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Thread: Flash with telephoto lens

  1. #1

    Default Flash with telephoto lens

    Hi all, simple question before knocking off..

    Assuming I was using the 70-200 IS, and a 580ex CANON, for some indoor photography. Would You switch the IS on or OFF, with the flash already firing that is.

    Been bugging me for a while, haha thanks.
    Canon 40D, 10-22, 35, 70-200
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  2. #2

    Default Re: Flash with telephoto lens

    its pretty much up to yourself if u want the flash or no flash to keep the natural color of the setting.

    IS just help u stabilize your shots, thus allowing u to shot at slower shutter speed but if your subject is moving around, u will need faster shutter speed and the flash comes in to help u brighten up your picture, with faster shutter speed the need for IS is not a must unless you are shooting at the tele end, as small shake can easily blur a picture even if your shutter speed is 1/60 with flash thus the IS will help in this case
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  3. #3

    Default Re: Flash with telephoto lens

    IS also helps you to compose your shot, and makes it "easier to focus" for me, as I can aim properly
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  4. #4

    Default Re: Flash with telephoto lens

    Ok ok so i assume that once you are using a lens with IS, the IS function is almost always on? yes/no?
    Canon 40D, 10-22, 35, 70-200
    http://theserialhobbyist.multiply.com

  5. #5
    Member gymak90's Avatar
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    Default Re: Flash with telephoto lens

    Why switch off IS when it helps you to shoot at slower shutter speeds?

    It is highly unlikely with flash, you can reach shutter speeds of 1/focal length indoors.

    IS should be switched off when you mount lens on a tripod.
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  6. #6

    Default Re: Flash with telephoto lens

    depends on how much ambient light you want to let in.. more ambient = longer shutter speed = IS useful

  7. #7
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    Default Re: Flash with telephoto lens

    Quote Originally Posted by munkey View Post
    Ok ok so i assume that once you are using a lens with IS, the IS function is almost always on? yes/no?
    yes and no!

    IS/VR doesn't really matter at 1/1000s+ shutterspeeds

  8. #8

    Default Re: Flash with telephoto lens

    Quote Originally Posted by Daedalus Trent View Post
    yes and no!

    IS/VR doesn't really matter at 1/1000s+ shutterspeeds
    Ah. But IS/VR helps when framing, especially if you have shaky hands
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  9. #9

    Default Re: Flash with telephoto lens

    Quote Originally Posted by GavinTing View Post
    Ah. But IS/VR helps when framing, especially if you have shaky hands
    But at 1/1000s???

  10. #10
    Member lennyl's Avatar
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    Default Re: Flash with telephoto lens

    Quote Originally Posted by GavinTing View Post
    Ah. But IS/VR helps when framing, especially if you have shaky hands
    Quote Originally Posted by monktian View Post
    But at 1/1000s???
    You frame in 1/1000? I take multiple seconds. Gavin said framing - when you're composing your shot in the viewfinder, before you capture.

  11. #11

    Default Re: Flash with telephoto lens

    Quote Originally Posted by monktian View Post
    But at 1/1000s???
    1/1000 is the time taken to "record" the picture. Framing is the process where you look into your viewfinder, and compose and focus.. It takes quite some time to do this.
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  12. #12

    Default Re: Flash with telephoto lens

    Yup I figured i'll just leave it on all the time, except with the tripods. Trivia - would a 580 bounced reach up to the 200mm focal? I dont really get the Guide Number jargon. bahhh RTFM
    Canon 40D, 10-22, 35, 70-200
    http://theserialhobbyist.multiply.com

  13. #13
    Member lennyl's Avatar
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    Default Re: Flash with telephoto lens

    Quote Originally Posted by munkey View Post
    Yup I figured i'll just leave it on all the time, except with the tripods. Trivia - would a 580 bounced reach up to the 200mm focal? I dont really get the Guide Number jargon. bahhh RTFM
    The distance to subject is the important part, not the focal length (except when we're talking about ultra wide angles and the inability of flash to cover the whole frame).

  14. #14

    Default Re: Flash with telephoto lens

    Quote Originally Posted by munkey View Post
    Yup I figured i'll just leave it on all the time, except with the tripods. Trivia - would a 580 bounced reach up to the 200mm focal? I dont really get the Guide Number jargon. bahhh RTFM
    GN refers to the distance. for example, GN of a 580EX is 58m. This means 58m at ISO 100, 50mm 1.4 I think. Can't really remember.

    It really depends. How high are you bouncing? What kind of photos are you taking? a 200mm used to take a house, or to take a face-shoulder portriat? or macro of ants? Yup. it all depends
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  15. #15

    Default Re: Flash with telephoto lens

    Okayy simple scenario im shooting at 200mm to get a headshot of the guy on the stage/podium. Im standing say 20-30m away .. bouncing 45 deg, it should reach rightttt
    Canon 40D, 10-22, 35, 70-200
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  16. #16
    Member lennyl's Avatar
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    Default Re: Flash with telephoto lens

    Quote Originally Posted by munkey View Post
    Okayy simple scenario im shooting at 200mm to get a headshot of the guy on the stage/podium. Im standing say 20-30m away .. bouncing 45 deg, it should reach rightttt
    Guide number = distance * f-number at ISO 100 (according to Wikipedia)

    For 580EX/EXII, your GN is 58, if the flash is zoomed in all the way.

    For subject 20-30m away, your light has to travel 30-40m. You will lose quite a lot of light bouncing as well.

    At that distance you're better off illuminating directly. And if you have strong backlight, you'd want to do what wildlife / bird photographers do and use a Better Beamer

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