The Jobo CPE-2 Plus Processor is a good economical choice to develop and process, film and paper in a controled environment.
There are only three important variables when developing film and prints. The three are time, temperature, and agitation.
When developing black and white film by hand without a processor, you change the development time based on changes in room temperature. There is a set formula (for a given chemical developer/dilution) that dictates that any increase in temperature will result in a decrease in time, and vice-versa.
It's important to realize that this is not true with color film. There is no uniform correction with respect to time and temperature, and therefore it's difficult to develop color film consistently without a processor that controls the temperature accurately.
The following is an explanation of how the CPE-2 Plus handles the three variables.
- Time: The CPE-2 Plus Processor does not automatically time the filling and draining of the chemical and rinse steps.
In order to achieve the correct timing, you will need a wristwatch, or a somewhat manual darkroom timer. The way you fill and drain chemicals differs with whether or not you're using the processor with the optional Lift Accessory.
- Temperature: The CPE-2 Plus Processor uses a water-bath to ensure even tempering of the chemicals, and the tank or drum that contains the exposed paper or film.
This is important with black & white processing to help you be more consistent -- but it's not critical. For people who only develop black & white materials,
- Agitation: The CPE-2 Plus uses a bi-directional rotation system to agitate the solutions.
It's very important that the rotation is bi-directional because it prevents the chemicals from forming flow patterns which could result in improper processing.
Another important point to mention about agitation is the perception that rotary processing increases agitation and therefore must result in a decrease in process time or over-developed negatives will result. This is true!
The same can be said of an increase in temperature causing over-development. This increased agitation can yield shorter development times without a decrease in consistency or process quality. (It should also be noted that agitation controls contrast more than density).