w w w . i n d i a w i l d s . c o m
home
about Sabyasachi Patra
diary
forums
image gallery
contact IndiaWilds
Home
About
Diary
Forums
Gallery
ContactUs

User Tag List

Results 1 to 4 of 4

Thread: about DOF

  1. #1
    Join Date
    19-08-09
    Location
    Satara, Maharashtra
    Posts
    1,283
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default about DOF

    Will there be any difference in DOF of 400mm,5.6 at f/5.6 and after addition of 1.4 t.c. resulting f/8?
    Dr.Jitendra Katre

  2. #2
    Join Date
    24-11-08
    Location
    New Delhi
    Posts
    16,591
    Mentioned
    0 Post(s)
    Tagged
    2 Thread(s)

    Default

    Yes.

    Depth of field is dependent on focal length, aperture as well as distance of the subject.

    When you attach a 1.4x TC to the 400mm f5.6 lens, the resulting combination is 560 mm f8. The depth of field will become much narrower.

  3. #3
    Join Date
    19-08-09
    Location
    Satara, Maharashtra
    Posts
    1,283
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    thanks Sabyasachi, but after attachment of t.c., will there be any physical change in diaphragm ?
    Dr.Jitendra Katre

  4. #4
    Join Date
    20-06-11
    Location
    Goa
    Posts
    736
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    Hi Jitendra,

    There is no change in diaphragm when you add a TC. F stop is the ratio of focal length and size of the lens opening.

    for example, lets consider 400 f5.6 lens

    When wide open i.e. at f5.6, the lens opening is around 71.5mm

    F stop = 400/71.5 = 5.6 (approx.)

    when we add the TC the focal length increases. 560mm for 1.4x. The diaphragm and the lens opening remains the same.

    F stop = 560/71.5 = 8 (approx.)

    This is how we get 560mm f8 with 1.4x. Similar is the case with 2x TC.

    Hope this clarifies your doubt.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

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