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Thread: Is this backfocussing?

  1. #21
    Member/Tangshooter
    Join Date
    May 2006
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    ClubSNAP Community
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    3,118

    Default Re: Is this backfocussing?

    Quote Originally Posted by raptor84
    I dont think it is since the main target is still in focus. The DOF seems to be moving back cause you alredy mentioned you are at the MINIMUM focuing disance so anything nearere will confir be OOF right? Try testing again slightly farther away?

    Perhaps when you did your shots you recomposed so they became OOF?
    Pls read again raptor84 post. U r using a 70-300 min. focusing distance is at least 1.5m..in order to have a fair test..u should measure at least 3m from ur focal plane to ur subject..so when stopping down ur aperture u will get a uniformity in sharpness for front and back..whereas at min. focusing distance u won't get anything sharp in front regardless how much u stop down..
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  2. #22

    Default Re: Is this backfocussing?

    Quote Originally Posted by blazer_workz View Post
    Pls read again raptor84 post. U r using a 70-300 min. focusing distance is at least 1.5m..in order to have a fair test..u should measure at least 3m from ur focal plane to ur subject..so when stopping down ur aperture u will get a uniformity in sharpness for front and back..whereas at min. focusing distance u won't get anything sharp in front regardless how much u stop down..
    That statement is not true. You should still be able to get something in front sharp if your DOF can accomodate. The min focusing distance is only mechanical.

  3. #23

    Default Re: Is this backfocussing?

    Quote Originally Posted by wong1979 View Post
    Looks OK to me this time.

  4. #24

    Default Re: Is this backfocussing?

    Hi wong1979,

    you mentioned you shot at AROUND 45 degrees. I am afraid you have to make sure that that camera is indeed EXACTLY 45 degrees to begin with cos a slight variation will affect the results by quite a fair bit. (Use a spirit level meter of something)



    Quote Originally Posted by wong1979 View Post
    I hv tried shooting on a planar text at around 45 degrees at F/11. Most of the time, it appears that the top line is sharper. Maybe the above test is flawed somewhere, but I was pretty sure that the selected text was in focus all the way. I'll try again.

  5. #25

    Default Re: Is this backfocussing?

    Thks for taking the time to provide the useful info. Perhaps it could be due to varying sharpness at different F-stops.
    But it does seems as though my centre sharpness is not good. Maybe that led me thinking that the focal point have shifted back as the F-stop goes up

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