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Canon_Patrick 8:34pm, 26 May 2013
This came up on an other topic I posted so I figured I'd share it. I made this reciprocity failure chart for long exposures with fomapan 100. The formula I used gives exactly the same times as the three examples listed in foma's own literature, so I assume we used the same formula.

I'm sure the same info is available somewhere online, but the charts i've found so far do not match this formula.
Fomapan 100 Reciprocity Failure Chart


Edit: I got bored and decided to expand the chart. It covers Foma 100/200/400, TMax 100/400/3200, and Tri-X 320/400.
Heres the new link: BW Reciprocity Failure Charts

I got the formulas here. I have verified all films against the manufacturer's spec sheet, except for TMax 3200 since I can't find the info from kodak. If you find it, please link.
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inetjoker 8 years ago
I love members with gumpchin.Thanks Patrick.
Canon_Patrick 8 years ago
I'll look up "gumpchin", then I'll get back to ya.
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inetjoker 8 years ago
It means drive and willingness to do things for others.
Canon_Patrick 8 years ago
Thank you, larry.
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jpr_me 8 years ago
Thank you!
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inetjoker 8 years ago
A Southern U.S term Spelling is all over the board for it as it is a Southern term.
morozgrafix 7 years ago
Thank you very much for posting those. Just for the record Foma 100/200/400 should also apply to Arista EDU Ultra 100/200/400 films.
Alchymia Obscura 7 years ago
Just curious, does anyone know anything about reciprocity failure at the fast end? Some of the Minolta maxxum cameras go as high as 1/12,000s in shutter speed and usually the linearity og the film fails at 1/10,000s. I don't remember ever seeing it addressed anywhere, though. Also, strobes on low power setting can reach those speeds.
Desert Sun Images 7 years ago
inetjoker:

A fourth grade teacher I know spells it 'gumption.'

And yeah, this is a great resource, thanks for posting.
efo 7 years ago
Has anyone done an empirical chart - based on measuring rather than a formula?
filmphotography.blog 7 years ago
That's really useful thanks
Thanks, really useful to me to!
StephenPridgeon 6 years ago
ditto - have just bought some 4x5 film - so many thanks for the work.
joosttermeer 5 years ago
Thanks so much for this!
I was wondering, do you know a thing about the development of this film when exposing it for long (let's say an hour)? I recall that I read somewhere that you have to lower the development time bij 10-20%, but I'm not sure. Hope you can help me out a bit.
spotted bit [deleted] 5 years ago
when compensating for reciprocity failure the highlights are pushed more than they need to. For example, if your meter reads 1 second, then zone V is already in the failure range and need compensation, but zones Vii or Viii need no compensation, and they will be overexposed. Decreasing the developing time controls those highlights. You can calculate how much they are "pushed" and decrease time accordingly.
jojonas~ 5 years ago
ah, I thought those shorter time recommendations were mainly about controlling contrast in night shots (with deep shadows and bright street lights)

good info!
analogman1961 5 years ago
Now I just need an exposure meter that's accurate at extremely low light levels...
Ondia! 5 years ago
Thanks a lot for this! Really great
1DunPhoto: Posted 5 years ago. Edited by 1DunPhoto: (member) 5 years ago
T-MAX 100 is the film i have exposed more than any other after twilight and before dawn and i'm good with those compensation times except for 1 second - with an accurate camera - which may be a bit dark. T-MAX 100 makes for a better exposure in my 40 to 80 year old leaf shutters set for 1 second, go figure?!

Good observation about possibly blowing zones VII and VIII when our efforts in dim light tend to be devoted to appeasing zone V; taming harsh highlights has been much simpler for me with films that require help. Strong running Fuji Acros on the other hand is great at night if there's nothing in the frame that will stop-down my dilated pupils.
1DunPhoto: Posted 5 years ago. Edited by 1DunPhoto: (member) 5 years ago
analogman1961:Gossen Luna-Pro (SBC) has a computer dial that reads 8 hours: I wouldn't know about that claim because i've never challenged it beyond 1 - 1/2 hours - which meters well enough but the meter has to be "woken up" at night with a spot, after that i can press the button again for an incident reading. It uses a 9v battery i could estimate lasts 3 or 5 landscape op's
Metrix X Posted 5 years ago. Edited by Metrix X (member) 5 years ago
A few years ago I spent some time with different films shooting city night scenes. Came to the conclusion that placing zones 6 to 8 and letting shadows fall where they may gave me good images of the city streets.

Toronto Skyline

25 Floors Below The World Moves By

metrix-x.rraz.ca/2013/08/a-note-on-long-exposures-recipro...
analogman1961 Posted 5 years ago. Edited by analogman1961 (member) 5 years ago
1DunPhoto:
I have a 1st-generation Luna Pro that I recalibrated to use 357/303 silver oxide batteries, instead of the original PX 13 mercury type. I used a DSLR as a reference to calibrate the exposure scales, and it's pretty accurate for bright outdoor use down to dim interior lighting. It also has scale indications for exposures up to 8 hours. As you mentioned, the CdS cell must be "primed" with some fairly bright light exposure before it will read accurately. For nighttime street scenes, and landscapes by moonlight or starlight, I'm still making an educated guess, using an EV chart. Reciprocity compensation is the wild card for long time exposures, and these tables should help (along with bracketing).
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