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Thread: Uneven aperture blades?

  1. #1

    Default Uneven aperture blades?

    Hi guys, I have a question regarding aperture blade opening of a lens. Does the blade opening have to be perfect and even on all side or can it be uneven like the pictures here?
    (my 18-70 3.5-4.5)

    Opening at smallest aperture. You can see the uneven sides.


    Mid-sized. One side is already a circle but the other side is still angular.


    Widest. It's a nice circle.


    I have another lens (50mm 1.8) and it looks perfect there. I'm just wondering whether I should bring it for service or just keep it for now, there's already some dust collecting inside it anyway. I don't think I see any effect on my pictures though.
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  2. #2
    Senior Member zac08's Avatar
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    Default Re: Uneven aperture blades?

    I guess the blades might be a lil sticky there. Or that it is not able to match the others in the positions required.

    You probably can inquire if someone can try to fix this for you at Nikon. Else you can check with Fatique if he can help you with this issue.
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    Default Re: Uneven aperture blades?

    hmm.... the blades of my Sigma 150mm look uneven too

  4. #4

    Default Re: Uneven aperture blades?

    I've seen two AFs 18-70 lenses, both have uneven aperture blades.

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    Default Re: Uneven aperture blades?

    Aperture blades are like that. U won't get a perfect shape at smaller apertures, even for those with 'circular' 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.

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    Default Re: Uneven aperture blades?

    Thanks for clarifying. But why then do bokeh'ed regions look circular when the aperture blades form an opening that isn't circular?

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    Default Re: Uneven aperture blades?

    Quote Originally Posted by Daedalus Trent View Post
    Thanks for clarifying. But why then do bokeh'ed regions look circular when the aperture blades form an opening that isn't circular?
    Actually, they don't. You have a 50/1.8; stop it down to f/4 and shoot with highlights in the background, you will notice that they take on the shape of your aperture opening.

  8. #8
    Senior Member zac08's Avatar
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    Default Re: Uneven aperture blades?

    Quote Originally Posted by Daedalus Trent View Post
    Thanks for clarifying. But why then do bokeh'ed regions look circular when the aperture blades form an opening that isn't circular?
    coz the Bokeh'ed regions are normally from wide open lenses.. and they are generally round at that stage.
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    Member/Tangshooter Redsun's Avatar
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    Default Re: Uneven aperture blades?

    oooooooo
    i've never really noticed the aperture blades are liddat

  10. #10

    Default Re: Uneven aperture blades?

    Quote Originally Posted by Snoweagle View Post
    Aperture blades are like that. U won't get a perfect shape at smaller apertures, even for those with 'circular' blades.
    Depends on the lens too. Most of my lenses maintain a circular shape till about f/5.6, but after that the aperture blades remain in a fairly symmetrical shape
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    Default Re: Uneven aperture blades?

    Quote Originally Posted by Snoweagle View Post
    Aperture blades are like that. U won't get a perfect shape at smaller apertures, even for those with 'circular' blades.
    Quote Originally Posted by Rashkae View Post
    Depends on the lens too. Most of my lenses maintain a circular shape till about f/5.6, but after that the aperture blades remain in a fairly symmetrical shape
    Same here too...the five-bladed aperture on my 35mm f/2 is a symmetrical pentagon when stopped down.

    Snoweagle, do you have any additional info that backs up your statement?

  12. #12

    Default Re: Uneven aperture blades?

    Quote Originally Posted by zac08 View Post
    coz the Bokeh'ed regions are normally from wide open lenses.. and they are generally round at that stage.
    That's right, the bokeh is formed from the blades but at wide (round) f, it's round anyway.

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    Default Re: Uneven aperture blades?

    Quote Originally Posted by calebk View Post
    Actually, they don't. You have a 50/1.8; stop it down to f/4 and shoot with highlights in the background, you will notice that they take on the shape of your aperture opening.
    Quote Originally Posted by zac08 View Post
    coz the Bokeh'ed regions are normally from wide open lenses.. and they are generally round at that stage.

    ahh, i see.Thanks a lot!

    didn't exactly measure the dimensions of OOF points of light in my photos

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    Default Re: Uneven aperture blades?

    Quote Originally Posted by Daedalus Trent View Post
    ahh, i see.Thanks a lot!

    didn't exactly measure the dimensions of OOF points of light in my photos
    Haha no its not the dimensions; it's the shape. With a five-bladed pentagonal aperture, you will get pentagonal highlights when you stop down.

  15. #15

    Default Re: Uneven aperture blades?

    hmm...after reading snoweagle's post i tried on my two lens and both got even aperture blades leh...

    i'm also pondering.. for extreme case if one of the several blades doesn't close at all, would it affect the DOF of the image since more lights went thru and also the exposure etc?
    [Canon EOS 5D II + 40D | EF 16-35mm f/2.8L II + 70-200mm f/2.8L IS II] [Fuji X-Pro1 + XF35mm f/1.4]

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    Default Re: Uneven aperture blades?

    Quote Originally Posted by calebk View Post
    Haha no its not the dimensions; it's the shape. With a five-bladed pentagonal aperture, you will get pentagonal highlights when you stop down.
    yea...the dimensions of the shape?

  17. #17
    Senior Member zac08's Avatar
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    Default Re: Uneven aperture blades?

    Quote Originally Posted by Daedalus Trent View Post
    yea...the dimensions of the shape?
    The dimension do not matter as they are made from the light source. The larger the source, the larger the shape.

    It's the shape of the it tat matters... the rounder, the better the aperture blades are able to make a circle. And normally you'd see it clearly when shooting wide open. This is when the blades are fully RETRACTED, you dun even see them...
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  18. #18
    Senior Member fatigue's Avatar
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    Default Re: Uneven aperture blades?

    I have seen more than 20 of this lens.
    Most of them got uneven aperture blades

    There's no problem with your lens
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    Senior Member zac08's Avatar
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    Default Re: Uneven aperture blades?

    Quote Originally Posted by fatigue View Post
    I have seen more than 20 of this lens.
    Most of them got uneven aperture blades

    There's no problem with your lens
    Problem with the construction? Or design issue?
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    Default Re: Uneven aperture blades?

    Quote Originally Posted by zac08 View Post
    Problem with the construction? Or design issue?
    Sounds like a design thing inherent with the 18-70...

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