RB67 Help, please

[Grim Tuesday]

There isn't anything as wide in the TLR line as the 50mm in the RB line.
And with no mirror clearance issues with the TLR, it may have been easier to obtain decent flat field performance with the 55mm lens for the TLRs than it was for the 65mm lens for the RB.
And as, among all the RB lenses, the 65mm lens permits the highest amount of subject magnification through close focus without an extension tube, the designers may have included the floating element to meet the needs of users who needed "quick" close focus capability.
There actually is another lens in the RB line that has a floating element - the Macro 140mm lens. For that lens, you adjust the floating element by checking the image magnification on the scale at the side of the camera, and then transferring that setting to the floating element ring.
If I am going out with a two lens setup, I often choose to put the 65mm and the 140mm in my bag. As a result, I'm used to dealing with it.

I always wondered why they couldn't put a biogon style lens in the TLR. It would require a different design for the viewing lens and taking lens (there's still a mirror for the viewing lens, albeit it needs less clearance than the swing of an SLR) but it would be so cool and they could have relatively easily made an ultrawide for the system.

My personal theory on why there is no floating element adjuster for the TLR is because it was prohibitively difficult to design into the dual lens design because the barrel can't be larger than 58mm or whatever or else it will hit the viewing lens's barrel. It may also have to do with the target audience of the camera which may have been less concerned with corner sharpness than the RB67's target audience. What these audiences were, I am not quite sure.

 

[AgX]

I'm guessing the helicoid would have been too complicated to have it cammed - the 50 2.8f/fe hasselblad has floating elements without a separate focus ring, but it doesn't have an internal shutter

All camera lenses for 35mm format that got floating elemens have them controlled automatically by a cam.

(Exclusions are manually controlled special effect lenses (DOF;Bokeh) which are technically similar, but here the resp. elements are not called floating.)

Where would you put the cam?

The cam could be installed inside the barrel, as done with those 35mm format lenses, where the resp.cam is similar to those cams employed in zoom lenses.

 

[MattKing]

The Mamiya TLRS were extremely successful and popular as wedding and portrait cameras.
Corner sharpness isn't as important with weddings and portraits.

 

[MattKing]

The cam could be installed inside the barrel, as done with those 35mm format lenses, where the resp.cam is similar to those cams employed in zoom lenses.

But how would you connect the cam to the focusing system, which isn't even part of the lens - it is behind it.

 

[AgX]

NOW I got your points...

Slow on the uptake.. RB67, Rollei 66... rack&pinion focusing


Sorry, I forgot about that.