Pentax mirrorless should retain K-mount. Here's how it can still be competitive with new mounts.

Started Oct 22, 2019 | Discussions thread
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Prognathous Veteran Member • Posts: 9,322
Pentax mirrorless should retain K-mount. Here's how it can still be competitive with new mounts.

They should retain K-mount for backward compatibility, but support shorter-flange for a new line of designed-for-mirrorless lenses. Here are a couple of options, both of which retain backward compatibility to existing K-mount lenses without losing infinity and without the need for an adapter.

Option 1 (which I already suggested previously on this forum) - expanding/collapsing lens mount (adjustable flange). With two modes:

  • Collapsed mode with new "for-mirrorless" lenses. In this mode the mount is closer to the sensor (similar to Sony E-mount or m43) and requires new lenses, designed-for-mirrorless.
  • Expanded mode with current K-mount lenses. In this mode the mount is in the same distance from the sensor as K-mount DSLRs, and for all intent is identical to K-mount. This would allow the camera to use current K-mount lenses without an adapter.


  • Support for legacy K-mount lenses when the mount is expanded (long flange) + support for newer lenses designed for when the mount is collapsed (shorter flange)
  • The body remains compact when new designed-for-mirrorless lenses are used
  • Possibly may be used to provide AF with MF lenses (by moving the lens closer or farther from the sensor)
  • Option to get better macro with new designed-for-mirrorless lenses (by moving the lens farther from the sensor, losing infinity but gaining shorter focus distance)
  • As a result of the last two points - potential to provide support for SLR/DSLR lenses of other brands (e.g. Canon EF mount, Nikon F mount) with AF.


  • Challenging to engineer a mechanism that expands/collapses the mount and is sturdy, accurate and not too heavy

Option 2. An internal optical group (in the body) that, when needed, slides between the legacy K-mount lens and the sensor to adjust for the shorter flange


  • Support for legacy K-mount lenses + newer lenses designed for the shorter flange
  • The body always remains compact
  • Possibly may be used to enhance stabilization if this optical group can move to compensate for shake (OIS)


  • Adjusting focus to infinity this way may be impossible to achieve. Did I mention I'm not an engineer?
  • Optical quality with legacy lenses will be reduced to some degree

In any case, providing built-in support for existing lenses without compromising size is a very attractive feature that would make Pentax mirrorless cameras unique. Hopefully if they do it they'll include an EVF and let someone other than Marc Newson design the camera.

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