I just finished speed testing some FP4+. It's one of my favorites, so I had to finally give it a somewhat reasonable test. This was using 4x5 sheet film, half sheet exposed and half unexposed.
Using my Starlite 2, I metered a white reflector and exposed it 4 stops less that the meter read. I took another reading, and gave 3 stops over the meter. Developedthem both normally, HC-110 Dilution H, for 9 minutes- 1 minute continuous agitation followed by 8 minutes of one tray tilt each 10 seconds and let them dry.
After 3 hours, I took readings of both, and the unexposed half frames for each. My -4 stops required a 1/3 stop to reach the density of the blank frame. My 3 stops over required a 4 1/3 stop increase to match the blank one. Based on what I've read, this means the speed and development are on the mark at box speed. I used 2 meters to evaluate the negatives, one does 1/3 stops and the other does 1/2 stops, and both were close... 1/2 vs 1/3 at the low end and 4 1/2 v 4 1/3 at the high end.
Is this workably accurate, given I have no access to a densitometer? Based on what I've read, it would appear to be. It just seems odd, based on what I've read, that it only took 2 exposed films.
By using a light meter as if it were a densitometer, you seem to have arrived at a density of 0.1 for the low frame and a density of 1.3 for the highlight. Flare could be messing with the result accuracy, but seems ballpark ok to me.
Followed a graph of my own (of a 400 speed film) with my fingertip up 7 stops from 0.1 ... I also came up with a density around 1.3. My graph measured 0.55 CI, and is a little "under" box speed development.
Suppose you lost speed like I did when I developed to 0.55 CI, then the speed might be approximately EI 250
Nice, you appear to have been lucky...
As Bill pointed out the exposure index test is valid but I think the development test is better performed printing the Zone VIII negative on your favorite paper. Give enough printing exposure to make the frame edge just black. The Zone VIII portion should be just 'off white.'
I don't have a graph to work with. I'm not even sure where to begin making one without a real densitometer. I also would likely need to read a bit more on how to properly interpret the results!
Originally Posted by Bill Burk
As far as luck goes, it definitely was either luck or God, as all the data shows FP4+ in Dilution B running 6-9 minutes. I was getting really dark negatives, so I tried dilution H with only a minor increase in time. 9 minutes leaves room for modification, without leaving me too rushed to finish before someone barges in! I've been able to expand the range, I think, just by adding 1 minute to the initial agitation, and developing for 10-12 minutes. A scene that metered from -3 to +1, came out -3 to +2-3 when printed.
Thanks for replying, and for the encouragement.
As soon as I can get some more paper, I will definitely give this a try. Thanks for the tip!
Originally Posted by ic-racer