Insect macros
  • tryinghard
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    Insect macros

    by tryinghard » Fri Aug 03, 2012 1:35 am

    Filthy fly...
    Image
    Filthy fly 2 by wookinator, on Flickr

    Image
    Filthy fly by wookinator, on Flickr

    Will extension tubes help to fill the frame more with the insect or will they degrade image quality ? As always any thoughts or feedback appreciated.

    Cheers
    PPOK
  • W G
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    Re: Insect macros

    by W G » Fri Aug 03, 2012 9:37 am

    tryinghard wrote:Will extension tubes help to fill the frame more with the insect or will they degrade image quality ? As always any thoughts or feedback appreciated.

    Cheers


    Tryinghard,

    A lot depends on the lens you are using. Lens designs are optimised at the design stage for working at particular distances or image sizes — usually somewhere between 10 feet and infinity. Extension tubes with a non-macro lens can get you into a region where the lens simply doesn't perform well any more.

    Macro lenses are better suited to close-up and macro work. For them, an extension tube is much the same as having a longer helical focus thread. Unfortunately, many modern macro lens designs in the DSLR world don't focus by extending the distance between lens and image plane but by a complex sort of inverse zoom effect where the closer you focus the shorter the focal length becomes. I have no idea how these lenses would work with extension tubes.

    An often overlooked means of focussing closer is with Portra lenses (dioptre lenses) which screw into the front of the lens like a filter. If you pay the extra and get multi-element Portra lenses they usually correct a regular lenses optical characteristics in order to produce better close-up results. They are small light and compact and you don't lose exposure through lens extension.

    Cheers,
    Walter Glover

    "Photography was not a bastard left by science on the doorstep of art, but a legitimate child of the Western pictorial tradition." —Robert Galassi
  • tryinghard
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    Re: Insect macros

    by tryinghard » Fri Aug 03, 2012 8:48 pm

    Thanks very much Walter- I'll look into the Portra lens. Really appreciate the feedback. I will look into how my lens focuses, it's a Tamron 90mm F2.8 1:1 prime.
    PPOK
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    Dalzine
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    Re: Insect macros

    by Dalzine » Sat Aug 04, 2012 12:08 pm

    If it's anything like mine then it focuses slowly, very slowly.

    Oh and externally, which can be a pain at times if you have to adjust the focus by a long way.

    Dale.
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