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05-15-2021, 02:48 AM   #1
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67 TTL Prism - Needle accurate? Meter working?

Hi guys, new here got a lovely 67 from Japan with the TTL.

I have a light meter on order, until then im using my phone, I just wanted to know from experience, is the TTL meter accurate? I guess that the middle +/- exposure means even exposure.

I read there is 5 or so stops from the bottom to top?

Lastly, my camera just want to check its working, the TTL only seems to move the needle when the lens is set to Auto, Is this normal?

when I flick it over to Manual the needle doesn't seem to work / rises up to + and stays there regardless of shutter change/stopping lens down etc.

Thanks ahead
Lewis

05-15-2021, 03:53 AM   #2
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Welcome to the forum, first read this about removing/mounting the TTL prism finder: ADVISORY: Pentax 6x7, 67 METER COUPLING CHAIN AND TTL METER PRISM - PentaxForums.com

The meter should work in both MAN & AUTO on the lens. Auto uses open aperture metering, MAN uses stop down metering - the aperture of the lens is stopped down to the set aperture when MAN is set at all times and not just during the exposure.

The camera uses a different metering circuit for Man & Auto. I'd try removing the lens and prism (see link above) and cleaning all contacts - there is a contact pin at 3 o'clock on the lens mount which moves when the Man/Auto switch changes. Try also to gently excercise the ISO dial to its extremes a few times.

The TTL prism electronics are fairly basic, now very old and often flaky, as such issues like this are not completely unexpected. Many on the forum have given up fighting them and use external meters instead.
05-15-2021, 05:47 AM   #3
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QuoteOriginally posted by johnha Quote
Welcome to the forum, first read this about removing/mounting the TTL prism finder: ADVISORY: Pentax 6x7, 67 METER COUPLING CHAIN AND TTL METER PRISM - PentaxForums.com

The meter should work in both MAN & AUTO on the lens. Auto uses open aperture metering, MAN uses stop down metering - the aperture of the lens is stopped down to the set aperture when MAN is set at all times and not just during the exposure.

The camera uses a different metering circuit for Man & Auto. I'd try removing the lens and prism (see link above) and cleaning all contacts - there is a contact pin at 3 o'clock on the lens mount which moves when the Man/Auto switch changes. Try also to gently excercise the ISO dial to its extremes a few times.

The TTL prism electronics are fairly basic, now very old and often flaky, as such issues like this are not completely unexpected. Many on the forum have given up fighting them and use external meters instead.
Hi there, thanks for the reply! Could you explain what open aperture metering vs stop down is ?

I know open vs closed apertures on the glass of course, but how does auto differ, will it auto select the best aperture based on a proper exposure etc?

---------- Post added 05-15-21 at 05:57 AM ----------

QuoteOriginally posted by johnha Quote
Welcome to the forum, first read this about removing/mounting the TTL prism finder: ADVISORY: Pentax 6x7, 67 METER COUPLING CHAIN AND TTL METER PRISM - PentaxForums.com

The meter should work in both MAN & AUTO on the lens. Auto uses open aperture metering, MAN uses stop down metering - the aperture of the lens is stopped down to the set aperture when MAN is set at all times and not just during the exposure.

The camera uses a different metering circuit for Man & Auto. I'd try removing the lens and prism (see link above) and cleaning all contacts - there is a contact pin at 3 o'clock on the lens mount which moves when the Man/Auto switch changes. Try also to gently excercise the ISO dial to its extremes a few times.

The TTL prism electronics are fairly basic, now very old and often flaky, as such issues like this are not completely unexpected. Many on the forum have given up fighting them and use external meters instead.
Thanks again, I tried to clean the contacts on the camera and the prism, all 3 of them just to be safe, still nothing.

So when I flick it to Auto, the meter starts working, and when I flick it to Manual, im able to operate the aperture but the meter doesn't move.

On auto, the aperture doesn't open / close ? Is this normal?

---------- Post added 05-15-21 at 05:58 AM ----------

Also would this indicate a issue with just the TTL or the camera itself? As im talking with the seller on either returning the whole thing or just the TTL, so if we can figure out if I can just swap out the TTL etc
05-15-2021, 07:33 AM   #4
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Original Poster
found this, says that the meter when set to manual the meter will not move, when on auto it will?

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