Every now and then we all experience the unfortunate event of failing camera equipment. On a recent trip to Churchill, Manitoba to do a Polar Bear shoot I had my Canon 500mm f/4 L IS lens fail on me. I picked up the camera and ready to do a shoot, activated the auto focus only to discover the lens would “hunt” for an accurate focus. The lens would almost lock onto an accurate focus and then back off to something of a shorter focus distance. This continual “hunting” for accurate focus would continue and never lock on.
Canon 1D Mark III, 500mm f/4 IS, 1/320 second @ f/8
So what does one do? While we all take for granted auto-focus lenses there was a time that we all had to manually focus. To make this task easier after every shoot I would set my camera back to the same settings so I knew exactly what my camera was set at as soon as I picked it up again. For me, I use aperture priority at f/8 and ISO at 200. On this trip I would set the ISO higher to 400 to ensure I was getting faster shutter speeds and also due to the lower light conditions that I would shoot in during the day.
Normally, I don’t have a routine for my lenses as they are full automatic. However, because I had no auto-focus on my 500mm lens I developed a routine and process for it. I would always set the focus to ~infinity. By doing this, when I picked up the lens and was ready to focus I only had to turn the focus ring in one direction to get an accurate focus. By setting the lens on infinity I knew I had to “push” the focus ring to the right which worked well when wearing gloves in the cold weather. Pulling the focus ring wasn’t as easy as pushing so I made certain the lens was set at infinity for that reason.
Canon 1D Mark III, 500mm f/4 IS, 1/800 second @ f/5.6