Canon 40D Auto ISO

Every time I go out PhotoWalking with the Canon 40D I try to focus on learning one new feature. Given the number of cool features in today’s digital SLRs, I’m sure I won’t run out of things to learn anytime soon. Last Sunday I decided to experiment with the “Auto ISO” feature while wandering through the woods of the Brazos Bend State Park near Needville, TX.

I generally use Aperture Priority AE mode (Av) when shooting with the 40D so that I can set a narrow depth of field (wide aperture) and relatively fast shutter speed since I would be using a 70-200mm f/4L lens hand-held for most of the walk. So I set the aperture to f4.5, the shutter speed to 1/125th of a second and the ISO to “Auto”. I also set my AF point to dead center. I figured that the light would vary throughout my walk from direct sunlight to almost complete shade and that these basic settings along with the Auto ISO, should get me some decent exposures. I was a little worried about hand-holding at 1/125th without an “image stabilized” lens but I’d been practicing Joe McNally’s “right-handed, left-eye, left shoulder grip” and thought I could do it for a few hours at least.

I hadn’t gone far when I spotted a game trail leading of into the woods so I decided to follow it for a few hundred yards to see if I could catch a shot of an owl, fox or deer. I was a little nervous however since it was less than 100 yards to a small bayou and what looked like a “game trail” to a (damn) yankee like me could turn out to be alligator tracks leading back to a nest. Hmmmm. What would Joe McNally do in a situation like this? Hell, what would Moose Peterson do?

Here's Looking at You Kid

Here’s Looking at You Kid
Copyright © 2008 Jeff Lynch Photography
Shot taken with a Canon 40D , 70-200mm f/4 L at 180mm, f/4.5, 1/125th sec at (Auto) ISO 400 on SanDisk digital film.

Well, I never got to find out because about 25 yards to my left stood a beautiful doe. I quietly brought the camera up to my eye, tucked it down into my left pectoral muscle for stability and snapped off about twenty frames in a little over 3 seconds. Boy, you got to love this digital technology! 6.5 frames per second and focused right down the center. Even at 72 dpi you can see the texture of the doe’s coat in the sunlight. So I ended up with a pretty good exposure with very little noise considering that the entire encounter took place in only a few seconds. Not too bad for a walk in the park!

This is a feature that you’ll need to experiment with in all three modes (Aperture Priority, Shutter Priority and Full Manual) to get a feel for what works best. I’ll be playing with this feature for the next few weeks to see how it works in low light and high contrast situations. Should be a lot of fun!