Pentax 18-55mm f/3.5-6.7 mirrorless APS-C lens patent

By PR admin | Published: June 8, 2012

Pentax filed a patent 2012-10830 in Japan for a 18-55mm f/3.5-6.7 lens (28-80mm equivalent) for APS-C mirrorless camera (like the K-01 or maybe for a new mirrorless model):

  • Patent release date: June 7, 2012
  • Patent filing date: October 17, 2010
  • Zoom ratio: 2.85x
  • Aperture: 3.6 - 6.7
  • Focal length: 18.60 - 53.00mm
  • Image height: 14.24mm
  • Back Focus: 3.00mm
  • 8 lens elements in 7 groups, 1 ED glass element, three aspherical elements

Related posts:

  1. Third mirrorless APS-C lens patent from Pentax: 16-55mm f/3.5-5.6
  2. Second mirrorless APS-C lens patent from Pentax: 18-70mm f/3.5-7.1
  3. Pentax patent for a 70-200mm f/2.8 lens
  4. Pentax 12-24mm f/3.5-4.5 lens patent
  5. Pentax files a patent for a DA 12-35mm f/3.5-4.5 AL WR SDM lens

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  • http://photo.stackexchange.com/users/4506 DragonLord

    f/6.7 is incredibly slow, but probably acceptable for mirrorless because contrast detection is not limited to a minimum aperture the way phase detection is. I’m worried, however, that this will seriously limit depth-of-field control and low-light performance.

    Notice how close the rear element is to the image plane–3mm back focus?!! This can only be an XS lens exclusively for mirrorless cameras. Are users willing to accept a slow lens for extreme compactness? I’m also concerned about how such a lens can be mounted–isn’t there a risk that the rear element will clash with the sensor or shutter assembly?

    • Warpig

      Indeed slow on the tele end. What surpriced me was the fact that already in 2010 they had the plan to build the K01, or a mirrorless with K-mount that uses the mirror space to conceal the lens. Smart move if you think so.
      I mean, the K01 is thick, very large compared to the NEX, the other APS-C mirrorless available, but both cameras work with lenses (obviously). So, as a system, not a camera, I think the K01 might be smaller than the NEX, as the latter only have 1 (mediocre) pancake and a few other big lenses. With the Pentax you got a bunch of lenses plus various pancakes.
      But any of these pancakes are zooms, newbies like zooms, but the kit 18-55 is too big (and it don’t look ‘cool’ on the camera either) but I think this lens is the answer to that.

    • Alex

      It’s “only” half a stop slower than the usual f/5.6. This is a kit lens, made to be as compact as possible; m4/3 has collapsible zooms, Samsung a compact 20-50, Sony… nothing yet. It could be interesting, but so far we’re only talking about a patent; no prototype, no real product rumour.
      We actually saw a prototype lens, K-mount with protruding rear element; however it wasn’t a zoom but a prime, and it couldn’t possibly reach 3mm back focus.

      Your concern about the aperture – there is an easy solution, just use a faster lens.

      Yes, I wonder if there’s room for a focal plane shutter…

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