By Match your lens choice to your actual shooting distance and subject size—a 400mm lens captures frame-filling shots of large wildlife at 50 feet, while smaller birds demand 600mm or longer reach. Calculate your effective focal length by multiplying the lens’s millimeter rating by your camera’s crop factor (1.6x for Canon APS-C sensors), meaning a 300mm lens delivers 480mm equivalent reach on a Rebel or 90D body.
Test your stability threshold before investing in super-telephoto glass. Most photographers struggle with sharp handheld shots beyond 400mm without image stabilization, and even the steadiest hands benefit from …
