Full width half maximum (FWHM) distribution as measured from the CFHTLS images (top panel) and from the Lyα 2-d spectra (bottom panel). Targets are shown with a solid line, serendipitous objects with and without photometric counterparts are shown with a dotted and dashed line, respectively. The CFHTLS image used was built by stacking the 25% best-seeing exposures, and has a final PSF FWHM of about 0.5′′. In the top panel, we just show serendipitous objects with a photometric counterpart.