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Thread: A 12.5mm Cosmicar that needs no machining

  1. #1
    Senior Member RichA's Avatar
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    A 12.5mm Cosmicar that needs no machining

    Unfortunately, it is f1.9 and not f1.4 like my other one.




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    Senior Member kds315's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Is this the one Vivek modified to a non vignetting lens?

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    Super Duper
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    Re: A 12.5mm Cosmicar that needs no machining

    Nope.

    This is the lens that Ranger9 posted about, a long time ago, in this forum. I have a sample of this (bought after Ranger's post). Its coverage is even less than that of the 12.5/f1.4's though the illumination is about the same.

    The one I modified to have full coverage is a Fujinon-TV CF12.5A 12.5mm f/1.4 lens.

    ( I tried to make a post on that:http://forum.getdpi.com/forum/showthread.php?t=12689 never finished. Will get to it sometime.

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    Senior Member kds315's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Thanks, I will have a look into this.

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    Member hodad66's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    looks interesting.....
    http://hodad66.com Sony A7r,A7II, Sony 70-300G, Rokinon 14/2.8, Leitz Wetzler 35/3.5, Leica R Summicron 50/2 & Elmarit 90mm/2.8, Contax N 24-85 & 70--200mm AND Canon FD 20/2.8, 135/2, 500mm 4.5, Minolta 35/1.8, 45mm/2, Nikon 28-50/3.5, 105/1.8, 180/2.8

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    Member hodad66's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Just got mine in but waiting for c mount adapter.......
    just ordered rear "c mount" cap and am looking for
    a front cap. Does 27mm sound right?
    http://hodad66.com Sony A7r,A7II, Sony 70-300G, Rokinon 14/2.8, Leitz Wetzler 35/3.5, Leica R Summicron 50/2 & Elmarit 90mm/2.8, Contax N 24-85 & 70--200mm AND Canon FD 20/2.8, 135/2, 500mm 4.5, Minolta 35/1.8, 45mm/2, Nikon 28-50/3.5, 105/1.8, 180/2.8

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    Member hodad66's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    From the first set of shots..... cropped of course.....

    http://hodad66.com Sony A7r,A7II, Sony 70-300G, Rokinon 14/2.8, Leitz Wetzler 35/3.5, Leica R Summicron 50/2 & Elmarit 90mm/2.8, Contax N 24-85 & 70--200mm AND Canon FD 20/2.8, 135/2, 500mm 4.5, Minolta 35/1.8, 45mm/2, Nikon 28-50/3.5, 105/1.8, 180/2.8

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    Member sangio's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    I was looking at buying a 12.5 Cosmicar 1.4; the price seems reasonable. Could someone please explain what machining is necessary to mount this lens on a G1?

    I assume a C-mount adapter is needed as well.

    Many thanks
    Santo

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    Senior Member RichA's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Quote Originally Posted by hodad66 View Post
    From the first set of shots..... cropped of course.....
    Nice shot and nice-looking cat!

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    Member hodad66's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Quote Originally Posted by sangio View Post
    I was looking at buying a 12.5 Cosmicar 1.4; the price seems reasonable. Could someone please explain what machining is necessary to mount this lens on a G1?

    I assume a C-mount adapter is needed as well.

    Many thanks
    Santo
    From what I've read a bevel needs to be run around the
    base so that it will screw further into the adapter
    thereby allowing infinity focus......

    See HERE
    Last edited by hodad66; 28th January 2010 at 19:05.
    http://hodad66.com Sony A7r,A7II, Sony 70-300G, Rokinon 14/2.8, Leitz Wetzler 35/3.5, Leica R Summicron 50/2 & Elmarit 90mm/2.8, Contax N 24-85 & 70--200mm AND Canon FD 20/2.8, 135/2, 500mm 4.5, Minolta 35/1.8, 45mm/2, Nikon 28-50/3.5, 105/1.8, 180/2.8

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    Member sangio's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Quote Originally Posted by hodad66 View Post
    From what I've read a bevel needs to be run around the
    base so that it will screw further into the adapter
    thereby allowing infinity focus......

    See HERE
    Thank you for the link, the comments in there were very useful.

    regards
    Santo

  12. #12
    Senior Member RichA's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Quote Originally Posted by sangio View Post
    I was looking at buying a 12.5 Cosmicar 1.4; the price seems reasonable. Could someone please explain what machining is necessary to mount this lens on a G1?

    I assume a C-mount adapter is needed as well.

    Many thanks
    Santo
    In case anyone is looking for one, Surplusshed.com is still offering that lens for only $25.00. The tricky part is that you have to carefully lathe or file the edge, taking care not to cut into the screw holes that hold the mount on the lens.

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    Member sangio's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Quote Originally Posted by RichA View Post
    In case anyone is looking for one, Surplusshed.com is still offering that lens for only $25.00. The tricky part is that you have to carefully lathe or file the edge, taking care not to cut into the screw holes that hold the mount on the lens.
    Thanks Rich.

    Can anyone tell me what the maximum distance this lens will focus to without machining? I would be using it mostly indoors so infinity focus isn't a big issue. And at a FL of 12.5 mm, the hyperfocal distance is about 4.3 feet at F8, so sharpness at infinity might be OK for non-critical use.

    Actually, for $25 there's not a lot of money at risk even if it doesn't work out.

    regards
    Santo

  14. #14
    Senior Member RichA's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Quote Originally Posted by sangio View Post
    Thanks Rich.

    Can anyone tell me what the maximum distance this lens will focus to without machining? I would be using it mostly indoors so infinity focus isn't a big issue. And at a FL of 12.5 mm, the hyperfocal distance is about 4.3 feet at F8, so sharpness at infinity might be OK for non-critical use.

    Actually, for $25 there's not a lot of money at risk even if it doesn't work out.

    regards
    Santo
    Alas, about 2" is the max focus distance with the lens at infinity with no machining.

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    Member kai.e.g.'s Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Santo, I have a Cosmicar 12.5mm f/1.2, and the answer is: "not very far". Before I machined* it, I recall being able to focus on objects no further than about 7 ~ 8 inches away at best when wide open. I wasn't able to achieve decent focus even at f/16.

    EDIT: RichA is probably closer to the truth with his 2 inch estimate. I only tried it once before setting to work on "machining" it. It certainly wasn't a useable distance for me!

    Cheers,
    Kai


    * machining = I turned myself into a human lathe: by using the reaming tool of a Swiss Army Knife held down with my right hand on a cookbook about 1.5 inches high, and then spinning the lens manually with my left hand upon a soft cloth, scraping it against the cutter for a few hours (with lots of breaks in between!)

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    Member hodad66's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    If you get the 1.9 (mine had no caps) the filter size is 43mm...
    http://hodad66.com Sony A7r,A7II, Sony 70-300G, Rokinon 14/2.8, Leitz Wetzler 35/3.5, Leica R Summicron 50/2 & Elmarit 90mm/2.8, Contax N 24-85 & 70--200mm AND Canon FD 20/2.8, 135/2, 500mm 4.5, Minolta 35/1.8, 45mm/2, Nikon 28-50/3.5, 105/1.8, 180/2.8

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    Member hodad66's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining





    G1, Cosmicar 12.5/1.9
    http://hodad66.com Sony A7r,A7II, Sony 70-300G, Rokinon 14/2.8, Leitz Wetzler 35/3.5, Leica R Summicron 50/2 & Elmarit 90mm/2.8, Contax N 24-85 & 70--200mm AND Canon FD 20/2.8, 135/2, 500mm 4.5, Minolta 35/1.8, 45mm/2, Nikon 28-50/3.5, 105/1.8, 180/2.8

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    Senior Member RichA's Avatar
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    What a poser that cat is!

    A prima-donna if ever I saw one.

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    Re: A 12.5mm Cosmicar that needs no machining

    Got an idea of what the 'effective' focal length would be after cropping to remove the vignetting?

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    Member hodad66's Avatar
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    Re: A 12.5mm Cosmicar that needs no machining

    Quote Originally Posted by PeterB666 View Post
    Got an idea of what the 'effective' focal length would be after cropping to remove the vignetting?
    I've been wondering that myself but have no idea. I have
    no other WA to compare it to......... other than an 8mm fish...
    http://hodad66.com Sony A7r,A7II, Sony 70-300G, Rokinon 14/2.8, Leitz Wetzler 35/3.5, Leica R Summicron 50/2 & Elmarit 90mm/2.8, Contax N 24-85 & 70--200mm AND Canon FD 20/2.8, 135/2, 500mm 4.5, Minolta 35/1.8, 45mm/2, Nikon 28-50/3.5, 105/1.8, 180/2.8

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