I am not an avid fill flash user, but I do use one for outdoor portraits. For Canon dSLRs I ran the gamut - 550EX, 580EX and 430EX, and for Nikon the SB-400. I liked the Nikon SB-400 the best because of its compact size. It is a no frills package, but for basic fill flash it is a great. My second choice is the Canon 430EX. It is larger, but delivers good results with a Sto-fen.

Mamiya’s 645 flash choices are limited since Mamiya does not make flashes. One option is a standard shoe mount flash used in manual mode with no TTL metering. Flash TTL functionality on the Mamiya 645AFD II requires a SCA3000 based flash such as the Metz units. I never used a Metz flash before, nor any of the SCA adapters. The Mamiya 645AFD and 645AFD II require the Metz SCA 3952 module. The older Mamiya 645AF uses the Metz SCA 3951 module. Sorting through Metz’s flash units and the product numbers takes awhile. There are some smaller models such as the Metz 28 and 32 series, but they are limited in their feature set. More or less a set-it and forget-it approach.

Metz has some newer shoe mount models such as the 44 and 54-series, but I just wanted something middle simpler for fill flash. Eventually I decided on the discontinued  Metz 40 MZ-3i because of its compact size. For those of you familiar with the Metz 40 MZ, clearly my “research” wasn’t as thorough as it should have been. There are earlier versions of the Metz 40 MZ - namely the 1i and 2i - and I have no idea what’s different between them. Experience has taught me to get the newest version, so the search began for the Metz 40 MZ-3i. I won an auction on Ebay and about a week later the box arrived. The 40 MZ-3i came in its original box. The box looked fine, though a bit big for such a small flash. Then I opened up the box, pulled out the case, opened the case and there’s the flash. HOLY SHIT! It’s huge!!! I have probably seen a 100+ pictures of the flash in the auction descriptions, but never attached to a camera. The 40 MZ-3i is huge! The flash looks overwhelming large atop the 645AFD II. People use these on Leica M5’s, M6’s and M7’s?!?! 

MINI REVIEW

The Metz 40 MZ-3i is simple to use. There are various programs and options, but TTL mode is probably where most people will keep it. The 645AFD II has a FEC adjustment button just below the upper LCD, so it is similar to using a Canon 430EX / 580EX on a Canon dSLR. There are some key points for medium format shooters:

1. •The guide number is 40 and at ISO 50 this translates into very little horsepower. The Canon 430EX on the Canon 1Ds Mark II was usually enough, but the Canon spent 99% of its life at ISO 100. The Metz is about the same guide number, but its output is halved due to ISO 50. Bumping up the ISO to 100 on the P25 takes care of that, though, at price of noisier files. I love Sto-fen Omni-Bounces. They help to take the edge off the flash, but they reduce the net output power. I doubt the Metz 40MZ-3i has enough power for bounce plus a Sto-fen. At this point the only real choice is the Metz MZ-54 4i.
   

2. •The 40 MZ-3i has a SECONDARY flash just below the main flash head. The upper unit rotates and pivots for whatever bounce orientation is needed. The secondary flash unit fires straight ahead like a mini fill flash. The secondary can be turned on or off as needed. Even smarter the flash comes with two little pieces of plastic which slide over the secondary flash and reduce the output by -1 EC or by -2 EC. I’m using the -2 EC diffuser and it works well, though an electronic adjustment would be nicer.
   

3. •Cycle time is slow - 4 to 8 seconds; the user manual states up to a max of 11 seconds. There are some options to vary how quickly the flash cycles, but those options modify the output power in one form or another. Thus the flash recycles quicker because less output power was used... um... DUH!
   

4. •The 645AFD II + the P25 + Metz 40 MZ is heavy. Holding the camera by its grip puts considerable pressure on the right thumb. One of the Metz potato masher styles with a flash bracket would be more comfortable for long periods of use.
   

5. •At this point I am undecided on the accuracy of Mamiya’s metering; preliminary images were under exposed. This may be due to the 40 MZ’s relatively weak output (ie - Guide No. 40). The 40 MZ has its own metering too, but I’m not sure how it interacts with (or overrides) the 645AFD II’s metering.
   

FINAL THOUGHTS

There are plenty of features to control/modify the output, and the integration with the Mamiya is okay. As far as bang for the buck goes, the 40 MZ is a nice $75-$125 option (via Ebay). The picture above was a quick test snap with 40 MZ and 645AFD II. There were a couple hot spots on the forehead and cheek bones; those were corrected in Photoshop. A Sto-fen Omni-bounce on the primary flash head would help. The hot spots may have been caused by the secondary flash, but with a -2 EC adjustment on its output, that seems unlikely. In other tests shots with the primary flash head firing straight up, aperture at F4 (Mamiya 80mm F2.8 AF lens) and P25 @ ISO 50, there was not enough output power. I bumped the P25’s ISO to 100 and F4 was usable.

I am going to sell it and pick up a Metz 54 MZ-4i. The 54 should have enough power and with a second SCA module it can be used on the Canon 5D. A used 54 MZ-4i costs about 2-3x more than the 40 MZ-3i, so if you want a very nice, but inexpensive flash. The Metz 40 MZ-3i may be discontinued, but it is still a viable flash solution, especially for cameras with good ISO 100-400 performance.