– Use the sharpest aperture. You can test every lens in your bag to determine which aperture is sharpest, but a good rule of thumb is that it will be about two or three stops from wide open—somewhere in the middle of the range, usually around f/8 or f/11. If nothing else requires you to use a wider or narrower aperture, default to the sharpest ones in the middle.
– Maximize depth of field with the best small aperture. Notice I didn’t say the minimum aperture? Because, after all, as the previous tip spelled out, you don’t want to stray too far from the middle of the aperture range if you don’t need to. Why use the relatively unsharp f/32 when the much sharper f/16 may provide all the depth of field you need? So you determine which aperture will allow you to get everything you need in focus, and use that aperture and nothing more. To determine this, use the next tip.
– Depth-of-field preview has been available on DSLRs for generations. In fact, in the days of manual cameras and film, it was one of the few controls beyond aperture and shutter speed a camera really had. These days it still works the same way—via a button on the side of the lens that, when pressed, stops down the aperture so that you can see through the lens with the aperture stopped down. Use it in conjunction with the next item and it’ll be even easier to determine depth of field.
– Live View allows you to preview a live feed direct from the sensor right on the back of the camera courtesy of the LCD. Since it’s much bigger than the viewfinder, the LCD screen is often preferable for checking critical focus, especially when zoomed in digitally in order to check fine details for sharpness. Use of the DOF preview button while in live view mode is a great work-around for the darkened viewfinder that accompanies DOF preview, as the Live View mode compensates for the stopped down lens.
– Use the fastest shutter speed possible. There’s a difference between sharpness and depth of field, so if what you need is one precise area of an image to be very sharp, and if that element is moving (like a person so often is) then you’d be better served to sacrifice depth of field in favor of a wide aperture that will allow you to use a very fast shutter speed. You can also up the ISO in order to buy yourself more speed; going from 1/60th to 1/250th, while only two stops faster, will make all the difference in the world with a moving subject. The same goes for 1/250th to 1/1000th if that subject is moving fast. It’s all relative, but let’s just say that the faster the shutter speed, the sharper your subject is going to be.
– Shoot JPEGs. Sure, RAW files are a lot more versatile in the long run, but if you’re concerned about immediate sharpness gratification, a JPEG coming out of your DSLR will already have sharpening applied, whereas the RAW file will not. If you’re not planning to sharpen your RAW files, then, you’d actually be better off to shoot a JPEG since it comes out of the camera with sharpening already applied. Now, I’m not endorsing JPEG shooting as an ideology, but I’m trying to be a realist: if you’re not going to digitally sharpen your files during process, your JPEGs will appear sharper than your RAWs.
– Add a flash. It doesn’t seem like a flash should have any effect on sharpness, but in practice it sure does. A short burst of light will serve to freeze a moving subject, and even on a stationary scene that flash has the optical effect of making edges appear sharper. Maybe this is simply a function of the flash duration being way faster than a shutter speed, or it could just be that it further defines small edges and textures and shapes for an increase in edge contrast. But either way, I promise you, it really does work.
– Mirror lockup. The small vibration from your DSLR’s mirror slapping up against the mirror box of your camera is enough to add movement, and blur, to any exposure. In order to eliminate vibration, many cameras offer mirror lockup. Conventional wisdom has mirror lockup used more frequently for long exposures, but in fact it’s most effective with shorter exposures because the vibration occurs for a higher percentage of the duration. Mirror lockup is a necessity of shooting in Live View too, as the mirror is lifted to allow the sensor to see the scene, so that’s an easy way to employ the technique. Otherwise, under normal viewing conditions, simply employ mirror lockup via the push of a button or the flip of a switch—or in some cases, by using the self-timer. (The self-timer, by the way, is the poor man’s cable release. It allows you to trip the shutter without touching the camera at the crucial moment.)