In article <4rn31j$9c4@hobyah.cc.uq.oz.au>, cochran@biosci.uq.oz.au says...

>I have often used a hand held light meter and simply transferred the
>exposure values to my lense.
>It has just dawned on me that this may not be correct since I haven't
>adjusted for loss of light due to lense extension.

So long as you are not using lenses on extension rings (or macro lenses),
there should be little problem. Though there is a slight loss of light
as a lens is moved toward its closest focus, it is unlikely that you will
notice a problem with this - unless (maybe) you are using a particularly
high-contrast film.
Hope This Helps