From: Robert Coe on 18 Apr 2010 20:42
On Mon, 12 Apr 2010 01:52:18 -0700 (PDT), Chrlz <mark.thomas.7(a)gmail.com>
: On Apr 12, 11:57�am, "Dudley Hanks" <dha...(a)blind-apertures.ca> wrote:
: > Here's a down-sized copy of the pic I'd like to submit for GDB's 2011
: > calendar.
: > http://www.blind-apertures.ca/images/TrafficCheck.jpg
: > Just wondering if Mich is in focus, or if there are any other glaring
: > problems ...
: > Have fun; pick it to pieces!
: > Take Care,
: > Dudley
: That's actually a pretty cool image - unconventional, but it works,
: somehow. The bits that should be sharp are, and you've got the depth
: of field about right for the shot that you (might have?!)
: visualised.. ;o)
: Technically, the sky is pretty badly washed out.. Ok, it's not the
: subject of the shot, but it's a bit distracting. I'm not an expert on
: the Canon's ability to fill-flash in this way, but I'm guessing the
: problem was using ISO 800... For daylight fill-flash shots with a
: focal plane shutter, I think that's asking for trouble... :)
I am an expert, sort of, having embarrassingly ruined a shoot a few years ago
by not knowing what I was doing.
What happens is pretty much what you indicated. If you turn on flash on a
Canon DSLR, it will refuse to use a shutter speed that requires both curtains
to be in motion at the same time. So if your ISO setting is so high that your
lens can't stop down enough to compensate, you're SOL. There's probably a
warning light to apprise you of the situation, but I either didn't see it or
managed to ignore it. I was taking photos of my daughter's family at the
beach, and all came out at least two stops overexposed.
It's an easy mistake for a newbie to make. You think, "I can ignore the (fill)
flash because its contribution to the exposure calculation is negligible."
Which is true as far as it goes, but the camera has to ensure that the effect
of the flash covers the whole image.
Some Canons have a special repeating-flash mode for situations where you need
a high shutter speed, but it isn't on by default.