Usability of Achromats?

Discussion in 'Ultra Large Format Cameras and Accessories' started by Hermes07, Aug 9, 2011.

  1. Hermes07

    Hermes07 Member

    Messages:
    14
    Joined:
    Apr 24, 2010
    Location:
    London, Engl
    Shooter:
    8x10 Format
    Title says it all really. Huge formats obviously mean long focal lengths - in some cases longer than you can find proper compound lenses in. Large achromats on the other hand are available in the 1800-3000mm range and not too expensive in modest diameters.

    What sort of usable coverage can you expect from them?

    Is stopping them down necessary to have any chance of a reasonably sharp picture (just talking basic contact printing standards here)?

    How about using them with smaller formats that just use the central few degrees of the lens' coverage - similar to the way they were designed to be used with telescopes?

    Would love to hear the thoughts of anyone who's tried this, before I go sending a few hundred dollars off to China for something that could turn out to be completely useless.