Teleconverter and aperture

Discussion in '35mm Cameras and Accessories' started by hammy, Nov 29, 2006.

  1. hammy

    hammy Member

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    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. Nick Zentena

    Nick Zentena Member

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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. Ole

    Ole Moderator Staff Member Moderator

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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! :smile:
     
  4. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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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.
     
  5. hammy

    hammy Member

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    Thanks.
    That's what I thought.
     
  6. Christopher Walrath

    Christopher Walrath Member

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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.
     
  7. Helen B

    Helen B Member

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  8. keithwms

    keithwms Member

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    Using a TC for macro? :confused: 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. naturephoto1

    naturephoto1 Subscriber

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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
     
  10. Helen B

    Helen B Member

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    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
     
  11. Lee L

    Lee L Member

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    Keith,

    I see you subscribed in October. Not to be condescending, but if you read through Helen B's other posts, you'll find that she's always meticulous and correct. I know there's a lot of underinformed and poorly worded junk on the web, but you won't see that coming from Helen.

    Lee
     
  12. keithwms

    keithwms Member

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    My comment had nothing to do with your gender, why bring that up? It's irrelevant.

    I did glance at the thread and I indeed did not find it enjoyable, as you had predicted.

    In fact,I posted my message because I know for a fact that some newcomers (boys and girls) confuse TCs with extension tubes. Simple.
     
  13. keithwms

    keithwms Member

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    My comment had nothing to do with Helen, her gender, or her qualifications.

    I think Rich responded to my post aptly, without resorting to issue of gender or my date of subscription.
     
  14. Dave Parker

    Dave Parker Inactive

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    I have been using Teleconverters for macro work since about day one, and that was close to 30 years ago...works for me, your mileage may vary,, I guess I pretty much use anything that will allow me to get the shot, I have also been known to stack 2 or 3 teleconverters to get a shot..

    Go figure.

    Dave