Fomapan 100: Development time reduction in case of long time exposure

[Dali]

Hi There,

Simple question: What would be the development time reduction to apply if I expose a Fomapan 100 film for 60 seconds (taking into account reciprocity failure)? My developer is usually homebrew D-76.

I read Foma litterature and I could not find anything written about adjusting the development time...

Thanks!

 

[rjbuzzclick]

I'd start with the standard development time (or whatever your adjusted 'standard' development time is). I would then adjust that (if needed) to compensate for your subject and how you metered and exposed.

I recently (last year) made a number of exposures inside of dark theaters with Fomapan 100 where my exposures were sometimes as long as eight minutes after reciprocity. I metered and exposed based on the shadow detail I wanted, and then compensated development based on the highlight detail I wanted to save.

 

[Doremus Scudder]

My rule of thumb for a starting point for finding the development compensation for extremely long exposures due to reciprocity failure is:

For every doubling from the original, non-adjusted, metered exposure time, reduce development be 10%.

Example: The meter says 4 minutes and the adjusted exposure (from a reliable chart from the manufacturer or testing) is 19 minutes (my times for 320Tri-X, BTW).
One doubling of 4 is 8, a further doubling of 8 = 16. 19 minutes is a lot closer to 16 than to the further doubling of 16 which would be 32, so I'd just develop 20% less, or an approximate N-1. Hope that's clear.

As you can see, even for very long exposures, you may not need much development compensation. I likely wouldn't compensate at all for a 60-second adjusted exposure, since the metered exposure time would be less than 30 seconds (i.e., no doubling). And, keep in mind that many scenes that require very long exposures are not all that contrasty and often benefit from the increased contrast.

I've used this method for exposures that lasted up to several hours with success.

Best,

Doremus

 

[Dali]

The exposure from the meter is likely to be 8 sec. According to Foma, I should then expose 8 sec x 8 times (3 stops correction), close to 60 sec.

Shots will take place outside by daytime, so the scene contrast should be normal.

 

[gone]

Here's a lot of info on that subject. I seem to remember something about reciprocity failure w/ some of the Foma films, not sure if that applies to the 100. I shoot that a lot, but rate it at 50 EI for daylight pics, which drops to 25 EI w/ a yellow filter.

https://live-fts.flickr.com/groups/67377471@N00/discuss/72157633721255138/