I have a big stable of Mamiya MF lenses, in both RB and M645 mount, everything from 50mm to 500mm.
So a couple of months ago, I came across a Mamiya RB lens to Canon EF adapter on the auction site. It piqued my curiosity, because in theory, using a MF lens on an APS-C (or even full frame) should give stellar image quality because you're really only using the center of the lens.
But at $160 (for the RB-EF), I didn't feel it was worth it to see.
Then I found the Mamiya 645 to EOS adapter for $30. Well, now it's justifiable. And as a coincidence, I was ordering some stuff from KEH, and they had the RZ - EF adapter with chip for $89. That too is reasonable and justifiable. So I bought both adapters.
The lenses I was most interested in trying out on my 50D was the 500mm reflex (645), the 120mm Macro (645), and really any of the RB's, but the 150mm Soft Focus is something I really want to experiment with.
Both adapters came today, and before it got too dark, I took some shots in the backyard, and here's how it turned out -
The 500mm (as expected) was a bear to keep steady, and focusing was really a challenge even with the Ef-S Super Precision Matte focusing screen. But I will say the 500mm is very sharp, especially for a mirror lens. I've used other mirror lenses, and they've all produced (IMO) crap.
I then tried the 120mm Macro. I bought this lens to e able to do 1:1 on 120 film of larger subjects, and also to potentially replace my Canon 100mm 2.8 Macro. I'll be doing my own unscientific comparisons in the near future, and we'll see how that goes. But, in a quick run through this afternoon, I was blown away with it on the 50D. The 120mm has a reputation of being one of the best macro lenses available, and I can see why.
I then moved to the RZ adapter with my RB lenses (250mm and 360mm). I've had these lenses for a while, and have been great on the RB, but I was hoping to get better IQ out of the 360mm on the Canon then I get from my Tamron 70-300mm, which is a fine lens. I find the Tammy to be a bit soft at the 300mm mark, so I was hoping for something better. And I got it. The RZ adapter has the AF confirm chip, so that made it a lot easier for me, and what I got were nice sharp images with no CA. Again, I'll be comparing the RB's to the Tamron more thoroughly, but I doubt I'll be replacing the Tammy.
The 645 adapter is great. It's small, well made, and simple like a basic M42 adapter. I will be adding on an AF confirm chip though, as I had a heckuva time hitting focus.
The RZ/RB adapter (it's the Fotodiox brand), is ok. I can't say it's great, but it's acceptable. The biggest drawback to it is the focusing helicoid. It's relatively narrow in diameter, and short in length, which makes focusing difficult. You can only turn it about 1/4 turn, then you have to reposition your hand to continue turning. It does have a tripod mount, which is nice, but that makes the focusing even more difficult. The rubber grip for the focusing helicoid could use more glue. It's stiff to focus, and the rubber would stretch, and I can see that becoming a real issue after extended use.
Another not-so-great feature of the RZRB adapter is that it has a shutter cocking ring. I guess it's good if for some reason the lens shutter were to trip, it's easy to open it back up, but I think really it is unnecessary. I can't see the shutter tripping on its own, and I actually tripped the shutter twice by accident by moving the ring.
Now, RB lenses are heavy. And the biggest issue I had with the RZRB adapter was when I tried to focus back from infinity with the 360mm. The helicoid didn't want to move easily (if at all), unless I tilted the lens up, to allow gravity to help. Not a good thing, IMO.
But, as the 645 adapter allows for the use of premium lenses, so does the RZRB adapter. So from the aspect of getting the most out of a lens, both adapters do the job very well. If you have Mamiya 645 lenses, I would tell you to grab an adapter without hesitation. The resulting edge to edge quality is what I thought it would be - fantastic. If you have RZ/RB lenses, and can live with the above mentioned issues in exchange for great IQ on the cheap, then I think it would be worth it.
Here's 2 samples. Both are 645 lenses (deleted the RB's).
500mm f/8 1/1600 ISO 640 (trying to offset camera shake) -tree is about 75' tall, and about 250' away