Photography News Issue 55

Photography News | Issue 55 | photographynews.co.uk

Technique

3. Checking the sensor

4. Camera bodies

Above You can physically inspect the sensor, but it’s often easier to shoot a white wall at a small aperture to check for problems.

Certainly the camera’s sensor is one of the principal things to check, and while dirt can be cleaned, scratches, though rare, cannot. Take off the body cap, lock the mirror up if required (this will likely be done via the setup menu) and inspect the chip. If you can, use a sensor loupe, like Visible Dust’s Quasar Plus. A test shot will all reveal dirt or

damage to the sensor. Attach a lens in manual focus, defocus it, set f/16 or f/22 and point it at a bright, even subject, like a white wall. Take a picture, zoom in on the screen and check for lines or smears, both of which can be damaged caused by poor cleaning or other mishaps. Any evidence of damage means the camera is best avoided.

Above On DSLRs check the mirror box moves freely, and, if possible check the number of shutter actuations, too.

One of the biggest factors in choosing a second-hand body is shutter count. Why? Well, even though cameras are increasingly electronic rather than mechanical devices, most cameras still have a shutter that needs to open and close to begin and end an exposure. The shutter count, also called shutter actuations, is how many times this has happened. All cameras have a limit, which obviously varies from entry level to pro bodies, so while a Canon EOS 700D might be expected to reach 100,000 shots, an EOS 1DsMark IV should guarantee something closer to 300,000. Of course these are just estimates of how long the shutter mechanism will last, but it can also be taken as an indicator of how well used the camera is. Amongst everything else, on a DSLR, every You can check basic sharpness with a test shot, but it’s best to use live view mode when doing this as a DSLR’s phase detect system may need calibration and adjustment itself. Try setting up on a tripod, focusing on a certain point of the frame and running through the apertures; sharpness wise, there’ll be a sweet spot, probably from f/5.6 to f/11, but if performance drops hugely at different settings, there’s a problem. It’s worth noting that using some older lenses may not look wonderfully sharp on the latest very high-res DSLRs; results can look a bit soft. After cycling through the apertures, are the exposures fairly even? If not, there may be a malfunction in the diaphragm, too. On lenses with a manual aperture ring, you can look through the lens as you open and close the diaphragm; some lenses like Nikon’s G series have a lever to control it. You can visually inspect the movement.

shutter count, and even then it’s likely to be buried within menus, so to find it most people download freeware shutter checkers or upload images to sites that will do the count for you. A physical inspection of the shutter and mirror box with a torch may also throw up problems: does it move freely? Is there oil or residue? Also check the viewfinder when the camera is on and off; some DSLRs need a battery on board for the viewfinder to function. Check whether the view is clear, orwhether there are scratches and dirt? And do the various modes of the LCDwork?

time the shutter opens the reflex mirror also moves up and down. You don’t need to worry about the mirror mechanism on CSCs, but they still have mechanical shutters. Age is another factor in shutter count though; just like a one-year- old car with 50,000 miles on the clock versus a five-year-old-car with the same mileage would suggest more sporadic and careful use. Few cameras actually display their

5. Lenses

Cosmetically checking lenses is a reasonable indicator of their quality, but you may not find any real problems until shooting with them, which is where warranties come in so handy. The best inspections involve checking the lens against another model using a lens chart, but you’re unlikely to have that luxury. It’s well worth taking the time to look at a new version of your chosen lens, or some other used examples for comparison though. Inspect front and rear elements for scratches or chips, remembering to remove the front filter if one is fitted. Are the contacts clean at the mount? Tilt the lens to the light

quickly and quietly? If focusing is staggery and sounds ‘gritty’ there may be problems. Use the zoom and manual focus rings, checking they move freely without slackness; sudden bumps in the zoom range can mean damage. Wear look wonderfully sharp on the latest very high-res DLSRs Some older lenses may not

and look through; a bit of dust can be expected depending on the age of the lens, but smears and fogging are more serious. Attaching the lens you can check some basics: does it focus

to the rubber is less serious and these can be cheaply

Above For second-hand lenses, see that the zoom and focus rings move freely, and cycle through the apertures to check for problems.

replaced in servicing.