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10-31-2018, 06:18 PM - 1 Like   #16
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From the referenced link: This is what we are arguing about -- an apparent increase in plate thickness (220 back is on the right). The 220 plate could be surface ground; the screw countersinks could be modified, if necessary. Otherwise, addressing motor life indirectly by measuring required motor torque for the two backs using 120 film in each would be difficult when they are in the camera. One would have to find a way to measure motor current to see if there was any difference, and somehow infer whether the torque generated was slightly higher or significantly higher.

It may be possible to use the 645N external cold weather battery pack, operate the camera with no internal camera batteries, and use a dummy battery in the battery pack that connected the circuit to a separate battery and current meter. I'm not motivated enough to buy a 220 back, construct a dummy battery, and try such an experiment, so I leave the idea dangling as bait for anyone more enthusiastic.

10-31-2018, 06:32 PM   #17
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While the numbers may be small as we P645, 645N and I presume P645NII users are a small group and the number having tried the conversion renders the group even smaller, there are a number of users on Photrio. I have asked anyone there who has made the conversion to state what the number of 120 films through the converted insert has been and whether any have experienced motor problems.

I have to say that the "Just don't do it " advice without some evidence of actual consequences of ignoring such advice leaves me sceptical of its veracity in practical terms.

asahijock
11-01-2018, 04:37 AM   #18
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I’ve been holding off because I’m not at home and don’t have access to my 120 and 220 backs.

If the extra thickness of the 220 pressure plate overcomes the spring movement, then the pressure plate will bottom out and could bind the motor. I rather doubt this is a problem. I suspect the reason for the thicker pressure plate had nothing to do with the motor, but was there simply there to help ensure film flatness with the 220 film.

It’s a DC motor—if it binds it will run slower. My experience has always been that 120 film causes more drag than 220 film, because of the separate backing paper.

But these cameras were designed for professional duty cycles—dozens of rolls a week. Hobbyists like most of us are unlikely to exceed that number in a year. Even if it did make the motor work slightly harder, I’d be surprised if it caused any issue.

In any case, I still have a few dozen rolls of 220 in the freezer. Getting someone to process it is the tricky bit—a 220 roll is loooong.

Rick “who needs to burn up that film” Denney
11-01-2018, 05:44 AM   #19
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QuoteOriginally posted by rdenney Quote
I’ve been holding off because I’m not at home and don’t have access to my 120 and 220 backs.

If the extra thickness of the 220 pressure plate overcomes the spring movement, then the pressure plate will bottom out and could bind the motor. I rather doubt this is a problem. I suspect the reason for the thicker pressure plate had nothing to do with the motor, but was there simply there to help ensure film flatness with the 220 film.

It’s a DC motor—if it binds it will run slower. My experience has always been that 120 film causes more drag than 220 film, because of the separate backing paper.

But these cameras were designed for professional duty cycles—dozens of rolls a week. Hobbyists like most of us are unlikely to exceed that number in a year. Even if it did make the motor work slightly harder, I’d be surprised if it caused any issue.

In any case, I still have a few dozen rolls of 220 in the freezer. Getting someone to process it is the tricky bit—a 220 roll is loooong.

Rick “who needs to burn up that film” Denney
Thanks for the useful reply Rick. As far as developing 220 film is concerned you might want to consider home developing The Jobo tanks will certainly hold 220 and the likes of Paterson and others will probably do so as well.

For the cost of the chemicals and tank, home developing will pay for itself quite quickly. OK if this is colour developing you have the issue of higher temps but a water bath of the right temp and placing the tank in it after each inversion cycle does work. Just a thought

asahijock

11-01-2018, 05:48 AM   #20
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QuoteOriginally posted by rdenney Quote
...

In any case, I still have a few dozen rolls of 220 in the freezer. Getting someone to process it is the tricky bit—a 220 roll is loooong.

Rick “who needs to burn up that film” Denney
Here is a 220-related link to where I have my 120 developed and scanned.
220 Film Processing ? Old School Photo Lab
11-01-2018, 06:40 AM   #21
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I’m pretty sure my local lab will do 220. But I hate doing it myself—it’s just too long and difficult to keep it from dangling somewhere it shouldn’t.

I still have 220 Nikor reels, but I don’t do much processing any more—time is more precious than the money to pay the lab. The exception is black and white, but I don’t do much of that any more.

Rick “who uses roll film mostly in the P67 and with view cameras” Denney
11-10-2018, 09:50 AM   #22
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Further to my post#20, my question on Photrio produced no replies at all so all interested parties will have to look at the users' experience here who have made the conversion and make a decision on that.

asahijock
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