K-mount adapters for Pentax new-mount cameras

Started 11 months ago | Discussions thread
TacticDesigns Veteran Member • Posts: 6,045
Another adapter variant . . . no motors + focus aid switch

Anders_Nilsson wrote:

Like Alex says - it has been done by Sony.

Also, the adapter could use a bulge in a strategic place (like Sony LA/EA4) to fit the AF motor for screw drive. A simpler version could do without. remember, Sony produced 4 versions, APS-C, FF, with and without PDAF so 4 variants.


Another variant for a Pentax K-mount to hypothetical mirrorless camera is one that does not have a motor to AF old lenses with screw drive, and also does not have a motor to actuate the aperture lever on K-mount lenses with an aperture lever.

So, basically an adapter specifically for manual focus Pentax-M and Pentax-A lenses.

Just random thinking here . . .

. . . with mirrorless, would it be possible to just let the lens stop down as your turn the aperture dial on the lens.

(For lenses that don't have an aperture dial, a dial on the adapter would let you open up and close down the aperture.)

The camera then takes a light reading on the stopped down lens for exposure calculation. And then just brightens up the EVF or rear screen to make composing possible? Basically a WYSIWYG way of displaying the scene.

To help with manual focusing . . . there could be a lever on the right side of this adapter that you press with your middle finger on your right hand. Sort of like the opposite of a DOF preview button. So when you press this focus aid switch, it opens up the lens so that you can focus with the lens at the shallowest depth of field.

This switch could be locked into position so that you can just concentrate on focusing. And then be release for the actual picture.

But this switch could also be pushed and held to focus, and then just released to take the picture. Locking is an option, not a requirement.

I don't know if it is required for the camera to know if the focus aid switch is pressed or not. The benefit of knowing is so it knows that the light reading is not valid and thus not spend energy taking a reading. But I guess it could be possible to ignore this and just taking light readings all the time and adjust the ISO and shutter speed continuously.

Hey . . . maybe even bring in one for m42 auto lenses? So when you press the focus aid switch it would activate the auto aperture pin of the auto m42 lenses.

Take care & Happy Shooting!

There is a Nikon F inc manual aperture control for Sony E mount so handing the manual aperture lever should not the that difficult.

The Pentax adapter would not use a pellicle mirror so i guess ODPDAF in the MILC would have to be able to interface with screw drive AF.

A more gung-ho adapter could use a helicoil focuser for old MF lenses and switches on the barrel to quickly set focal length as well as sensing aperture set but I doubt such an adapter would emerge though it has been made for Leica M to (i think) Canon.

Even more insane would be an adapter with a built in mirror and OVF that mates to a MILC body but now we are leaving the solar system. I think the Zeiss Olympia used such a system in the 1930's.

But the real question is - can Pentax and Tokina together design and produce quality MILC lenses that are substantially cheaper than Sony? If so, they might be able to stay viable in the market.

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