A used camera is easiest to judge in your hands, and the days after it arrives are when your return window is still open. Most sellers give you a few weeks, and eBay's Money Back Guarantee covers a camera that doesn't match its listing for 30 days after delivery. So don't let it sit in the box. Set aside an hour on the first day and work through this list in order. You'll need a charged battery, a memory card for each slot, a lens you know well and a computer.
Check what arrived against the listing
Before you switch anything on, lay out what came in the box and compare it with the listing. Is the battery the maker's own, as listed, and does the charger fit your outlet? Does the serial number on the base match any photo the seller posted? Is the body cap there, and the strap if one was shown? Photograph everything now, so you have a record if something is missing.
Then look the body over in good light. Check the lens mount for gouges or bright wear on the lugs, the hot shoe for bent springs, and the rubber grip for lifting at the edges. Open every door. Card doors should latch firmly, and the rubber port covers should seat flush.
Charge it and read the firmware
Charge the battery fully before you judge anything. A battery that won't hold a charge is cheap to replace, but you want to know whether the battery or the camera is the problem. Once it's on, find the firmware version in the setup menu and compare it with the latest on the maker's support site. An old version isn't a fault, and updating is free. It's often the fix for bugs owners complained about, so update now if there's a newer one.
Read the shutter count
Take a few photos and read the count with the method for your brand from our shutter count guide. Compare it with what the seller said. A few hundred more than quoted is normal, since sellers test cameras too. Thousands more is a mismatch, and it's worth a message to the seller while you can still return the camera.
The sensor test
Set the camera to aperture priority at f/16 or f/22, the lowest ISO, and manual focus set close so the subject is blurred. Photograph a plain blue sky or a white wall, filling the frame. Open the file on a computer and look at it at full size. Dust shows as soft gray spots. A few are normal and come off with the camera's cleaning cycle or a blower. Look for anything sharp-edged, streaky or ring-shaped that won't move after cleaning, which could be a mark on the filter itself.
For hot pixels, put the cap on the lens, set manual exposure at one second or longer at base ISO, and take a frame. Repeat at a high ISO. At full size you'll probably see a few colored dots, which is normal on any sensor. Dozens of bright dots, or lines and bands across the frame, are not. Some bodies, Olympus among them, have a pixel mapping option in the menus that maps out stuck pixels, so run it if yours does and test again.
Screen, viewfinder and buttons
Show a plain white image and then a plain black one on the rear screen and in the viewfinder, and look for dead or stuck dots, uneven patches and lines. Try the touchscreen in every corner if it has one, and flip or tilt the screen through its full range, watching for flicker as the hinge moves.
Then press every button and turn every dial while watching the display. It's tedious, but a dead button or a dial that skips settings is easy to miss until the day you need it. Don't forget the AF joystick, the lock switches and any buttons on the battery grip if one came with the camera.
Cards, ports and connections
Format a card in each slot, shoot a burst to each, and check that both cards read on your computer. Plug in a USB cable and check that the computer sees the camera, and that the body charges over USB if it should. If you'll use HDMI, a microphone or a remote, test those ports too. Pair the camera with its phone app if you'll use wireless transfer. A flash on the hot shoe should fire and sync.
Focus, stabilization and video
With your known lens, focus on a detailed subject at the widest aperture and check the result at full size. On a DSLR, test both the viewfinder autofocus and live view. If the viewfinder shots are consistently in front of or behind the subject while live view is sharp, the camera or lens may need fine-tuning, which many DSLRs offer in their menus as AF microadjustment or AF fine-tune. Mirrorless bodies focus on the sensor itself, so this problem is rare on them.
If the body has in-body stabilization, shoot handheld at a slow speed, around 1/8 second with a normal lens, with stabilization on and then off. The difference should be obvious. Listen for grinding and watch for a viewfinder image that jumps or drifts on its own. If you shoot video, record ten minutes at the setting you'll use most and see whether the camera warns about heat.
A real shoot
Finally, take it out and use it the way you plan to. Shoot a few hundred frames: some fast bursts, some long exposures, some in dim light. Problems that tests miss, like a shutter that hesitates when warm or a battery door that pops open in a bag, show up in real use. If everything works, you've bought a good camera. Keep the box, the listing and your test photos, and enjoy it.
If something is wrong
Message the seller first, with the photos and files that show the fault. Most sellers will take a camera back or offer a partial refund, especially when you can show them the evidence. If they won't, open a return request through eBay within the window. Don't try to repair it, open it up or send it for service yourself, which can complicate a return. Then pick your next one with what you learned, using the listing red flags guide and the checklist on each camera page.
