Dent on Mamiya Rb67 50mm lens normal?

[Alex Foo]

When you explained to me, I thought it to be plausible, maybe the wide angle lens needs its back element deeper inside thus the dent there to avoid the mirror hitting it.

I went over to Mamiya site to look at the lens pic, it's pretty small, but if you see close enough, you can actually see the dent there, lol.

[ContaxRTSFundus]

As everyone has said, the 'dent' is a design feature to ensure internal clearance of the rear element assembly.

The way the lenses are secured to the camera body guarantees that the lens will sit correctly on the RB or RZ bodies and there is no risk of the mirror accidentally catching the rear assembly of the lens. Of course, if you use this Sekor C 50mm on the RZ67, you have to move the bellows forward by 7mm so even less of a problem. By comparison, if you look at the mount of the RZ's Sekor Z 50mm, it's totally different and the rear element assembly is noticeably more shallow.

[Alex Foo]

Thanks for further explaining on it. Now me, or any future owners if any, will know that the dent is intentional and purposeful.

Btw guys, there is a black ring adapter thingy that came along the lens box. It seemed as if it would wrap around the back lens assembly. I couldn't find it's usage in the 'manual'. My guess is that it's for usage on other bodies e.g. RB67, proS or even RB67. Any ideas on it?

[MattKing]

Thanks for further explaining on it. Now me, or any future owners if any, will know that the dent is intentional and purposeful.

Btw guys, there is a black ring adapter thingy that came along the lens box. It seemed as if it would wrap around the back lens assembly. I couldn't find it's usage in the 'manual'. My guess is that it's for usage on other bodies e.g. RB67, proS or even RB67. Any ideas on it?

It's probably the adapter that fills the extra space in the lens mount throat on an RZ67 or RB67 Pro SII/D.

[ContaxRTSFundus]

Thanks for further explaining on it. Now me, or any future owners if any, will know that the dent is intentional and purposeful.

Btw guys, there is a black ring adapter thingy that came along the lens box. It seemed as if it would wrap around the back lens assembly. I couldn't find it's usage in the 'manual'. My guess is that it's for usage on other bodies e.g. RB67, proS or even RB67. Any ideas on it?

It is for exclusive use with the RB67 ProSD and as was said, it compensates for the slightly wider mount on that model.

[Alex Foo]

Thanks guys, I went back and checked the proSD indeed has a wider mount, and plugging the ring in will enable to lens to mount on the camera snugly. ( I din notice it and mounted the lens directly on the camera without the ring, I'm sure it wouldn't hurt the lens or the camera this way, just mayb it will be more prone to vibration or very minor misalignment.)

Oh btw, mamiya replied me in a very straight-to-the point kinda way: That is part of the design.
That's it, the whole email, lol.