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Thread: Hermagis image size

  1. #1

    Join Date
    Jun 2006
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    Brazil
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    139

    Hermagis image size

    hello,

    I have an old Hermagis Portrait lens, Petzval type, marked as Nš 5. I checked that it focus infinity at ~300 mm (12 inches) from image to the Waterhouse stop slot. It is quite big: 8 inches tall and lenses have a bit more than 3 inches diameter. I am planning to build up a wood camera for wet plate with it and my question is: what is the maximum plate size this lens will cover?

    Thanks for any insight about it


    Wagner

  2. #2

    Join Date
    Sep 2007
    Location
    AZ
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    3,862

    Re: Hermagis image size

    It would probably be a good 5x7 lens, and would also cover Wholeplate but you'd have to check how well.

  3. #3

    Join Date
    Jan 2009
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    Denmark
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    5,278

    Re: Hermagis image size

    Basically, this lens is the same size as the Dallmeyer 3b and the Ross cabinet no. 3 and lots of others with the same speed. With whole plate, the image at edges and corners will definitely be degraded.

  4. #4

    Join Date
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    Re: Hermagis image size

    Click image for larger version. 

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    Thanks for your input. Meanwhile I decided to check it out also experimentally (quick and dirty). Some adhesive tape, cooking paper, cardboard, blanket and a side table. Conclusion: at infinity the image circle for a Hermagis Nš 5, Petval design, serial number 46.559, is around 28cm. Well, whole plate is 8 x 10" or 20 x 25 cm square root of 400+625 is 32 cm, not 28. So not enough for 8 x 10". At least in landscape photos. But this is a portrait lens, so I assume it is intended to work at a greater distance from film and hence get a larger image circle than at infinity. Am I right? I could not check this possibility yet. I need to wait tomorrow when the sun will lit my curtains. Otherwise I get a image that is too dim to assess its diameter.

  5. #5

    Join Date
    Nov 2007
    Posts
    181

    Re: Hermagis image size

    whole plate is not 8x10".
    and yes, you're right, it will cover more at portrait distances. but it will still be too wide for a good portrait perspective on 8x10".

  6. #6

    Join Date
    Jun 2006
    Location
    Brazil
    Posts
    139

    Re: Hermagis image size

    Yes, good point. 300 mm is like "normal" lens for 8 x 10. I will think about it. Thanks.

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