Test your sharpness

Nikon’s MTF charts show results when shooting with the lens wide open, but sharpness will vary depending on the aperture used, and is often 2-3 stops from shooting wide open. To find a lens’s sweet spot, pop your camera on a tripod and shoot the same subject (a flat sheet of text taped to a wall works well) through the entire aperture range. Flicking through the images at 100% on your computer screen will quickly reveal where your lens’s sweet spot is.