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Thread: How to read Guide table?

  1. #1

    Default How to read Guide table?

    Hi to all,

    I am playing with my 380ex and was checking out guide table for my 380ex, but I don't quite understand some of the nos...

    Guide No.Table 380ex

    The guide no. table is right after the specifications table.

    The part I don't understand are those no. beside the various shutter speeds.
    Eg. at shutter speed 1/180 the nos. are 11.2, 12.3, 15, 16.6, 17.6, 20.3

    What are these nos.? Aperture setting?


    Any advise is greatly appreciated. Thanks!
    Last edited by Sukoo; 5th June 2005 at 12:35 PM.

  2. #2

    Default

    No one can advise?

  3. #3

    Default

    I give up reading guide tables and numbers quite a while ago. Decided to rely on practical experience instead.

  4. #4

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    Quote Originally Posted by snowspeeder
    I give up reading guide tables and numbers quite a while ago. Decided to rely on practical experience instead.

    Not quite the answer that I am expecting..
    But Thanks!

  5. #5
    Senior Member denniskee's Avatar
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    1) top row
    flash coverage
    (when the zoom set to 28, it means it is able to cover the angle of view of a 28mm lens). this is a auto detection function whenyou mount a EF / EF-S onto the eos camera, ie the flash zoom head will zoo to the foca lengthl of the lens (ie if user zoom in lens from 28 to 50, the flash zoom head will follows).

    2) row 2 from top
    guide no. @ various zoom setting of the flash head
    when focal length of lens 24mm, the guide no. is 21, use 50mm lens, guide no is 31

    3) 2nd column from left, row 4-13
    this show the various shutter speed.

    4) matrix from column 3-8, row 4-13
    its shows the guide no of the flash with the FP (focal plane or high speed sync) flash mode with respect to the zoom setting of the flash zoom head.
    the guide no in row 2 is valid as long as shutter speed does not exceed the x-sync speed. once it exceed, user need to set the flash to FP mode.
    though you gain in speed, you lose on range.
    eg. lens used is 50mm, flash head zoom to 50mm, max x-sync of the camera use is 1/60, but shutter speed required is 1/250. so user set flash to FP mode. but now the guide no is not as stated in row 2 (31), but (14.8)

    to maximise the camera eqpt you had invested, the best way is to understand the spec and use of each mode. you have taken the correct step. but that is not enough, it is best that you go through what I will consider the "bible" of the canon flash technology.

    http://photonotes.org/articles/eos-flash/index.html#fp
    photography makes one sees things from all angles.

  6. #6

    Default

    Thanks!

    Quote Originally Posted by denniskee
    1) top row
    flash coverage
    (when the zoom set to 28, it means it is able to cover the angle of view of a 28mm lens). this is a auto detection function whenyou mount a EF / EF-S onto the eos camera, ie the flash zoom head will zoo to the foca lengthl of the lens (ie if user zoom in lens from 28 to 50, the flash zoom head will follows).

    2) row 2 from top
    guide no. @ various zoom setting of the flash head
    when focal length of lens 24mm, the guide no. is 21, use 50mm lens, guide no is 31

    3) 2nd column from left, row 4-13
    this show the various shutter speed.

    4) matrix from column 3-8, row 4-13
    its shows the guide no of the flash with the FP (focal plane or high speed sync) flash mode with respect to the zoom setting of the flash zoom head.
    the guide no in row 2 is valid as long as shutter speed does not exceed the x-sync speed. once it exceed, user need to set the flash to FP mode.
    though you gain in speed, you lose on range.
    eg. lens used is 50mm, flash head zoom to 50mm, max x-sync of the camera use is 1/60, but shutter speed required is 1/250. so user set flash to FP mode. but now the guide no is not as stated in row 2 (31), but (14.8)

    to maximise the camera eqpt you had invested, the best way is to understand the spec and use of each mode. you have taken the correct step. but that is not enough, it is best that you go through what I will consider the "bible" of the canon flash technology.

    http://photonotes.org/articles/eos-flash/index.html#fp

  7. #7

    Default

    Think my IQ too low I guess..
    After reading the link u provided I still don't quite understand. Maybe have to read through a few times..
    Anyway already bookmarked the link..

    But since I am using a prosumer cam.. the focal plane part is really "chim" catch no ball...

    So it looks like only the nos. on the 1st two rows is useful to me. By reading the flash head zoom from the flash and using the GN and ISO to workout the closest aperture settings...



    Quote Originally Posted by denniskee
    1) top row
    flash coverage
    (when the zoom set to 28, it means it is able to cover the angle of view of a 28mm lens). this is a auto detection function whenyou mount a EF / EF-S onto the eos camera, ie the flash zoom head will zoo to the foca lengthl of the lens (ie if user zoom in lens from 28 to 50, the flash zoom head will follows).

    2) row 2 from top
    guide no. @ various zoom setting of the flash head
    when focal length of lens 24mm, the guide no. is 21, use 50mm lens, guide no is 31.....
    http://photonotes.org/articles/eos-flash/index.html#fp
    Last edited by Sukoo; 6th June 2005 at 09:51 AM.

  8. #8
    Senior Member denniskee's Avatar
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    just take Focal Plane mode = Fast Pulsing mode.

    there are times when you want to use flash as fill in light, but the shutter speed is much higher than the camera's x-sync speed. thats where the FP mode on the flash comes in.

    eg.
    subject is back / side lited by a strong light source, so the face will be dark, under-exposed because the caerma takes average metering of the whole scence, hence the fast shutter speed.

    it you want, can meet up and i can explain to you in greater detail. always like to share knowledge with a fellow photog who is keen to know more.
    photography makes one sees things from all angles.

  9. #9

    Default

    Oh u are simply great Dennis! I really appreciate that!
    Since the 380ex's specs stated figures for the flash's FP mode so I'm sure 380ex is FP mode capable, but is FP mode functional when pairing with G5?(my cam)






    Quote Originally Posted by denniskee
    just take Focal Plane mode = Fast Pulsing mode.

    there are times when you want to use flash as fill in light, but the shutter speed is much higher than the camera's x-sync speed. thats where the FP mode on the flash comes in.

    eg.
    subject is back / side lited by a strong light source, so the face will be dark, under-exposed because the caerma takes average metering of the whole scence, hence the fast shutter speed.

    it you want, can meet up and i can explain to you in greater detail. always like to share knowledge with a fellow photog who is keen to know more.

  10. #10
    Senior Member denniskee's Avatar
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    yes, it will work on your G5
    photography makes one sees things from all angles.

  11. #11

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    Quote Originally Posted by denniskee
    yes, it will work on your G5
    I really looking forward to meetup with u. Will buy u dinner or lunch...
    I'm rather tight in schedule this week. Maybe sometime next week? Will u be available next week?
    Can PM me what day u can make it?

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