BTZS film testing with Jobo and Expert drums

I've finally persuaded myself to get my processes in line as much as possible so I am about to embark on some extensive film testing using Phil Davis' BTZS system. Anyone out there done testing with an expert drum on a Jobo? Do I stop the drum and grab a piece of film out at each development interval (then replce the lid and put it back onto the machine)? Or do I simply process each piece, one at a time from start to finish (to avoid the interuption of rotation etc)?

One other thing, if I'm using my enlarger to expose the test sheets - I have a ZBE VC cold light head on my enlarger with a built in timer etc. However, I'm not sure how accurate exposures of less than 1/2 second would be on any cold light head - would I be better off installing a shuttered lens for the purposes of the testing and relying on a mechanical shutter instead?

Thanks.....

Donsta said:

I've finally persuaded myself to get my processes in line as much as possible so I am about to embark on some extensive film testing using Phil Davis' BTZS system. Anyone out there done testing with an expert drum on a Jobo? Do I stop the drum and grab a piece of film out at each development interval (then replce the lid and put it back onto the machine)? Or do I simply process each piece, one at a time from start to finish (to avoid the interuption of rotation etc)?

One other thing, if I'm using my enlarger to expose the test sheets - I have a ZBE VC cold light head on my enlarger with a built in timer etc. However, I'm not sure how accurate exposures of less than 1/2 second would be on any cold light head - would I be better off installing a shuttered lens for the purposes of the testing and relying on a mechanical shutter instead?

Thanks.....

Click to expand...

I did one piece at the time, if you have the expert drums they are about impossible to open without the foot pump, having to do this in the dark and having the lid bounce all over the place was not my idea of fun.

Before I got the sensitometer I used a shutter in the enlarger, even so the exposures were not accurate. I would recommend you get a 15 watt bulb with a timer and just measure how far you have to be to get 4 EV.

Good luck and dont dispair, once you get it done you wont have to do it again...

Jorge

How important are extremely accurate exposure times - I can find my most consistent Copal 1 shutter (I have a tester) and use that? Do you think that the interuption method (i.e. all the sheets in at once) has serious downside? I'm pretty comfortable with getting the lid off on my 3010 drum - I can literally ease it off with a couple of quick pumps - it's the 3063 drum lid that flies off like a rocket!

Jorge said:

I did one piece at the time, if you have the expert drums they are about impossible to open without the foot pump, having to do this in the dark and having the lid bounce all over the place was not my idea of fun.

Good luck and dont dispair, once you get it done you wont have to do it again...

Click to expand...

I manage to get the lid off my expert drums without that foot pump. However, I doubt that you want to be barefoot in the darkroom to do it. I just put the tank on the floor, hold it with my feet and carefully pry up the edges, rotate the tank a bit and do it a second time. Comes right off. But this is done in the bathroom in the light after the final wash is done.

Donsta said:

Jorge

How important are extremely accurate exposure times - I can find my most consistent Copal 1 shutter (I have a tester) and use that? Do you think that the interuption method (i.e. all the sheets in at once) has serious downside? I'm pretty comfortable with getting the lid off on my 3010 drum - I can literally ease it off with a couple of quick pumps - it's the 3063 drum lid that flies off like a rocket!

Click to expand...

As you know the expert is Phil, so you should really ask this in his forum, but IMO consistent exposures are important to build the family of curves, I imagine the shutter speeds would be consistent and if there is an error it should also be consistent.

Another issue is developer exhaustion. If you put all 5 sheets in the drum, will you be using a new batch of developer every time you take one out? are you going to develop your shots the same way? I say do it the way you plan on doing your regular shots. Consistency is the key.

Donsta said:

I've finally persuaded myself to get my processes in line as much as possible so I am about to embark on some extensive film testing using Phil Davis' BTZS system. Anyone out there done testing with an expert drum on a Jobo? Do I stop the drum and grab a piece of film out at each development interval (then replce the lid and put it back onto the machine)? Or do I simply process each piece, one at a time from start to finish (to avoid the interuption of rotation etc)?

One other thing, if I'm using my enlarger to expose the test sheets - I have a ZBE VC cold light head on my enlarger with a built in timer etc. However, I'm not sure how accurate exposures of less than 1/2 second would be on any cold light head - would I be better off installing a shuttered lens for the purposes of the testing and relying on a mechanical shutter instead?

Thanks.....

Click to expand...

I believe it would be very difficult logisticlaly to remove a sheets of film after each development interval, and even if you were able to do so interrupting the rotation would give inconsistent results. So my advice would be to do the sheets one at a time. This also introduces some consistency issues but they are manageable if you take a lot of care in using the exact dilution of the developer, the exact amount of develper for each sheet of film, and can control temperature to one degree F or less.

How accurate does the exposure need to be? Very accurate, in my opinion, especially if you hope to compare films in terms of effective film speed. In fact, I think that would be impossible even with a modern Copal shutter and if your goal is to compare EFS you really need either a light integration system or a sensitometer. On the other hand, if your only interest is in creating a family of curves to show you how long you need to develop to get a certain contrast index, a variation of up to about 10% in the shutter speed might be acceptable.

For best results I would really recommend that you invest in a few tubes for your testing. This method of agitation gives results very similar to JOBO, and by careful attention to how rapidly and consistently you rotate the tubes in the water bath it should be possible to exactly duplicate results in Jobo for a given time of develoment.

Sandy

Send me the film you want exposed and a prepaid return mailer and I'll expose your film on my sensitometer.

Steve