using "floating cell" question rb67

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

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

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

David H. Bebbington said:

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).

Click to expand...

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.

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