thebeginning said:
how did you compensate for the 1250 ISO if you don't mind me asking? Did you develop for higher, lower, straight for 1250? I've heard of people shooting at 320 and developing for 400, for instance. I usually shoot and develop around 1600 with tri-x and love the results.
Diafine is a 2 bath, compensating developer. Changes in development time and temp don't have much effect compared to how they effect single solution developers. No matter what film (well, it should be a traditional BW process emulsion), or what ISO I shot it at, the developing process is the same. 4 min in each solution with minimal agitation (agitation can effect how Diafine works).
In a single bath developer the developing agent and the activator are mixed together; as you agitate you are putting fresh developer to work where it has depleted. With a 2 bath compensating developer they are seperate. First I soak the film in developer, then pour it out leaving only the developer that has soaked into the emulsion, and lightly coats the film. Then I fill the tank with activator. The developer working on the highlight areas quickly depletes, and development slows down or stops, while in the shadow areas it keeps going.
I love Diafine for my Widelux shots because in many situations I'll get some pretty wild contrast range over the 140 degree angle of view. The compensating effect kind of sorts this out by itself.
Another interesting trait of Diafine is that it seems to give approx a 1 stop speed boost to most traditional emulsion BW films (not much of a speed boost for tabular grain BW films like Tmax or Delta). Many people claim it gives Tri-X (TX-400 not TXP-320) a 2 stop speed boost to ISO 1600. After using it now for a few years I like the results I get from Tri-X at ISO 1250.
Another cool thing about Diafine is that it will evaporate from use before it is depleted, so it lasts for years and 100s of rolls of film. I just mixed up my second batch. The first gallon (actually 1 gallon each of solution A and B) lasted about 1.5 years, and was used to develop over 500 rolls of film. It was still developing film just fine, but some sort of scum started growing in the bottom of the jug, so I finally mixed up some new stuff. Most folks don't seem to get the scum, so somehow I contaminated my 1st batch.
The main downside to Diafine is lack of developmental control, and it always lowers contrast. Not a big deal in many cases, but if shooting in low contrast lighting, your neg will be very low contrast. Diafine isn't for every project, but it has some traits that make it handy sometimes, and it doesn't have a shelf life to worry about (unless you contaminate it like me).
Just google it and you'll find lots more info. We've also discussed it in the Darkroom section here at TPF.
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