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Thread: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

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    FotoResearch fotoresearch's Avatar
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    Question HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

    Welcome everyone,

    I just became the owner of this lens: HERMAGIS 440mm Aplanat No.4 Series II. // Serial number: 36070 //

    I have only one problem with it, on the lens iris - instead of the aperture markings I have the number markings

    1
    2
    4
    8
    16
    32
    64

    What aperture corresponds to these numbers?

    It is difficult for me to determine whether I should use the US or French measure
    How can you check it?

    Someone told me that the initial f value of my lens should be: focal lenght divided by the diameter.
    In my case it will be: 440mm / 60mm (about) = 7,33
    So should I assume that my lens start from f/8 and this is French system?

    Best
    Lukasz
    Lukasz Majewski www.fotoresearch.com

  2. #2
    Foamer
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    Re: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

    I'm going to assume that 1 means fully open, 2 means half as much light, 4 means a fourth as much light.......


    Kent in SD
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    Re: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help


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    Re: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

    Thank you for your answer.
    The material is interesting, it didn't give me an answer in 100% - straightforward, but at least I know in which direction I'm going.
    I will have to do some tests - I'm lucky that I have cheap mammography films - financially, the tests won't hurt.
    Lukasz Majewski www.fotoresearch.com

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    FotoResearch fotoresearch's Avatar
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    Re: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

    When I was looking for answers on the web, it was not explicitly stated where it meant ... so I will have to test
    Lukasz Majewski www.fotoresearch.com

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    Re: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

    Hi

    ".....focal lenght divided by the diameter......." of the width of the lens element/glass is exactly what I would be doing

    good luck and regards

    Andrew

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    Unwitting Thread Killer Ari's Avatar
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    Re: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

    I had the same query years back. All I remember was someone telling me "f/16 is f/16".
    I guess what he meant was that f/16 is the same in the US or standard system. The other stops you'll have to figure out.

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    Re: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

    Somewhere on the net I found this representation of value.

    Iris No | f value
    1 = f/10
    2 = f/14
    4 = f/20
    8 = f/28
    16 = f/40
    32 = f/56
    64 = f/81

    At the beginning I thought that my initial value of f is 8, .... but during the test on f / 9, and saw that the picture is underexposed.
    So it may turn out that the following values will match.

    Tomorrow tests for each aperture value.
    Lukasz Majewski www.fotoresearch.com

  9. #9

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    Re: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

    I found this on the internet some time ago and use it with my Hermagis lens.Click image for larger version. 

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    Re: HERMAGIS 440mm Aplanat No.4 Series II - and iris as f numbers - little help

    It is not that difficult to measure them: https://apenasimagens.com/en/measuring-lens-aperture/

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