Can you swap inserts on a RB67?

[Dani]

First post here, really new to medium format. I just got today a beautiful RB Pro SD that went through major surgery by Paul Ron, excellent work!

I got two backs for it a 4x5 120 and a 220. My questions is, could I just swap the inserts and use the 4x5 120 in the "case" of the 220? the cases look the same except for the cut out.
Thanks!

 

[480sparky]

They're not interchangeable. Because of the difference in thickness between 120 film (which will have paper backing) and 220 film (which won't), the plane of focus will vary between them.

 

[Dani]

Thank you, I see now. I guess I'll start looking for a 120 back then.

 

[Athiril]

The plane of focus should be the same for both actually. The emulsion side of the film needs to be at the same distance, so if it fits inside the enclosure it should be fine, all the works of the back, including the pressure plate and behind the film thickness is regulated by the insert and nothing to do with the case, the case just seals it from light.

 

[Sirius Glass]

Welcome to APUG

Enjoy your new camera.

 

[Dani]

That's what I thought at first, the 4x5 120 does fit inside the enclosure of the 220. That's when I thought I'd be able to interchange the enclosures.

 

[480sparky]

The plane of focus should be the same for both actually. The emulsion side of the film needs to be at the same distance, so if it fits inside the enclosure it should be fine, all the works of the back, including the pressure plate and behind the film thickness is regulated by the insert and nothing to do with the case, the case just seals it from light.

But a 220 insert expects film without a paper packing, so the pressure plate will be held closer to the plane of focus. If you try to run 120 film through it, you might damage either the film or paper or both.

 

[Xmas]

You are just as likely to win the lottery if you don't have a ticket.

 

[rbultman]

I guess it depends on the specific back and insert. The insert has the winding mechanism, pressure plate, and says 120 or 220 on it. The shell holds the insert and just has rollers for the film. I have 120 and 220 Pro SD backs but I can't check them now. I'm not sure if the 4x5 120 back would have a compatible insert. Can you post pictures?

 

[Dani]

I sure can post some pictures. The insert is exactly the same as the 220. I'll go take some pictures.

 

[MattKing]

What is a "4x5 120 back"?

Do you mean a 6x7 120 back?

You can swap the inserts and outer shells, as long as you stay within the same "generation".

The "Pro" inserts with the "Pro" outer shells.

The "Pro-S" inserts with the "Pro-S" outer shells.

and

The "Pro-SD" inserts with the "Pro-SD" outer shells.

 

[Sirius Glass]

120 inserts will produce different spacing than the 220 inserts since the 120 inserts expect a paper backing and the 220 inserts do not. Thus at any point the rolled film diameters are different and the spacing will be too close or too far apart when the inserts are switched. Do you want to waste film or have the negatives overlap. The choice is yours.

 

[Dani]

Yes, my bad! I meant 6x4.5 120 back

 

[Dani]

Here are the backs
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[MattKing]

Yes, my bad! I meant 6x4.5 120 back

So in essence, you have a 6x4.5 insert for 120 film, a 6x7 insert for 220 film, and two compatible exterior shells.

The inserts determine what film and format you end up with, while the outer shells just help to keep it dark.

A long time ago Mamiya used to maintain a user forum which included a FAQ section where the question of using 120 film in 220 backs was canvassed. The advice was that it was usable, but not recommended, because it was liable to cause excess wear on the 220 insert, and because, of course, the counter in a 120 insert will tell you that there are more than ten shots available.

 

[Dani]

Thanks! I understand. I was just trying to avoid using the 220 back with 120 film and thought I could just swap them, saving some money in the end.

 

[Xmas]

So in essence, you have a 6x4.5 insert for 120 film, a 6x7 insert for 220 film, and two compatible exterior shells.

The inserts determine what film and format you end up with, while the outer shells just help to keep it dark.

A long time ago Mamiya used to maintain a user forum which included a FAQ section where the question of using 120 film in 220 backs was canvassed. The advice was that it was usable, but not recommended, because it was liable to cause excess wear on the 220 insert, and because, of course, the counter in a 120 insert will tell you that there are more than ten shots available.

You cannot meaningfully use the small format back in the 220 holder you will get overlapping frames.
You can use 120 film in a 220 back and holder you need to check the loader marks to get 10 frames on the film and you need to stop after ten.
It matters not that the back wears out.

 

[MattKing]

Actually......

All of the meaningful mechanism is in the insert part. Essentially, it is the back - the outer shell is just that - a shell.

If you look at the shells themselves, you will note that there are no indications on them as to what format they are to be used for, or whether they are for 120 or 220. That is because they can be used with any insert of the same generation, and the nature of the resulting "back" will be determined solely by the insert itself.

I have RB67 Pro generation 6x4.5 inserts for 120. I don't know whether Mamiya made any RB67 6x4.5 inserts for 220. Whether or not they did, the outer shells paired with them to make a complete back would have no influence on the film used in them, or the format of the resulting negatives or transparencies.

EDIT: After looking at the various manuals I have copies of, it looks to me like Mamiya at least intended to make a 6x4.5 insert for 220 film to be used with the RB67 Pro-SD. No such insert was made for the Pro or Pro-S.

 

[Xmas]

Actually......

All of the meaningful mechanism is in the insert part. Essentially, it is the back - the outer shell is just that - a shell.

If you look at the shells themselves, you will note that there are no indications on them as to what format they are to be used for, or whether they are for 120 or 220. That is because they can be used with any insert of the same generation, and the nature of the resulting "back" will be determined solely by the insert itself.

I have RB67 Pro generation 6x4.5 inserts for 120. I don't know whether Mamiya made any RB67 6x4.5 inserts for 220. Whether or not they did, the outer shells paired with them to make a complete back would have no influence on the film used in them, or the format of the resulting negatives or transparencies.

The shell does have a frame memo in the photo?
The back has a counter for 10, 16, or 20, trying to get 16 6x7 frames on 120 film is a good trick?

 

[roby02091987]

You can not interchange any of these inserts and/or shells, and the reason is pretty obvious (and I don't know why others keep telling otherwise).

First: look at the shells. One side is quite the same, the other is not: one has a hole for 6x4,5, the other for 6x7. They are not "just a shell".
Second: inserts are calibrated for a certain film thickness (for 120 o 220 format) AND frame size. A 6x7 back advances the film for a little more than 7cm (frame size + a little frame spacing), a 6x4.5 back avdances for about 5 cm, more or less.
That said, using a 6x7 shell on a 6x4.5 insert will get you 16 6x7 frames all overlapped. Vice versa, a 6x4.5 shell on a 6x7 insert, will give you 10 6x4.5 negative with an enormous spacing between frames.

I see only two logical answers to your question:
1) simply use the 220 6x7 back (6x7 insert with 6x7 shell) with 120 film, keeping in mind to change roll after 10 exposures.
2) (better option) try to sell the 220 back and buy a 120 back for 6x7. If your budget is low, you could also sell both backs and buy a new 6x7 120 back.

A 220 back is quite useless, since 220 rolls are a quite expensive rarity (and imho they are going to disappear almost completely). 6x4.5 ... why would you even use a 6x4.5 back on a big, fat 6x7 camera?

 

[Xmas]

A 220 back is quite useless, since 220 rolls are a quite expensive rarity (and imho they are going to disappear almost completely). 6x4.5 ... why would you even use a 6x4.5 back on a big, fat 6x7 camera?

All your post I've not quoted is good and better than my abstract attempts but

220 colour is still avilable?

One of our number has a 6 cm splitter for 70mm cine ... ECN 2 save backing paper

Just bought half a dozen Trix320 2.50 220 GBP each exp 08.

If you want 16 pano shots with 55mm saves film costs.

 

[roby02091987]

All your post I've not quoted is good and better than my abstract attempts but

220 colour is still avilable?

Well, I've seen b&h has some 220 portra 160 rolls... and that is the only 220 film they have.
Also macodirect.de has some 220 film, but only portra 160 and 400.

I'm unable to find any other type of 220 film still produced and sold today.

Just bought half a dozen Trix320 2.50 220 GBP each exp 08.

If you want 16 pano shots with 55mm saves film costs.

But, that is 7-years expired film... i do not consider it, even for test shooting, because results could be way unpredictable.
As of today, if one wants fresh 220 film, there are only two choices: portra 160 or portra 400. A way too limited choice in my opinion.

 

[rbultman]

What is a "4x5 120 back"?

Do you mean a 6x7 120 back?

You can swap the inserts and outer shells, as long as you stay within the same "generation".

The "Pro" inserts with the "Pro" outer shells.

The "Pro-S" inserts with the "Pro-S" outer shells.

and

The "Pro-SD" inserts with the "Pro-SD" outer shells.

This is correct. You can swap them within the generation, and as long as the mask size is the same. For example, you can swap inserts between 120 6x7 and 220 6x7. Doing so probably doesn't get you much unless one of your shells is bad for some reason.

You cannot meaningfully use the small format back in the 220 holder you will get overlapping frames.

This is partially correct. If you use the 645 insert in the shell with the 6x7 mask, the frames will overlap since the mask in the shell is bigger than the advance mechanism in the 645 insert. Conversely, if you use the 6x7 insert in the 645 shell, nothing bad happens, you just only get 10 shots per roll instead of 15 for 120, or 20 instead of 30 for 220, and there is a lot of spacing between frames.

All of the meaningful mechanism is in the insert part. Essentially, it is the back - the outer shell is just that - a shell.

If you look at the shells themselves, you will note that there are no indications on them as to what format they are to be used for, or whether they are for 120 or 220.

The shell does have a frame memo in the photo?
The back has a counter for 10, 16, or 20, trying to get 16 6x7 frames on 120 film is a good trick?

As Matt King stated, the counter is in the insert, not the shell. it is on the insert next to the advance lever. Matt just forgot about the mask being part of the shell.

 

[rbultman]

A 220 back is quite useless, since 220 rolls are a quite expensive rarity (and imho they are going to disappear almost completely). 6x4.5 ... why would you even use a 6x4.5 back on a big, fat 6x7 camera?

A 220 back is useful as is a 645 if your goal is to change rolls less often, or you like the aspect ratio of 645 over 6x7. As you suggest, you are "wasting" the camera when using the 645 back on the 6x7 camera due to carrying around the extra glass and body size needed to shoot 6x7. A dedicated 645 camera, like the Mamiya 645 Pro, is much lighter, if that matters to you. You might want to still use the RB for other reasons with a 645 back, for example if the wider selection of leaf shutter lenses are important to you, you already have an RB and don't want to buy another system just to have it be tailored to 645, or you want an all-mechanical camera which does not depend on batteries for operation.

I have used 220 film in my GA645 on vacation in order to reduce roll changes despite that fact that 220 film is more than twice as expensive as 120. For me in that circumstance, the extra expense per frame of 220 was worth this convenience. Commercial development from at least one development house is only 2X as expensive so the cost per frame for developing is a wash between 120 and 220.

As of today, if one wants fresh 220 film, there are only two choices: portra 160 or portra 400.

Correct. I have bought Portra in both 160 and 400 in 220 from B&H. It is the only film available in 220 as far as I know. If B&W were available in 220 I would use it in 6x9 cameras. I find reloading the Fuji GW690II while doing night photography a little fiddly.

 

[Xmas]

As Matt King stated, the counter is in the insert, not the shell. it is on the insert next to the advance lever. Matt just forgot about the mask being part of the shell.

There is however a warning on the 645 shell as well as a warning on the 645 insert as the counter won't help to avoid an accident when you get to 11 you have wasted 10 clicks... You can see these on the photo.

Some people work with prepared inserts rather than swapping backs eg if the other backs have different film types I have four backs and two spare inserts... 120/220 capable motor drive.

If you forget to remove replace the box top during a shoot you have a problem.