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03-21-2012, 08:19 PM   #1
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TTL Meter not working

I remember reading somewhere, long ago, instructions on how to initially set something up by opening the back of the camera and putting the lens on, I was hoping this was when I got the meter... but, hasn't worked so, any other suggestions would be great.
Also on the body of my camera there is a loose copper chain at the left side of the top of lens mount notch , hanging out from somewhere inside, and there is a small metal piece that slides back and forth that slides too freely. I have had the meter working since this little "issue" on unknown origin has shown up, but the meter stopped working at some point when I took off the lens - which is why I was hoping there was something else I could try.
The camera works fine, only the meter is not working.
If no one has any suggestions, maybe a repair place I can mail the camera to safely? I live in rural Colorado at the moment.

Pic of the chain: yfrog Photo : Shared by

03-21-2012, 09:32 PM   #2
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The broken chain was caused by removing the TTL prism when a lens was mounted on the 6x7 or 67 camera. You have to removed the lens first, then it's safe to remove the TTL prism.

Eric can fix it, email him to verify the cost, here is a link to his web site:

Here is a link to the Pentax 67 manual:

Here is a link to the TTL prism manual:

03-22-2012, 01:39 AM   #3
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The coupling chain is really quite frail and easily broken; here and there DIY types with patience and nimble fingers (and good tools!) have made good on it. Prevention though is the best first aid.
There is a very specific (if quirky in the Pentax mould) way of dismounting and remounting the TTL prism and lens, and in what order, to prevent functional damage to that coupling chain that you have now experienced.

With the TTL metering prism in-situ, it is fine to change from one lens to another as often as you wish. If the following procedure was not followed, dismounting the lens will exacerbate the risk of damage.

If you remove the TTL prism, say for cleaning the focusing screen, you must remove the lens. This resets the coupling chain. Then a) re-mount the TTL prism and then b) remount the lens, all in that order. Finally, reset the shutter speed dial of the TTL prism by giving it a few tweaks back and forth until there is a click as the coupling pin is seated on the shutter speed dial of the body. If there is no coupling there, likewise the meter will not work.

In an emergency, with no coupling chain, use a handheld meter to bypass the TTL meter.
03-22-2012, 03:10 AM   #4
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Actually, this person had a great set of instructions....

The other point is the removal thing. The greater chance of breaking the chain, in my tests, is if the foam is bad or gone from the TTL-Prism which sets it lower. This makes the linking tab reach deeper and if you mount the TTL while the lens is not positoned proper or removed, the tab will block the camera's tab. A quick spin of the aperture ring later and the tab may snap.

03-26-2012, 12:40 PM   #5
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Thanks everyone

Good to know. I didn't get a manual with my prism so I would not have even guessed. I'll read the documentations and links you attached and get a hold or Eric if I can't come up with a fix for it. I'm glad the camera is still worth repairing rather than replacing, my other Pentax cameras don't seem to hold their value long at all. Look forward to being able to use my 67 with the prism again soon!

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