Sharpness vs. V‐magnitude results from PSF fitting for our clusters (circles), Bik et al. (2003) cluster candidates (squares), and all detected objects (dots) in the WF chip 2 in field 2 of M51. The two solid lines represent 2.5 σ envelopes. Objects inside the envelope are considered to be unresolved point sources, while those below the lower envelope are considered to be extended sources. Note that all our clusters are below or along the lower envelope, while most of the Bik et al. (2003) cluster candidates are between the envelopes.