Usability of Achromats?

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

  1. Hermes07

    Hermes07 Member

    Apr 24, 2010
    London, Engl
    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.