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01-17-2013, 04:56 AM   #1
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Join Date: Jan 2013
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smc pentax m 50mm 1.7 lens won't stop down

Hi Folks,

attaching my question here hoping for being rescued from my despair: My smc pentax m 50mm 1.7 lens on my K-01 just won't stop down. It doesn't feature an A-Setting.

- function of aperture ring / diaphragm on lens is ok if lens is detached or camera powered off
- menu setting of aperture ring is ok and camera releases (however only at f1.7
- AF switch on the body next to the lens ist set to MF
- lens aperture ring is set to, let's say f8

--> powering the camera on, opens the lens to f1.7 and it never stops down and it doesn't do so upon release, too.

What am I doing wrong?

01-17-2013, 05:47 AM   #2
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Join Date: Jan 2013
Posts: 10
Original Poster
Well solved it. It won't work in ISO-Auto Mode.

Is there absolutely no way to get a permanent metering and use ISO-Auto? Would be veeery handy ....
Having to press the green button prior to each shot is somewhat silly.
01-17-2013, 07:02 AM   #3
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GabrielFFontes's Avatar

Join Date: Jul 2011
Location: Rio de Janeiro, Brazil
Posts: 647
A very simple trick that might help you a bit (for example, i used to use my M 50mm 1.7 at f2 or f2.8 a lot of the times, so this helped a lot).
Pentax M lens "trick" - YouTube
01-17-2013, 07:47 AM   #4
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 4,260
You could try tricking the camera into thinking an "A" lens is attached: short out the "A" pin and insulate the proper pins for min and max apertures.

01-17-2013, 08:16 AM   #5
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Original Poster
Thank you very much. The M lens trick ist just great and quickly implemented.
I'll check out the pin insulation

Last edited by pixxmania; 01-17-2013 at 08:31 AM.
09-11-2013, 03:50 AM   #6
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Join Date: Mar 2009
Location: Germany
Posts: 62
I like the M lens trick, too. What I would like better is a firmware upgrade that disables the offending contacts.

Pentax advertises that older lenses can be used with the K-01 and we shouldn't have to use "tricks" to get the camera to perform as advertised.

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