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09-17-2011, 03:59 PM   #1
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P67 TTL prism not metering correctly?

Had my 6x7 for a while now, and up until recently the meter would indicate the exposure when I rocked the on/off to the on position. Now, even in bright conditions it doesn't do anything, but if I switch the aperature control/DOF preview switch on my lens to manual, then the meter works without me even setting it to the on position. I haven't removed lens or TTL prism from the body since I got them. I'm assuming the current behavior is not correct, though it got me wondering if I've been using it wrong all along. I always assumed that the meter was mechanically connected to the lens to adjust for the indicated aperature when the aperature control was set to auto.

09-17-2011, 05:45 PM   #2
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I would say, do try to remove it. Check to see if the contact are getting dirty or just clean them anyway.

[

The contact look like this. Hopefully that might clear up the problem or it will be a little more serious.

Not indicated above is that "A" mode passes via the frame so clean the lock points too.

In the extreme problem and common these days is the TTL's capacitors are getting old and drying out. I've had to service them on one of my TTLs. It is tiny work and requires decent soldering skills.

Last edited by MysteryOnion; 09-17-2011 at 05:56 PM.
09-17-2011, 06:03 PM   #3
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Both conditions are not what my 67 does. Try removing the lens and then the prism, clean the contacts that interface with the meter and check if the chain tab moves when you rotate the aperture tab on the lens mount. MysteryOrion posted some good pictures of what I'm talking about in the thread 6x7 Metered Prism just recently. I'd note his camera looks to be an older 6x7 because both my 6x7 and 67 do not have that metal shield around the voltage contacts where the prism interfaces to the body.

The meter working when turned off when the DOF preview is engaged is not what mine does. Unless that is what a very early model did, I'd say something is wrong there too.

Last edited by tuco; 09-17-2011 at 07:37 PM.
09-17-2011, 06:34 PM   #4
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I have to say that I'm not clear on the behavior of the single position TTL? Is that what we are looking at... noodle0?

tuco... good point about the chain... I forget it could detach. ...Yes my camera is the "6x7" and with a MLU, but not the silver spool tabs and it does have the cut for the advance lever.


Last edited by MysteryOnion; 09-17-2011 at 07:03 PM.
09-17-2011, 09:15 PM   #5
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I removed the lens and prism, wiped off the three contacts (my 67 also doesn't have the metal plate) and put everything back together. It's now working like it did originally. Just to clarify, I have the prism with the spring loaded rocker switch. Rock it back to turn on, push it forward to turn off. Tuco, is this the expected behavior for this version of the prism?
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09-17-2011, 10:51 PM   #6
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QuoteOriginally posted by noodle0 Quote
...
Rock it back to turn on, push it forward to turn off. Tuco, is this the expected behavior for this version of the prism?
Yes. Good to hear you're back in business.
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