using "floating cell" question rb67

[Erik L]

Hi folks, Just picked up a new toy, rb67 s with a 50mm sekor c and a 127mm sekor c. The lenses are a mystery to me as I'm used to simple large format lenses which are idiot proof I have no documentation and mamiya's site doesn't offer any help either that I could find. Can someone please give me a simple explanation in using the "floating cell" ring if that is the correct words to use. Thanks so much
regards
Erik

 

[Travis Nunn]

Hi Erik, pm me your email address and I'll send you the Pro-S manual which answers your question.

 

[David H. Bebbington]

The idea is that, with a "normal" floating-element lens, the floating movement is created by focusing the helical mount (so that you in fact don't notice it). With Mamiya RB/RZ, focusing is by bellows and rack-and-pinion, so Mamiya has made provision for you to adjust the floating element separately by turning a ring to match the distance you have focused on. In fact, of the 4 RB lenses I have, the 50 C and 90 KL have floating elements, the 180 and 360 KL simply have a ring in the same place which is a depth-of-field indicator (no floating element). You will only see a gain in sharpness through floating element adjustment if you photograph something that shows up field flatness and use a large aperture to do this. It would seem that Mamiya thinks you need a floating-element design only with retrofocus lenses (which is why I have never seen a view camera lens wth a floating element).

Regards,

David

 

[Steve Smith]

In fact, of the 4 RB lenses I have, the 50 C and 90 KL have floating elements, the 180 and 360 KL simply have a ring in the same place which is a depth-of-field indicator (no floating element).

Thanks for posting this. I too have the 50 C and 90 KL (and 180C) but I thought that only the 50 had the floating element. I will pay more attention to the 90 now!


Steve.

 

[Erik L]

Thanks guys! I'm new to this format and wasn't quite sure about that feature
thanks again!
Erik

 

[David Brown]

http://www.mamiya.com/assets/pdfs/6x7/RB67_Pro-S_v7.pdf