john Domingues wrote in article <01bcc794$e9cacac0$797274cf@default>...

> Does anyone know why when I place my 60mm micro on 2.8(on the lens barrel)
> I most of the times get 3.5 on the display panel and viewfinder?

As the lens is focused closer, its effective aperture reduces (this is
most noticeable with macro lenses, since they focus closer than
non-macro lenses...). Since the f-stop in a simple lens is the
distance between the diaphragm divided by the diaphragm opening
diameter, if that distance is increased by focusing the lens closer
to the subject, the effective aperture (named by the f-stop) must
decrease... (larger f-stop number = smaller aperture...).
Hope This Helps
David Ruether - http://www.fcinet.com/ruether