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Thread: 6 1/2 x 8 1/2 (full-plate?) Extreme Wide Angle

  1. #1

    6 1/2 x 8 1/2 (full-plate?) Extreme Wide Angle

    I assume this lens is for Full Plate. I won it on ebay and it doesn't seem to have a makers name. It has aperture stops on a wheel and I am finding out if they are of the American or European progression. I have't yet got a figure for the max aperture.
    What focal length in mm are we talking about for the diagonal of a full plate?
    As to the optical design.....

  2. #2
    All metric sizes to 24x30 Ole Tjugen's Avatar
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    Re: 6 1/2 x 8 1/2 Extreme Wide Angle

    The image diagonal is about 10 1/2", or 265mm or so.

    "Extreme wide angle" often means that the image angle is greater than 90°. That corresponds to a focal length of 132.5mm assuming 265mm image circle (at 90°, coverage is 2x focal length).

    Assuming the intended coverage is 100° the focal length is at least 113.3mm. More than 100° was often specified, but rarely realistic.

    So at a rough guess, what you've bought is an Extreme WA Rectilinear, 5" focal length, f:16.

    Or something like that...

  3. #3

    Re: 6 1/2 x 8 1/2 Extreme Wide Angle

    It is definitely f16 max aperture, the wheel stops being marked in the Uniform System.
    Would a European maker have marked their lens stops thus for export to the US/
    This creature is anonymous, no makers name or that of a supplier. The only engraving being "6 1/2 x 8 1/2 Extreme Wide Angle" and the marks on the stops.
    Is this lens American or European?? If the lens were European would the maker have supplied it with the lens barrel & flange in a metric thread form or European?
    It may be the only way of establishing a place of origin.

  4. #4
    All metric sizes to 24x30 Ole Tjugen's Avatar
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    Re: 6 1/2 x 8 1/2 Extreme Wide Angle

    If you look at the thread dimensions for Compound shutters, you'll have an idea about the probability of European makers using metric threads...

    The aperture numbers could well be US, but I wouldn't quite discount Stolze either - Stolze 16 is f:12.5, doubling with each stop just like the US.

  5. #5

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    Re: 6 1/2 x 8 1/2 (full-plate?) Extreme Wide Angle

    "US" doesn't mean United States, it stands for Uniform System. The (British) Royal Photographic Society pushed for its use for awhile.

  6. #6

    Re: 6 1/2 x 8 1/2 (full-plate?) Extreme Wide Angle

    Were anonymous lenses a common thing?
    I would have thought that a optical manufacturer with any pride in their products would want to put their name to them.
    From browsing that auction site I have seen lenses with both a makers name and another which may be a distributor or a camera maker they were supplied with.

  7. #7
    All metric sizes to 24x30 Ole Tjugen's Avatar
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    Re: 6 1/2 x 8 1/2 (full-plate?) Extreme Wide Angle

    Anonymous lenses were very common. So were otherwise anonymous lenses marked with a retailer's, camera manufacturer's or importer's name.

    The most famous lens makers of a century ago are, not surprisingly, those who marked their lenses...

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