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Thread: Focal Reducers

  1. #1
    Join Date
    Apr 2006
    Northland, New Zealand
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    Default Focal Reducers

    New topic.
    Focal Reducers have been around for many years for telescopes, but now I see they're becoming extremely popular for adapting full frame, even medium format lenses to e.g. M4/3 cameras. Other combinations as well, but my interest is in the M4/3 option.
    More specifically, it seems that they could be an excellent tool for increasing the light gathering power of a lens for astrophotography ( I might abbreviate that to AP, its a long, slow word to type, especially with just two fingers).
    Searching eBay gives a quite bewildering array of options, and prices. Searching Google also gives a wide range of opinions, but not much in specific details such as sharpness, distortion etc.
    So, does anyone on this forum have any experience, information, opinions which would be applicable to AP ?
    Twin E-620/70-300mm/14-42mm/pinhole lens, plus 8mm FE, Tokina AT-X 90mm macro, and Zeiss 500/8 mirror.

  2. #2
    Join Date
    Jun 2008
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    Default Re: Focal Reducers

    The Metabones SpeedBooster seems to be quite popular, but from what I have heard, you loose a fair amount of sharpness in exchange for some speed. Stands to reason. Just like TCs, unless they are specifically designed for one particular lens they are going to bugger up the whole optical formula. DSLR lenses are SO complicated with so many elements, it doesn't take much. A good ED APO triplet telescope is so simple that field flatteners and focal reducers work well enough, but I have my doubts about the kind made one size fits all for SLR lenses. That said.... never tried one myself, so maybe I should keep my trap shut.

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