Lens Mounts (AF/KAF2)

jeagle · 04-08-2009, 04:14 PM

Hello all
This may seem like a silly question, but if you don't ask then you may never find the answer.
I am looking a purchasing a new lens (either Tamron or Sigma) for my K20D. Question is that these lenses have an compatible Pentax AF mount which I know will fit the KAF2 mount, but will any of the functions (auto/manual focus, M, TAv, Av, etc) be restricted or limited with lenses that have an AF mount.

Any assistance is greatly appreciated

Cheers
Glenn

jglover · 04-08-2009, 05:34 PM

No, they should work just fine.

jeagle · 04-08-2009, 06:19 PM

Thank you John

Marc Sabatella · 04-09-2009, 12:15 PM

In theory someone could probably create an AF lens that lacked auto-exposure (ability to work with the various modes like P, Av, Tv, etc). But as far as I know, there exists no lens like that. All auto focus lenses for Pentax are also auto exposure. The reverse is *not* true - there are lenses that have auto-exposure functionality but not AF. Those include all lenses marked "Pentax-A" or that list their mount type as PKA (I think). In practice, I don't think there are too many of those out there aside from the Pentax-A lenses, but there are a few at least.

res3567 · 04-12-2009, 04:33 PM

Originally posted by Marc Sabatella

In theory someone could probably create an AF lens that lacked auto-exposure (ability to work with the various modes like P, Av, Tv, etc). But as far as I know, there exists no lens like that. All auto focus lenses for Pentax are also auto exposure. The reverse is *not* true - there are lenses that have auto-exposure functionality but not AF. Those include all lenses marked "Pentax-A" or that list their mount type as PKA (I think). In practice, I don't think there are too many of those out there aside from the Pentax-A lenses, but there are a few at least.

Yes. I have a KA 75-200 f4.5. Is a MF lens with AE functions. It is a push pull design and is one of my favorates.

04-08-2009, 04:14 PM	#1
jeagle Guest	Lens Mounts (AF/KAF2) Hello all This may seem like a silly question, but if you don't ask then you may never find the answer. I am looking a purchasing a new lens (either Tamron or Sigma) for my K20D. Question is that these lenses have an compatible Pentax AF mount which I know will fit the KAF2 mount, but will any of the functions (auto/manual focus, M, TAv, Av, etc) be restricted or limited with lenses that have an AF mount. Any assistance is greatly appreciated Cheers Glenn

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04-08-2009, 05:34 PM	#2
jglover Forum Member Join Date: Nov 2008 Location: Chicago, IL Posts: 98	No, they should work just fine.

04-09-2009, 12:15 PM	#4
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	In theory someone could probably create an AF lens that lacked auto-exposure (ability to work with the various modes like P, Av, Tv, etc). But as far as I know, there exists no lens like that. All auto focus lenses for Pentax are also auto exposure. The reverse is not true - there are lenses that have auto-exposure functionality but not AF. Those include all lenses marked "Pentax-A" or that list their mount type as PKA (I think). In practice, I don't think there are too many of those out there aside from the Pentax-A lenses, but there are a few at least.

04-12-2009, 04:33 PM	#5
res3567 Veteran Member Join Date: Sep 2008 Location: Houston Tx. Photos: Gallery Posts: 1,876	Originally posted by Marc Sabatella In theory someone could probably create an AF lens that lacked auto-exposure (ability to work with the various modes like P, Av, Tv, etc). But as far as I know, there exists no lens like that. All auto focus lenses for Pentax are also auto exposure. The reverse is not true - there are lenses that have auto-exposure functionality but not AF. Those include all lenses marked "Pentax-A" or that list their mount type as PKA (I think). In practice, I don't think there are too many of those out there aside from the Pentax-A lenses, but there are a few at least. Yes. I have a KA 75-200 f4.5. Is a MF lens with AE functions. It is a push pull design and is one of my favorates.