120 film in 220 film back?

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narsuitus

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I have a Mamiya RB67 with two 220 film backs that I never use.

What bad things would happen if I used 120 film in the 220 film backs?
 
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I have a Mamiya RB67 with two 220 film backs that I never use.

What bad things would happen if I used 120 film in the 220 film backs?
The spacing of your frames will be off and it will be a bit harder to wind your film because 220 backs aren't designed to have film with a paper back going through it.
 

MattKing

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And most important of all, you will be really disappointed with the results from frames 11 through 20!
 

Cholentpot

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The spacing of your frames will be off and it will be a bit harder to wind your film because 220 backs aren't designed to have film with a paper back going through it.

My Bronica S2 has a switch for 120 or 220 using the same back. I don't have any 220 to test out though...
 

MattKing

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My Bronica S2 has a switch for 120 or 220 using the same back. I don't have any 220 to test out though...
Technically speaking, the Mamiya RB67 "backs" are actually just a relatively thin outer shell. All the working parts are in the insert. The insert is so important, I have never seen a "back" (the shell) sold separately from an insert, although I understand that in the past that could happen.
When you see people referring to the RB67 backs, almost invariably they are actually referring to the insert+back combination.
 
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And most important of all, you will be really disappointed with the results from frames 11 through 20!
I think with some cameras, the camera will stop counting when the film spool is empty. But I would think a photographer would be suspicious if there's no drag when he winds his film due to an empty film spool.
 

MattKing

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I think with some cameras, the camera will stop counting when the film spool is empty. But I would think a photographer would be suspicious if there's no drag when he winds his film due to an empty film spool.
The RB67 doesn't stop when the film runs out.
If you have a 120 6x7 back (actually back + 120 insert), after the 10th shot it will just advance without stopping. Your "clue" to open the back is the change in sound and feel when the backing paper comes free from the feed spool.
But if you have a 120 roll in a 220 6x7 back (actually back + 220 insert), after the tenth frame the backing paper will just be advanced one more frame's distance. That advance will continue both before and after the backing paper comes free from the spool until the frame counter reaches 20, after which it will advance freely.
The same considerations apply for the 645 backs = inserts, except of course the numbers change.
I've never seen one of the fabled 6x6 inserts and don't know if there was a 220 version.
IIRC the 6x8 inserts were/are switchable between 120 and 220.
 

Dennis-B

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The RB67 doesn't stop when the film runs out.
If you have a 120 6x7 back (actually back + 120 insert), after the 10th shot it will just advance without stopping. Your "clue" to open the back is the change in sound and feel when the backing paper comes free from the feed spool.
But if you have a 120 roll in a 220 6x7 back (actually back + 220 insert), after the tenth frame the backing paper will just be advanced one more frame's distance. That advance will continue both before and after the backing paper comes free from the spool until the frame counter reaches 20, after which it will advance freely.
The same considerations apply for the 645 backs = inserts, except of course the numbers change.
I've never seen one of the fabled 6x6 inserts and don't know if there was a 220 version.
IIRC the 6x8 inserts were/are switchable between 120 and 220.
The 6x6 backs were 120/220 interchangeable.
 

Fin

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Many many bad things will happen... An orange moron could well begin to systematically dismantle and ruin the most powerful country of the world. Meanwhile in another country that once upon a time was a bit of a big deal, years of lies and propaganda has tricked the people into thinking that, figuratively speaking, shooting both their own legs off with a shotgun is a good idea... Wait, that's already happening! Ah well, I suppose loading a roll of 120 in a 220 back is pretty much at the opposite end of the 'bad things' scale then!

In all seriousness, some people used to do this many years ago in a photography center I worked in, which had a couple of RBs. From what I can remember, the frame spacing was a bit further apart and they used to close the back and start the wind from just before the line, then shoot blank frames from 11 until the end of the roll.

I have and use a 220 back with my SQ-A and I use it in a similar way. Load the film the same and once I have shot frame 12, put the lens cap on and shoot 3 or 4 blank frames to wind the film off. The only thing I did was remove the pressure plate and bend the springs down a bit because 120 with paper is slightly thickth than 220. Despite all the rubbish I read on the internet, it works perfectly!
 

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I heard that if you use 120 film in a 220 insert, it will be slightly out of focus because the 220 insert expects no paper backing, and therefore the pressure plate is "closer" to the focus plane. I have never tried this to confirm. This might one of those "rubbish on the internet" that Fin talked about.
 
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No, there is absolutely no focusing problem, as the paper is on the BACK, not in the front. The emulsion-side of film will sit on the rails as usual, wether there is or there isn't any paper on the back.

I also don't remember ever having any spacing problem, as there is a rolling sensor which checks the actual length of the wounded film.

As already written, you just have to remember that at frame 10 the roll is over, as the 220 back will keep going as if there was still film in it.
 

GEORGE Lynn

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Realizing this is a very old thread, but owning a Mamiya RB ProS with dedicated Pro S backs in 120, 220 and a motorized 220/120 back I will give a brief description of them and their difference
The 120 back has a small diameter roller that sits just slightly offset to the left of the full film location. The tension block in the center of the base is large.
The 220 back has a much larger roller where the film goes around to the front and the new film holder sits not so much directly over it but much further to the right. The full and empty rollers are also much closer together than on the 120 back. The center tension block is also much smaller.
The 220/120 back is much like the 120 back. The rollers are the same size and spaced the same. The center tension block is the same. The difference seems to be that it has two removable pressure plates. One labeled 220 and one 120. They are the same dimensionally. To the naked eye they apear the same thickness but the 220 plate has a hole that keeps it from pressing on the counter.
So as far as using different film other than what the back is labeled I have no opinion.But it seems the dedicated 120 and 220/120 are nearly identicle except for the hole in the pressure plate.As far as using 35mm film I have no idea. I will simply hold on to my 220 in the hopes the film might make a comback.
The Mamiya RB fills nearly all my needs but I may start lookin for a nice Pentax 67. I enjoy the format and both are great fairly inexpensive cameras for what they are and there are great lenses available for a price that will not break the bank.Its a great place to start for an avid amature.
 

M Carter

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I've used a 220 back with 120 film; zero issues. When you finish frame 10, advance and shoot another frame or two - you'll hear the backing paper slide through. You don't need to shoot til frame 20; opening the back to unload the film resets the counter. It's a good way to get more backs for lower cost.
 

REAndy

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I've used a 220 back with 120 film; zero issues.
Which camera system please? I notice I can get 220 inserts/backs for Mamiya 645 for much less than 120 backs/inserts. But I don't which camera system you have had no issues with.
Thanks,
REAndy
 

M Carter

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Which camera system please? I notice I can get 220 inserts/backs for Mamiya 645 for much less than 120 backs/inserts. But I don't which camera system you have had no issues with.
Thanks,
REAndy

RB67, that's what the OP was asking about.
 

Steve Roberts

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I have the opposite problem - a few 120 cameras, none that will take 220 but a stock of 220 Plus-X in my fridge that came my way very cheaply. I'm getting around the problem by chopping the film in two and re-loading each length with 120 backing paper. Works very well.
Steve
 
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narsuitus

narsuitus

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Thanks to all for providing me with valuable information.

I ran an outdated roll of 120 film through one of my 220 backs just to feel the difference in the tension when winding the film. I did not notice any significant difference in tension. I did, however, notice that after the 10th frame, I had to advance the film to about the 13th frame to reach the end of the roll.

I have ordered fresh rolls of Ilford Delta Pro (ISO 3200) 120 film because that is the film I would like to use in my two 220 film backs for my Mamiya RB67.

I will post my results after I shoot and process a test roll.
 
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