Canon 30D - Manual (Page 22)

Page 22 of 35 © Ken Rockwell 2006
15: Shutter Curtain Sync (Flash Mode) is how you select rear-curtain sync
to make moving objects look like they're moving in the right direction,
presuming you're using a slow shutter speed in Tv, Av or M modes.
0: 1st curtain: Flash fires as soon as the shutter opens.
1: 2nd Curtain: Flash fires at the very last instant of exposure. If a
subject is moving and making a blur under ambient light, the final
image will have the subject stopped with a ghost flash image at the
beginning of the blur. This results in a sharp image with blurs behind a
moving subject, implying speed.
The default above (same for all cameras) puts the blur in front of a moving
object, which looks silly.
Nikon makes this easy to select with a direct button and knob, no menus.
Sadly, Canons can't do slow sync in Program mode as Nikons do. You have
to work in M, Tv or Av.
16: Safety Shift in Av or Tv is great. I wish Nikon had this.
0: Disable. If the camera runs out of apertures or shutter speeds to
work with the one you've chosen in Tv or Av, you get over or under
exposure. This is silly.
1. Enable: if you've selected a shutter speed in Tv mode or an aperture
in Av mode and the light isn't right to get a correct exposure with that
setting, the 30D is smart enough to change your chosen value to get
the right exposure. It works great!
Example: Set 1/500 in Tv mode. In a dark room, the finder will blink the
maximum aperture of the lens, since it's gone to the largest aperture and still
can't get enough exposure at 1/500. When you press the shutter halfway,
you'll see the aperture stop blinking and a lower shutter speed appear. The
30D will shoot at the maximum aperture and a slower shutter speed, instead
of being stupid like my Nikons and underexposing the image.
I love this. I leave it enabled. I wish my Nikons could do this.