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07-21-2015, 04:31 AM   #1
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Aperture Blades not visible (SMC Takumar 67 135mm f4)

Hi,

I just bought a Pentax 67II with a SMC Takumar 67 135mm f4 Macro lens. When I look through my lens and move the aperture ring from f4 to f32 I noticed, that I can't see the blades at all.
Is this normal for this lens (I have heard about lenses where the blades only move when the shutter goes off), or should i return / CLA it?

Thank you

07-21-2015, 06:54 AM - 1 Like   #2
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Some lenses will only close the aperture to the set value, if you activate the aperture lever on the lens. But I dont know what the usual behaviour of the Takumar is.
07-21-2015, 07:07 AM - 1 Like   #3
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I just checked the Takumar 6x7 1:4.5 75mm, off camera.
To put the AUTO/MAN lever into manual mode it is necessary to first slide it (clockwise looking from camera rear) then lift up the upper part of the lever so it locks, displaying "MAN"
Then when the aperture ring is adjusted, the diaphragm can be seen moving, looking into the rear of the lens.

When the lever is flicked it will move Anticlockwise by spring to display "AUTO"
In AUTO the diaphragm is held open regardless of aperture ring setting. It will stop down if you move the stop down round pin on the rear of the lens body. (provided the aperture ring is not at wide open f/ )
07-21-2015, 07:17 AM - 1 Like   #4
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Auto Takumar lenses have an Auto/Man switch on the lens. On the rear of the lens there are two pins - a very short one on the mount and a longer one.

If the short pin is not depressed (it gets depressed when the lens is fully screwed on a body or the Pentax K-mount adapter) the Auto/Man switch will lock in the Auto position.

When the switch is in the Auto position the iris stays fully open until the auto aperture (long) pin is depressed. Then the iris will close down to the set f-stop.

When the switch is in the Manual position the iris will stop down to the set f-stop regardless of whether or not the auto aperture pin is depressed.

07-21-2015, 07:26 AM - 1 Like   #5
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QuoteOriginally posted by Not a Number Quote
ens is fully screwed on a body or the Pentax K-mount adapter) the Auto/Man switch will lock in the Auto position.

When the switch is in the Auto position the iris stays fully open until the auto aperture (long) pin is depressed. Then the iris will close down to the set f-stop.
Hi NAN,
I think you are referring here to the M42 mount here but o/p has a Takumar 67 lens which is different.
07-21-2015, 07:38 AM - 1 Like   #6
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Ha Ha! Just realized that - where's my morning coffee?
07-21-2015, 08:21 AM   #7
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Thank you very much for your replies! Indeed there is a man/auto switch, I will check it out when I get home.
I got worried a little bit there and I didn't want ro waste a whole filmroll to test the aperture, but you helped me fast here, thank you again
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