Ilford FP4+ ISO/ASA Rating

[Juergen Sattler]

I am calibrating my system for the use of Ilford's FP4+ rated at 125 ASA. My results indicate that the real ASA rating is more like 400 - which strikes me as odd - I would have expected SOME difference, but this seems huge. Did anyone here go through the same testing with this film and what were your results? I used two different light meters (Sekonic and Pentax Spot) and they both agreed, I then calibrated my enlarger and the Standard Contact time for the paper I am using and got this 400 ASA result. Thank You in advance.

[John Berry ( Roadkill )]

My speed is 100 using pyrocat-hd. Negs keyed to the new Azo #2 which does use a lot longer scale.

[Richard Schlesinger]

About ISO 100 is where I end up with FP4+. Are you looking at a density just above fb+f? About .1 or .15?

[Ron Marshall]

My speed test gave me 125 in D76 1+1 and 250 in HC110 Dilution B

[Christopher Perez]

My rating of FP4+ souped in D-76 was 250. So 400 is not unthinkable. Film speed can be a very "relative" thing, depending upon the various elements in one's system of work. :-)

[Juergen Sattler]

Thanks for all the answer. I also use D76 in a rotary processor. I took a reading of a gray card in the shade as Zone V and then calculated the Zone I value and did 4 additional shots of +1, +2, -1 and -2. Before I had determined the Standard Contact Printing time to get absolute Paper Black. I used that SCP time to determine the first visible gray beyond black as my Zone I and to my big surprise I ended up with this 400 rating. I guess tomorrow I'll do some controlled shots at that speed and see what comes out of it. I am printing on Ilford Multigrade Paper IV.

[Bob._3483]

Have you used this method before? Did you allow for bellows factor if you focussed on the card, or did you focus at infinity? I get EI 80 in ID-11 1+1 for 5.75 minutes @24C (rotary).

[Joseph O'Neil]

I dunno about 400, but I agree with you about the overall speed rating not being what it says it is.

For what it is worth, the past ten years, I have always shot any and all B&W films, all formats, at around half thier rated ISO/ASA. For example, both HP5+ and Tri-X in 4x5, I shoot both at 200.

However, I have always found the one exception to that personal rule is FP4+. It shoots - for me - right one. I think commercailly it should be rated at around 200 ASA. But I'm not complaining.
joe

[Juergen Sattler]

Bobo,
yes I focused at infinity and made sure that the gray card filled the entire GG. I re-did the entire test this morning and I end up with an ASA rating of about 300. I don't have a way to measure the density of the negative - so I have to go by what I see on the contact print - first descernible gray as Zone I. This is the first time I am calibrating my system (I have been shooting color film mainly until now) = so it is possible that there is a flaw in there somewhere, but I am following the instructions of a book called "The Zone System" and it makes sense to me what they describe.

I will take the camera out this afternoon and take some pictures with the 300 rating and we'll see what comes out - I will let you know. Thank You for all your responses.

Juergen

[Bob._3483]

Yours is much the same method I use, except that I use a bath towel instead of a grey card as it has texture and is big enough to focus on without apreciable bellows extension. I find this easier to judge the ZII (hint of texture appearing) and ZVIII (almost lost the texture) values to narrow down development time. One problem with the "just grey discernable from black" is the light you use to view the test prints under - having said that, I found only about half a stop difference between a very bright light and a reasonably dim one.

One good test is to contact print your negatives for the standard time you have already found for your paper and processing time and see how they look under your normal viewing lighting - you will soon see if your Zone II shadows and Zone VII/VIII highlights show what you expected when you placed the zones when taking the shot.

Have fun!