LENS TEST / FOCUS & ALIGNMENT
Lens Calibration Test Screen
A high-contrast flat target for repeatable comparisons of focus placement, centering and sharpness across the image field.
FIELD METHOD
SET UP A REPEATABLE TEST
- Keep it flat.Show the image at 100% on a flat screen, or print the PDF at Actual Size. Avoid a tilted or rippled target.
- Square the camera.Use a tripod, place the lens axis through the target center, and make opposite edges parallel in the frame.
- Remove variables.Use low ISO, a short self-timer or tether, fixed lighting and stabilization off on a locked tripod.
- Compare, then repeat.Test wide open and at two stopped-down apertures; refocus and make several frames before judging a pattern.
INTERPRETATION
READ THE FRAME, NOT ONE CORNER
Compare details at equal distances from the center. One consistently weaker side can suggest camera-to-target tilt or lens decentering; uniform softness is more often focus, motion or insufficient target detail. Repeat after rotating the camera and lens before assigning the cause.
Use as a comparative screen. A flat chart can reveal asymmetry and field consistency, but it is not a calibrated MTF bench or a slanted AF micro-adjustment ruler.