How to test a used lens

[PatrickO]

I have just bought a used lens off ebay - Tamron 28-75mm f/2.8

When it arrives I would likes to give it a thorough test/check so that if there is a fault I can report if back promptly.

Do you have a set of formal tests you would do after buying a second hand lens?

 

[arclight]

http://www.amateurphotographer.co.uk/how-to/other/535470/checking-a-second-hand-lens-for-faults

Google is your friend. AP published a useful check list. Possibly the worst problem that you can encounter is the fault that is not obvious by which I mean an intermittent fault that only appears now and again.

 

[DaveKing]

I test a lens by first visually inspecting it, look for any scratches on the glass or 'clouding' (signs of fungus). If nothing looks untowards mount it on the camera and take a shot wide open at infinity focus, and then completely closed up (f22 or whatever the largest aperture is). Then repeat at close focus. Finally I will just shoot away at a few random objects and inspect the files on my computer, if all checks out the lens is fine!