Using an F-series lens with an 'A' setting on a Pentax dSLR

Ex-Camera · 09-10-2015, 03:49 PM

The lens in question, a nifty SMC Pentax-F 35-80mm f4-5.6, has been attached to my Pentax K-50 for several days (and will be for several more, weather permitting). I have the lens working properly in Manual mode by following the instructions that came with the camera's manual, and pressing the green button to get through-the-lens metering before every shot. This operation is essentially no different from my fully manual 50mm prime.But on the 35-80mm there are electrical contacts which suggests some kind of data transmission is occurring between lens and camera. So, is it really possible to change the lens' aperture using one of the wheels on the camera body? If so, how?
I've had experience with both DA and M lenses before, but this one seems a bit different from both. For one, the camera's rear LCD shows F-- (just like with an SMC-M), but f5.6 is always written to the EXIF, regardless of the aperture ring setting.

vonBaloney · 09-10-2015, 04:01 PM - **1 Like**

Put the aperture ring on 'A' (use the little button to get it into that position and it should stay locked in until you push the button to get it out). Then it will work exactly like any newer DA lens -- autofocus, all camera modes, metering, etc...

Adam · 09-10-2015, 04:03 PM - **1 Like**

Originally posted by Ex-Camera

the camera's rear LCD shows F--

It shouldn't, if the aperture ring is set to "A". If you still see F--, try cleaning the contacts. If the problem persists the lens is defective.

In any case, keep the aperture ring set to "A" and pretend it's a DA lens, because everything works in exactly the same way. You can use the e-dials to change the shutter speed/aperture in all 4 shooting modes.

Originally posted by Ex-Camera

. I have the lens working properly in Manual mode by following the instructions that came with the camera's manual, and pressing the green button to get through-the-lens metering before every shot.

This procedure is only necessary with manual lenses.

Rimfiredude · 09-10-2015, 04:06 PM - **1 Like**

Put the lens on A and and use Aperture Priority. The wheel on the camera will work to set the aperture.

Ex-Camera · 09-10-2015, 05:58 PM

Dialing in the 'A' setting did the trick. Funny, but I thought the ring was already turned to A, but following advice and pressing the little button at the side of the lens got it all the way there. Kinda silly of me. Ugh. A big thanks to everyone!

09-10-2015, 03:49 PM	#1
Ex-Camera New Member Join Date: Sep 2015 Photos: Gallery Posts: 7	Using an F-series lens with an 'A' setting on a Pentax dSLR The lens in question, a nifty SMC Pentax-F 35-80mm f4-5.6, has been attached to my Pentax K-50 for several days (and will be for several more, weather permitting). I have the lens working properly in Manual mode by following the instructions that came with the camera's manual, and pressing the green button to get through-the-lens metering before every shot. This operation is essentially no different from my fully manual 50mm prime.But on the 35-80mm there are electrical contacts which suggests some kind of data transmission is occurring between lens and camera. So, is it really possible to change the lens' aperture using one of the wheels on the camera body? If so, how? I've had experience with both DA and M lenses before, but this one seems a bit different from both. For one, the camera's rear LCD shows F-- (just like with an SMC-M), but f5.6 is always written to the EXIF, regardless of the aperture ring setting.

09-10-2015, 04:03 PM - 1 Like	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Originally posted by Ex-Camera the camera's rear LCD shows F-- It shouldn't, if the aperture ring is set to "A". If you still see F--, try cleaning the contacts. If the problem persists the lens is defective. In any case, keep the aperture ring set to "A" and pretend it's a DA lens, because everything works in exactly the same way. You can use the e-dials to change the shutter speed/aperture in all 4 shooting modes. Originally posted by Ex-Camera . I have the lens working properly in Manual mode by following the instructions that came with the camera's manual, and pressing the green button to get through-the-lens metering before every shot. This procedure is only necessary with manual lenses. 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 purchasing one of our Pentax eBooks. 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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09-10-2015, 04:01 PM - 1 Like	#2
vonBaloney Pentaxian Join Date: Oct 2011 Location: Albuquerque, NM Posts: 6,029	Put the aperture ring on 'A' (use the little button to get it into that position and it should stay locked in until you push the button to get it out). Then it will work exactly like any newer DA lens -- autofocus, all camera modes, metering, etc...

09-10-2015, 04:06 PM - 1 Like	#4
Rimfiredude Veteran Member Join Date: Oct 2014 Location: Washington Photos: Gallery Posts: 2,176	Put the lens on A and and use Aperture Priority. The wheel on the camera will work to set the aperture.

09-10-2015, 05:58 PM	#5
Ex-Camera New Member Join Date: Sep 2015 Photos: Gallery Posts: 7 Original Poster	Dialing in the 'A' setting did the trick. Funny, but I thought the ring was already turned to A, but following advice and pressing the little button at the side of the lens got it all the way there. Kinda silly of me. Ugh. A big thanks to everyone!