MorseBlog

In the quest for more consistent 4x5 film development I have taken a few steps outlined in past articles. The next 'criticism' of might setup might be the use of a Cibchrome drum rotation system that only rotates in one direction. Looking at Jobo and other solutions I would like to target 25 RPM as a lower bound of speed and reverse every rotation or two. I timed the rotation unit and it already achieves the lower bound at 25 RPM. I looked at the power supply and confirmed this was a DC power supply (12v on the nameplate) so I knew I could control the direction with polarity. Next I opened the motor base by carefully prying it apart with a table knife. The two parts of the housing are held by interference fit of the 4 holes that hold the rods in place. Once inside I could measure the voltage and current (18v peak, 200mA peak). I also saw there was lots of room for electronics. My approach which is simple, but massive technological overkill, is to use a small Arduino Pr...

Introduction In other posts I have documented my use of Cibachrome drums which are designed to develop 8x10 sheets of Cibachrome color print paper. Cibachrome has not been made since 2009 so these come up often. I also found the motor unit that rotates the drum. Cibachrome Drum  Drum with Motor Unit I originally bought this to develop Cibachrome from expired paper and chemicals ( See link here. ).  Eventually I made us of it to develop 8x10 film as a cheap developing tank. For 8x10 you roll the film up emulsion facing inside so that it lines the inside of the drum. This is done of course in complete darkness. The lid is then screwed on and after that the rest of the operations can happen in normal room light. The lid has a small reservoir that holds about 250 ml of chemistry. You fill the reservoir with the developer while the drum is upright. The the drum is laid on its side and rotated. (I would roll it along the kitchen countertop until I got the motor unit.) ...

I bought a Cibachrome daylight print processing drum a few years back when I experimented with Cibachrome using expired film and chemicals I bought online. Since then I have used the drum to process 8x10 and 4x5 large format film. It works well; already dimensioned for 8x10 print film, it has a light tight top where chemicals can be poured in an out without losing the light tightness. This means once the film is loaded it can be processed in normal room light which is a huge advantage. I have seen them sold for as little as $8.00. Drum-based developing has other advantages in that it is less likely you will scratch the emulsion compared to tray developing and can achieve more uniform development compared to tank developing. They can also be used in a water bath to regulate temperature if needed. The nature of the tank is also such that it does not immerse all the film all the time and so uses less chemicals. The lid is unscrewed and in the dark the film is loaded on the inside wal...