Reciprocity failure correction for ilford fp-4 plus

[wskmosaic]

Does anyone know of reliable reciprocity failure correction data for Ilford FP-4 Plus black and white film. There is receint (2003) data on HP-5 Plus from Howard Bond. Ilford's own data sheet, besides being too short, contends (unconvincingly) that its single correction plot applies to all its black and white films. Howard Bond did tests for HP-5 Plus, and other films, in 2003. But has anything been done since, or ever, on FP-4 Plus, which requires it more.

Additionally, does anyone have any information on development reduction to accommodate for the increased exposure given these films in reciprocity failure correction?

tnx
Warren

[Ian David]

I generally use the same reciprocity numbers (based on Bond) for both FP4 and HP5. Seems to work pretty well.

Ian

[vinny]

https://www.google.com/search?q=fp4+reciprocity&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

[Heroique]

For Ilford b/w films (such as FP4+), here’s a set of numbers from Steve Simmons’ Using the View Camera – a personal set that’s probably as good as anyone’s for starters. Your own personal testing is what really counts in the end, of course, so take careful field & darkroom notes!

The following numbers, Simmons explains, are often longer than those recommended by the film manufacturers. “It is far better to err slightly on the overexposure side with negative film,” he says. Well, of course, Steve. ;^)

Remember also to test for adjusted development times – the longer metered times may require reduced development times. If you know what film reciprocity does to your low and high values, you know why this is so!

Metered time (sec.) / actual time necessary (sec.)

2 / 3
4 / 7
8 / 19
12 / 33
16 / 50
24 / 93
32 / 145
45 / 250
60 / 378
90 / 853
120 / 1670

[wskmosaic]

Thanks;
That's the best answer I've gotten--and I've done a lot of asking.
w


For Ilford b/w films (such as FP4+), here’s a set of numbers from Steve Simmons’ Using the View Camera – a personal set that’s probably as good as anyone’s for starters. Your own personal testing is what really counts in the end, of course, so take careful field & darkroom notes!

The following numbers, Simmons explains, are often longer than those recommended by the film manufacturers. “It is far better to err slightly on the overexposure side with negative film,” he says. Well, of course, Steve. ;^)

Remember also to test for adjusted development times – the longer metered times may require reduced development times. If you know what film reciprocity does to your low and high values, you know why this is so!

Metered time (sec.) / actual time necessary (sec.)

2 / 3
4 / 7
8 / 19
12 / 33
16 / 50
24 / 93
32 / 145
45 / 250
60 / 378
90 / 853
120 / 1670

[wskmosaic]

What I'm beginning to find is that some people use systems other people abhor, and both seem to do ok. Sounds like a bit of personal preference. No?

[wskmosaic]

I have spent several days going over those entries, and the results vary all over the lot. There's a batch of information; it's just a matter of deciding what works for you, I guess.

tnx

[Michael Alpert]

Metered time (sec.) / actual time necessary (sec.)

2 / 3
4 / 7
8 / 19
12 / 33
16 / 50
24 / 93
32 / 145
45 / 250
60 / 378
90 / 853
120 / 1670

My experience with this film corresponds with these numbers, though when making a still-life photograph, I increase the time (bellows factor). I also increase the time when the subject were dark and I want to insure that I hold the shadow detail. I often rate the film at 100 instead of 125. This is one of my favorite films; I find that a small amount of over-exposure does no harm.

[Lachlan 717]

What I'm beginning to find is that some people use systems other people abhor, and both seem to do ok. Sounds like a bit of personal preference. No?

It is not necessarily personal preference. It is also due in part due to processing paradigm. Without knowing how you intend to develop, any system is only going to be a starting point.

If you have access to a Densitometer, why not do some indicative testing? Perhaps you could chose one system's recommendations and do 2 seconds, 8 seconds, 30 seconds and 2 minutes, then extrapolate the data from this spread?

[Maris Rusis]

Reciprocity failure can't be corrected by increasing exposure alone. Development has to be reduced to tame the increase in contrast caused by the shadows "failing" but the highlights "not failing". But what happens with roll-film and sheet film where you would prefer not to give individual development to individual frames? A different reciprocity correction chart is called for. Here's mine for mid-tone metered time versus given time:

1/1
2/2
4/5
8/10
15/22
30/50
60/120
120/300

The reciprocity compensation in this list is much less than the usual figures put forward but it avoids the difficult dense negatives that result when development is not reduced. The photographs that result tend to have somewhat empty shadows but I contend that empty shadows are logically consistent with the experience of looking into dark places. I would rather show the darkness than compensate it away.

[Vaughn]

Good point, Maris. I use the film's RF to increase the contrast on the neg for alt processes. Not so much extra exposure for the shadows, and a little more dev for the highlights.

[wskmosaic]

Maris:
Your numbers are remarkably similar to Howard Bond's (cited elsewhere in this thread), for HP-5 Plus. You use them for FP-4 Plus, Right?
Warren

[Maris Rusis]

Yes, the numbers are similar to Howard Bond's but perhaps a little less strict. I use the same numbers for all films except Fuji ACROS which I don't shoot and infrared (Ilford SFX and Efke IR820) for which I don't make any reciprocity corrections at all. To make things easy on myself I tend to walk away when the meter indicates exposure times in excess of about a minute.

[Andrew O'Neill]

I ran some reciprocity tests over ten years ago for both FP4 and HP5. Compensation is the same for both films. Also, there is such a minute increase in contrast that I don't even bother with development time compensation.