Battery Drain Issues on Mamiya AFDIII/Phase One 645AF

Discussion in 'Medium Format' started by rishij, Jun 16, 2011.

  1. I recently bought a Phase One 645AF (Mamiya AFD III) from Capture Integration.

    I use a HM401 film back with it.

    I noticed from the beginning that battery life was dismal. Often a set of newly charged AA batteries (2400mAH Maha Imedions or 2700mAH Maha Powerexes) would only power a few rolls. In the cold weather, often the camera would die after one roll. When left *off*, the batteries would be dead within 2 days.

    So I did some testing with my multimeter. I put my ammeter in series with my Phase One 645AF + batteries & found a 27mA continuous draw when the film back is in place. 0mA draw when the film back is detached. Removing the battery from the film back has no effect.

    27mA! That's crazy! Assuming linearity, if you have a set of 2700mA-hrs AA batteries in there (pretty much the highest capacity AA you can find), that means they'd all be *fully* drained in 100 hours! Half-drained in 50 hours (2 days)! And since half-drain is enough to lower the voltage so as to fall well below 9v, it's no surprise that my camera dies within a day or two even when off!

    I hear tons of mixed reports -- some people reporting similar issues, others reporting no issues when batteries are left in there for months, even with the film back on.

    Could people report back with their experiences? I find it hard to believe that a company would release a Mark III version of a product that has a continuous drain of 27mA! And if they did, they should take some responsibility for it. Phase One was at first reluctant to admit anything was wrong; after pushing the subject, they said I can send it in even though they doubt there's anything they can do about it.

    If anyone else wants to try with their body, all you have to do is connect a multimeter in current mode in series; i.e., connect a wire from the + terminal in camera to + terminal on battery holder (top of exposed AA battery), then connect - terminal on battery holder (bottom of exposed AA battery) to + terminal on multimeter, then connect - terminal on multimeter to - terminal in camera (alligator clips or leads do the trick just fine). Leave camera in 'locked' position.

  2. I find it hard to believe that a company would release a Mark III version of a product that has a continuous drain of 27mA! And if they did, they should take some responsibility for it.​
    There's a reason Mamiya's camera assets were liquidated twice, first by the original Mamiya sporting goods company, and then by the IT company that they sold the assets (but not the business) to.
  3. Whoa, my head's spinning just from doing a Google search on what you just brought up Joseph. I had no idea.
    No wonder I couldn't find any information on modifications to Mamiya 645 film backs to solve the film flatness issue (I started a thread here: &, instead, had to buy a pre-modified HM401 back from a service manager at an inflated price from MAC group (Mamiya America Corporation).
    Wow, so you're pretty much on your own with these products huh?
    For example, save for the few modified HM401 backs Ramesh (service manager) has sitting around at MAC group, the average end user can't even buy a Mamiya 645 film back that doesn't introduce gross bends into the film that lead to every 2nd photo being completely out of focus (even at f/16) in the middle of the frame.
    I really wish a modern company just started making medium/large format film cameras... but I guess 'demand' has spoken... :(
  4. Rishi,
    Sorry to hear that - no wonder you are shocked! My experience with my older model 645AFD is that the batteries can sit in the camera for (at least) several weeks without noticeable decrease, but then I am leaving a Kodak digital back connected to it, not a film back, and Lithium batteries, not rechargeables.
    I have a couple of a film backs, so I'll see if I can borrow a multimeter and do the tests you mentioned.
    As a matter of interest, just how "inflated" is the MAC price for the modified HM401 backs?
    And could the modification have anything to do with the weird current draw? (Can't see why it should, but they might have botched something).
  5. Ray -- what is the model # of the film back you use?
    I wondered the same thing -- could it be the modified film back? But the modified film back is only modified in the following ways:
    1. One roller is removed so that now there is only one roller on the 'feed' side of the film magazine. It sits very close to the area being exposed so that the bend is introduced into an area of film very close to the film just previously exposed. You'll see why in a second.
    2. The electronics (I assume) are modified so as to move the film more in between exposures. The bent film, sitting close to the area of film just exposed, advances beyond the pressure plate for the next exposure. This way, the bent film is never exposed. It sits between exposures.

    I'd be surprised if such modifications would cause extra drain... no reason they should, at any rate.
    The price of this modified back was quoted to me as being $549; when I expressed disbelief at that price tag given that 'like new' HM401 backs can be bought from for $249, additionally stressing that this redesign of the back was incumbent upon Mamiya b/c the previous back had an inherent design flaw, Ramesh offered the back to me for $375. He also mentioned that Mamiya America (MAC group) can't do anything to existing HM401 backs... so the rest of you not purchasing this special HM401 back (wonder how many are left) are stuck with a gratuitously underperforming medium format system.
    Which I continue to stress is just sad, and an insult to the R&D Kodak & Fuji still put into film.
  6. Also, I'll see if I can get my hands on a HM401 (unmodified) locally this weekend to run the same test.
  7. My word -- I rented an old film back for the 645 AF/AFD, & the camera shows no current draw when off when this back is attached. Attach my HM401 (modified), & I again see the 27mA constant draw.
    At this point I have nothing to do but wish myself good luck in dealing with MAC group. Because I'm gonna need it.
    Good grief,
    P.S. Given the overwhelming response, I can see how popular medium format is!
  8. When on, the respective current drain is:

    645AF back: 100mA
    HM401 modified back: 150mA

    Suddenly, it's no longer surprising my batteries barely last me one roll sometimes. Unacceptable, Mamiya, unacceptable. What on earth.

  9. Wanted to update this thread for the sake of posterity:
    I got yet another modified HM401 film back from Ramesh at the MAC Group. It does not have the battery/current drain issue; however, it puts less spacing in between frames (and is *actually* a 15 exposure film back... my first modified HM401 was more of a 13-14 exposure back due to the vastly increased spacing between frames). I was worried that with the less spacing I'd still see the bend introduced into the film within the exposure area... turns out it seems fine. I let film sit in there for days, then advanced one frame; the film looked flat. Perhaps just the removal of that one extra roller takes care of all the bending problems.
    If you want to try & get a modified HM401 back to deal with the film flatness problem, you need to contact Ramesh at the MAC Group ( according to I would try calling 914.347.3300 (according to their website:

    Ask for Ramesh, and ask about the modified HM401 film back that has one of its rollers removed and puts extra space in between frames. Then, when you get it, test it out! Load your film, then let it sit for a day or so. Then, take an exposure so that the film advances. Pop off the film back, remove the safety plate, and see if there's a bend within the exposure area. Hopefully there isn't!

    Furthermore, if you know how to, test the current draw :)

    This is the setup for testing it... should be obvious to anyone somewhat electronics savvy:

    It can be a bit difficult connecting the leads inside the battery compartment of the AFD body... but it's doable. Just don't short anything :) The film back should really have no draw when the body is off.

    Good luck to anyone going this route. Without that modified back, I would never invest in the Mamiya 645AFD system for film shooting.

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