Diafine is a two-part compensating powder film developer which has been used and valued by many analog photographers for many years. Diafine was a well-known film developer during the heydays of analog photography because of its ability to produce and even surpass the effective film speed of black-and-white film. Try Diafine with a roll of pushed Kodak Tri-X and you will be convinced immediately.
Diafine is a very compensating developer which allows you to achieve a very wide exposure latitude without the necessity to change the used temperature or development time of the developer. Therefore, it is practically possible to develop films which are rated at different ISO's in the same tank with the same development time. This also makes it a very economical developer. Diafine also offers an ultra-fine grain, maximum acutance and a very high resolution. Diafine is not recommended for those who are looking for a film developer which offers full contrast control.
The Diafine powder developer is nowadays hard to find in Europe since it's only made by one manufacturer based in the USA. The packages that can be bought in our region also sell at high prices. Luckily, the Italian photo chemical manufacturer Bellini has developed a liquid equivalent of this special film developer called Duo Step which is the product that is been offered here. This developer is inspired by Diafine and should produce results that are nearly identical to the original powder formula since it processes highlights and shadows also independently (two-part developer). This product was brought on the market on special request of our UK colleagues Nik&Trick. Thank you for that!
Mix part A and part B with 500ml of water each to get two solutions of 1 liter;
Develop your film(s) in part A for approximately 3 minutes. Use gentle agitation for the first 20 seconds and then five seconds for each following minute;
Drain part A without rinsing the film;
Apply part B using the same time and agitation as used for part A;
Rinse the film for approximately 1 minute;
Apply the fixer and wash the film just like any other black-and-white film (you can use a wetting agent if prefered).
The developer is re-usable several times and will be out of use once part A is insufficient to fully submerge your film(s). The developer will discolor over time which is normal.