Mamiya 645

I wish to buy a Mamiya 645 body to use for astrophotography with my

Pentax APO telescope.

 

Can anyone tell me if any of the 645 models comes/came with a

mechanical shutter?

 

This is important as I tend to expose for up to 1 hour at a time and

I have found that 35mm camera's with electronic shutters soon empty

the batteries.

 

Many thanks

 

Ian King

The 645s all have electronically controlled shutters. I think the B setting is held open by a solenoid as well. I've never checked to see if any of the speeds work without battery power, but I don't think they do.<br>It would be fairly easy to make some sort of adapter to apply an external 6v source to the battery compartment.

OK. I checked it out. My vanilla 645 works the opposite to how I expected it to. With the battery out, the shutter stays open indefinitely, on any speed setting. It can only be closed again by putting the battery back in.

Bronica's have a T(time) setting which is mechanical, no battery required. They also have the Bulb setting which is batttery controlled

A correction to Pete Andrew's response: the user manual for the M645 1000s (which you can download as a PDF file from www.mamiya.com/assets/pdfs/645/M645_1000S_v4.pdf) shows that to close the shutter (and return the mirror, unless you've separately used the mirror-up lock) you *don't* have to reinsert the battery - you just have to press the "battery check" button on the camera. I tried this on my M645 1000s and yes, it works.

 

I also do astrophotography with the Mamiya (though not through a 'scope at prime focus, just yet - I must get around to making an adapter for that) and have never had a problem battery-wise. One interesting point made in the user manual is that the electrical consumption is the same *regardless of shutter speed*. This is because with the Mamiya moving-coil shutter, opening the shutter is a purely mechanical action, and power is only required to close it. How much time passes in between the opening and closing is irrelevant. So on "B" with a cable release, and availing of the mirror lock-up to reduce vibration, long exposures should not drain the battery any more than regular snapshot exposures. The other option, as Pete pointed out and I have clarified, is to use the sort of "T" setting - remove the battery, set any shutter speed, (optionally) lock up the mirror, start the exposure (you can even use the mechanical self-timer to do this - no cable release is needed, as you don't have to keep pressure applied to the shutter release in this batteryless mode), and use the "black hat" trick to cover the lens/scope aperture before pressing the battery check button to end the exposure. I don't know in a technical sense what goes on as a result of pressing the battery check, but it does close the shutter without the need for the battery.

 

So the short answer to your query is "yes" - the older M645 models, at least. As for the newer M645 Super/Pro models, I don't know, but I am pretty certain that I recall seeing a genuine "T" (mechanical) setting in the specs list for one of these newer ones.

Battery power is not consumed to hold the shutter open on the old M645 or 1000S models, only to trigger the closing of the shutter. You should get many thousands of exposures from a battery, even multiple hour long exposures. No need to remove the battery. The circuit will even continue to work well in very cold conditions when the battery output is less than normal.