[bolty]

Hi, I've had my eye on a canon 17-40mm L lens up for private sale.

I've never bought a used lens, and other than checking to see if its shiny and pretty looking, I really dont know what to look for or what I should be asking. I was hoping to get some advice.

They claim the lens has a UV date code, which I am guessing is pretty recent. So, newer is better here I guess??

I know this may be a silly question but what is considered reasonable depreciation for a good lens??

[vachss]

When buying a lens I'll mount it on my camera body to check autofocus function and accuracy (using live view at 10x). Do this at both ends of range if a zoom lens. Look at both front and back surfaces for scratches/spots and look through the lens to see if there's any embedded dust/crap. If there are any switches or controls then verify that that work and aren't loose. Verify that the focus and zoom rings turn smoothly. That's pretty much it for me.

UV date code means 2007 manufacture - recent enough not to worry.

As far as depreciation: Figure a used lens in mint condition should go for ~80% of new cost (whether it's 10 days or 10 years old). Some particularly common lenses that are sold as part of kits (like the Canon 18-55, 28-135 and 24-105) will go for less. Some really expensive or hard to get lenses may go for more. For a 3 year old 17-40 in good shape I wouldn't pay more than about $600.