Canon High Power Flash for Powershot cameras

Archived from groups: rec.photo.digital (More info?)

On Fri, 22 Jul 2005 16:13:51 GMT, Mark Cutler wrote:

> I just received the CANON High Power Flash HF-DC1 and have tested it
> with my S1-IS camera. As advertised, it does double the range of the flash.
> However, at it's maximum setting, with my telephoto lens at its maximum
> setting, I seem to lose all benefit of the camera's Image Stabilization.

It seems unlikely that the flash could prevent the camera's IS
from working. It's wireless, triggers by sensing the camera's
flash, and doesn't communicate with the camera. If it's turned off
does the camera's IS still work properly taking the same type of
flash shots that you found problematical with the HF-DC1 powered on?
Maybe at the maximum zoom setting you're near the borderline of
being able to hold the camera steady enough for the IS to work, and
the additional weight of the flash is what' causing the problem at
maximum zoom.


> At the medium setting on the flash, the Image Stabilization still works, but
> the power of the flash is only slightly better than the normal flash alone.

Despite its name, the HF-DC1 is a fairly low powered flash. It's
only 'high power' when compared with the underpowered flashes built
into most cameras. When used at the medium setting you shouldn't
expect to see more than a modest boost over the camera's built-in
flash. You can use multiple HF-DC1 flashes, and the use of the
medium and low power settings are probably most useful when the
flash isn't attached with the bracket to the camera, but is used to
provide supplemental light to different (usually more distant)
objects in the scene.

Archived from groups: rec.photo.digital (More info?)

On Sat, 23 Jul 2005 14:38:17 GMT, Mark Cutler wrote:

> I tried several tests of exactly the same picture with the flash attached, but
> turned on or turned off. The telephoto was always at its maximum setting.
> Every shot with the flash off is crisp, but underexposed. Every shot with the
> flash on is nicely exposed, but blurry. I agree with your logic - this makes no
> sense. But it definitely happens and very consistently.
>
> Since my first post I made some more tests and discovered that the image
> stabilization works nicely with the flash on when the camera is set to "P"
> mode. My earlier tests were all with the camera in "AUTO" mode.

Were the re-tests that you mention in the first paragraph above
done using "P" mode or "Auto" mode? Assuming that it was in "Auto"
mode then it might be that an excessively long shutter speed was
used, and you can check this in the EXIF data. And then it might be
that it wasn't the IS that helped to make the shot crisp, but the
very short duration of the combined flashes. At reduced power the
output of the HF-DC1 is probably about the same as the camera's
flash, and probably of about the same duration, but it may not
precisely coincide with the camera's flash. It's probably close
enough so that even if there is some overlap, the combined flash
duration is not much longer than that of just the camera's flash,
and pictures seem about as sharp as when the HF-DC1 isn't used.

But when the flash's output is set to "High", it's duration is
longer, allowing more of the camera's movement to be caught. This
movement is always going to be there to some degree if you don't use
a tripod. The IS system reduces, but doesn't eliminate it. If the
above is what's happening with your camera, then it may be that when
switching from "Auto" to "P" mode your camera used a higher shutter
speed, which was long enough to catch all or most of the light
emitted by the camera's flash (not surprising that no light would be
wasted since the camera and flash were designed as a single system).
But this faster shutter speed might have truncated some of the
HF-DC1's output, making for the crisper pictures you've taken in "P"
mode. Again, I don't know if this is what's happening, but it might
be confirmed by a quicker shutter speed in the EXIF data, especially
if the power provided by the HF-DC1 seems not quite as high as when
it was used at maximum power with the camera in "Auto" mode.