Processing time with Jobo Machine vs Tubes???

[bobbysandstrom]

Does anyone one know from experience what you might expect with regards to time differences using either a jobo w/ expert drum or say, btzs tubes? One might assume times would remain the same. Is this correct?

thank you

 

[LAMitchell]

Not sure what a btzs tube is but if you are talking similar to a Paterson 'agitate every 30 seconds' tank then its 25 - 30 percent less time due to constant agitation. i.e. 3:15 for colour film becomes 2:25 in the Jobo.

 

[antielectrons]

Have a look here:

http://unblinkingeye.com/Articles/Rotary/rotary.html

 

[grahamp]

The Jobo times will be the same or shorter, but you really have to make your own comparative tests. There are other factors to consider over and above the continuous agitation - fill and drain time, pre-rinse or not, developer choice, and temperature stability. If you are one of the 'stand development' crowd, the time will be shorter

I find I have a little more contrast using my standard time with FG-7 1+15 in the Jobo versus a small inversion tank - maybe N + 0.5 or about 110% of the optimum time for me.

Start with your regular time and a pre-rinse as recommended by Jobo (monochrome - I'll leave the C41/E6 for others), and see what happens. There seem to be two areas of contention - continuous = more contrast, and pre-rinse is/is not necessary. The right method is the one that works for you!

 

[pentaxuser]

Not sure what a btzs tube is but if you are talking similar to a Paterson 'agitate every 30 seconds' tank then its 25 - 30 percent less time due to constant agitation. i.e. 3:15 for colour film becomes 2:25 in the Jobo.

I have only ever processed colour neg film in a constant rotary processor, namely a Job and always used 3:15. I thought colour is always 3:15 at constant rotation be it hand or Jobo machine.
I can't say that 2:25 wouldn't be OK as I have never tried but this is nearly a minute less than my rotary time of 3:15 I'd be surprised if this is adequate. if it was then my 3:15 should be considerably over done at nearly 50% more but it isn't.

We need to clear this one up quickly

Pentaxuser

 

[bobbysandstrom]

Being as tube processing IS continuous agitation, I'm assuming the times would be the same as with using the Jobo. (considering fill and dump time of course) If anyone can confirm this that would be great. Otherwise I'm going to find out sooner than later as I'm about to go try it. I was hoping to save myself a couple of harder to print negs. :-}

thanks

 

[Rolfe Tessem]

Being as tube processing IS continuous agitation, I'm assuming the times would be the same as with using the Jobo. (considering fill and dump time of course) If anyone can confirm this that would be great. Otherwise I'm going to find out sooner than later as I'm about to go try it. I was hoping to save myself a couple of harder to print negs. :-}

thanks

I use a Jobo ATL-1000 as well as BTZS tubes for 8x10, but I've never done the same process in both so I can't exactly answer your question. However, I can't think of any reason why the times shouldn't be the same, or very, very close.

Something that bears mentioning is that Jobo recommends a 5 minute pre-wash for everything. The reason isn't that you need the pre-wash -- the reason is that it brings the times pretty much exactly into conformance with the published times for intermittent inversion processing. The continuous agitation speeds things up, but the 5 minute pre-wash slows things down by an equivalent amount. Jobo did this simply so that they didn't have to experiment and publish new times for the hundreds of film/developer combinations. You can certainly process without a pre-wash if you do the experimental work to figure out the reduced time. Kodak did this work for Xtol, since it came out after rotary processors were in wide use and those times are on the Kodak website.

 

[LAMitchell]

I have only ever processed colour neg film in a constant rotary processor, namely a Job and always used 3:15. I thought colour is always 3:15 at constant rotation be it hand or Jobo machine.
I can't say that 2:25 wouldn't be OK as I have never tried but this is nearly a minute less than my rotary time of 3:15 I'd be surprised if this is adequate. if it was then my 3:15 should be considerably over done at nearly 50% more but it isn't.

We need to clear this one up quickly

Pentaxuser

Thats what it said on the packet (Speedibrew Celer-41), I prewashed to get all to 38c and developed for 2:25, the BLIX stays the same. The negs are good, it works for me. If you find yours works then don't change it, there's something different in our processes and it works!

 

[Jim Noel]

I have found development times in the Expert drums to be 10-15% shorter than the same film/developer combinations in smaller Jobo drums. Apparently the larger diameter, and the arangement of the interior tubes allow for even greater agitation than a smaller tube. I run both the Expert and the 2500 drums at the same speed so that is not a part og the equation.

 

[JHannon]

Being as tube processing IS continuous agitation, I'm assuming the times would be the same as with using the Jobo. (considering fill and dump time of course) If anyone can confirm this that would be great. Otherwise I'm going to find out sooner than later as I'm about to go try it. I was hoping to save myself a couple of harder to print negs. :-}

thanks

Might be an interesting experiment... expose two sheets of film to a stepwedge for the same exposure. Then process one in a tube and the other in the Jobo (same developer, temp and time). The film steps could then be read and plotted for comparison. Just a crazy idea, ignore if you wish...

 

[pentaxuser]

Thats what it said on the packet (Speedibrew Celer-41), I prewashed to get all to 38c and developed for 2:25, the BLIX stays the same. The negs are good, it works for me. If you find yours works then don't change it, there's something different in our processes and it works!

Thanks. I've learnt something new here. I was always under the impression that colour neg processing chems were all more or less the same. I've used Tetenal, Nova and Jessops and read a couple of books on it and all were 3:15.

I had another look at my books which list about 5 different brand chems and all are 3:15. However the books are all about 10 years old now. My thoughts are that maybe the older processes haven't changed but Speedibrew which may be newer to the market place had taken advantage of a development (excuse pun) in the development process and come up with a faster process.At 2:25 Speedibrew is aptly named

I wonder what it is about Speedibrew that makes it much quicker?

If PE or other members knowledgeable about colour neg chemistry are following this thread, maybe they could comment.

Pentaxuser

 

[bobbysandstrom]

J:
If I had 8x10 tubes I'd do that. Just was trying to avoid blowing 25 sheets of 8x10 film to do the BTZS tests being as I have Phil's numbers for the tubes. If the numbers translated I'd save myself a lot of time and energy.

Thanks everyone for your responses.

Bob

 

[LAMitchell]

Thanks. I've learnt something new here. I was always under the impression that colour neg processing chems were all more or less the same.
Pentaxuser

Pentax, they are all the same, something about the C41 process. Although Speedi do do another chem called Speedi-41 for big time pushing of two stops or more. That has some wierd bits like you only need to do the first step in the dark, then you can watch the rest as it develops.
If I was developing in a tub though where agitation is every thirty seconds then I would dev for 3:15. But as the Jobo is constant agitation it reduces the time required for developing. Temperature also makes a big difference in time.

 

[sanking]

Bobby,

There should be little difference in time. However, bear in mind that more vigorous agitation will reduce time of development, less agitation will add time. Jobo rotation is usually fixed by the user at some specific RPM, whereas the RPM of BTZS tubes can be varied greatly by how fast you spin the tubes. In fact, you could do this very gently, using only 4-5 RPM, or very fast, up to 50-60 RPM. But if you spin the tubes at about the same rate of the Jobo in terms of RPM results should be very similar.

Sandy

Does anyone one know from experience what you might expect with regards to time differences using either a jobo w/ expert drum or say, btzs tubes? One might assume times would remain the same. Is this correct?

thank you