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#1
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Looking for a film processor
Greetings all and a very happy new year...
My question is about film processors. I need to upgrade my darkroom. This cold spell has pushed me into considering a film processor. To maintain constant temperatures @ 20 degrees is a nightmare. Plus I want to try my hand at E6 processing, where the temperature is a little more critical. I shoot 5x4 and 120. Is there anyone out there can help with some sound advice. Everytime I look online the name Jobo keeps springing up. I know nothing about these machines and would appreciate a kick in the right direction. John |
#2
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Never used a film processor, but Jobo are a very good make, and Nova also make at least 1 film processor, check out their website at nova.co.uk, Richard
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#3
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Your basic requirement would seem to be a tempering bath with an accurate thermostat. Nova, and Jobo have made these, and may still do so. The Nova unit is just a heated bath with an accurate thermostat, whilst the Jobo unit will also take care of the agitation aspect. Other than offering that simplistic description I cannot help further, but I'm sure others here will.
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#4
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If it was solely B&W then there are a number of cheap solutions such as load the film in the very cold darkroom and then process elsewhere such as the kitchen or heat water in a shallow basin to say 20/21C and use as a makeshift water bath in the darkroom. You could try a dry run with water instead of dev and a water bath to check what temp it needs to be to hold the tank at the right temp for your known dev time.
C41 or E6 is a different matter and as Dave says I think you'd need a thermostatically heated unit or a Jobo. Nova or Secondhand Darkroom Supplies will probably have used units and occasionally one will come up on e-bay. Mike |
#5
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I have a basic Jobo (a CPE-2) which works quite well. They were designed originally for colour processing I think and should certainly suit your needs for C41 and E6. However, it would be worth running some tests to ensure the liquid inside the tank is the correct temperature, because if there's a big difference between ambient and process temperature you may need to set the water bath to a higher temperature. I picked my Jobo up a few years ago for £50, complete with several print drums.
For b+w a water bath is the simplest route. Either use a fishtank heater, or heated tray, or keep a jug of hot water handy to top it up to keep the temperature correct. Our ProcessMaster II attacks the issue from the opposite direction, sensing the liquid temperature and adjusting the process time to suit. Absolute accuracy of temperature for b+w is not critical, but you need to adjust the development time if it differs from 20C and the ProcessMaster II does that for you automatically. |
#6
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I have an old Jobo CPE2 which I only use for B&W and it does a fine job. But, as Richard has said, I have noticed a difference in water temperature between the top and each end of the unit.
I have read that some people use an aquarium water circulator to keep the temperature even throughout the tank. If it helps the Jobo manual is online. |
#7
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Did 15 rolls of Double-X today and took advantage to illustrate my point about the temperature variations. Not a problem for B&W but needs monitoring for colour.
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#8
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Mperson, good illustration of temps around the Jobo processor, when aiming for 20. I haven't yet tried B&W on a Jobo but found that the water bath at either end where the 2 thermometers are clipped was the same temp within about 0.2/0.3 degrees C and that seemed to be good enough for C41.
I'd always put a thermometer into the dev beaker to ensure it was at the right temp. I must admit that I have never bothered to test the dev temp after 3 mins 15 secs to see if the correct temp was maintained but if the film is pre-wet for say 5 mins rotation with the correct temp water then the correct temp dev added for 3 mins 15 secs, I suspect that the drop, if any is very small. Certainly my colour neg film used to look OK and the prints I obtained seemed fine. If you look on APUG where there are many colour neg fans then you'll find that most users suggest that a slight variation in temp isn't critical. Yes there will be those who tend to predict disaster if there is any deviation, at all, from the correct temp but this may reflect their own psyche rather than the real situation. Some of the same people will also tell you that all RA4 printing has to be done in total darkness as well despite clear evidence of there being RA4 safelights Conventional wisdom seems to suggest that the tolerances are very small indeed( I think that + or - about 0.2 degrees C is often quoted) but in reality the margin is larger than that. Mike |
#9
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For sheer accuracy of temperature, Nova is hard to beat. For convenience, Jobo. Life is always a compromise...
Cheers, R. |
#10
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I would have thought that common sense should tell you that any system that works via convection from the heating element will be warmest adjacent to the heating element getting cooler the further you are from heating element. This is modified by the convection currents within the tank which may give unpredictable temps at different areas within the bath.
Common sense should also tell you that the way to resolve the uneven temp is to keep the bath well stirred which will even out the temp very quickly. Running the motor with a tank in place is likely to do that fairly efficiently. An E6 specialist I have conversed with tells me that even the developer bath is not critical but as close to 38deg as possible is best. The other baths can be significantly off from 38deg and you won't experience problems. i.e. There is a lot of myth about how critical this stuff is. Colour processing is far more fogiving than people think. But as always, consistency of procedures and temps from one run to the next is likely to give consistent results from one run to the next.
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