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04-26-2014, 07:39 AM   #1
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K3 and the 1.7x AF adapter?

Hello wise forumusers!

I received my K3 yesterday after the seemingly endless week spent cameraless since I dropped my K5 on the tarmac.

I broke my DA* 300mm too, so while I wait for its replacement, I wanted to try out my ancient 300mm f4 SMC lens in combination with my 1.7 AF converter. But the camera doesn't seem to register the lens at all...

I seem to recall having to set the focal distance manually on the K5 when using the converter - but here I am not prompted for a focal length. The camera simply behaves like no lens is mounted.

I think I must have forgotten some setting that needs to be changed, but I can't find anything in the manual. So I turn to you - because usually someone in here ALWAYS knows what to do!

04-26-2014, 07:57 AM   #2
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I dont know how it's called on the K-3 but you have to enable triggering without the aperture ring in A(utomatic) position. Its the last setting in the K-30.

Here are far more details on it:
04-26-2014, 08:08 AM   #3
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Custom menu #26 - set use aperture ring to 2.
04-26-2014, 09:00 AM   #4
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Thanks a bunch, both of you. Didn't think about the fact that aperture was manual...

04-27-2014, 10:11 AM   #5

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Hi MetteHHH,

Did setting the camera to recognize the aperture ring solve the problem? To me, this doesn't make any sense. The AFA is recognized by Pentax DSLRs as an F series lens with no FL specified. Recognizing the aperture ring doesn't come into play with an F series lens since they are all "A" and AF compatible.

I think your problem is that SR is turned "Off". With the AFA mounted, when I turn SR off, the FL input screen does not appear when the camera is powered up, but with SR "On", the FL input screen always shows when the camera is powered up.

One more thing to remember when using your SMC 300/4 with the AFA. Make sure the aperture ring on the lens is set at f4. This gives you a max Av of f6.8 with the AFA. Pentax AF sensors start to get challenged when the max aperture approaches f8, and f6.8 is only about a half stop faster, so stopping down the lens, even just one stop, will probably cause the AF system to stop functioning, except in very bright light. One last edit: -- this caveat only applies to manual aperture lenses since they would normally be stopped down before acquiring AF lock. Any "A" compatible lens would have an automatic aperture actuation and would focus and meter wide open, then stop down just before the exposure.

BTW, congrats on your new K-3 -- sorry to hear about your K-5 and DA* 300. . .


Last edited by snostorm; 04-27-2014 at 10:50 AM.

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