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08-01-2016, 08:39 PM   #1
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K -> Q question

Hello,

I have a quick question about adapting K mount AF lenses to Q mount.

Has anyone ever checked the AF pin signals of both K & Q mount to see if they match?

This has probably been investigated some time ago, but its also possible it was not.

I see that the canon EF-M and EF mounts use the same electrical signals so that only a simple pass-thru mount adapter is needed to AF with EF mount lenses when mounted on an EF-M camera. Maybe the nikon 1 series is like this as well.

It would be great to have AF with K mount lenses on the Q mount camers. Maybe if the signals are different someone has worked out an electrical translation circuit to allow for AF of K on Q mount. Any news on that?

Thanks
K

08-01-2016, 09:11 PM   #2
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The spec is bound to be different as the K mount uses just a single contact for data transmission. The many other contacts are a really basic way of transmitting the maximum aperture to film cameras with auto aperture support. The only reason DSLRs still have them (correct me if I'm wrong) is to support A-series lenses, which can't be identified electronically.

I haven't heard of any plans for an AF Q adapter. Power drain would likely make this very challenging, also.

Adam
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08-01-2016, 09:29 PM   #3
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QuoteOriginally posted by Adam Quote
The spec is bound to be different as the K mount uses just a single contact for data transmission. The many other contacts are a really basic way of transmitting the maximum aperture to film cameras with auto aperture support. The only reason DSLRs still have them (correct me if I'm wrong) is to support A-series lenses, which can't be identified electronically.

I haven't heard of any plans for an AF Q adapter. Power drain would likely make this very challenging, also.

Thanks for the reply. That's very interesting about the K mount data transmission specification. So now, in 2016, with the K1 and other cameras on their way, an archaic one-pin lens-to-body data channel is still in use??? Maybe Pentax needs to do more than minor updates to the K mount specification. Maybe this has something to do with their AF lagging the so-called "major players."

About the Q mount, it could be that the pin-out of it is compatible with K mount, with the extra pins being dummies or extra ground connections. I agree that its not likely, but have you seen the Q pin-out assignments? I wonder what they are and if it is an entirely new design or if there is a continuation of the K mount in a modified form. I find these things interesting in and of themselves.

About the already abysmal battery life, it would be even worse with a larger lens, though that wouldn't deter me from trying to rig something up if a simple circuit is all that's requires.

K
08-01-2016, 09:53 PM   #4
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QuoteOriginally posted by Adam Quote
The only reason DSLRs still have them (correct me if I'm wrong) is to support A-series lenses, which can't be identified electronically.
Perhaps this is so but why do they still put the pins (other than the "A" and "data") on lenses. Without an aperture ring the lenses aren't completely supported on "A" cameras.

08-01-2016, 10:04 PM - 1 Like   #5
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QuoteOriginally posted by Not a Number Quote
Perhaps this is so but why do they still put the pins (other than the "A" and "data") on lenses. Without an aperture ring the lenses aren't completely supported on "A" cameras.
They can be used just fine on A-series film bodies or newer, though the image circle might not fully cover the frame with a DA lens. For example, you can use the DA 50mm F1.8 on the Super Program or MZ-S, but you can't change the aperture manually. On the PZ-1, however, you can change it manually using e-dials.

QuoteOriginally posted by krema Quote
Thanks for the reply. That's very interesting about the K mount data transmission specification. So now, in 2016, with the K1 and other cameras on their way, an archaic one-pin lens-to-body data channel is still in use??? Maybe Pentax needs to do more than minor updates to the K mount specification. Maybe this has something to do with their AF lagging the so-called "major players."
You can read up on the spec here:
The Evolution of the Pentax K-mount - Articles and Tips | PentaxForums.com

This article includes an overview of what each contact does on different variants of the K-mount.

I'm not sure the interface is the limitation, it's more likely that the AF modules and motors are to blame.

Adam
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08-01-2016, 10:52 PM   #6
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A single pin serial interface can move a lot of data.
08-11-2016, 11:27 PM   #7
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An af Pk to Q adapter would be great. Power wouldn't have to be a problem. Just build a larger battery in the base of the adapter.
Thanks
barondla
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