Sunday, September 14, 2008

Modifying a Mamiya Tele-Converter 1.4xRZ to fit an RB67

By J Michael Sullivan

We RB67 owners are second-class citizens when it comes to comparing our beloved beast of a camera to its electronic brother the RZ67. Perhaps one of the most obvious examples is that Mamiya never offered a 1.4x teleconverter for the RB67 — something in my opinion is a glaring omission. Fortunately, the RZ67 and RB67 share the same mounting ring. I wondered: could I modify the RZ67 teleconverter to work with an RB67? I figured I'd give it a try.

First thing was to procure a Mamiya 1.4x tele-converter. Lucky for me there was one in exc+ condition on eBay that with some counter-bidding I was able to purchase for only $142. Upon inspecting it, it was clear that the primary problem with mounting it to the RB67 was two obnoxious studs that got in the way of the tele-converter from being mounted properly on the otherwise identical RB67 lens mount. Amazingly, I could find NOTHING on the internet regarding whether these two studs had any purpose other than preventing RZ lenses from mounting on RB bodies. I decided that they must serve no other purpose and herein document the steps I took to modify the 1.4x tele-converter for use with my RB67.

Equipment needed:
- a small "jewelers" philips screw driver
- a 1/16" drill

Estimated time:
- 5 minutes

STEP 1: Note the two offending studs — these prevent RZ lenses from being mounted onto an RB body.

STEP 2: Remove the plate by unscrewing the 4 mounting screws with your jeweler's philips screwdriver. Be careful not to lose the Shutter Release Lock Pin (see previous image).

STEP 3: Flip the plate over and using the 1/16" drill, drill out the soft bronze studs BY HAND (do not use a power drill).

STEP 4: Dust it off, and align it back on the teleconverter, being sure to locate the Shutter Release Lock Pin back in its proper location. Re-attach the 4 mounting screws

STEP 5: Verify that you can manually move the shutter cocking pins

STEP 6: Mount the teleconverter on your RB67

STEP 7: Mount your lens on the teleconverter (Note: the teleconverter is optimized for 90mm to 180mm lenses)

STEP 8: Verify that you can cock the shutter

STEP 9: Take your picture! (Note that you will need to add exactly 1 stop more exposure to compensate for the 1.4x longer lens)

And that's about it. Here is a sample photo using a Mamiya RB67 + 250mm + 1.4x teleconverter:


OldUncleMe said...

Great info, thanks! I'm now itching to try it out. You make it look very simple.

J Michael Sullivan said...

It *IS* simple!!!! And best of all, this same technique also works on the RZ Tilt/Shift adapter!

Anonymous said...

Sweet mod! Now I can make more toys to play with !!

Alex said...

Nice mod there. I'm wondering does this procedure apply to RZ lenses?

I just worry the mirror or whatnot might hit the RZ lens if there's ever a way to fit them on RBs.