enlarger with a carrier with glass, but I think the ANR glass might reduce the contrast.

Hilo · Nov 26, 2019

guangong said:
A Leitz Focomat glassless carrier presses 35 mm neg against Newton glass sitting below condenser lens. I only used glass carrier with odd sized negatives smaller than 35mm, and never with glassless carriers, so I wouldn’t have noticed any difference.

You are talking about the Focomat Ic. I was talking about the Focomat IIc

markbau · Nov 26, 2019

Hilo said:
This is what comes to mind first.

Something else: if your glass carrier has an Anti Newton glass on top, this could also be part of the reason. For 135mm I have two negative carriers for the Focomat IIc, with (AN) glasses or glassless. It makes a difference. I have never found that a problem, because it is simple to correct . . . in fact I like this parameter as it gives me extra possibilities.

My carrier does not have anti-newton ring glass, it was a 67 glass carrier, the blades are a bit wonky so yes, there was some light spilling outside the picture area, I never thought that might cause a lowering of contrast but I think you're right.

glass carrier, reduced contrast.

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