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  1. #1

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    Teleconverter and aperture

    I've got a simple question here I've always wondered about

    I have a 2x teleconverter that I regularly use on my 50mm f1.8

    When using my teleconverter on my 50mm 1.8, does the aperture remain the same? In other words, is it a 100mm 1.8?

  2. #2

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    No. You lose 2 stops IIRC. The focal length is twice the length but the aperture size is the same. So the F/stop must change.

  3. #3
    Ole
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    2x teleconverter -> 2x the aperture number (two stops). 1.4x teleconverter -> 1.4 times the aperture number (one stop).

    It's simple, really!
    -- Ole Tjugen, Luddite Elitist
    Norway

  4. #4
    David A. Goldfarb's Avatar
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    You lose two stops, usually in addition to a little transmissive loss, which can be around 1/3-1/2 stop. You don't need to think about it if you are metering through the lens, but if you use a handheld meter or non-TTL auto flash, and if you shoot slides, you might want to run some tests.
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  5. #5

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    Thanks.
    That's what I thought.

  6. #6
    Christopher Walrath's Avatar
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    Yeah, I've found through personal lens tests that teleconverters do not begat the same image quality as a longer lens or a longer zoom on that lens. Of course you have to weigh whether you want to have one lens or four when in the field, what have you.
    Thank you.
    CWalrath
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  7. #7
    Helen B's Avatar
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    Masochists may be interested in this current thread on photo.net about exposure compensation with a teleconverter when used for macro.

    Best,
    Helen

  8. #8
    keithwms's Avatar
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    Quote Originally Posted by Helen B View Post
    Masochists may be interested in this current thread on photo.net about exposure compensation with a teleconverter when used for macro.

    Best,
    Helen
    Using a TC for macro? I guess you mean an extension tube; I wouldn't use a TC for macro. As for exposure adjustment with an extension tube, it's just a bellows factor issue.

  9. #9
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    Keith,

    Yes the teleconverters can and are frequently useful for close-up or macro work. As an example this would allow the use of a lenses with or/without extension tubes, bellows, or even diopters. Helen is quite right about and quite knowledgeable about the affects of teleconverters and macro work. I would have to read what she indicates more carefully in the thread on the other site. However, if you are using a camera with an inboard meter, the through the lens metering should tend to make the appropriate corrections for exposure. Bracketing as is the usual procedure should yield good results. If however, there is no inboard metering, then you will have to make corrections.

    Rich
    Richard A. Nelridge
    http://www.nelridge.com

  10. #10
    Helen B's Avatar
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    Quote Originally Posted by keithwms View Post
    ... I guess you mean an extension tube...
    Well, what would I know? I'm only a girl. My guess is that it would have been better to have looked at the thread before commenting. I did warn you that it was for masochists, though.

    Best,
    Helen

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