>Thanks to everyone for the comments.
>
>I imply from the statements obtained that a 63x lens satisfies
>most applications because its high NA brings us very high
>resolution. Beside the physical resolution the magnification seems to
>be important to enable a given detector to record all resolvable
>details. Would Mark Auty's 100/1.4 thus resolve better than a
>63/1.4? Would (image) pixelation of a given bacterial cell
>obtained by the x100 lens thus appear less grainy if both
>images were zoomed to the same size?


The resolution is solely determined by the NA.  Thus both lenses
will resolve exactly the same things.  However the 100x will give
more optical magnification.  Using a 10x eyepiece my (elderly) eyes
are not capable of resolving the detail which the x63 lens will
resolve.  (200nm x 63 x 10 = 0.126mm - too small for me!).  But
this is not a problem with a confocal microscope since we can
simply zoom up.  This is NOT magnifying the pixels, it means
that we are scanning a smaller area, with just as many pixels.

However this does assume that the scan mechanism is capable of the
required accuracy.  If this is not so, whether because of poor design,
wear or site vibration, you may need the extra optical magnification.
But it woud be preferable in the long run to get the microscope
fixed!  Any good quality confocal system _should_ be capable of
delivering 200nm resolution with a x63 NA 1.4 lens, and most of those
I have tested are capable of it with no great difficulty.  In this
case the 100x lens will help not at all (but it will be easier to see
fine details non-confocally looking through the eyepieces).  Both lenses
are expensive!
                                        Guy Cox

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