Martin,

What, exactly, are you using to weigh your lens -- your bathroom scale? :-)

Since you mean "for postage purposes," is the lens already packaged?

No matter. What you could do is go to the local post office and aske the window
clerk to weigh it for you (when I sold some stuff on eBay, the clerks at my
local post office were gracious enough to do that). Alternatively, you could do
what I did: I took one item I sold on eBay to the local mini-mart's deli
counter and asked them to weigh it on their scale. Certainly an odd request,
perhaps, but it helped.

Dieter Zakas