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Thread: Aperture blade question

  1. #1

    Default Aperture blade question

    Hi guys, i have a used nikon 35-105mm F3.5-4.5 AIS manual nikkor. the other day i was looking through the lens to check for fungus and noticed that the aperture blades do not form a smooth opening from F3.5-F5.6. I mean, the blades should be forming a smooth shape and not have any jagged edges, right? is this normal?

  2. #2

    Default Re: Aperture blade question

    you mean it's heptagonal instead of perfect circle?

  3. #3

    Default Re: Aperture blade question

    its not a perfect circle. i know most lenses dont have aperture blades that form perfect circles unless there are many blades. its something like a polygonal shape but at the vertices or edges, the blades are jagged as in the edges protrude out.

  4. #4

    Default Re: Aperture blade question

    It's normal.

  5. #5
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    Default Re: Aperture blade question

    It all depends on the number of blade yr lens have. Usually to produce gd bokeh, should have at least 7 blades.
    Canon EOS 5D, 24-70 f/4 L IS, 50 f/1.2 L, 70-300 f/4-5.6 L IS, 600EX-RT. Sigma 12-24 f/4.5-5.6 EX.

  6. #6
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    Default Re: Aperture blade question

    Quote Originally Posted by stonko View Post
    Hi guys, i have a used nikon 35-105mm F3.5-4.5 AIS manual nikkor. the other day i was looking through the lens to check for fungus and noticed that the aperture blades do not form a smooth opening from F3.5-F5.6. I mean, the blades should be forming a smooth shape and not have any jagged edges, right? is this normal?
    In which aperture do you see the jagged edges? If on max aperture, it should be ok. Closing down and you will see the jagged disappear.

    Regards,
    Arto.

  7. #7
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    Default Re: Aperture blade question

    Quote Originally Posted by Snoweagle View Post
    It all depends on the number of blade yr lens have. Usually to produce gd bokeh, should have at least 7 blades.
    While it is true the number of blade usually can produce good bokeh, many factors in lens involved in produce good bokeh. For example: blade construction, glass quality, coating quality, max aperture, etc.

    Regards,
    Arto.

  8. #8
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    Default Re: Aperture blade question

    sounds normal but a picture might be better.
    “How fortunate for leaders that men do not think.” - Adolf Hitler

  9. #9
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    Default Re: Aperture blade question

    That "jagged edge" is ok because the the image "circle" at the focal plane is bigger than the sensor/film frame so the edge is not visible in your photos.
    You'd need an infinite no. of blades to get a perfect circle anyway.

  10. #10
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    Default Re: Aperture blade question

    Quote Originally Posted by arpinkor View Post
    You'd need an infinite no. of blades to get a perfect circle anyway.
    Or none (no blade at all) for perfect circle .

    Regards,
    Arto.

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