Mamiya RB67 Pro S Extension Tube

[ezippy]

I just purchased a Mamiya RB67 Pro S with a 65mm C lens. I would like to use an extension tube with it and, from reading the user manual, only the No. 1 tube may be used with that lens. Additionally, from reading other forums, it seems that the Pro SD tubes will not fit the Pro S camera mount. My question is in looking for a No.1 extension tube that will fit my camera, is there an easy way to tell the difference between an S and an SD tube just from looking at images on ebay?

Seems as though ebay sellers might not necessarily understand, or appreciate the distinction in their descriptions. The 2 sets of images appear to be the same, but are described differently. Any suggestions would be appreciated.

 

[Alan Edward Klein]

Here's the compatibility chart.
file:///C:/Users/Alan3/Documents/Alan%20and%20Janet's%20Files/Receipts%20for%20Purchases/Mamiya%20RB67/RB67%20Chart%20of%20what%20fits%20what%20model%20lens%20viewfinders%20etc.html

 

[Alan Edward Klein]

Looks like you want the RB67 No1 ext tube.

 

[xkaes]

It's interesting how that table specifies "RB C" lenses. I can't think of any reason why, non-"C", "RB" lenses should not be included. As far as I know the only difference with the "C" lenses is that they are multi-coated.

 

[ezippy]

Looks like you want the RB67 No1 ext tube.

Thank you for the chart — I think I found the answer to my question — it seems that the sd tubes have the sd moniker on the side of the tube.

 

[MattKing]

While the mount itself doesn't change between the Pro, the Pro-S and the Pro-SD, the Pro-SD has a larger "throat" area than the Pro-S and the Pro. That was necessary to accommodate a couple of the larger K/KL lenses: the RB 75mm L PC Shift Lens and the RB 500mm APO/L Lens, which are too big to fit on the earlier cameras.
The SD extension tubes are probably larger in diameter, and fill that larger throat.
The earlier tubes most likely work on the SD as well, but the accessory lens mounting ring that helps increase the stability of the mount is recommended.

 

[Mamiya_Repair]

It's interesting how that table specifies "RB C" lenses. I can't think of any reason why, non-"C", "RB" lenses should not be included. As far as I know the only difference with the "C" lenses is that they are multi-coated.

There is a good reason that the non-C lenses should not be used with extension tubes: The earlier lenses (non-C) used a different shutter (a Seiko 653) that required more energy to cock the mechanism. When used with an extension tube, the camera is under even more pressure to cock the shutter and this can lead to camera failure. Same reason that these early lenses are not torque compatible with the RZ67 when using RB lenses on the RZ and can lead to early failure of the already strained RZ67 cocking mechanism.

 

[MattKing]

There is a good reason that the non-C lenses should not be used with extension tubes: The earlier lenses (non-C) used a different shutter (a Seiko 653) that required more energy to cock the mechanism. When used with an extension tube, the camera is under even more pressure to cock the shutter and this can lead to camera failure. Same reason that these early lenses are not torque compatible with the RZ67 when using RB lenses on the RZ and can lead to early failure of the already strained RZ67 cocking mechanism.

@Mamiya_Repair :
This is very useful information - so useful that I would ask that you start a thread on its own for it!

 

[xkaes]

And all this time I thought the only difference was the coating -- much like the Minolta Rokkor vs Rokkor-X lenses. Thanks for the education.

 

[Mamiya_Repair]

And all this time I thought the only difference was the coating -- much like the Minolta Rokkor vs Rokkor-X lenses. Thanks for the education.

While the coating was one of the differences, the new shutter style on the C lenses provided for an external sync socket that could be replaced when worn. The earlier lenses had the sync socket as part of the shutter housing and it could not be replaced without replacing the entire shutter. And, the 65mm C and 90mm C lenses had new formulations that took advantage of the new 30mm shutter opening.

 

[MattKing]

@Mamiya_Repair
Hint:
A thread titled "Differences in the old, pre-C Mamiya RB lenses" would be great.
Or just ask if you would like me to create that for you from your existing posts.

 

[Mamiya_Repair]

Sure, do create a thread if you think it would be useful

 

[MattKing]

Sure, do create a thread if you think it would be useful

Done - you can find it here: https://www.photrio.com/forum/threa...d-pre-c-mamiya-rb-lenses.206750/#post-2794621

 

[Alan Edward Klein]

It's interesting how that table specifies "RB C" lenses. I can't think of any reason why, non-"C", "RB" lenses should not be included. As far as I know the only difference with the "C" lenses is that they are multi-coated.

The chart mentions that there are pre-1978 lenses. Could those be different than the later RB pre-C lenses?

 

[MattKing]

I believe that 1978 was when the C lenses came in, but @Mamiya_Repair would likely know more.

 

[Mamiya_Repair]

I believe that 1978 was when the C lenses came in, but @Mamiya_Repair would likely know more.

Mamiya multicoated most of the RB67 lenses by 1974 production with some exceptions: the 250mm, which was not multicoated until 1979; the 500mm which was multicoated starting in 1980.

 

[ezippy]

This was a helpful discussion — thank you all for your input.