K-mount adapters for Pentax new-mount cameras

Started 11 months ago | Discussions thread
Skip py Contributing Member • Posts: 846
Re: K-mount adapters for Pentax new-mount cameras

Barry Pearson wrote:

The new D FA* 50mm f/1.4 has no mechanical coupling. Quiet. Fast. All weather.

Still having an eye on this one but I already have the old F f/1.7, so ...

3. find a niche compatible with existing lenses and new PLM ones

If next Pentax can't focus my old lenses, then ... switch to Canon or Nikon or Sony. With such gems I'll manual focus as well (or even better) with other brands.

My two cents ...

Good, comfortable and weather sealed small bodies are the roots of Pentax, and they're probably working with this in mind today.

"Small" isn't my highest priority. (But see the photos at the end). And the size and weight of lenses needs to be taken into account. It is tricky to make a a light long FF lens.

But Nikon are using a Fresnel technique to make a significant improvement, so I am optimistic about the possibilities.

I still have the Canon 400mm f/5.6 just in case, but this one is really disturbing, especially with Z6 (or Z7) with an adapter making good use of such a lens ! If this adapter had a rear filter like Canon's one - and if I had the ca$h ! - I'd probably go with Nikon.

Not only would a comprehensive adapter be essential for Pentax, but I'm sure such a kit/bundle would be popular for people wanting to exploit all their existing K-mount lenses. Or to be able to buy new K-mount lenses to use on such a Pentax new-mount mirrorless camera.

Dreaming of using other mount lenses is a big plus with short registration, if Pentax or third party offer such an option. It reminds me of a small company providing a M mount camera (sort of)


The Canon "Drop-In Filter Mount Adapter EF-EOS R", which is currently offered with a "Variable neutral density filter" and a "Circular polarising filter", comes complete with a drop-in plain glass non-filter to use when not using the filters. I would expect it to avoid such a shift.

This Canon with Variable ND and CPL is really a great move. I'd like to know what are the caracteristics of drop-in replacement : thickness and index for equivalent optical path. It's common for lenses but I was refering to the shift needed for inbody filters : the body would have to be a little thicker. If IQ is good enough, using slimmer filters would be good for price, weight and body dimensions!

2. Tilt Shift adapter for Pentax's 645 lenses retaining AV/EV/AF capabilities would be a bless for landscape and architectural photographers: I guess that it's impossible with technologies available nowadays, at least at a reasonable cost?

I have no idea! I use the Samyang T-S 24mm F3.5 ED AS UMC .

I'm still using the old Pentax 28mm Shift lens but I'd be curious to see how Pentax/Ricoh could bring a competitor to ARAX TS adaptor for AF 645 lenses keeping autofocus and metering. Too specialised ? But what a challenge for engineers !

A switchable x1.4 TC would be nice to have too - like Canon's 200-400mm or Nikon's 180-400mm - but must be harder to design or incompatible with too many lenses ? I'd love to have one with the 150-450mm ... and switch it on occasions for that little more reach.

I was on a workshop with someone using that Canon lens. It is far too heavy for me! Nearly 4 kilograms, and a price that appears to be based on its weight in gold!

I'm currently experimenting with the Pentax DA 1.4x converter on the D FA 150-450mm lens.

That was exactly my point : a x1.4 TC you could leave (or not) on the body for occasional longer reach (switch on or off on the road). I like the crop mode with this lens for easier framing, but closer look is sometime a must.

Penalty of only 350g for a combo (rear filter + x1.4) seems fair ?

I'm optimistic on this one (121g for Canon's adapter with rear filter + 225g for the x1.4).

I'd gladly add it to my "walk-around system" : I mean the K-1'' + D FA 150-450mm

A few comparisons among my own camera bodies for amusement:

I like your comparison with Z1P and K-1 !

Some room for improvements...

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