my rb question of the week

I didn't want to disappoint you guys by not continually asking my questions.
I have a body and a back, just waiting for the lens.
Does 120 film work in a 220 back? I was wondering if there would be any focus problems..
I am also trying to figure out this grid. It is 5x5 squares, and than an xtra set of lines around the square about 3-4 millimeters out. How can you tell where the image lays on the back from where the image is in the grid?
Thanks!

Bear with me (I haven't used my RB's in quite some time now): I don't think that you could use 120 film in the 220 back, there could be problems with the pressure plate (but don't quote me on this).
If I remember correctly, the grid shows a set of red (?) lines corresponding to the back orientation to landscape format. These lines disappear when you change the back to portrait orientation and you have to use the broken lines of the grid to frame.

Here's the link to the manual if you don't already have it:
http://www.mamiya.com/assets/pdfs/6x7/RB67_Pro-S_v7.PDF

I played around with the pressure plate a bit and it pushes in pretty far, so I dont think I will have a problem with the little extra bit of paper...
I dont see any red in the grid. I have an older pro, not an S.

if I remember correctly 120 in a 220 back will work but is not recommended - from past reading i recall it may cause slight focus issues and I think it wears some part of the mechanism, which I guess would also mean you are wearing your film at the same time ...

Not to sure about the grid GG - I have noticed however that even with the normal GG on an RZ with no lines or wotnot and just the little framing 'flaps' that I still get a larger image on neg than I actually see in the finder ... Usually in the form of slight vignetting or appearance of objects I specifically put out of frame ... So my answer is that potentially neither of the frames are correct (assuming the RB is the same as the RZ in this respect)

(;

The RB and the RZ differ in the pattern they show on the ground glass, if you take the ground glass out, you will notice the red lines that come into play are actually built into the camera and not on the glass, you really have to be careful with many of the RB's around now a days, due to the fact that many of the ground glass screens have had lines added to them by end users to reflect what they are using the camera for, if you have a screen that has a 5x5, it may be you have one of the screens that have been modified, you will want to do a few shots and note where you saw the image and where it was in relation to the lines on your screen.

Normally, 120 can be used in a 220 back, but be aware, you will get more jams with the 120 over the thinner 220 film, even though the back has a large range of movement with the pressure plate, they were tuned to the particular type of film they were designed for, a good amount of them have enough wear in the springs by now that most of the time the 120 thickness will not present a problem, but as with anything else in photography, do some testing before your in the midst of an important shoot.

Dave

No problems at all with your questions here, it's always a pleasure to talk about the RB, one of my all-times favourites.

As it always happen with this question, most of the people will reply (and already replied) to watch out for problems due to thickness and other, as written in all manuals.

However, it is now 15 years that I'm regularly using 220 backs with 120 films with no problem at all, and it's no surprise since the constructive differences are almost unexistant, and if you think about it you can easily figure that the pressure a spring device operates when overloaded by the difference in thickness of a 120 compared to a 220 film is negligible in theory and zero in real world.

The only true difference is the counter: you have to remember that you have only ten frames, as the back will not leave the tail free at frame 10.

However, seen the actual product availability, I can't figure any other use of a 220 back rather then trying to fill it with a 120 film. And it even works!

I used to own an RB years ago, but I remember having a motorized back that allowed both 120 and 220. All you'd have to do is rotate the pressure plate for either type of film. This back is worth looking into because as you know every time you fire the RB you have to cock the mirror and then advance the film. With the motorized back all you have to do is cock the mirror and the back advances the film.
Ara