What Makes a Lens a Petzval?

Discussion in 'Large Format Cameras and Accessories' started by Fotoguy20d, Dec 30, 2008.

  1. Fotoguy20d

    Fotoguy20d Subscriber

    Messages:
    1,234
    Joined:
    Jan 23, 2008
    Location:
    NJ
    Shooter:
    4x5 Format
    I've seen old brass lens listed as being petzval lenses. What makes a lens a petzval and what makes it special?

    Thanks,
    Dan
     
  2. Q.G.

    Q.G. Inactive

    Messages:
    5,682
    Joined:
    Jul 23, 2007
    Location:
    Netherlands
    Shooter:
    Medium Format
    A Petzval lens is a very old, very simple lens design, consisting of two positive doublets, one on each side of the aperture.
    Decent image quality, but over a limited field. And for its period (mid 19th century), very fast.

    What realy made it special - its claim to fame - is that it was one of (or perhaps the) first lenses that were calculated, and not just made up relying on experience and craftmanship.

    Being rather simple - thus cheap -, fast, and pretty good, it was popular for a while.
     
  3. jimgalli

    jimgalli Subscriber

    Messages:
    3,571
    Joined:
    Sep 7, 2002
    Location:
    Tonopah Neva
    Shooter:
    ULarge Format
    The Petzval was designed in 1840 and is generally considered to be the first mathematically designed lens. There's a good page about them here. The design has a signature effect of extreme center sharpness that is very shallow and falls off to excellent oof bokeh. Pushed beyond their design constraints they get the additional effect of swirlyness out in the far edges which people seem to like. The signature effect really lends itself to portraiture where the sharp center is all you really need to draw attention to your subject.
     
  4. brian d

    brian d Member

    Messages:
    396
    Joined:
    Jan 30, 2008
    Location:
    Indiana
    Shooter:
    Multi Format
    Just look at mr. Galli's work and you will see what makes it special
     
  5. smieglitz

    smieglitz Member

    Messages:
    1,941
    Joined:
    Oct 18, 2002
    Location:
    Climax, Michigan
    Shooter:
    Large Format
    Probably should mention that just because a brass lens is old, that doesn't make it a Petzval. There were other designs such as Rapid Rectilinears, etc., that were contemporary with Petzvals and look similar externally.

    Petzvals exhibit a certain roundness and three-dimensionality in the way they render images and this, along with their great speed made them desirable for portraiture.
     
  6. jimgalli

    jimgalli Subscriber

    Messages:
    3,571
    Joined:
    Sep 7, 2002
    Location:
    Tonopah Neva
    Shooter:
    ULarge Format
    A very nice thing to say. Thanks!