RB67 PRO-SD 220 645 back question

[mtjade2007]

Hope someone who uses one can help. I just picked up a RB67 Pro-SD 645 back for 220 rolls for a project from KEH. The back looks very new and everything appears to work well. However, I discovered that it will only do 30 645 frames on a 220 roll. The frame counter reached 30 and the roll also reached the end. I found the frames are spaced at nearly 15mm apart.

Is this right at all? It looks like the counter won't continue above 30 this seems to be what is designed in the back. But then why? Why frame spacing is so wide? Isn't it supposed to be 32 frames on a 220 film for 645 format? Does this mean frame spacing for this back is bad and need repair? Wasting 2 frames is not really a big deal but such a wide frame spacing looks really stupid. My Pentax 67ii has a 3-5mm frame spacing and yields 21 frames on a 220 roll. It would be funny to switch to 645 from 6x7 only to get 9 more frames out of a roll of 220.

Can anyone answer this question please. Thanks a lot.

 

[MattKing]

It is probably designed this way. My Mamiya 645s (Super and Pro) get 30 frames per 220 roll.

Matt

 

[Nick Zentena]

Number of frames depends on the camera. IIRC Pentax even changed it with various models of the Pentax 645.

Is your Pentax67 supposed to get 21 frames? I would have expected 20.

 

[mtjade2007]

I believe it is designed to be 30 frames. The frame counter will not move above 30. It is the frame spacing that makes it look odd. It is about the width of my finger. My Pentax 67ii does give 21 6x7 frames. The counter goes up to 21. The manual says it gives 21 frames on a 220 roll but only 10 on 120.

 

[PHOTOTONE]

The Mamyia 645 only gets 15 frames on 120. If the RB-67 pro-sd-220-645 back counter only goes to 30, then that is all it will give you. I think Mamyia standardized on 15 and 30 (120 and 220 respectively), whereas the Hasselblad A16 back does 16 frames on 120.

 

[mtjade2007]

Thanks, Phototone. It's really not a big deal 15/30 or 16/32. Just want to make sure the back I got is not defective. I was a bit shocked to see the frame spacing so wide though. Other than that the Mamiya back looks really well made. I do not have a RB. I am going to use the back on a Camerz monster portrait camera. It will not be for school portrait then. It will be just a studio portrait camera that produces 30 645 images per 220 roll.