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02-03-2012, 08:52 PM   #1
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6x7 Lenses on 645n & Stop-down Metering Trouble

I've had an exposure disaster on a recent photo trip that was quite disappointing. I want to make sure it won't happen again.

I was shooting with my Pentax 645n and two lenses - the native 645 FA 75/2.8 and the 6x7 Takumar 55/3.5 (using the Pentax 6x7 to 645 adapter).

The 6x7 lens overexposed a lot when stopped down. I haven't had this problem shooting wide open. On the other hand, the 645 lens produced correct exposures with the camera's built-in meter, as always...

Just to confirm, to use stopdown metering, I should keep the camera in "A" mode and flick the switch on the lens to "AUTO"?
I did that and stopped down: the metered shutter speeds got progressively longer which seemed OK (but turned out very inaccurate at smaller apertures, as I mentioned).

02-03-2012, 09:13 PM   #2
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You don't even need to stop down meter with 6x7 lenses, do you? I know you don't on the 645d.

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02-04-2012, 11:05 AM   #3

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I'm thinking that your lens should have been set to "manual" for your body to meter correctly.
02-04-2012, 05:38 PM   #4
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I am with Adam. A properly adapted 6x7 lens should function with open aperture metering and support auto-exposure on your 645N. No stop-down required. It sounds to me like you are metering stopped down and shooting wide-open.


02-04-2012, 07:03 PM   #5
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Good advice all! I'll try keeping the lens switch in MANUAL instead. For some reason, I thought it had to be AUTO (maybe based on M42 Takumars I used before)

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