Re: Flash vs. Ambient light...


"Douglas" <just@xxxxxxxxx> wrote in message
news:fj1tnu$lok$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxx

"David" <davidd31415@xxxxxxxxxxx> wrote in message
news:_cGdnUYDNpWuWM7anZ2dnUVZ_viunZ2d@xxxxxxxxxxxxxx


Why did the camera choose 15 s in Av mode when in M mode 1/125 s was
sufficient. It seems to me that the M mode shot was not operating in
"fill flash" mode like the website stated.

I am still working on getting through this part but the answer didn't
immediately jump out at me
http://photonotes.org/articles/eos-flash/index2.html#confusion.

I wish that the exif data contained two more pieces of information:
1. If the flash was operating as "fill flash" or "regular flash."
2. What flash power level was used.


For correct use of fill flash you should set the flash to "high-speed"
mode and the camera to either program mode or Aperture priority (Av mode)

For aperture priority mode you will always get the camera deciding
exposure based on ambient light. You can set a custom function for 1/250th
shutter speed in Av mode but the camera will still meter for ambient light
if the ambient exposure requires a higher shutter speed.

Thanks Douglas,

When you say "the camera will still meter for ambient light" do you mean
that the camera will calculate flash power such that the flash will be used
in place of ambient light? I'm hung up a bit on the terminology.

The only really successful way to use a Canon speedlite on an EOS camera
is in full manual mode and let the flash decide on the level of light to
emit. I know this sounds a little odd but truly, The ETTL part is an
accurate metering method only when it suits the conditions.


I just did a bit of research on ETTL. If I understand correctly, it fires a
pre-flash and the camera uses the pre-flash image to meter. I'm confused
though. This is what I read:
http://photo.net/bboard/q-and-a-fetch-msg?msg_id=0006Wn. It says that the
metering system will adjust the "real" flash duration. Yet on this page:
http://www.dpreview.com/learn/?/key=metering, metering is defined as
measuring the light and calculating the proper exposure. I thought exposure
was the combination of shutter speed, aperture, and ISO level. Does the
metering system calculate flash power as well as the other factors?

Also, do I have a choice to use modes other than ETTL with a Canon speedlite
on an EOS camera? If I read correctly, the flash decides on the level of
light to emit during manual mode only (this sounds different than what I was
reading in the EOS flash tutorial)? Is the flash not using ETTL?

If you then use the camera set to (for example) F/5.8 with a shutter speed
of 1/125th or more, You will get acceptable pictures most of the time.

I now use a Nikon speedlite on my Canon EOS. I use the flash in full auto
mode (measures its own exposure requirements) for all indoor shots with
the camera in manual mode. Outdoors I still use the EX 580 Canon flash
for fill flash.

I've read a lot about these flashes and none of it made sense to me until
I worked on the presumption Canon speedlites work as fill flash nearly all
the time. The only way to get their power output is to switch to 100%
manual. Had I realized the limitations of a Canon speedlite, I'd never
have parted with my Metz stuff.

Douglas


Do the Canon speedlites ever work as fill flash in manual mode? How would I
know if it was not working as fill flash in other modes?

David


.

Relevant Pages

  • Re: Flash vs. Ambient light...
    ... Why did the camera choose 15 s in Av mode when in M mode 1/125 s was ... What flash power level was used. ... ambient light if the ambient exposure requires a higher shutter speed. ...
    (rec.photo.digital)
  • Re: Rebel XT and Mac OS9: impossible to combine??
    ... > You could also consider loaners - see if the store will let ... borrow a camera to shoot their daughter's wedding. ... My 5700 definitely meters flash even when using an external ... > a big zoom range, ...
    (rec.photo.digital)
  • Re: Photo help needed
    ... It has all the other controls a $500 camera should have. ... I believe that the Canon ... That is why you need a lens with a large aperture - to reduce the amount ... of flash needed to illuminate the bird. ...
    (rec.birds)
  • Re: 70-300mm DO IS?
    ... > So you actually figured out how to use the Canon 'system' flash, ... > Canon 'system flash' you had wouldn't work reliably on your 20D... ... > by claiming it's not a "real" Professional camera. ... "Olympus" is not a goddess..."I've taken the image of a Greek goddess Her ...
    (rec.photo.equipment.35mm)
  • Re: rebel Help Please
    ... I did use a remote release and tripod. ... Flash washes out bad. ... either the camera or the subjects are moving. ... the flash tends to have detrimental effects on colours in the pictures, ...
    (rec.photo.digital.slr-systems)