Lens coverage question

Discussion in 'Large Format Cameras and Accessories' started by Peter Schrager, Jul 27, 2010.

  1. Peter Schrager

    Peter Schrager Subscriber

    Messages:
    2,069
    Joined:
    Jul 19, 2004
    Location:
    fairfield co
    Shooter:
    Large Format
    I have a beautiful Wollensak Aprochromatic 15 inch lens in barrel and want to know the coverage of this lens...this is before I contact Sk Grimes about putting it into a shutter ....thank you in advance
    Best, Peter
     
  2. John Kasaian

    John Kasaian Member

    Messages:
    1,030
    Joined:
    Sep 24, 2002
    Theres lots of links on the Large Format Photography Home Page to tables with lens data.
     
  3. jbbooks

    jbbooks Member

    Messages:
    173
    Joined:
    Apr 15, 2005
    Shooter:
    Multi Format
  4. Dan Fromm

    Dan Fromm Member

    Messages:
    4,133
    Joined:
    Mar 23, 2005
    Shooter:
    Multi Format
    The general rule with process lenses is: if a G-Claron, 68 degrees, else if not engraved "wide angle", 45 degrees, else 68 degrees.

    There are exceptions. For example, some users claim that Konica Hexanon GRIIs cover more than 68 degrees. And as can be seen here http://www.cameraeccentric.com/html/info/wollensak_2.html y'r Wolly probably covers even less. Remember that the circle covered at infinity is half the circle covered at 1:1.
     
    Last edited by a moderator: Jul 29, 2010
  5. Alan Davenport

    Alan Davenport Member

    Messages:
    91
    Joined:
    Jul 23, 2003
    Location:
    Portland - O
    Shooter:
    Large Format
    Peter,

    I understand these can be had pretty reasonably priced and used for general purpose large format work. The problem with published coverage figures for apo lenses is that they assume you are going to use them for critical process work. If you intend to use this for 8x10 contact landscape work you will find that the useful coverage is more than that published. I use a 210 mm Reproclaron for 5x7 landscape and for contact printing and it has way more useful coverage than advertised.

    Your best bet is to put it on an 8x10 camera(if that is what you are going to be using it for?) and see where the vignetting occurs and see how far out the useful (sharp) field extends. How far towards the vignette does it lose its "edge". A 7x magnifier works well for this. I've done this on a couple of lenses for my 8x10. A 120mm SuperAngulon and a 16.5 cm Angulon. They gave sharp images farther out than expected.

    Alan
     
  6. steven_e007

    steven_e007 Member

    Messages:
    829
    Joined:
    Mar 13, 2007
    Location:
    Shropshire,
    Shooter:
    Multi Format
    I've noticed that when a lens is being sold the seller often boasts about a much bigger field of coverage than the manufacturer specified!

    There is a difference between the size of the maximum circle of light you can see on the film (which will fall off progressively towards the edge) - the circle of light which falls off to an 'acceptable level' as defined by different manufacturers' criteria - and the circle of acceptable sharpness, again judged by some criteria relevant to the application - which can be quite tight for a process lens. Big Tessars, for example, often produce a circle of light much greater than the coverage quoted by the manufacturer, as the sharpness falls away long before the brightness does....

    I'd stick your lens on the biggest camera you have, use cross movement or rising front to get as much 'edge' on the film as possible and take a picture with it. Decide yourself at what point the sharpness ceases to be acceptable.