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Thread: Rapid Angulaire Lens

  1. #1

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    Rapid Angulaire Lens

    I just received this lens its a 4 inch lens approximately 35mm high and 40mm wide for the body,
    Like a fool I did not check to see if the wheel for stops had numbers , well it does not have any
    numbers on the rotary stops wheel, is there a simple way too figure out the apertures on this wheel

    please no geometry or other fancy calculations only 8 Th grade educated

    the largest hole is 10mm
    next largest is 8mm
    next is i think 4mm
    next is i think 2mm

    thanks for the help
    Attached Thumbnails Attached Thumbnails 8-06-12-3-.jpg   8-06-12-57.jpg   8-20-12-8240013.jpg  
    Lauren MacIntosh

    Whats in back of you is the past and whats in front of you is the future now in the middle you have choices to make for yourself:

  2. #2
    Vitaliy AK
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    Re: Rapid Angulaire Lens

    You mean F-numbers?

    Focal length / diameter of aperture = F number.

    e.g. you have 100mm (4 inches) FL, biggest hole is 10mm -
    100/10 = 10 (so, this one will be F/10)
    next aperture has is 8mm diameter -
    100/8 = 12,5 (this one F/12,5)
    etc...

  3. #3

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    Re: Rapid Angulaire Lens

    An "F10" is a bit unrealistic for this type, so a check of the focal length is called for!
    The "Martin" must be a retail outlet. The engraving distribution on the barrel is very similar to early Berthiot wide angles and casket sets, so they may have used them as a model or even as a source.

  4. #4

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    Re: Rapid Angulaire Lens

    How the lack of a front lens escaped me - I have no idea!
    These wide landscape type are typically around F11.

  5. #5

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    Re: Rapid Angulaire Lens

    Steve: the front lens is next to the it, I removed the lens so as to show the F-stop's
    on the wheel better


    Quote Originally Posted by Steven Tribe View Post
    How the lack of a front lens escaped me - I have no idea!
    These wide landscape type are typically around F11.
    Lauren MacIntosh

    Whats in back of you is the past and whats in front of you is the future now in the middle you have choices to make for yourself:

  6. #6

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    Re: Rapid Angulaire Lens

    So could I safely think that F-11 would be the largest opening and
    the next would F-16 and then F-22 and then F-32 for testing purpose
    just for testing purpose's
    Lauren MacIntosh

    Whats in back of you is the past and whats in front of you is the future now in the middle you have choices to make for yourself:

  7. #7

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    Re: Rapid Angulaire Lens

    It is quite unusual (but very useful for "alternative" photography!) to have an f stop outside the manufacturer's recommended limit.
    Otherwise they are all F16, F15, F16 etc.
    The presence of the F10 stop could be a suggestion from the maker that the rear achromat could be used as alone with its much longer focal length - but, of course, no longer F10! There were plenty of casket aplanat sets from France which were dual single/double cell recommended.

    I suddenly remember that I sold a similar anon. wide angle aplanat a few months ago. This had illogical F values for the different size holes. It is obvious (now!)that some of these values refered to normal use and some for the use of the rear cell only! And I thought it was because of a drunken engraver!

  8. #8
    All metric sizes to 24x30 Ole Tjugen's Avatar
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    Re: Rapid Angulaire Lens

    If the holes are 10, 8, 4 and 2mm and the focal length is 100mm, then the apertures are as follows:

    100/10 = 10
    100/8 = 12.5
    100/4 = 25
    100/2 = 50

    So f:10, f:12.5, f:25, and f:50.

    Do not assume that old lenses will have apertures in the "standard modern series" - f:8, f:11, f:16, f:22 and so on. There were many different "series" in se, and many do not even follow THOSE!

    French lens makers seem to have had a preference for this series, ending at a nice even f:100. The 12.5, 25, 50 is rather common.

  9. #9

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    Re: Rapid Angulaire Lens

    thank you very much Ole. well that should be fun with a Light meter, the funny part is this lens could almost fit in a watch pocket
    thanks again Ole :


    Quote Originally Posted by Ole Tjugen View Post
    If the holes are 10, 8, 4 and 2mm and the focal length is 100mm, then the apertures are as follows:

    100/10 = 10
    100/8 = 12.5
    100/4 = 25
    100/2 = 50

    So f:10, f:12.5, f:25, and f:50.

    Do not assume that old lenses will have apertures in the "standard modern series" - f:8, f:11, f:16, f:22 and so on. There were many different "series" in se, and many do not even follow THOSE!

    French lens makers seem to have had a preference for this series, ending at a nice even f:100. The 12.5, 25, 50 is rather common.
    Lauren MacIntosh

    Whats in back of you is the past and whats in front of you is the future now in the middle you have choices to make for yourself:

  10. #10

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    Re: Rapid Angulaire Lens

    If you have a Weston Master, it has a lot of the "other" f-stops on the dial. Even if it does'nt work any more, just set the Weston to agree with your working meter, than read off the exposure at-or-close to your f-stops on the rotary wheel stops.
    Quote Originally Posted by seawolf66 View Post
    thank you very much Ole. well that should be fun with a Light meter, the funny part is this lens could almost fit in a watch pocket
    thanks again Ole :

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