Fomapan 100 Reciprocity clarification

Kino · Mar 15, 2024

Going to start shooting Fomapan 100 in LF sizes. Found this thread which addresses this issue:

Fomapan 100 Sheet Film Reciprocity

I appreciate there has been lots of talk about this subject but I was wondering just how accurate the Fomapan Data Sheet is when it comes to reciprocity. 15 seconds metered time = 2min 15 seconds, 6 seconds metered = 30 seconds according to their chart. Has anyone gone to town to test these and...

www.photrio.com

@Ian Grant, has anything changed with your statement of 2016? I take it the extension factor is added to the top of this reciprocity adjustment, correct?

@revdoc, your table of quoted times, is it based on box ISO value?

Thank you.

Mark J · Mar 15, 2024

I would work out the extension factor first, then the reciprocity factor. Maybe that's what you meant though.

retina_restoration · Mar 15, 2024

Bellows extension factor is always added first, and then calculate the reciprocity.
I use the Reciprocity+ app to calculate reciprocity of the various films I use, and have found the values generated for Fomapan 400 and 100 to be very accurate.

Kino · Mar 15, 2024

Thank you both. I see I will have to write out a check list until I become comfortable with the procedure.

revdoc · Mar 15, 2024

Kino said:
Going to start shooting Fomapan 100 in LF sizes. Found this thread which addresses this issue:

Fomapan 100 Sheet Film Reciprocity

I appreciate there has been lots of talk about this subject but I was wondering just how accurate the Fomapan Data Sheet is when it comes to reciprocity. 15 seconds metered time = 2min 15 seconds, 6 seconds metered = 30 seconds according to their chart. Has anyone gone to town to test these and...

www.photrio.com

@revdoc, your table of quoted times, is it based on box ISO value?

It's based on metered exposure time, regardless of the ISO you use. I rate it at 50 ISO, myself.

MTGseattle · Mar 16, 2024

Filter factor too if applicable. I'm only chiming in as typing this will further help etch the workflow into my own memory.

Mark J · Mar 22, 2024

I just developed a 5x7" Foma 200 negative and got a data point for you :
This was a dark scene of some fungus on a log in the woods and looked to be 8sec at f/32
It was also at about 1:2 macro ( mag = 0.5 for the calc ) so that was an extra stop, to 16sec.
I was guessing the reciprocity but remembered that Ian had suggested it was much better than the datasheet.
So I used about an extra stop, to give 30sec.

The negative is over-exposed ( not enough to spoil it, though ).

So this seems like even less reciprocity than Ian suggested.

Sorry I can't be more accurate than this. I remember I placed the dark areas for a Zone 3, but they came out more like Zone 4, this was with a slight +dev ( only 10%-ish on time though )

Kino · Mar 22, 2024

Mark J said:
I just developed a 5x7" Foma 200 negative and got a data point for you :
This was a dark scene of some fungus on a log in the woods and looked to be 8sec at f/32
It was also at about 1:2 macro ( mag = 0.5 for the calc ) so that was an extra stop, to 16sec.
I was guessing the reciprocity but remembered that Ian had suggested it was much better than the datasheet.
So I used about an extra stop, to give 30sec.

The negative is over-exposed ( not enough to spoil it, though ).

So this seems like even less reciprocity than Ian suggested.

Sorry I can't be more accurate than this. I remember I placed the dark areas for a Zone 3, but they came out more like Zone 4, this was with a slight +dev ( only 10%-ish on time though )

Thanks Mark. I suspect it has a lot to do with individual development methods as well, so the old adage to "test, test, test" still is the best policy.

Rick A · Mar 22, 2024

Mark J said:
I just developed a 5x7" Foma 200 negative and got a data point for you :
This was a dark scene of some fungus on a log in the woods and looked to be 8sec at f/32
It was also at about 1:2 macro ( mag = 0.5 for the calc ) so that was an extra stop, to 16sec.
I was guessing the reciprocity but remembered that Ian had suggested it was much better than the datasheet.
So I used about an extra stop, to give 30sec.

The negative is over-exposed ( not enough to spoil it, though ).

So this seems like even less reciprocity than Ian suggested.

Sorry I can't be more accurate than this. I remember I placed the dark areas for a Zone 3, but they came out more like Zone 4, this was with a slight +dev ( only 10%-ish on time though )

Foma 200 is a hybrid emulsion film, not like Foma 100 and 400 which are traditional emulsion films, it does not react the same.

Mark J · Mar 22, 2024

Yes, I know. But Foma should really correct their datasheets.
For the 400, the datasheet shows 2.5 stops extra for 10sec.
For the 200 they have 3 stops extra for 10sec.
If I'd followed their advice, I'd have totally blown this image.

revdoc · Mar 23, 2024

I use these formulae to make correction tables for Foma films, and they've been very accurate for for pinhole photographs. All credit goes to whoever worked these out. (i've never used these for the non-Foma films listed, so I can't vouch for their accuracy.)

Fomapan 100 Reciprocity clarification

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