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Old Oct 24, 2003, 8:39 AM   #1
NHL
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Default Everything you need to know about Canon flash!

... I've just found this interesting article:
http://photonotes.org/articles/eos-flash/

Of particular note, be careful with High-Speed sync!
Quote:
Note an important point - FP mode does not help you freeze motion; the name “high-speed sync” is a bit misleading in this regard. Normal flash photography is very good at freezing motion on film, since the flash burst is so incredibly brief. However when you use FP mode flash the flash unit pulses the light output to simulate a longer-duration burst of light. Since the flash burst is not particularly brief you can’t freeze motion as easily, even with high shutter speeds. The mode is called high-speed sync since it lets you synchronize flash exposure with high shutter speeds, not that it lets you take high-speed photographs.
... the article also went into 3rd-party manufactured flashes as well.
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Old Oct 24, 2003, 9:29 AM   #2
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I've read portions of this write up before. It's very good. There is an other one which I should should read:

http://bobatkins.photo.net/info/faq30/flashfaq.htm

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Old Oct 24, 2003, 11:10 AM   #3
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Did you see this part:
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Finally, E-TTL has been a particular problem for digital users. Many users report serious problems with wildly varying exposure when using an E-TTL flash unit with their Canon EOS digital camera, particularly the D30 and D60. Some of these problems stem from the users focussing and recomposing and failing to use the flash exposure lock (FEL) feature, which sets the wrong area around which the flash will meter. But many problems can’t be blamed on this.

The main problem appears to stem from the way in which E-TTL on these bodies biases flash exposure heavily to the focus point. For more information please consult the section on E-TTL flash metering patterns.

For this reason many digital EOS users are giving up on E-TTL and are going back to the old-style autoflash units. Still, at least with digital you have a rear-panel preview and histogram, so you can tell right away if a flash photo failed to work. And apparently the EOS 10D has revised E-TTL algorithms which rely on centre-weighted average metering for E-TTL flash, even if the lens is set to autofocus mode.
No wonder my 'antique' Metz 45CT-5 did a better job here... Now at least I understand why my 550EX always tend to overexposed even with the revised E-TTL! :lol: :lol: :lol:
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