[keyofnight]

Hey guys! I'm looking to get into medium format, so I have a couple questions about the Pentax 6x7/67/67ii.

I read that the 67/67ii eat through batteries for long exposure shots because a solenoid is used to lock the mirror. Is that true?

I also read that the 6x7 is all mechanical except for the meter (much like the awesome Pentax MX, LX, K1000, and related cameras), but they added a mirror lockup feature later on. Do the 6x7s with MLU use the same battery-powered MLU mechanism the 67 and 67ii use?

[smigol]

I can confirm that the earlier 67 and 6x7 need batteries to do MLU and hold the shutter open! However, once you start the exposure, you can safely remove the battery and then replace it when you need to close the shutter. One possibility is to use the external battery device that you can find on ebay sometimes or you can use the hat trick to cover the lens as you start and stop the exposure.

[blackcloudbrew]

I can't speak on the 67 or 67ii but I do have the original 6x7 without MLU and it was my understanding that on the 6x7 when they added MLU that was the battery eater as it holds the shutter electrically. The 6x7 with or without MLU does require a battery to trigger the shutter. Personally, unless I'm shooting below about 1/30th I'm not really worried about MLU and as I don't have it anyway, I just ignore the whole issue. I've done long time exposures with a cable release and have not seen any real movement (the camera is on a tripod of course) issues. That may have answered some part of your question.

[tuco]

I've had the same battery in my 6x7 for at least 5 years now (if not longer) and I have done lots of long exposures in that time (in the range up to 4 minutes typically). But I use a WLF most of the time. Something like wide field astrophotography would be more taxing on the battery I suspect. But I wonder how much you really have to worry about it for casual long exposure work.

[Silent Street]

Not all 6 x 7 bodies have the MLU function; these are typically the older Asahi Pentax models. It is a very useful feature to have though.
MLU is used for each and every exposure on my 67 as I'm determined to wring out the very best performance of the optics I have invested in. It's no big deal to me to be tethered to a tripod.
The MLU does place a drain on the battery by way of, as you mention, the solenoids. The longest exposure I have done on the 67 so far (45mm f4, polariser EV6.5) in a rainforest last weekend was 45 seconds, mirror up, bulb mode. These short duration time exposures are of no real threat or consequence in terms of battery reliability (I do carry spares). Battery life is around 5-6 hours with the mirror / shutter continously open, which does not particularly endear the 67 to repeated long-duration exposures (but I'm sure others will disagree). That's why I prefer my EOS 1N and invervalometer for astrophotography, chiefly star trails (no power drain in bulb mode). The 67 is a beautiful piece of machinery that excels in many other ways of course so MLU, or lack of it, should not be a deciding factor on whether to get a 67 / 6x7. Just get one and love it.

[keyofnight]

Right on, guys. I wanted a camera without electronics (beside a meter), but I think this camera is too cool. If I find a deal, I'll pick one up.

[Silent Street]

Oh, these pups bristle with mod-con electronics: a few resistors, lengths of coloured wire, a LED for the battery check, potentiometer and a capacitor or two.

[MysteryOnion]

I was just wondering KeyofNight, how long are you looking to expose for?

[keyofnight]

I was just wondering KeyofNight, how long are you looking to expose for?

Not sure. I was thinking about doing stylized night sky photography. (: I don't know what that requires, but I was thinking 30-60' exposures?

[MysteryOnion]

...once you start the exposure, you can safely remove the battery and then replace it when you need to close the shutter.

I checked both my bodies and they do this fine as SMIGOL said. You can put into 'B' and lock with a release cable, then pull the battery... come back and re-plug the battery and release the shutter.

I've read it is easier to do if you have the battery remote as the tripod mount might get in the way for easily yanking the battery out. The remote battery attachment has a socketed connection.

[Silent Street]

^
The tripod mount makes that procedure just so much of a hassle. I've tried it and fumbled during a long Bulb (night) exposure, dropped the battery and then spent another hour scratching through the grass for it! What the 67 / 6x7 really needs is an offsete tripod mount hole, or an additional one.

I use an EOS 1N in bulb with an intervalometer for star trails; it uses no power in Bulb and stops/starts unattended throughout the night while I sleep at camp. Neato!. But the Pentax... if you like to fiddle and fumble with the battery it's OK, but I don't think it really endears itself to long Bulb exposures by dint of that mode using power, unless the battery be removed as described.

[tuco]

Put a lens cap on the lens, open the shutter, remove the battery, mount on a tripod then remove the lens cap. Put the lens cap on after the long exposure, remove from the tripod, put the battery back in and close the shutter, perhaps.

[smigol]

Sometimes you can find the remote battery packs that have a cable connecting to a dummy battery in the body. I picked up on on the auction site that was NOS. The original kit had a small spacer device that allows clearance for the cable from the tripod. I've also used a device that was cobbled together by another person that featured 3 AA batteries with a headphone jack that allowed easy disconnect.

Either way, covering the lens is a standard procedure for closing the shutter.

[nightfly]

I have run my 67 body with literally hundreds of hours of long exposures with no ill effects. A battery will typically last 4 to 5 hours in total. A better method is to use the safety button trick. I have fashioned a device that holds the safety button in to accomplish long exposures without a battery. No solenoids powered during exposure this way. Cobbling AA batteries sounds like another plan, but I need my camera on a tripod or piggybacked on a scope and this is prohibitive for me. YMMV.

Hutech designed a unit I speak of, but I made my own. It is easy to make one.

Hutech Astronomical Products - Pentax Battery Eliminator