>Dear Guy Cox (and to others who have measured this):
>   what is your FWHM in the x, y, and particularly z-dimension using
>100 nm beads and the mentioned objective (63x, 1.4 N.A.). I recently
>measured this on our Zeiss LSM410 and was disappointed: 1.8 um FWHM
>with a Zeiss Plan-Neofluar (40X N.A. 1.3 oil) in the z-axis. In the y
>x dimension the FWHM was as expected diffraction limited.
 
 
I'd be pretty disappointed by this figure too.  Measurements I
got, with the abovementioned x63 NA 1.4 lens, on a Bio-Rad MRC600,
were lateral FWHM 250nm, axial 600nm.  I thought these were a little
disappointing, actually. I wonder if you have a refractive index
mismatch problem?
 
                                                Guy Cox