looooooong exposures on Mamiya 645 af(d)

[david_love2]

<p>Is the shutter dependant upon the battery in the Mamiya 645 af or afd. This question is about photographing minutes and hours in the night sky for star trails etc. I don't think the battery would last such a long time for one exposure and I am concerned the shutter would shut down.( or maybe even lock up?). I know the 645 pro and prior (manual) cameras should have no problem. Does anyone know if the shutter is completely battery dependant, or is there some kind of "work-around" so that one can take these looooong exposures. Thanks</p>

[john_a5]

<p>I would be surprised if you would have a problem. The batteries, 8 AA as I remember, can shoot well over 3 hours of continuous use. I think as long as you have the shutter set to open it wont shut down either--I don't remember that it ever shut down when left on!?!</p>

[steve_parrott]

<p>If you have your owners manual, look on page 65. You can use TIME mode to do long exposure and keep the shutter open without battery power. Here are the steps straight out of the book, though I have never done it with my AFD.<br>

1. Set the mode dial to T (time) mode<br>

2. Turn the front or rear dial to set the aperture<br>

3. Press the shutter release button. Determine the composition, focus, then press the shutter release button. The shutter opens.<br>

4. Once you have achieved the desired exposure time, turn the exposure mode dial to X. The time exposure mode is cancelled and the shutter closes.<br>

In step 3, it sounds like the shutter release button is actually pressed twice to get the time mode started, but again, I have never done it with my camera.<br>

Good luck!</p>

[ondebanks]

<p>Hi David,</p>

<p>Long astronomical exposures? Welcome to my world!</p>

<p>I recently got an AFD. The B (bulb) mode will run down the 6 AA batteries (although the manual indicates that you will still get several hours out of them), but the T (time) mode will not - it is purely mechanical. The AF and AFD have a T mode. Note that the later AFDII, AFDIII and DF *DO NOT* have a T mode! This was one of the reasons why I went for an AFD and not a later model.</p>

<p>Now I got my AFD kit at the same time as a separate purchase of a Kodak DCS 645M digital back...and I have been so taken with the latter that I've only done astro tests with the digital back, and the film back is languishing for the time being. So I haven't yet actually done a T mode exposure, as digital backs don't work reliably (or in many cases, at all) with the T mode, because they need a clear electrical signal to terminate the exposure...of course, film doesn't care about such things! [The drift towards medium format digital backs is probably why Mamiya dropped the T mode from the AFDII and later models]. Anyway, it hardly matters, since 30 seconds on M mode is about the maximum practical exposure with the Kodak back because of the dark noise (hot pixels). Stacking exposures measured in seconds rather than minutes is the way to do astrophotography with this and similar backs (ZD, Leaf, Hassy/Imacon, Sinar) - only the Phase One P+ backs really go to minutes duration, although the annoying thing about them is that the dark frame subtraction cannot be optionally disabled as it can with the Kodak back, so you lose 50% of your clear-sky time!</p>

<p>Getting back on-topic - you can be reassured that if shooting film, with the AF or AFD, the T mode will not drain the batteries. What film do you use? E200 is still the astro king in my book.</p>

[david_love2]

<p>First...thanks for the quick replies to my question.<br>

Second..my apologies for taking so long to acknowledge your replies.<br>

Glad to hear that not only should it not be a problem, but also that actual experience shows it is very do-able. I have not done any of these type of looooooong exposures. I have attempted them, with a Nikon F80, but the battery always died well before I wanted it to. The longest exposure I have completed was with the F80 at about 30 seconds (night time street scenes) and I used Kodak BCN400 b&w because there is no reciprocity concerns. Thanks again.</p>

[david_love2]

<p>I forgot to add that the reason I asked, was that I wanted to attempt to do some work like Chris Conrad at <a href="http://www.petroscans.com">www.petroscans.com</a></p>