K-mount adapters for Pentax new-mount cameras

Started 11 months ago | Discussions thread
Barry Pearson
OP Barry Pearson Veteran Member • Posts: 8,723
Re: Something to think about...

Alex Sarbu wrote:

The D FA* 50mm required an unprecedentedly (at least, for Pentax) tight construction.

It was found - late in the process - that the barrel couldn't properly support the heavy front group, which led to a slight but significant misalignment - impacting the optical performance.

Long story short, they solved that issue with special support components. Also, the lens mount has "the highest number of screws ever used" - for structural rigidity.

What would happen when you add an adapter? Can it be rigid enough? I believe Lloyd Chambers warned about adapters introducing such misalignments.

Where might the problems lie?

Between the lens and the adapter, or
Between the adapter and the camera when the adapter has this lens attached?

For interest, I've tested the D FA* 50mm f/1.4 attached to the Pentax DA 1.4x Rear Converter, which I think is a comparable case:

Using the Pentax 1.4x Rear Converter on K-1-series

While the image quality was poor, I didn't notice a rigidity problem. And if all the components are under the control of Pentax, we can hope they do a good job!

I would like to have a tripod mount for this lens. The tripod bush on the K-1-series is about 38mm behind the lens mount, which makes the whole combination "unconvincing" (to put it mildly) on a tripod.

The (old) Canon M-mount adapter, and the (new) Nikon FTZ adapter, have extensions downward to the base-level of the cameras. Those extensions have 1/4" tripod bushes.

If a (hypothetical) Pentax new-mount to K-mount adapter did likewise, that would move the tripod bush more than 40mm towards the lens, perhaps 50mm or more. That would provide a better balance on a tripod. The whole of the camera would be behind the tripod bush.

(The new Canon RF adapters don't have tripod bushes).

 Barry Pearson's gear list:Barry Pearson's gear list
Ricoh WG-6 Panasonic LX100 Ricoh GR III Pentax K-7 Pentax K-3 II +27 more
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