Problem with Pentax KP and smc da 50mm f/1.8 lens

Vandon · 03-30-2018, 06:57 PM

I just got a new SMC DA 50mm from amazon and the auto-focus does not seem to work with my KP. It makes spinning noises but the focus ring does not spin and it does not auto focus at all. I tried the lens with my old K-50 and it seems to auto-focus OK. I also have a DA 18-135 and a DA 55-300 PLM and those both auto-focus just fine on the KP. Does anyone have any ideas? Thanks in advance.

Adam · 03-30-2018, 07:09 PM

Check the AF drive shaft on the camera. Does it appear dislodged or recessed? If not, try wiggling the lens a little after mounting it to ensure that the gears engage. Also, try cycling the AF/MF switch, as it physically pushes the drive shaft out.

**UncleVanya** · 03-31-2018, 05:45 AM

Do you have any other screw drive lenses? Both of your other lenses have internal motors and don't use the screw drive to focus.

Vandon · 04-02-2018, 06:00 PM

After wiggling it a bit it seems to be working...

03-30-2018, 06:57 PM	#1
Vandon New Member Join Date: May 2014 Location: Silicon Valley Posts: 10	Problem with Pentax KP and smc da 50mm f/1.8 lens I just got a new SMC DA 50mm from amazon and the auto-focus does not seem to work with my KP. It makes spinning noises but the focus ring does not spin and it does not auto focus at all. I tried the lens with my old K-50 and it seems to auto-focus OK. I also have a DA 18-135 and a DA 55-300 PLM and those both auto-focus just fine on the KP. Does anyone have any ideas? Thanks in advance.

03-30-2018, 07:09 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 49,797	Check the AF drive shaft on the camera. Does it appear dislodged or recessed? If not, try wiggling the lens a little after mounting it to ensure that the gears engage. Also, try cycling the AF/MF switch, as it physically pushes the drive shaft out. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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03-31-2018, 05:45 AM	#3
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 18,150	Do you have any other screw drive lenses? Both of your other lenses have internal motors and don't use the screw drive to focus.

04-02-2018, 06:00 PM	#4
Vandon New Member Join Date: May 2014 Location: Silicon Valley Posts: 10 Original Poster	After wiggling it a bit it seems to be working...

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