masking negatives in preparation for cropping: a difficult dilemma (in theory)

Interesting question:

When you wish to print only a tiny portion of a negative, say only 1/10th of the whole area, does masking the rest of that negative (so that there is then no extraneous projection of that 'waste' onto the easel) benefit the printed image in that that image retains greater contrast (because it is now not having to compete with the extra ambient light that masking has prevented)?

It seems obvious that masking would allow this fortunate circumstance to happen. But, if you choose to print the WHOLE negative, then would that small portion (indeed, the whole print) suffer slightly from ambient lighting presented from the whole negative's projection?

Perhaps it sounds foolish to present this as a 'dilemma', but it would be interesting to dissect whether or not that isolated small section (actually, the whole print if the whole negative is printed) would suffer as a result, and that the whole negative being printed would, thus, have to be printed to a slightly greater contrast in order to mitigate all that ambient light. Does any of this make any sense? (If not, carry this to a theoretical extreme: if you printed 1/100th of the negative, all that extraneous light from an unmasked negative would seemingly HAVE to have a slight fogging effect.) - David Lyga

Right, cropping is no problem. But it is interesting to note that when printing the whole image, the whole image receives slightly more fog than if only a tiny, masked portion is printed. This probably will not be noticed but, theoretically, it MUST occur (and, by definition cannot be prevented if the whole negative is being printed). - David Lyga

If you have an adjustable masking negative carrier you can easily test the effect with the blades in or out on your cropped image. In my darkroom the white light surrounding a negative can have a dramatic effect. For example printing a Minox negative with a light system designed for 35mm (and no masking) produces a dramatic decrease in contrast, so I always mask the white light around a negative. I think most advanced darkroom workers do the same. This is because many glass carriers don't mask the image, they sandwich the entire negative with surrounding light spillover.

Yes, fog happens, but usually no one notices (unless extreme like the Minox example, ic-racer). But it is an interesting topic to discuss, or at least notice. The very image-forming light causes very slight fog overall and, whether within the camera or upon the enlarger's baseboard, it exists. Thus, there is NO theoretical possibility of attaining a totally fog-free image. Maybe I am pressing this too far but maybe others will have something to say, as well. - David Lyga

It is flare on the enlarging lens of most concern, but 'extra' image forming light bouncing off the white baseboard, hitting the wall and coming back to the paper is also possible. I'd agree that many things cause flare or fog, even going back to the careful use of a compendium shade when making the original image on film.

So one might think the 'cropped' image has better composition than the full negative, one might also think the tonality of that important cropped central portion of the negative can be improved by reducing lens flare during printing.

It is true that there must be some flare effect from a whole neg being printed, but if the lens is good then it would be minimal and (importantly) massively overpowered by the image-forming illumination. In any case, a neg-carrier with masking arms is pretty much standard isn't it(?), and any alternative/extra masking could be done with a simple black paper mask on top of the carrier, or around the easel.

I suppose I'd agree that there must be a flare effect, but that it is simple to ensure that it is minimal.

Michael R 1974 said:

This is why sensitometric testing is done by contacting rather than projection. But excepting fairly extreme circumstances Henry's tests showed even stray light around the negative in a carrier has less of an fee than one might expect.

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Yes, Michael, you cannot get around the fact that, for 'purists', contact printing captures ONLY the image, nothing more to compete with that ideal. Thanks. - David Lyga