Which statement best describes zoom lens pre-focus calibration?

• A. It is unnecessary for modern lenses
• B. It is performed by focusing on a distant target at each zoom setting
• C. It is done by calibrating in post-production
• D. It uses autofocus for every shot

Answer: (B)

The idea being tested is that the focus point can shift when you change the zoom setting, so you calibrate the lens by checking focus at each focal length. Many zoom lenses aren’t perfectly parfocal, meaning the plane of sharpest focus moves as you zoom in or out. By focusing on a distant target at every zoom setting, you align the lens’s focus with the sensor plane for each specific focal length. This ensures that when you actually shoot at any zoom level, the image stays sharp without guessing or relying on autofocus alone.

Choosing a distant target at each zoom setting is the best description because it directly accounts for how focus changes with zoom and sets the correct focus early. Other options don’t fit: some lenses still benefit from calibration, so it’s not unnecessary; calibrating in post-production can’t fix real-world misfocus captured on the shoot; and relying on autofocus for every shot doesn’t perform the pre-shot calibration needed to lock in the correct focal plane across the zoom range.