large format printing - 4x5

[darkroom_rookie]

With B&W and some papers it can affect the contrast.

Ian

Does it affect recent RA4 papers such as Ultra Endura? Does the contrast increase or decrease with long exposures? Can the contrast be successfully reduced by adding sodium sulfite to the developer? (A lot of questions, I know...)

d_rookie

 

[RalphLambrecht]

Does it affect recent RA4 papers such as Ultra Endura? Does the contrast increase or decrease with long exposures? Can the contrast be successfully reduced by adding sodium sulfite to the developer? (A lot of questions, I know...)

d_rookie

My measurements show a slight contrast increase with exposure time, probably due to an elevated exposure loss in the shadows, causes by non-uniform reciprocity failure.

 

[BetterSense]

Sounds like it could be used as a way to deliberately increase contrast.

 

[RalphLambrecht]

Sounds like it could be used as a way to deliberately increase contrast.

Possibly, but with 1/4 grade increase per 5 stops of exposure difference, there must be more efficient methods.

 

[BetterSense]

I wouldn't know; was under the impression that the only way to control contrast with color negative printing was to use a different paper or film, and there aren't many papers available anymore.

 

[Ian Grant]

The effects of long exposures on contrast can also be affected by scattered reflections causing fogging, not enough to necessarily raise base fogging rather having a similar effect to flashing. Most enlargers spill some light and this is why black walls are usual near enlargers, but columns often have chrome plated parts and I've seen issues on odd occasions.

With RA-4 Colour balance can shift slightly with reciprocity, this is why pro labs calibrated their roll head printers so the exposures were constant regardless which lens (so enlargement size) was used.

Ian

 

[RalphLambrecht]

I wouldn't know; was under the impression that the only way to control contrast with color negative printing was to use a different paper or film, and there aren't many papers available anymore.

As Ian(?) said: different developer work.