is there a way or guideline to determine a fair value of a used lens? what is actually the expected life time of a lens? (we know for example how to calc depreciation or a fair price of a used car ...)
how much depreciation should we take into consideration after the 1st year, 2nd year, etc? let's say, for argument sake, the lens is in good optical and cosmetic condition ...
appreciate your thoughts, helps and guides. cheers.