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The Key to Sharp Images
photo by John Campbell
All of the following points will help you get the pin-sharp images that you often see in glossy magazines. Some of the terminology used might not be clear at the moment, but as sharp images are something that we all want to achieve as soon as possible, I decided to put this near the top of the list of articles.
If possible, use the sharpest aperture for your lens. This is usually about 2 stops down from the maximum aperture. So if you have an f/2.8 lens, optimum sharpness will be around f/5.6. Many professionals will do some test shots when they buy a new lens to assess the optimum aperture. For zoom lenses, the optimum aperture may vary for different focal lengths (usually a smaller aperture (higher f-number) at longer focal lengths).
The lens itself can have an effect on image sharpness. Most kit lenses that come with DSLRs are not going to be particularly sharp (especially at maximum and minimum apertures). Investing in better quality lenses (read that as expensive) can make a significant difference.
Use the lowest ISO possible. High ISO means more noise, which generally means the camera uses a greater level of noise reduction. This will impinge on the sharpness of the image.
Use a tripod - preferably a sturdy one. Pro photographers will often use a tripod even in daylight and with a fast shutter speed as it really can improve overall image sharpness.
Pressing the shutter button can cause the camera to move (even when it's on a tripod) so use a remote form of release. There are two basic types - cable release and wireless shutter release. Most DSLRs will support at least one of these..
If you are using a tripod but don't have a remote release, use the timer (set to two or five seconds if this is an option). Press the button then lift your hand clear of the camera.
Another source of vibration is the mirror moving up to reveal the shutter and sensor. Many cameras feature a mirror lockup capability which moves the mirror on the first press of the button and takes the picture on a second press.
Many lenses now come with Image Stabilisation (Canon IS lenses and Nikon VR lenses for example). This is great if you want to hand-hold the camera, but if there is little chance of there being any camera shake (ie. on a tripod), then turn the image stabilisation OFF.
Post processing can be used to increase the apparent sharpness of an image after it has been transferred to the PC. Most image software features something called the 'unsharp mask' which despite the name, actually makes the image appear sharper. Learn to use this properly, as it's easy to mess up an image if you don't understand the different settings.
With a DSLR, use live-view if available. Not many people know this, but the image you see when looking through the viewfinder is not exactly the same as the image that will be captured by the sensor. Specifically if using a large aperture (such as f/1.4 or f/1.8) it shows an image with a greater depth of field than will be projected onto the sensor when you press the shutter release. So if you are using manual focus (common for macro photography), it is best to use live view, and use the zoom feature to check accuracy of the focusing.
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