Finally, a camera lens compressor

Discussion in 'Digital Photography' started by RichA, Jan 15, 2013.

  1. RichA

    RichA Guest

    RichA, Jan 15, 2013
    #1
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  2. RichA

    RichA Guest

    On Jan 14, 11:30 pm, RichA <> wrote:
    > They've had high-end lens compressors for telescopes for over 20
    > years, while all we've really seen from camera lens makers are
    > extenders.
    >
    > http://www.dpreview.com/news/2013/01/14/metabones-and-caldwell-photog...


    I'd just like to elaborate. Telescope telecompressors typically
    reduce effective focal lengths and ratios by 30-50%. So, for example,
    a 1000mm f/10 telescope used in conjunction with a compressor would
    become effectively a 700mm f/7.0 or a 500mm f/5.0. Some of the
    telescope compressors also provide field flattening effects.
    RichA, Jan 15, 2013
    #2
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  3. RichA

    Martin Brown Guest

    On 15/01/2013 04:33, RichA wrote:
    > On Jan 14, 11:30 pm, RichA <> wrote:
    >> They've had high-end lens compressors for telescopes for over 20
    >> years, while all we've really seen from camera lens makers are
    >> extenders.
    >>
    >> http://www.dpreview.com/news/2013/01/14/metabones-and-caldwell-photog...


    The big challenge to do it for a camera lens is that there is
    essentially no additional back focus to play with. The design has to be
    very thin and also well corrected to be useful hence the insane price.

    A telescope has a lot of back focus and you can simply alter the focus
    setting after putting a chunky field flattenr or telecompressor into the
    optical train. A camera lens will barely focus at infinity or very
    slightly beyond to cater for near IR imaging.
    >
    > I'd just like to elaborate. Telescope telecompressors typically
    > reduce effective focal lengths and ratios by 30-50%. So, for example,
    > a 1000mm f/10 telescope used in conjunction with a compressor would
    > become effectively a 700mm f/7.0 or a 500mm f/5.0. Some of the
    > telescope compressors also provide field flattening effects.


    The two most common ones are 0.63x by Celestron and Meade. The available
    backfocus on a catadioptric scope allows considerable leeway in adding
    drift length the enhance the magnification/compression effect with some
    minor loss in quality. The limits on my scope are detailed at:

    http://www.nezumi.demon.co.uk/astro/zoom/zoom.htm

    Getting a compressor to focus at all in a photographic setting with the
    limited adjustment available on a normal lens is quite a trick. But I
    doubt if many people will stump up $600 for the novelty value.

    --
    Regards,
    Martin Brown
    Martin Brown, Jan 15, 2013
    #3
  4. RichA

    RichA Guest

    On Jan 15, 2:41 am, Martin Brown <|||>
    wrote:
    > On 15/01/2013 04:33, RichA wrote:
    >
    > > On Jan 14, 11:30 pm, RichA <> wrote:
    > >> They've had high-end lens compressors for telescopes for over 20
    > >> years, while all we've really seen from camera lens makers are
    > >> extenders.

    >
    > >>http://www.dpreview.com/news/2013/01/14/metabones-and-caldwell-photog....

    >
    > The big challenge to do it for a camera lens is that there is
    > essentially no additional back focus to play with. The design has to be
    > very thin and also well corrected to be useful hence the insane price.
    >
    > A telescope has a lot of back focus and you can simply alter the focus
    > setting after putting a chunky field flattenr or telecompressor into the
    > optical train. A camera lens will barely focus at infinity or very
    > slightly beyond to cater for near IR imaging.
    >
    >
    >
    > > I'd just like to elaborate.  Telescope telecompressors typically
    > > reduce effective focal lengths and ratios by 30-50%.  So, for example,
    > > a 1000mm f/10 telescope used in conjunction with a compressor would
    > > become effectively a 700mm f/7.0 or a 500mm f/5.0.  Some of the
    > > telescope compressors also provide field flattening effects.

    >
    > The two most common ones are 0.63x by Celestron and Meade. The available
    > backfocus on a catadioptric scope allows considerable leeway in adding
    > drift length the enhance the magnification/compression effect with some
    > minor loss in quality. The limits on my scope are detailed at:
    >
    > http://www.nezumi.demon.co.uk/astro/zoom/zoom.htm
    >
    > Getting a compressor to focus at all in a photographic setting with the
    > limited adjustment available on a normal lens is quite a trick. But I
    > doubt if many people will stump up $600 for the novelty value.
    >
    > --
    > Regards,
    > Martin Brown


    Some of the telescope varieties (from APM) cost $700 each. But $600
    is a lot until you begin comparing it to the cost of adding a wide
    angle lens of any quality to your bag.
    RichA, Jan 15, 2013
    #4
  5. RichA <> writes:

    > They've had high-end lens compressors for telescopes for over 20
    > years, while all we've really seen from camera lens makers are
    > extenders.
    >
    > http://www.dpreview.com/news/2013/0...d-booster-lens-adapter-for-mirrirless-cameras


    Not really possible for most lenses on their intended lens mounts
    because of distance issues, you know. This is possible for putting
    other mount lenses on Micro Four Thirds because there's room for it.

    --
    Googleproofaddress(account:dd-b provider:dd-b domain:net)
    Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
    Photos: http://dd-b.net/photography/gallery/
    Dragaera: http://dragaera.info
    David Dyer-Bennet, Jan 15, 2013
    #5
  6. RichA

    otter Guest

    On Jan 14, 10:30 pm, RichA <> wrote:
    > They've had high-end lens compressors for telescopes for over 20
    > years, while all we've really seen from camera lens makers are
    > extenders.
    >
    > http://www.dpreview.com/news/2013/01/14/metabones-and-caldwell-photog...


    This is neat! The white paper is definitely worth a look, too:
    http://www.metabones.com/images/metabones/Speed Booster White Paper.pdf

    I've been disappointed in the image quality of mirrorless cameras like
    the Sony NEX compared to full frame, but this could change things.
    otter, Jan 17, 2013
    #6
  7. RichA

    RichA Guest

    On Jan 17, 4:42 am, otter <> wrote:
    > On Jan 14, 10:30 pm, RichA <> wrote:
    >
    > > They've had high-end lens compressors for telescopes for over 20
    > > years, while all we've really seen from camera lens makers are
    > > extenders.

    >
    > >http://www.dpreview.com/news/2013/01/14/metabones-and-caldwell-photog...

    >
    > This is neat!  The white paper is definitely worth a look, too:http://www.metabones.com/images/metabones/Speed Booster White P...
    >
    > I've been disappointed in the image quality of mirrorless cameras like
    > the Sony NEX compared to full frame, but this could change things.


    You have to be specific about what is wrong with the NEX images
    compared to the FF.
    RichA, Jan 19, 2013
    #7
  8. RichA

    RichA Guest

    On Jan 15, 1:42 pm, David Dyer-Bennet <> wrote:
    > RichA <> writes:
    > > They've had high-end lens compressors for telescopes for over 20
    > > years, while all we've really seen from camera lens makers are
    > > extenders.

    >
    > >http://www.dpreview.com/news/2013/01/14/metabones-and-caldwell-photog...

    >
    > Not really possible for most lenses on their intended lens mounts
    > because of distance issues, you know.  This is possible for putting
    > other mount lenses on Micro Four Thirds because there's room for it.
    >


    I've been trying to think of a way around the issue, and I don't think
    there is one. The mentioned white paper say there is no way to do it.
    Making the lens into a shorter focal length results in a shallower
    light cone that won't reach the sensor, as you said.
    The "tack-on" cheapies from outfits like Raynox that people can screw
    into the filter end of camera lenses are pretty dreadful optically, no
    matter if they are compressive or telephoto. In telescopes, the
    compressors typically add some colour fringing, except for the most
    expensive ones.
    For now, wide angle camera imaging needs a wide angle lens. But, for
    the users of NEX, m4/3rds, etc., they can double the "size" of their
    lens collection without increasing bulk much by using that
    compressor.
    RichA, Jan 19, 2013
    #8
  9. RichA

    otter Guest

    On Jan 18, 6:29 pm, RichA <> wrote:
    > On Jan 17, 4:42 am, otter <> wrote:
    >
    > > On Jan 14, 10:30 pm, RichA <> wrote:

    >
    > > > They've had high-end lens compressors for telescopes for over 20
    > > > years, while all we've really seen from camera lens makers are
    > > > extenders.

    >
    > > >http://www.dpreview.com/news/2013/01/14/metabones-and-caldwell-photog....

    >
    > > This is neat!  The white paper is definitely worth a look, too:http://www.metabones.com/images/metabones/Speed Booster White P...

    >
    > > I've been disappointed in the image quality of mirrorless cameras like
    > > the Sony NEX compared to full frame, but this could change things.

    >
    > You have to be specific about what is wrong with the NEX images
    > compared to the FF.


    No, I'm not going to get into a pissing war over cameras. It is just
    my preference, that's all. The NEX is a fine camera, but not for me.
    Sorry if it seemed like I was putting it down.
    otter, Jan 19, 2013
    #9
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