Last week, I photographed a baseball game between the Southern Illinois Salukis and the Fighting Illini at Illinois Field in Urbana. CLICK HERE to view some of those images.

I practically live on a baseball field. Between managing a 14U travel team and a Fall baseball team, I coach more than 100 games a year. And, that number of events doesn't count the practices! But, it's been a long time since I photographed a game.

One of my favorite perspectives for shooting baseball is behind the catcher. By using my Through the Fence trick, it's possible to capture interesting images of the pitcher. However, during the game I was having some trouble getting tack sharp images. So, I immediately went through the following checklist:

• Was my lens pressed close enough to the backstop? Yes it was.
• Was my shutter speed fast enough to stop the action? Yes, it was. My slowest shutter speed was 1/2000th of a second. Most shots were faster.
• Was my ISO setting low enough to avoid image quality issues? Yes...the highest ISO setting was 400.
• Was I introducing camera shake? No...I activated Vibration Reduction and later placed the camera on a tripod.

Yet, my percentage of tack sharp images still wasn't high enough.

Then, it dawned on me. I was manually focusing on the pitcher before he delivered the pitch. If he was in the set position, I focused on the leg that was closest to home plate. But, many of my images were captured after the pitcher took his stride to the plate. Many of the pitchers take a stride of approximately six feet.

I used a 500mm lens at an aperture of f/4. From 120 feet away, my depth of field is just 4 feet. So, when the pitcher strides six feet towards the batter (and me), he is striding right through the depth of field for acceptable focus. He is no longer rendered sharp at the point of delivery. If an image isn't tack sharp, I simply delete it.

Fortunately, I diagnosed the problem quickly and captured several sharp pictures of the action that afternoon.

Drasen JohnsonPitcher Drasen Johnson in a Fighting Illini vs. Southern Illinois baseball game at Illinois Field at 1605 S Wright Street on the campus of the University of Illinois in Champaign, Illinois on March 14, 2015