Features
The PIRA film processor is not just another agitator!
It’s a semi-automatic film developing solution that enables you to achieve the same consistent results as the more “professional” lab-oriented machines but without the added size, weight, complexity and cost from a number of components such as: Heated water bath, mechanical film transport or pumps for feeding and draining chemicals.
Instead, the Darkroom Helper builds on the more traditional approach of pouring and switching the chemicals manually, but providing you with automation and control for the most critical parts of the process:
– Process temperature.
– Agitation.
– Correct timings per step: Developer bath, bleach, fix and so on.
– State of chemicals: Fresh or exhausted.
Temperature
Keeping the temperature stable is critical for consistency.
In order to maintain the right temperature, an internal heating sleeve is integrated into the base, acting like a “dry” water bath without all the added complications (tubing, draining, re-circulation pump, etc).
This also works with the larger 2×120 Paterson tank. The internal agitation and overall larger volume of chemicals ensure that temperature stays on target despite the taller shape.
The heater radiates just enough heat to prevent the internal contents from cooling down and can be calibrated by the user to compensate for diverse ambient temperature conditions.
Note: Due to safety reasons, and to keep the cost of the device reasonable, this is a low power heater. In order to bring the chemicals up to working temperature an external solution like a sous vide is needed.
Agitation
The unique agitation concept implemented in the Darkroom Helper is the reason why the “dry” water bath design described above is possible: It allows the tank to remain stationary while the reels inside are rotated.
This is achieved with the help of six pairs of neodymium magnets.
One set is located at the base of the device driven by an electric motor:
And the other magnets are embedded into a thin disc that sits inside the tank at all times:
And the other magnets are embedded into a thin disc that sits inside the tank at all This disc is designed in such a way that it doesn’t interfere with the normal assembly and operation of the tank: filling/removing chemicals, closing the light-tight lid and so on.
All the user needs to do is slide the disc on the tank core (center column) before inserting the reels.
The default motion is to intermittently rotate the reels back and forward in an upright position.
However, for those who prefer constant motion a second agitation mode is also available: Continuous rolling
In this mode the motor will rotate continuously and if desired the tank can be placed on its side with the lid on. The magnetic coupling ensures that the tank doesn’t slip out of place.
The user can set the speed and how long it takes to switch directions (for example to reverse spin every 10, 20 or 30 seconds).
Timings
Every chemical bath can be customized with the desired length of time.
Additionally the user can choose the number of steps, for example if you want a stop bath, final rinse, blix or separate bleach + fixer and so on.
Once the time has finished for that step an audible beep goes off and the LCD screen displays what chemical to pour next:
State of chemicals
Most color developing kits are designed to be reused a certain number of times, however the manufacturer will often recommend to extend the developing time depending on how many rolls have been processed already.
With the Darkroom Helper there’s no need to manually keep track of this since the internal memory saves how many rolls are developed in each session (the user selects this prior to start) and it will automatically increase the developer time accordingly.
Furthermore, you can select exactly how to compensate: By increasing a percentage amount or by adding time in seconds, for example: Add 2% on each additional roll or Add 5sec on each additional roll.
Note: If using one-shot developers (like Rodinal) automatic compensation can be set to zero.
