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Thread: My Cycle Poco 5x7 is Very Excited...

  1. #1

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    My Cycle Poco 5x7 is Very Excited...

    about its new Lens Board Extender!

    It can now focus an 11" lens from 15-20' to infinity at f16!
    Attached Thumbnails Attached Thumbnails IMG_0258.JPG   IMG_0259.JPG   IMG_0265.JPG   IMG_0266.JPG  

  2. #2
    Tin Can's Avatar
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    Re: My Cycle Poco 5x7 is Very Excited...

    Good idea!

    I have a question, which way was the GG?
    sin eater

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    Re: My Cycle Poco 5x7 is Very Excited...

    The usual way--frosted side facing the lens, IIRC. It was made for plates, so I added a spacer to the GG frame for proper film holder T-depth and carved out a new rib lock channel for modern film holders. This is the No. 3. No extension, only 8 1/2" bellows. But extremely light weight--only 1lb 14oz w/o lens.
    Attached Thumbnails Attached Thumbnails IMG_0260.JPG   IMG_0261.JPG   IMG_0262.JPG   IMG_0263.JPG  

  4. #4
    Tin Can's Avatar
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    Re: My Cycle Poco 5x7 is Very Excited...

    Well, I now have 5 cycle cameras and all of them had GG to rear

    As 3 of them are almost unused, I now think GG backwards was done to make them a tiny bit smaller

    I am working on measurement to prove theory

    Very nice rig!
    sin eater

  5. #5

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    Re: My Cycle Poco 5x7 is Very Excited...

    If they were used for film, it is possible the GG was reversed to correct for the 1/16" difference in the T-depth surface of the film compared to the surface of the glass plate they were originally manufactured for.

    Thanks!

  6. #6
    Ron (Netherlands)'s Avatar
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    Re: My Cycle Poco 5x7 is Very Excited...

    Very nice device, but aren't the light rays - partly - not hindered by the funnel?
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    Re: My Cycle Poco 5x7 is Very Excited...

    Ron, you are correct--this wouldn't be possible with a shorter/wider angle lens...or a longer focal length lens. I'm using a Turner Reich Series II triple convertible lens, the 6 1/4'--11'--14' combination. The vignetting is terrible with the 6 1/4 combined focal length. But I designed this specifically for the 11" lens.

    Alas, I still cannot use the 14" lens as there would also be too much vignetting with it. The constraint is the 2 1/4" opening on the original lens board frame, which is reduced to 2" by the light trap on the inside of the extender box.

    The 11" fl is the "sweet spot" for this application. The 11" lens is mounted on the rear of the shutter. When the 11" lens is used solo, the 14" front lens is removed. So the focus point for the 11" lens is somewhat behind the shutter.

  8. #8

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    Re: My Cycle Poco 5x7 is Very Excited...

    Quote Originally Posted by Tin Can View Post
    Well, I now have 5 cycle cameras and all of them had GG to rear

    As 3 of them are almost unused, I now think GG backwards was done to make them a tiny bit smaller

    I am working on measurement to prove theory

    Very nice rig!
    I think the classic reason why many cycle cameras have the GG apparently mounted the wrong way is that they were used in the late "gentleman amateur photographer" era post 1900. The introduction of the revolutionary autochromes came around 1907. This system had the pigments/filters between the glass surface and the silver layer. The glass plates were mounted with sensitive coating away from the subject. In many cases, it would be more practical to reverse the GG to get the T distance correct. Perhaps the difficulties/expense of autochromes lead to an early retirement of cycle cameras?

  9. #9
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    Re: My Cycle Poco 5x7 is Very Excited...

    Steven, that is an excellent supposition and perhaps the answer I have been seeking

    They are lovely lightweight cameras!

    4 of them, the bellows are intact and usable, perhaps they were stored closed, even the leather outer decoration are in fine condition, after treatment

    The #9 is light and heat damaged, as it must have been stored open. The leather covering is brittle with glue failing, bellows on the verge of collapse. I will replace the bellows, glue the leather and condition

    All my plate holders are nearly unused, the #9 has no DDS wear internally

    Thank you

    Quote Originally Posted by Steven Tribe View Post
    I think the classic reason why many cycle cameras have the GG apparently mounted the wrong way is that they were used in the late "gentleman amateur photographer" era post 1900. The introduction of the revolutionary autochromes came around 1907. This system had the pigments/filters between the glass surface and the silver layer. The glass plates were mounted with sensitive coating away from the subject. In many cases, it would be more practical to reverse the GG to get the T distance correct. Perhaps the difficulties/expense of autochromes lead to an early retirement of cycle cameras?
    sin eater

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