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Astrophotography and Sketching >> Film Astrophotography

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Michal1
sage


Reged: 07/25/10

Loc: Czech Republic, Central Europe
Mirror hanging problem
      #6164357 - 10/29/13 11:15 AM

Sometimes I encounter the problem with mirror hanging with my Pentax 6x7. It seems to be more and more frequent. This year I lost 1-2 frames in each film due to this problem. In internet discussions, it is attributed to weak battery. But I don't use any battery at all, because I have a battery elliminator. I've noticed that the mirror hangs after that I press the MLU button and the battery is out. However, in some cases the mirror hangs even if I'm quite sure that I haven't pressed the MLU button. Please help.

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Nightfly
Pooh-Bah


Reged: 06/20/07

Re: Mirror hanging problem new [Re: Michal1]
      #6165306 - 10/29/13 08:30 PM

Do you have the battery eliminator engaged fully prior to activating the MLU?

I'm assuming you are using the "safety button" trick for long exposures using no battery.

If so, I have encountered this problem if the cable release is not fully depressing the safety button. Also, I have had weak cable releases that allow some motion of the button once engaged.

Jim


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Michal1
sage


Reged: 07/25/10

Loc: Czech Republic, Central Europe
Re: Mirror hanging problem new [Re: Nightfly]
      #6166276 - 10/30/13 12:08 PM

I don't press MLU intentionally. I've noticed that it causes mirror hanging at daylight, when I was playing with the camera. Therefore I think that perhaps I press it accidentally, when I change lenses in dark. Once the mirror hanged even if I was really careful not to touch the MLU button. I will check my battery elliminator, thanks for advice.

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Nebhunter
Carpal Tunnel


Reged: 10/04/03

Loc: Frostbite Falls
Re: Mirror hanging problem new [Re: Michal1]
      #6167370 - 10/30/13 09:36 PM

Michal I've had similar issues. I found that the release cable - being 20" long and being that fabric coated type - will start to "give" - relaxing thereby releasing some tension on the bypass button. Somethings this just trips the shutter, and sometimes the mirror would hang.

I coated the fabric material with some nail polish or glue type material to harden the fabric. I use one large loop with the cable from the camera back to the DUP plate where the release is held firmly with a twist tie. The cable is also tied off along the way to prevent any flop or movement.

I think a short cable in stainless steel mesh would be the answer, but try finding one these days. Hope this helps.

Igor


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Michal1
sage


Reged: 07/25/10

Loc: Czech Republic, Central Europe
Re: Mirror hanging problem new [Re: Nebhunter]
      #6174194 - 11/03/13 06:07 PM

I have checked the cable release. It did not retract in 3 hours spontaneously. But it retracts, when the release is bended. When I shoot, I insert the release between the pipes of the camera holder, so that it can't move much. I will try to use an ordinary bolt instead of the cable release to press the safety button.

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Nebhunter
Carpal Tunnel


Reged: 10/04/03

Loc: Frostbite Falls
Re: Mirror hanging problem new [Re: Michal1]
      #6180259 - 11/07/13 12:44 AM

I was thinking along similar lines Michal. Trying to eliminate those weak spots that can ruin a nights work. I was thinking of taking a cable release - cutting it off just behind the head. Leave the plunger extended, and epoxy fill the head to hold everything in place. Then screw in or out the head to activate the bypass button. Easy enough to cover the lens before unscrewing the head to prevent movement. Let me know what you come up with.

Igor


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