Is there a way of calculating how much reduction in development time is needed to counter the increased contrast when using long exposures?
Is there a way of calculating how much reduction in development time is needed to counter the increased contrast when using long exposures?
If you use the Zone System, you figure out where the highlight falls, and do whatever N minus development necessary. It's trickiest when the shadow is in reciprocity territory and the highlight is not. When the highlight also is long, apply the reciprocity correction to see how far it is away from your taking exposure.
The only reliable way is to test. Films differ in this respect.
Since we are basing exposure on a shadow value, the highlights will often render higher than metered due to the compensation for reciprocity. Sometimes this is good, other times we need to compensate.
My rule of thumb with conventional films is a 10% reduction in development for every doubling of the metered value due to reciprocity failure correction. E.g., meter reads 6 sec. but I need to expose 12 sec = N* - 10%. Meter reads 15 sec but I need to give 60 = N* - 20%.
*Or whatever development is indicated, e.g., N-1 - 10%, etc.
Tabular-grain films seem to need less compensation, but testing is your only real indicator. When in doubt, try to make a second negative; develop one and adjust for the second till you get a handle on things.
Best,
Doremus
GoodoldNorm: Thank you for asking this question! Precisely what's needed at this point since I've just been shooting the equivalent of late day (flat narrow dynamic range), post sunshine shots with long exposure... and just read Stroebel's admonition with respect to development of long exposure shots. And so thank you as well to Doremus Scudder formerly of Austria but late of Oregon... where I was meant to visit (but didn't) during our very Covid summer. Nice rule of thumb and good place to start. Of course I complicated the learning exercise by using filters, color and B&W film. But this was and will be a learning exercise... which of course means we will afterwards be filled with both some measurement of amazement for what works, and more likely a similar and possibly greater measure of what to do next time.
Some of us use normal development, or even more, to increase the contrast! One of Sexton's "Quiet Light" tricks.
"Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China
Yes, and this is probably the case for the vast majority of exposures. People tend to think that a given exposure is either in reciprocity failure or not. In reality that's hardly ever the case. Mostly what we get are *parts* of the exposure experiencing reciprocity failure while the rest behaves normally.
And this, this right here, is why I moved from Tri-X to TMY. That cured a whole lot of my Zone III control problems.
Bruce Watson
Indeed! I think the contrast increase caused by reciprocity failure looks different than that achieved by developing longer; it stretches out the shadows instead of the higher values. I'll throw on a ND filter every now and then just to push the film into reciprocity failure so I can expand contrast and get that look. A great tool.
Best,
Doremus
With my alt processes, I like the look of my prints from negatives that have 'hefty' shadows...some small clear areas, but lots of information in the shadows. This increases my exposure times, of course. Some alt processes can create a printed-out image during exposure...this can hold the highlights back slightly and can give a smooth tonal gradation. One of many variables (e.g. my carbon prints can have detail in areas of pure black due to the raised relief).
Sometimes I will add more exposure, and sometimes I will not, due to Reciprocity Failure (RF). That will depend on the situation in the shadows and what I would like to happen there. I will sometimes 'ignore' RF in order to create some deeper shadows than are present....perhaps it is a nice overcast day under the redwoods. Since I am contact printing, I want some areas that are too small to see detail in, to be clear -- they'll be sure to hit black at the print's minimum exposure time and I can work with rest of the shadows and highlights from there.
Its all rock and roll, sometimes in the field I'll wet my finger, stick it in the air, and wonder why my finger's cold. I try to repeat my successes, and if I fail, again, I try to fail a different way this time. Every scene is different, no matter how much the same they are...must be, judging from the variety in my negatives. It is the dialog between the negative and the print that will tell one how to treat both ends of the process.
"Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China
Very tricky issue when photographing ocean surf...with intermittent highlights due to transient zone-8 sea-foam surges. The solution involves observing the time ratio of "on surge" to "off surge" - which might mean a three minute exposure that, while lengthened from that which was metered originally, still needs absolutely no development compensation. Pretty cool actually!:
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