Author Topic: Might be of some use to hp5+/fp4+ users  (Read 1042 times)

LT

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Might be of some use to hp5+/fp4+ users
« on: September 06, 2011, 09:42:07 PM »
I've been messing around  - literally wasting film - to nail down long exposure reciprocity adjustments for my fave 2 films  - HP5+ and FP4+.

I'm sure this info is available elsewhere, but I've looked loads and can't find it. The ilford chart included in the data sheets only goes up to about 30 seconds as the non-adjusted time, and I was looking for longer than that.  And, to be honest, whenever I use that chart, I end up with over exposed negs so I've done a bit of testing. Here are my results.


1, 2 & 4 secs = no adjustment needed.

8 secs = 10 secs

15 secs = 30 secs

1 min = 1 min 50 secs

2 min = 3 min 30 secs

4 min = 11 min 30 secs

8 min = 25 min

16 min = 1 hour 30 min

to be honest, once beyond 5 min actual exposure, accuracy is not crucial. These times were all gained using D 23 developer (1:3) and exposing film at box-speed, based upon a crucial shadow reading reduced by 2 stops (zone III placement if you are into that kind of thing)

L.

Francois

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Re: Might be of some use to hp5+/fp4+ users
« Reply #1 on: September 06, 2011, 10:19:55 PM »
Shoot... At last spring's rummage sale, there was a huge color densitometer for sale. If shipping wasn't so expensive, I should have sent it your way! It was only about the size of a big microwave oven :)
Francois

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astrobeck

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Re: Might be of some use to hp5+/fp4+ users
« Reply #2 on: September 06, 2011, 10:52:46 PM »
Wow, those numbers are very close to pinhole exposures.