If you’re buying a used camera or lens, it’s a good idea to give it a thorough going over to make sure everything works before handing over your cold, hard cash. Here’s what to check for.
Checking That a Camera Works
For all their technical complexity, there’s not a huge amount that can go wrong with a digital camera: if it works, it works; if it doesn’t work, it doesn’t work. There’s not much middle ground. With that said, here’s what to do to check a camera out.
Look it Over Visually
The first step is to look the camera over thoroughly. Are there any cracks, dents, breaks, or bad scuffs? You should expect a little wear and tear on a used camera, but nothing too bad.
Open the battery and SD card hatches. Do they open smoothly? Do the battery and memory card go in and out smoothly? What about the pins? Are they clean and undamaged?
Have a look at the lens mount and in particular the contacts that send information to a lens. Are they in good condition? Attach a lens to the camera. Does it go on smoothly? Is there any play between the camera and lens or does it have a nice, tight fit? Does the camera show a warning?
What about the hot shoe or built-in flash? Do they work? Do they look damaged?
Push all the buttons and turn all the dials. Is anything stuck or catching? When you adjust things, does the camera do what it’s supposed to?
Have a look at the tripod plate. Is it damaged?
Check the diopter. Does it adjust properly?
It shouldn’t take you more than a few minutes to work your way over a camera, poking and prodding and making sure everything looks right and does what it’s meant to. As I said at the top, if a digital camera is broken, it tends to be really broken.
Check the Shutter, Mirror, and Burst Mode
With the externals looked over, it’s now time to pay proper attention to the internals. Remove any lens that’s attached to the camera and look at the mirror. Is there any apparent damage?
Select a shutter speed of about 1/3rd of a second. Is the mirror action smooth? Does the shutter action look good? It will move fast, so it’s hard to tell, but if there’s a problem you might see or hear it.
Select the maximum shutter speed, put the camera in burst mode, and hold down the shutter. Is the shutter action smooth and continuous? Do you hear anything weird or catching? The camera should happily shoot until you fill the buffer.
Check the Lens Controls
Attach a lens that you own and trust to the camera. Select a few different shutter speeds and apertures and take a few shots. Do they look as you’d expect? Does the lens seem to respond to the controls or are you getting an error?
Select the narrowest aperture, look down the barrel of the lens, and hold the depth of field preview button. Did the aperture blades close smoothly? Is the aperture symmetrical? When you release the button, do the blades open without catching?
Check the Autofocus
Manually select an autofocus point, select a wide aperture, focus on something, and take a picture. Inspect the image to check that the point you focussed on is actually in focus. Repeat the process a few times and make sure the autofocus changes smoothly between them.
Check the Sensor and LCD
If the camera has Live View, turn it on and make sure the screen looks good. Take a totally overexposed image and a totally underexposed image: they should be pure white and pure black. Inspect them on the back of the camera looking for any stuck pixels on either the screen or the sensor.
Transfer the images to a computer and give them another quick look over. Does everything look as it should?
Check the Shutter Count
Camera shutters fail over time. They’re normally rated for between 100,000 and 300,000 actuations, depending on whether it’s an entry-level or professional camera—you can find out from the manufacturer’s website. If you’re buying a used camera where everything else looks good, the most likely future problem is that the shutter will fail from use.
Use your laptop to check the camera’s shutter count. If it’s less than 50,000 or so, then the camera probably has lots of life left in it. As that number gets higher, the more likely it is to need a shutter replacement in the future. Compare whatever the number is to the shutter’s rating and then decide how much you’re prepared to pay.
Checking That a Lens Works
Like cameras, there’s not a whole lot that can go wrong with a lens that doesn’t leave it very obviously broken. Here’s how to check one over.
Look it Over Visually
Look the lens over visually. Make sure the glass isn’t badly cracked or scuffed. Look through the lens and make sure there’s no dust or fungus caught between the elements. Have a look at the filter ring, too. Do the threads all look okay?
What about the lens mount? Do the contacts look good? Does it mount solidly to your camera with no play between the two? Are there any errors?
If it’s a zoom lens, does it zoom smoothly? Do all the switches and dials work without catching?
Check the Focus
Attach the lens to your camera, select an autofocus point, and take a photo. Check the image to see that where you focussed is actually in focus. Repeat the process with different focus points, apertures, and subjects.
Put the camera in manual focus mode and look through the viewfinder. Focus manually on a few different subjects and take a photo. Do they look as they should? Did the lens focus adjust smoothly?
Check the Aperture Controls
Set your camera to the lens’ minimum aperture, look through the lens, and press the depth of field preview button. Do the aperture blades move smoothly? Is the aperture symmetrical?
Check the Image Stabilization (If It Has It)
If the lens has image stabilization, turn it on and take a few test shots at slow shutter speeds. Does it seem to be working? Put the camera in live view, and hold the lens next to your ear. Can you hear the IS motor working as you move about?
Buying used camera gear is pretty safe, especially if you buy it from a reputable source. Cameras and lenses tend not to break a little: they are either in good shape, or they’re paperweights.