Third-party lenses and Focus point selection

khenna · 03-27-2015, 11:36 AM

Hello

I'm on the brink of buying a K-50 but still wondering about the focus point selection
with the Sigma 17-50 f2.8
According to the manual of the K-50 (p105): The focus point selection mode is fixed to [Spot: The center of the viewfinder] regardless of this setting when using lenses other than DA, DA L, D FA, FA J, FA or F lenses. To me this means that the focus point can not be changed for a third-party lens. Somehow I must be wrong as in this thread https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/210420-k-30-focus-se...-question.html the focus point can be changed for a Sigma 70mm f2.8. (Manuals of th K-30 and the K-50 are the same about this subject)

Does the manual mean something completely different and if so how?

Regards
khenna

enoeske · 03-27-2015, 11:52 AM

Originally posted by khenna

Hello

I'm on the brink of buying a K-50 but still wondering about the focus point selection
with the Sigma 17-50 f2.8
According to the manual of the K-50 (p105): The focus point selection mode is fixed to [Spot: The center of the viewfinder] regardless of this setting when using lenses other than DA, DA L, D FA, FA J, FA or F lenses. To me this means that the focus point can not be changed for a third-party lens. Somehow I must be wrong as in this thread https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/210420-k-30-focus-se...-question.html the focus point can be changed for a Sigma 70mm f2.8. (Manuals of th K-30 and the K-50 are the same about this subject)

Does the manual mean something completely different and if so how?

Regards
khenna

Pentax does not list what third party lenses work with their camera because its not their product or responsibility to ensure that other peoples' lenses work on their camera.

However, as long as the camera has autofocus and can transmit exposure data to the camera body, then the focus points should move as expected.

stevebrot · 03-27-2015, 11:58 AM

The short answer is Yes, the Sigma should support all AF and exposure modes on your camera. The distinction is between AF lenses and manual focus lenses. With manual focus lenses, there is no AF (duh), but the camera does support focus confirmation using the AF system. In that case, only the center focus point is available.

There are a few things that the K-50 will not support with non-Pentax glass (e.g. automatic lens correction and MTF program line), but overall the level of compatibility is very high.

Steve

03-27-2015, 11:36 AM	#1
khenna New Member Join Date: Nov 2013 Posts: 12	Third-party lenses and Focus point selection Hello I'm on the brink of buying a K-50 but still wondering about the focus point selection with the Sigma 17-50 f2.8 According to the manual of the K-50 (p105): The focus point selection mode is fixed to [Spot: The center of the viewfinder] regardless of this setting when using lenses other than DA, DA L, D FA, FA J, FA or F lenses. To me this means that the focus point can not be changed for a third-party lens. Somehow I must be wrong as in this thread https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/210420-k-30-focus-se...-question.html the focus point can be changed for a Sigma 70mm f2.8. (Manuals of th K-30 and the K-50 are the same about this subject) Does the manual mean something completely different and if so how? Regards khenna

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pentax Medium Format Third Party Resources II: T/S-lenses (Tilt and/or shift lenses)	veraikon	Pentax Medium Format	3	04-29-2017 12:39 PM
focus point selection	Norman Rodewald	Visitors' Center	4	04-23-2014 07:18 AM
Third party lenses that don't focus in the wrong direction?	whojammyflip	Pentax SLR Lens Discussion	2	06-21-2010 05:08 AM
Third party lenses that don't focus in the wrong direction?	LittleSkink	Pentax SLR Lens Discussion	6	09-02-2008 10:14 AM

03-27-2015, 11:52 AM	#2
enoeske Veteran Member Join Date: Jul 2009 Location: Surprise, Az Photos: Gallery Posts: 2,136	Originally posted by khenna Hello I'm on the brink of buying a K-50 but still wondering about the focus point selection with the Sigma 17-50 f2.8 According to the manual of the K-50 (p105): The focus point selection mode is fixed to [Spot: The center of the viewfinder] regardless of this setting when using lenses other than DA, DA L, D FA, FA J, FA or F lenses. To me this means that the focus point can not be changed for a third-party lens. Somehow I must be wrong as in this thread https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/210420-k-30-focus-se...-question.html the focus point can be changed for a Sigma 70mm f2.8. (Manuals of th K-30 and the K-50 are the same about this subject) Does the manual mean something completely different and if so how? Regards khenna Pentax does not list what third party lenses work with their camera because its not their product or responsibility to ensure that other peoples' lenses work on their camera. However, as long as the camera has autofocus and can transmit exposure data to the camera body, then the focus points should move as expected.

03-27-2015, 11:58 AM	#3
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	The short answer is Yes, the Sigma should support all AF and exposure modes on your camera. The distinction is between AF lenses and manual focus lenses. With manual focus lenses, there is no AF (duh), but the camera does support focus confirmation using the AF system. In that case, only the center focus point is available. There are a few things that the K-50 will not support with non-Pentax glass (e.g. automatic lens correction and MTF program line), but overall the level of compatibility is very high. Steve