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07-26-2014, 06:10 PM   #1
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Pentax needs to make an autofocus Q-PK adapter.

There is probably room for one more long reach tele lens in Q mount. Keeping the lens aperture bright enough to avoid diffraction is more difficult as the focal length goes up. This makes more expensive lenses which limits sales.

It would make sense for Pentax to make an AF Q-PK adapter. This way the expensive lenses could be shared between APS-c and the Q bodies. This would boost the sales of lenses like the 200 & 300 DA*and even the 55-300 zoom..

It is no secret that the inexpensive Q-PK adapters have cut into the sales of the Pentax oem adapter. The Pentax offers a leaf shutter, but it is tough to explain this advantage in a timely manner. An auto focus Q-PK adapter would offer users a large benefit that could be explained in one or two sentences.

The adapter would probably need a decent size battery built in. It would be great if a K3 or K50 battery could be used. Add a rotating tripod mount and it would be wonderful. The Q could become the ultra telephoto camera to beat. Imagine shooting birds in flight with the Q.
thanks
barondla

07-26-2014, 06:15 PM   #2
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QuoteOriginally posted by barondla Quote
There is probably room for one more long reach tele lens in Q mount. Keeping the lens aperture bright enough to avoid diffraction is more difficult as the focal length goes up. This makes more expensive lenses which limits sales.

It would make sense for Pentax to make an AF Q-PK adapter. This way the expensive lenses could be shared between APS-c and the Q bodies. This would boost the sales of lenses like the 200 & 300 DA*and even the 55-300 zoom..

It is no secret that the inexpensive Q-PK adapters have cut into the sales of the Pentax oem adapter. The Pentax offers a leaf shutter, but it is tough to explain this advantage in a timely manner. An auto focus Q-PK adapter would offer users a large benefit that could be explained in one or two sentences.

The adapter would probably need a decent size battery built in. It would be great if a K3 or K50 battery could be used. Add a rotating tripod mount and it would be wonderful. The Q could become the ultra telephoto camera to beat. Imagine shooting birds in flight with the Q.
thanks
barondla
they would need to build a shutter in the adapter, which they probably won't do, look at the way the adapter works, both end will be open to access. yes it would be easy to fix, but they will have to fix a ton of them due to user errors. The problem with the Q is that they got too cute and built the shutter in the lens.
07-26-2014, 06:55 PM - 1 Like   #3
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QuoteOriginally posted by clockwork247 Quote
they would need to build a shutter in the adapter, which they probably won't do, look at the way the adapter works, both end will be open to access. yes it would be easy to fix, but they will have to fix a ton of them due to user errors. The problem with the Q is that they got too cute and built the shutter in the lens.
The existing k2q pentax adapter has a shutter, I don't see an issue adding the contacts and circuitry to control AF lenses. Now adding an AF motor would be a little harder but the existing adapter is big enough to package everything but the battery and that could be under the adapter integrated into a tripod mount.
07-26-2014, 07:18 PM - 1 Like   #4
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While it would limit the number of useful lenses, the AF needn't necessarily have a screwdrive motor.

07-26-2014, 09:22 PM   #5
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Why not do it like the AF adapter Pentax had. You would refocus your lens, and then the adapter would then fine tune it and get it in focus, kinda like the 1.7 AF teleconverter does. This would be awesome for MF lenses too.
07-26-2014, 10:09 PM   #6
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QuoteOriginally posted by VoiceOfReason Quote
Why not do it like the AF adapter Pentax had. You would refocus your lens, and then the adapter would then fine tune it and get it in focus, kinda like the 1.7 AF teleconverter does. This would be awesome for MF lenses too.
Think this requires magnification optics in the adapter. The Q usually doesn't need more magnification with adapted lenses and it definetly doesn't need a smaller effective aperture. Diffraction is always a consideration with adapted lenses on a Q. Even the Pentax DA*300 performs best at f5.6. Add the 1.7X of the original K mount teleconverter and the aperture is over f9 on the 300. Sharpness will suffer. Would be neat if it worked.

I would give up AF on manual focus lenses, and screw drive AF lenses, to get in motor lenses to AF on a Q. This should be possible fairly easily. Don't know if the AF programing in Q lenses works the same as Kfa mount. If not, some electronics would be required in the adapter to translate.

thanks
barondla
07-27-2014, 03:45 AM   #7
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Could an AF function be added to a speed booster?
07-27-2014, 07:27 AM   #8
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QuoteOriginally posted by barondla Quote
Don't know if the AF programing in Q lenses works the same as Kfa mount. If not, some electronics would be required in the adapter to translate.
Don't forget power. Even if the voltages are the same, it's going to take more power to turn a larger and heavier lens - possibly more than the Q is designed to provide to the lens.

Also, if you are going to go to that much trouble for AF, wouldn't you want auto-aperture as well? That would require another motor to operate the aperture arm.

07-27-2014, 09:12 AM   #9
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QuoteOriginally posted by THoog Quote
Don't forget power. Even if the voltages are the same, it's going to take more power to turn a larger and heavier lens - possibly more than the Q is designed to provide to the lens.

Also, if you are going to go to that much trouble for AF, wouldn't you want auto-aperture as well? That would require another motor to operate the aperture arm.
AF adapter with its own power pack!
07-27-2014, 09:18 PM   #10
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Adding a screw drive motor may introduce a lot of torque that would have to be absorbed by the Q mount. The camera assembly with the adapter and lens would want to spin around the motor. That could cause damage. I would see internal DC motor focusing being a better option in terms of the mechanics although it would severely limit the range of AF lenses that could be used.

Don't get wrong. I'd be all over an AF Q/K adapter!
08-06-2014, 06:16 AM   #11
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I would pay very, very good money for an AF Q-PK adapter that worked with screw drive lenses. Aperture would be nice too, but AF is where it's at. Without AF, the Q-PK adapter is an expensive toy, but not of any real use to me -- which is why I have a Fotodiox adapter. It's a cheap toy, and let me play around with adapted lenses enough to figure out that yup, I still can't shoot manual focus worth a damn.

Charles.
08-06-2014, 07:17 AM   #12
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Seriously? Pentax can't even provide reasonably priced extension tube or a helicoid, let alone any that can DO that. IF they ever made it, it would be a $750 street priced item...
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