MattKing
Moderator
1) With almost no exceptions, I only use rotary agitation development of film when I am also using replenished developer;
2) Part of the reason I use a full tank, is that when using replenished developer, there is no economic downside to using a full tank. With replenishment, you use/discard/replenish the same amount for each roll, irrespective of how full the tank is;
3) If you vary the volume of replenished developer in the tank, it changes how much oxidation of developer happens in the tank, which in turn means that replenishment amounts will need to vary, which in turn means that to ensure consistency you will need to employ additional process monitoring steps and tools - such as Control strips and densitometers - which I don't have or want to use for black and white film development;
4) JOBO doesn't recommend any particular volume of developer. It only advises what minimum amount is needed to ensure film gets fully exposed to developer. Other than some concerns about excess weight straining the machines, there is nothing from JOBO that tells you not to use more. Of course, if you use considerably too much, it will leak out when the tank gets turned on its side;
Why would I try using less than a full tank of developer, when it doesn't cost any more to use the full tank, and when it takes one less important variable out of the consistency equation?
I happily use half tanks for stop bath, 1st fixer, 2nd fixer and then HCA. Their activity doesn't vary importantly due to oxidation, and in essence, each step is done to completion, rather than to a ideally consistent mid-point.
When I use other, non-replenished developers, I usually use them diluted, one shot and with normal inversion agitation. In those relatively infrequent occasions, I use the amount of developer necessary to cover the reels, plus a bit. The effects of oxidation are relatively minor when you use one-shot, diluted developer this way. And with one shot use, you don't encounter any of the consistency concerns that re-use brings rise to.
2) Part of the reason I use a full tank, is that when using replenished developer, there is no economic downside to using a full tank. With replenishment, you use/discard/replenish the same amount for each roll, irrespective of how full the tank is;
3) If you vary the volume of replenished developer in the tank, it changes how much oxidation of developer happens in the tank, which in turn means that replenishment amounts will need to vary, which in turn means that to ensure consistency you will need to employ additional process monitoring steps and tools - such as Control strips and densitometers - which I don't have or want to use for black and white film development;
4) JOBO doesn't recommend any particular volume of developer. It only advises what minimum amount is needed to ensure film gets fully exposed to developer. Other than some concerns about excess weight straining the machines, there is nothing from JOBO that tells you not to use more. Of course, if you use considerably too much, it will leak out when the tank gets turned on its side;
Why would I try using less than a full tank of developer, when it doesn't cost any more to use the full tank, and when it takes one less important variable out of the consistency equation?
I happily use half tanks for stop bath, 1st fixer, 2nd fixer and then HCA. Their activity doesn't vary importantly due to oxidation, and in essence, each step is done to completion, rather than to a ideally consistent mid-point.
When I use other, non-replenished developers, I usually use them diluted, one shot and with normal inversion agitation. In those relatively infrequent occasions, I use the amount of developer necessary to cover the reels, plus a bit. The effects of oxidation are relatively minor when you use one-shot, diluted developer this way. And with one shot use, you don't encounter any of the consistency concerns that re-use brings rise to.