Buy, test and resell used camera lenses

Lenses hold value for decades but sell cheap when the seller can't say whether they work. Testing and honest grading is the whole margin.

How it works

Camera lenses are precision objects that are hard for a layperson to evaluate. Estate sales, general thrift stores and non-photographer sellers price them low because they can't say whether the glass is clear, the aperture snaps, the focus is smooth or fungus has set in. A photographer buying from them takes on all that risk and prices accordingly.

You remove the risk. Mount the lens, shoot a test chart and a bright background, check for haze, fungus, scratches, oil on aperture blades and stiff focus, then list it with sample shots and a plain-language grade. Tested lenses sell for a large premium over "untested, as is."

What it actually takes

A camera body or adapter that can mount the common lens types you'll encounter. Adapters for old manual lenses are cheap.
A few hundred to buy your first lenses; most of the profit is in the mid-range, not the exotic.
A bright flashlight, a blower, lens cloths, and the knowledge of what fungus and haze look like.
Proper packing. Lenses shipped loose in a box arrive as scrap.

Where it goes wrong

Buying without a market check. Some once-expensive lenses are worth very little now because a modern equivalent is better and cheap.
Fungus. It spreads, it can't be sold as clean, and it can contaminate your own gear if stored together.
Overgrading. One angry buyer and a return wipes out the margin on five lenses. Grade harder than you think you should.
Competing on the famous lenses. Everyone knows which ones are valuable; the margin is in the reliable, unfashionable workhorses.