Archived posting to the Leica Users Group, 2007/07/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Phil Swango asked: My interest in Diafine is mainly that I do very little BW film these days and when I do I want something versatile, easy to use and long-lasting. Diafine is pretty cool, but like most cool things it?s somewhat quirky. Diafine is a two-bath developer, containing a lot of phenidone, hydroquinone and bisulfite. You put the film in the A bath for three minutes with gentle agitation, put the A bath back in its bottle and pour the B bath into the tank, leaving it for 3 minutes again with gentle agitation, then pour the B bath into its bottle, stop in plain water and fix. Why the rigmarole? It?s often claimed that the first bath merely soaks the film without any development, but there is more than enough sulfite in the A bath to raise the pH (make it alkaline) enough to start development. You can show this by exposing a frame, developing in the A bath for 3 min and then stopping and fixing. You don?t get much development, but it's a lot more than none. The B bath contains an activator (alkali) that accelerates development and exhausts whatever developer is left in the emulsion. The dense areas get exhausted first, and development continues in the thinner areas until the developer is all used up. What this means in practical terms is: It?s not very sensitive to time or temperature variation (within limits). It has a profound compensating effect, so it works well for rolls of film shot in mixed, very contrasty lighting. The highly active developers in it mean that many films gain speed (more on this below). The separation of developer and activator and good slug of preservative means it lasts almost forever, or at least until it doesn't cover your film anymore (seriously). Although the formula has never been published, I have listed an acceptable substitute below that acts almost indistinguishably from the commercially available product. The A-bath contains about 35 g/L sulfite, about the same as D76 1+3. The B-bath contains about 65 g/L. I am of the school that thinks a little sulfite helps in a developer, but that a lot is probably bad. Results from Diafine aren?t as sharp as from highly dilute solvent developers, but the compensating effect and the push it provides can be worthwhile. The fact that the film is only in developer for 6 minutes altogether probably helps retain some sharpness. Some say Diafine gives a ?true? push, but sensitometry shows that it?s false economy- like all other pushes, the toe stays pretty much put, but the push does start further down the curve than for most one-bath developers. For really savage pushes (TMZ at 12800, anyone?) DDX, T-Max or T-Max RS developers are probably still better choices. In very contrasty scenes where EI 1250-2400 are necessary, Tri-X and Neopan 1600 behave very well in Diafine. It?s pretty much unbeatable for night photography with Acros @ EI 100 and that combination seems very, very sharp. I?ve also used it with TMY @ EI 160-200 for working in very contrasty direct Australian sunlight, where Pan F+ @ EI 80 also works well. The chief disadvantage of most 2-bath developers is that you get only a single EI ? you cannot modify your exposure to change the contrast of a scene on the film ? all you get for adding or subtracting exposure is a similarly contrasted but too dense or too thin frame. With a film developed in a regular developer, I tend to expose more in high-contrast scenes and less in low-contrast scenes. This doesn?t work with Diafine, which is okay as long as you are willing to use it mainly when the light is very contrasty. I wouldn?t recommend it as an all-the-time developer, for the simple reason that in anything lower than normal contrast, you get negs that are so flat it?s barely believable. There aren?t any films that ameliorate this, although Pan F and Acros show more contrast than higher speed films. These aren?t very useful in dim, flat light (admittedly this is a somewhat rare condition) because of their slow speed. Years ago, when I was first simplifying my systems and materials, I considered using only Kodak XX (B&W cine film, not the old Super-XX) and shooting it at EI250 and developing in Xtol 1+3 for normal scenes and shooting at EI640 and developing in Diafine for low-light, contrasty scenes. I later settled on one developer (Xtol 1+3) and two (later three) films - Neopan 400 and 1600 (and later Acros ? although like Mark Rabiner, I find myself using very much less Neopan 400 since I started using Acros). Steve Anchell?s "The Darkroom Cookbook" gives a "Diafine-type" formula: Solution A: Water at 125F/52C 750 ml Sodium sulfite, anhydrous 35 grams Hydroquinone 6 grams Phenidone 0.2 grams Sodium bisulfite 6 grams Room temperature water to make 1.0 liter Solution B: Water at 125F/52C 750 ml Sodium sulfite 65 grams Borax 20 grams Cold water to make 1.0 liter Any temperature between 68F/20C and 80F/27C is acceptable, times do not have to be adjusted. Soak in solution A for 3 minutes then move to solution B for 3 minutes. Do not rinse in between A and B. Do not use a presoak Do not use an acid stop bath, use a 30 second to 1 minute water rinse after solution B. An alkaline fixer is recommended but does not seem to be required. Note: do not get any B bath in the A bath. You will observe something very similar to the Xtol ?sudden death syndrome?. The alkali will allow everything in the A bath to oxidise rapidly. I also find that gentle agitation is more useful and provides better consistency than ?soaking? the film in each bath (stand development). Definitely use a plain water stop. I?ve used both alkaline and ordinary fixers ? both seem to work. Diafine and similar formulas are not, as sometimes claimed, ?panthermic? but they do tolerate a wide range of temperatures. Above 25C you?ll observe more activity and under 20C you?ll see a marked decrease. Its results are also not entirely uninfluenced by time, but less so than one-bath developers. You can keep recycling your Diafine for a long, long, long time. I have tended to throw it out when the A bath gets to 50% its original volume, but it does not ever seem to die if looked after. Results change with age ? probably due to bromide build-up and changes in sulfite / metabisulfite equilibrium. There is a sweet spot in the middle that old-timers have told me can be maintained by replenishment, but I?ve never tried this. If you like to use your camera in very contrasty light Diafine will save you some headaches, but I don?t think it is ?universal?. I am going to mix and experiment with a few Diafine formulae and different films over the next few months, so stay tuned. Other 2-bath developers Cachet AB55 gets around the single EI problem by the A bath being mixable at half, ?normal? and double-strength and Cachet handily providing times for different CIs with a few films. This is a good choice if you use a medium format camera with different backs and want some flexibility. If I was going to put the effort in to work that way, however, I?d be using Xtol. I can't find an approximation for this developer, but it's a phenidone HQ formula, so making one up shouldn't be too hard. Tom A?s divided D76 formula is here: http://leica-users.org/v02/msg05860.html Again, a really great developer. Tom?s times are too long for me, but he does say he likes ?bullet proof? negatives. Dante Stella handily points out that the addition of 1 g of glycin to the A bath and 10 g of sodium carbonate to the B bath creates another handy push developer. Johnny Deadman?s pseudo-divided D76 http://leica-users.org/v10/msg07140.html and Xtol are described here: http://leica-users.org/v13/msg12048.html as John said, surprisingly, it really works. The main problem with these processes is that you need to monitor the activity of the A bath ? it?s just regular Xtol or D76, so it dies (in fact I think the Xtol is a one-shot only option from my limited experience). As I mentioned in my Xtol rant, the development by-products of ascorbates are acidic development inhibitors ? this makes ascorbate a somewhat impractical component for a re-usable two-bath developer. There is a two-bath developer described here: http://www.apug.org/forums/archive/index.php/t-30162.html that claims a life of a couple of months. I haven't tried it. Another Tom A formula for a divided developer (much of this is snipped straight from a message from Tom): Divided Pyrocat (published in Leica Photography #1/1968). Part A Water ( room temperature is fine) 100 ml Pyrocatechin (or Catechol) 10 grams Sodium Sulphite 2 grams Potassium Bromide 0,5 grams Part B Water ( room temperature again) 100 ml Sodium Hydroxide 10 grams Potassium Bromide O,5 grams The Pyrocatechol/catechine is toxic and treat it with respect ( don't lick the spoon!) The volume of Sodium Sulphite is so small that it dissolves quickly. You can use distilled water but I have not seen any difference from my filtered darkroom supply. Let it sit for a while to ensure that everything has dissolved - stir occasionally. The B is quick to mix. The Sodium Hydroxide does generate heat when it is added to the water (remember always add acid/alkali to the water -never the other way around as it can splatter and give you nasty burns to hands and face). USE Take 20 ml of A and add 250ml of water (room temperature) in a clean beaker and the same for the B solution (20ml B/250 ml water) in a different beaker. Be careful that no B goes into the A beaker as it will kill the A solution! I usually do batches of 5 or 10 rolls and mix up A/B in appropriate volume. This is a 1-shot developer and you dump it after a run. However, it is quick to mix and this way you are assured that it is always fresh. Pour your mixed A into the developing tank and agitate every 30 sec for 4 minutes. Nothing much happens here, mainly saturating the emulsion. Pour out the A and without rinse, pour in the B solution. Again agitate every 30 sec for 4 minutes (2 turns each time and bang it against the counter for the first 3-4 agitation cycles to knock out any airbubbles). Dump the B and a quick rinse in water and fix as usual. Once the negs have been washed and dried, they look muddy and greenish/gray but that is how they should be. Once you put it into the enlarger you will find that they print fine! I don't know how well they would scan. It is a convenient developer as it is quick to mix and consistent in result. Because of it being a A/B developer you have less chance of frying the highlights as the only active developer compound is the miniscule amount that is absorbed by the emulsion in the A-bath. The B bath only serves as an alkaline activator and "jumpstarts" the process. It is difficult to overdevelop with the split formulas ( the main advantage), but you can not push-process either. TriX stays at 400 ASA and XX seems to give a consistent 250 ASA in natural light (but rate it at 200 ASA in tungsten). Pyro-developers are not fine grain developers, but the acutance is very good and this formula is typical. Most films that I have done with it have normal grain (for the speed), except Bergger 200 film - truly ugly grain! So, there?s plenty to experiment with there. Tom?s divided pyrocat developer derives its grain structure from the very high alkalinity and pyrocat primary developer. To answer Phil?s initial question: if you?re willing to mix up a batch of Divided D76 (or but some from Formulary) or AB-55, you?ll probably get more ?normal? results and a bit more flexibility than from Diafine. Let me know how you go, if you try any of these. Marty -- We've Got Your Name at http://www.mail.com! Get a FREE E-mail Account Today - Choose From 100+ Domains