Results 1 to 2 of 2

Thread: A couple of lens technical questions

  1. #1

    Join Date
    Dec 2006
    Posts
    953

    A couple of lens technical questions

    Question #1)
    I have an 12" rapid rectilinear with waterhouse stops that sit in the center of the lens between the two equal elements. I recently bought a front-mounted shutter. I have roughly calculated the fstops for the waterhouse stops. However, if I instead use the iris on the front mounted shutter do I need to calculate the fstops differently with the iris forward of the front element than when it was between the two?

    Question #2)
    I have a convertible f5 petzval. When the rear element is reversed and placed on the front of the shutter alone, it becomes roughly an f8 lens (and surprisingly sharp at that). However, with the rear element mounted alone, is the depth-of-field now; a) identical to the original pair at f5, b) equivalent to the original pair at f8?, or c) something else?

  2. #2

    Join Date
    Sep 2003
    Location
    Harbor City, California
    Posts
    1,748

    Re: A couple of lens technical questions

    #1. Using the diaphragm of the front-mounted shutter is not a good idea. It will cause vignetting.

    #2. Something else. The DOF will now be governed by the focal length and aperture of the rear element alone.

Similar Threads

  1. My stupid lens question.
    By e. a. smith in forum Lenses & Lens Accessories
    Replies: 30
    Last Post: 20-Mar-2007, 15:54
  2. Lens viewing angles
    By swmcl in forum Lenses & Lens Accessories
    Replies: 23
    Last Post: 6-Nov-2006, 14:01
  3. Can bellows "stretch" lens?
    By Ken Grooms in forum Cameras & Camera Accessories
    Replies: 19
    Last Post: 25-Oct-2006, 19:35
  4. Installing a packard shutter
    By Mark_3632 in forum Lenses & Lens Accessories
    Replies: 11
    Last Post: 27-Sep-2004, 08:35
  5. Replies: 11
    Last Post: 2-Jan-2002, 22:22

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •