Some mirrorless options for Pentax

Started Aug 25, 2018 | Discussions thread
Fogel70
Fogel70 Senior Member • Posts: 1,302
Re: Some mirrorless options for Pentax

Barry Pearson wrote:

Fogel70 wrote:

.... There is too much stuff inside the K-mount for this type of design. The power zoom connectors and mech aperture lever limit the diameter of the protruding part so much that the rear lens diameter would have to be too small to be able to protude the lens much into the mount.

The diameter of the protruding part would have to be limited to 20-25mm, so rear lens element could probably not be more than 15-18mm, so it would only be useful for slow lenses and you would have to keep a small rear lens like that far from the sensor to avoid limiting image quality. So it will not make much advantage on design, only disadvantage as these K-mount lenses would not be compatible with K-mount DSLR.

For information, on my D FA* 50mm f/1.4, once the standard lens mount connections have been accounted for, the remaining hole has a diameter of about 35mm.

That is the outer diameter of the rear of the tube that slides in and out when focusing. The rear element is a little less than that, about 30mm.

With rear lens element protruding into the lens mount you will need free space around the protruding part to avoid damaging lens or camera attaching and removing the lens. And if rear lens element is used for focusing it will mean more limitations as the focusing mechanism has to be fitted inside the protruding part too.

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Samsung GX-10 Pentax K-7 Sony Alpha NEX-7 Sony a7 Pentax K-3 II +17 more
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