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Thread: random lenses on G1

  1. #1
    PeterLeyssens
    Guest

    random lenses on G1

    Hi,

    I've been following the threads about mounting cine and other lenses on the G1 with great interest. I've been thinking about mft for its portability, but experiments with optics make the system that much more interesting !

    So, I was looking around on eBay for a few lenses and now I'm bewildered. I've seen lenses from 4,5mm to 450mm and nothing makes sense anymore

    There's 3 things that I'm confused about:
    1) Systems with sensors smaller than mft: using a tele lens as a wide angle ?

    Suppose I take a lens for a super8 camera or something even smaller. Let's say for this system, a standard lens (which is comparable to a 50mm on a film caera or 25mm mft) is 5mm. Suppose I find a 10mm lens, then it would be a tele on that system. If I mount it on mft, the 10mm focal distance is a wide angle of 20mm EFV. What happens ?

    2) Systems with much larger sensors: using a wide angle lens as a tele

    Suppose I get a Schneider 65 f8 Super Angulon, which is a lens for a 4x5 field camera that compares to an 18mm super wide on a 35mm film camera. On the mft, it would turn out to be a 130mm EFV tele ! What happens ?
    (just forgetting for a moment that it'd be hell to try and mount it and that it also has its own shutter... just the lens principles)

    3) I find a lot of weird lenses for projectors, microscopes, ... Can I use these ?

    Finally, Ive seen a chart of coverage of several cine lenses (how many mm image circle, compared to 22 for mft) somewhere but I don't find it anymore. Thanks for pointing me there, and thanks for all the fun in this forum !


    Peter.

  2. #2
    milapse
    Guest

    Re: random lenses on G1

    I'm confused by your question!

    I'm sure someone can chime in on the 'equivalent' concept but there is not really a wide/tele flop... The lens image circle and focal length are what determines the 'result' on the micro fourthirds.

    1.your 8mm lens will throw about a 12mm IC so you'll get ALL the FOV but tons of vignette.

    2.yes technically that's what happens but I assume mounting a 4x5 would be futile and full of ghosts due to all that light bouncing around in there!

    3.yes technically you could use any lens on any camera if your willing to Macgyver it together:


    ...16mm lens chart for mFT...
    A. Image circles:
    Last edited by milapse; 17th May 2009 at 05:43.

  3. #3
    PeterLeyssens
    Guest

    Re: random lenses on G1

    Quote Originally Posted by milapse View Post
    I'm sure someone can chime in on the 'equivalent' concept but there is not really a wide/tele flop... The lens image circle and focal length are what determines the 'result' on the micro fourthirds.
    The reason why I'm asking is the following. Say, we have the Angulon 65mm 4x5 lens. Because its purpose is wide angle on 4x5, the front lens will be quite curved to capture all that light coming in from a 100 degree field of view. On mft, we won't be using the 100 degrees, because a 65mm mft lens only has a field of view of under 20 degrees !

    On the other hand, suppose we have a 1/4" camera lens that is 10mm focal length. It is a tele, comparable with the 35mm Sigma lens for 4/3 cameras or a 70mm on a film camera. The FOV is something like 35 degrees. If we mount it on our mft camera, the 10mm is a very wide angle lens of about 95 degrees FOV, so it should have a curved front element like the Angulon !

    I know that theoretically, the only parameters is really the FOV that the lens will give on mft. But practically, a lens has been designed for one size of "sensor" or film and for the FOV that it will provide for that film size. So I'm wondering what will happen when mounting lenses for extremely different film sizes onto mft



    Quote Originally Posted by milapse View Post
    1.your 8mm lens will throw about a 12mm IC so you'll get ALL the FOV but tons of vignette.
    OK, because the film size of the (say, 1/4" CCTV) lens is too small to cover the mft sensor, it will give me everything I want, but on a too small surface on the mft sensor. Understood.


    Quote Originally Posted by milapse View Post
    2.yes technically that's what happens but I assume mounting a 4x5 would be futile and full of ghosts due to all that light bouncing around in there!
    Well, even if we forget about all the practical mounting issues... Suppose I have a way to mount this angulon lens so that it focuses, gives no ghosts etc.

    The angulon lens has a 100 degree FOV on 4x5 inch. Will I just get a cut-out of the angulon image ? So, will the G1 just show that bit in the middle that happens to fall on its sensor ?


    Quote Originally Posted by milapse View Post
    3.yes technically you could use any lens on any camera if your willing to Macgyver it together:
    Cool ! Where is my duck tape ?


    Peter.

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