Most "used camera buying checklist" articles give you fifteen things to look at — body condition, strap lugs, battery door, memory card slot cover, hot shoe contacts — and treat all fifteen as equally important. They're not. On a used digital camera, one failure mode causes the overwhelming majority of real disappointments: the zoom motor, the lens itself sticking or wobbling, or a sensor defect that only shows up once you actually take a photo. Everything else on the long checklist is cosmetic or nice-to-know by comparison.

The one test that matters

  1. Power the camera on and zoom the lens through its full range, both directions, more than once. Listen for grinding, catching, or a motor that hesitates partway through.
  2. Watch the lens barrel itself while it extends — a healthy lens moves in a straight, even line; a loose or previously-dropped one visibly wobbles side to side.
  3. Take an actual photo of a plain, evenly lit surface (a wall, a piece of paper) and zoom into the corners on a screen. Sensor defects and stuck pixels show up as color blotches, dark spots, or soft/blurry corners that a quick glance at the LCD won't catch.
  4. Autofocus on something simple and watch whether it locks confidently or hunts back and forth.

If all four of those come back clean, the camera is very likely fine — cosmetic wear on the body almost never predicts whether it keeps working.

Buying shipped, not in person

That four-step check assumes you have the camera in your hands. If you're buying from a shipped listing, none of it is available to you before you pay — you're trusting the listing photos and the seller's word that "the zoom works fine."

TestPass's digicam category exists for exactly this gap: it has the seller run this same zoom/lens/sensor check on camera before you commit. It's currently an early-stage category (TestPass labels it experimental while it's still building a track record), so treat it as a genuinely useful extra signal rather than a certification — but it's the same specific check above, not a generic unboxing video.