Want to Buy RB67 Pro SD backs

Arthurwg said:

I have a 6x8 motorized back for sale, as new. $200.00

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MCB18 said:

Look for the 220 backs, they are cheaper. Ignore the folks that say the paper messes with the focus, the DoF of 120 is large enough that it doesn’t matter anyway, unless you’re using a stupid fast lens.

Also, I can tell you from experience that it doesn’t matter, as can anyone who has run 35mm through a 120 camera. If the theory had any truth, 35mm panos in MF cameras would always be out of focus.

I think it is also worth noting that many early 220 capable cameras didn’t bother moving the pressure plate around (look at old Hasselblad backs and Rolleiflexes), and it worked out well just fine.

This is definitely more information than you asked for, but I know that someone is going to comment saying that you shouldn’t run 120 in a 220 back, film plain blah blah blah… just know that the only issue you’ll have is that the back won’t stop at 10/16 exposures, so you’ll have to remember to stop then. And it’s also 25-50% cheaper.

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MattKing said:

Way back in the day, Mamiya America maintained a Mamiya user forum.
In that forum, they had an FAQ section that dealt with using 220 backs - both for the RB67 and the 6x4.5 cameras - with 120 film.
As it is film rails that set the focus plane, not the pressure plate, there are no focus issues to worry about.
The concern relates to three issues:
1) the frame counter - there is nothing more disappointing than realizing that the last few shots you took would have been frames 13, 14, 15, 16 etc. on a 220 roll, if you hadn't forgotten that you have 120 loaded;
2) the narrower channel for the film (instead of a channel for film plus backing paper) means that there is more resistance, which leads to more wear on the back itself, including the film winding mechanism. That was identified as a real problem for high volume commercial users in particular; and (IIRC)
3) the narrower channel for the film (instead of a channel for film plus backing paper) and the lack of any protective backing paper means that if there is any debris in the way, the likelihood of the film being scratched is increased.
In my mind, #1 is by far the greatest concern.
Good luck in your search.

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MCB18 said:

Look for the 220 backs, they are cheaper. Ignore the folks that say the paper messes with the focus, the DoF of 120 is large enough that it doesn’t matter anyway, unless you’re using a stupid fast lens.

Also, I can tell you from experience that it doesn’t matter, as can anyone who has run 35mm through a 120 camera. If the theory had any truth, 35mm panos in MF cameras would always be out of focus.

I think it is also worth noting that many early 220 capable cameras didn’t bother moving the pressure plate around (look at old Hasselblad backs and Rolleiflexes), and it worked out well just fine.

This is definitely more information than you asked for, but I know that someone is going to comment saying that you shouldn’t run 120 in a 220 back, film plain blah blah blah… just know that the only issue you’ll have is that the back won’t stop at 10/16 exposures, so you’ll have to remember to stop then. And it’s also 25-50% cheaper.

Click to expand...