From: Jack Fulton (jefulton1@attbi.com)
Date: 04/09/03-09:07:05 PM Z
Well, I'll say, Scott, this is much more thorough than something so you are
in the book of serious folks.
I trust your tests to be most accurate and will file those ISO's for future
use.
By the way, how do you like the film?
Best
Jack
> Hi Jack,
>
> For my tests I:
> 1. Taped a piece of white mat board to a wall outside in open shade
> 2. Set up my camera so that the board filled the viewfinder
> 3. Set the focus at infinity
> 4. Metered for zone V using the manufacturer's rating of 125
> 5. Calculated exposures for zones 0 to X
> 6. Made 3 sets of exposures for zones 0 to X on each roll; plus
> additional exposures for zones I and VIII (keeping all exposures
> between 1/500 and 4 seconds; including reciprocity)
> 7. Develop according to manufacturer's recommendations for each
> developer
> 8. Read and average densities for each zone with a B&W densitometer
> 9. Plot densities on graph paper and find where the curve crossed the
> 0.10 density line to find the film speed
>
> I shot 3 rolls of film for each of the 3 developers (FX-37, D-76/ID-11, and
> Xtol) I tested and came up with very similar results for each. The first
> roll with each developer was processed using published recommended times.
> For the second roll with each developer I tried minimal agitation by
> increasing the time by 100% and agitating every third minute. The third roll
> was developed using increased dilution and adding 100% to the times. Each of
> the nine tests showed almost no density (about 0.01-0.03) above fb+f below
> the zone III exposure. My tests with Pyrocat-HD also showed the same results
> though the stain makes those tests useless. Each developer was mixed from
> raw chemicals about an hour before development.
>
> Published times for Arista Pro 125 (aka Ilford FP4+) state that:
>
> EI should be 160 in FX-37 (1+3) for 4.50 min at 68F
> EI should be 200 in D-76 (1+1) for 11.00 min at 68F
> EI should be 250 in Xtol (1+2) for 13.75 min at 68F
>
> My tests show that the EI in these developers (at the above dilutions and
> times) is 12-25. Much, much lower than published data. I thought that the
> chemistry might have been bad, but tests done with 400 speed film in the
> same chemistry show EI's of 250-320. I am at a loss as to what is going on
> here. I should be getting film speeds close to manufacturer's specs if not
> better.
>
> Scott
> smwbmp@starpower.net
>
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