Efke 50 sheet film, HC110, Jobo Drum

[jack_hui]

Hi all,

I have just bought one pack of Efke 50 (4x5) sheet film, and have done
some tests. The result is strange for me.

ND (@ISO25): 6min, HC110 1:99 (Yes, 1:99) in Jobo 2840
paper drum, approx 10 rpm hand rotation (@20 DegC)

N+1 (@ISO40): 11min, HC110 1:99 (@20 DegC)

Anyone got any similar result ??

Thanks, Jack

[Bjorn Nilsson]

If you get N dev at 6 minutes and N+1 at 11 minutes they seem a bit far apart, but you are using high dilution, which can explain things. ISO 25 and 40 seems normal.

//Björn

[jack_hui]

I feel it so strange, b/c the dev. time from efke is about HC100(B), 7 min, ISO50 ..
which is very big different from mine ...

I will do some field time later this week ....

[Donald Qualls]

Your dilution is weaker than the published Dilution B, which would tend to lengthen your time relative to theirs, but you're agitating continuously, while the published time is most likely for intermittent agitation. My experience over a range of films and developers is that agitation can effectively run on seven levels: continuous, 30 second cycle, 1 minute, 3 minute, five minute, semi-stand, and full stand (this applies to tanks where the film is fully submerged and doesn't have another sheet against the emulsion; in trays or partially filled "rolling" tubes, other factors intervene), with each step corresponding to approximately 50% change in the development time to give the same contrast (but no change in true film speed, if agitation is all you change -- the shadow areas get the same development with any agitation, because agitation reduces local exhaustion which doesn't occur where there's very little exposed halide to develop). That makes your 1+99 at 6 minutes, continuous agitation, about equivalent to the published 1+31 at 7 minutes with agitation every minute (you're at roughly 3x for dilution, and 1/2 for two agitation steps; give or take some variance in your desired contrast vs. theirs and some fudge factor for the time it takes developer to soak into dry gelatin before actual development starts, that's what a researcher would call "not a statistically significant difference").

Different films require different amounts of development adjustment to change contrast, and a very high dilution increases local exhaustion, which tends to decrease contrast; roughly doubling time instead of adding 20-40% isn't at all out of line with your high dilution regardless of the film used.