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Thread: Tamron 90mm macro f2.8 - variable aperture at close range??

  1. #1
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    Default Tamron 90mm macro f2.8 - variable aperture at close range??

    Hi all you macro gurus out there,

    I just bought a 2nd-hand Tamron 90mm Di f2.8 macro lens from a fellow CSer. I've found that I can only get the maximum f2.8 aperture when working at 3m distance or greater. Any closer and the maximum aperture progressively reduces. At its minimum focusing distance (about 30cm), the maximum aperture is only f3.8.

    I was told by the seller that this is 'normal'. Just wanna check with other CSers: is this your experience with this lens/other macro lenses? Or did I just buy a defective lens?

    Thanks for your input!

    NB: I'm using the lens on a Nikon D80.
    Last edited by Melee; 8th June 2007 at 09:23 PM.
    "Photography is 50% photographer, 40% light, and 10% equipment." -- Petteri Sulonen

  2. #2
    Moderator catchlights's Avatar
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    Default Re: Tamron 90mm macro f2.8 - variable aperture at close range??

    yes, it's the way it works.

    at 1:1, you lost one stop of light, so it is f3.8 (f4)
    Shoot to Live, Live to Shoot
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    Default Re: Tamron 90mm macro f2.8 - variable aperture at close range??

    Thanks for the quick reply! Feel much better now....
    "Photography is 50% photographer, 40% light, and 10% equipment." -- Petteri Sulonen

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    Default Re: Tamron 90mm macro f2.8 - variable aperture at close range??

    Quote Originally Posted by catchlights View Post
    yes, it's the way it works.

    at 1:1, you lost one stop of light, so it is f3.8 (f4)
    Thanks...Learn something new...
    I own this lens before for my canon system, how close even 1:1, my F-stop is still F/2.8 if i set it atF/2.8...

  5. #5

    Default Re: Tamron 90mm macro f2.8 - variable aperture at close range??

    Nikon bodies display the effective aperture for macro lenses, Canon's doesn't. But it shouldn't affect anything.

    I think at minimum focusing distance the max effective aperture of Tamron 90mm is f/5.6.

    BC

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