How to use K/L floating lens for RB67

peterB1966 said:

A corollary question, re “read the distance and set the ring”… I presume you are talking of reading the distance of the graph on the side? On the 90mm the graph flatlines after a meter or two… I presume after that you guesstimate?

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I don't have a RZ67 to look at, and the only illustration I have available lacks the colour necessary to pick out which colour curve relates to the 90mm, but I'm not clear that any of the curves "flatline".
Are you sure you are using the Distance Scale in the manner intended?
FWIW, I used to use my scale focusing experience when I did this with my RB lenses with floating elements, rather than relying on the Distance Scale.

MattKing said:

I don't have a RZ67 to look at, and the only illustration I have available lacks the colour necessary to pick out which colour curve relates to the 90mm, but I'm not clear that any of the curves "flatline".
Are you sure you are using the Distance Scale in the manner intended?
FWIW, I used to use my scale focusing experience when I did this with my RB lenses with floating elements, rather than relying on the Distance Scale.

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No, I am not, which is why I asked the question - see the image below, the green line for 90mm meets the distance ruler at .9m and thereafter you have to guess - but I realise now that that is for any distance less than .9 meters, not greater. Which explains my confusion, and answers my question!

P.S. I am still talking of the RB67, not RZ67

Lenses with the "floating system" are intended to be used on the RB67 pro-SW (W for "waterproof").

When fitted with a lens with "floating system", the lens will float, preventing the camera from sinking down and being useful only as a boat anchor.

peterB1966 said:

A corollary question, re “read the distance and set the ring”… I presume you are talking of reading the distance of the graph on the side? On the 90mm the graph flatlines after a meter or two… I presume after that you guesstimate?

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Just focus, then read the distance ( estimating it is also ok ) and set said distance on the floating ring. If you're very meticulous you can even double check if the focus is correct afterwards.

You don't need to be precise with the floating system, just an approximate will do. Consider that a regular (non-floating) wideangle is like having a floating wideangle but with the "floating ring" set at infinity distance all the times. Many such "non-floating" wideangles exist which are very good, to put an example the 35/2.0 Nikkor AI.

The floating system will compensate for certain abberrations when using the lens at close distances.

peterB1966 said:

View attachment 284113

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This label/scale was invented by Mamiya marketing deparment to lure you into collecting all the lenses for the system. You know, every time you see this scale, your brain will think "i haven't bought the ____ lens yet... hmmm..."