After some time back finally having finished the article series on lens defects, I also finally got around to finalizing the the companion piece on how to quickly (and even relatively surreptitiously) test lenses. You can access this guide here: The quick lens test.
Allow me to say a few words about the logic behind this guide:
Firstly, this guide assumes that you will be able to touch the lens and is thus only suitable for flea markets, garage sales, goodwill stores and the likes.
Secondly, it does not aim to be foolproof. Instead, it aims to be efficient. Therefore, the quick lens test is is divided into three levels.
Level 1 – no tools, just your hands
Level 2 – add a flashlight
Level 3 – add testing the lens
The logic behind these levels is that there are basically three types of situations for F2F lens trades:
In situation A you are browsing a garage sale and you stumble upon some old lenses. The seller, who is standing there surveying his clientele, is oblivious to this whole ‘legacy lens fad’ and thinks he’s selling paperweights. In this situation you need to make a quick assessment on the general state of the lens or lenses without drawing the sellers attention, because otherwise the seller might suddenly get suspicious and raise prices until the deal no longer seems as attractive. Level 1 of the testing regimen is tailored for this situation.
Situation B is otherwise similar (the seller is standing there), but this time the seller knows that legacy optics are more than paperweights. The price they’re asking is no longer a pittance, but – assuming the lens is in shape – still an attractive deal. In this situation you can afford to scrutinise the lens thoroughly, because you’re not giving anything away. Simultaneously (unless the price is in triple digits), you’re not really in the situation where you can ask the seller whether you could take the lens for a half-hour spin. Levels 1 and 2 combined are what you can (and should) do in these cases.
Situation C is no longer a flea market or garage sale, but is the shop. Whether the shop should be an antiques shop or a camera shop does not really matter. Now you are totally justified in practicing due diligence to the fullest. Ask to take the lens for a spin, inquire about returns, nitpick about each scratch (in the hope of a discount), but most importantly, give the lens the full Level 1-2-3 treatment.
Finally, there are also situations in which you should consider forgoing any and all testing. Intrigued? Read the article. Enjoy.