How to get Super Sharp Images - by Clive Bryson
Getting your digital images super sharp is something that most photographers want. To obtain clean, crisp, sharp images, be aware of the following guidelines.
Before exploring how to improve sharpness, we should look at the main causes for lack of sharpness:
Poor Focus - the most obvious way to get images that are ‘un-sharp’ is through having them out of focus. This might be a result of focusing upon the wrong part of the image, being too close to your subject for the camera to focus, selecting an aperture that generates a very narrow depth of field or taking an image too quickly without checking it is in focus.
Subject Movement - another type of ‘blur’ in shots is the result of your subject moving - this is generally related to shutter speed being too slow.
Camera Shake - similarly you can get blur if you as the photographer generate movement while taking the image - this often relates to either shutter speed and/or the stillness of your camera.
Noise - ‘noisy’ shots are ones that are pixilated and look like they have lots of little dots over them (get up close to your TV and you’ll get the same impact).
Here’s a list of 10 basic things to think about when shooting to get sharp images.
1. Hold Your Camera Steady
A lot of blur in the photos that I see is a direct result of camera shake (the movement of your camera for that split second when your shutter is open). While the best way to tackle camera shake is to use a Tripod (see 2.) there are many times when using one is impractical and you’ll need to shoot while holding your camera. Use both hands, keep the camera close to your body, support yourself with a wall, tree or some other solid object etc.
Tripods are a way to reduce (and even eliminate) camera shake. While not always practical, the result you’ll get when you do go to the effort of hauling one around can be well worth it. Monopods will only remove camera shake in the vertical direction but are better than using no support.
3. Shutter Speed
Perhaps one of the first things to think about in your quest for sharp images is the shutter speed that you select. Obviously - the faster your shutter speed the less impact camera shake will have and the more you’ll freeze any movement in your shots. As a result you reduce the likelihood of two of the main types of blur in one go (subject movement and camera movement). Remember the ‘rule’ for handheld shutter speeds:
Choose a shutter speed that is at least as fast as one over the focal length that you are currently using on your zoom lens or one over the focal length in the case of a prime or fixed focal length lens:
if you have a lens that is 50mm in length don’t shoot any slower than 1/60th of a second
if you have a lens with a 100mm focal length shoot at 1/125th of a second or faster
if you are shooting with a lens of 200mm shoot at 1/250th of a second or faster
Keep in mind that the faster your shutter speed is the larger you’ll need to make your aperture to compensate - this will mean you have a smaller depth of field which makes focusing more of a challenge.
Aperture impacts the depth of field (the zone that is in focus) in your images. Decreasing your aperture (increasing the number - say up to f/20) will increase the depth of field meaning that the zone that is in focus will include both close and distant objects. Do the opposite (for example moving to f/4) and the foreground and background of your images will be more out of focus and you’ll need to be more exact with what you focus your camera upon. Keep in mind that the smaller your aperture the longer your shutter speed will need to be - which of course makes moving subjects more difficult to keep sharp. Remember though, that many lenses do not perform well optically beyond f16, so read up on your particular lens especially with regard to aperture versus resolution. This is usually shown with a lens resolution chart.
The third element of the exposure triangle is ISO which has a direct impact upon the noisiness of your shots. Choose a larger ISO and you’ll be able to use faster shutter speed and smaller aperture (which as we’ve seen help with sharpness) but you’ll suffer by increasing the noise of your shots. Depending upon your camera (and how large you want to enlarge your images) you can probably get away with using ISO of up to 400 (or even 800 on some cameras) without too much noise but for pin sharp images keep it as low as possible). A good rule is to use the native (lowest) ISO for your camera, which often is 100 or 200. If you have to use a higher ISO, use the lowest one that will let you shoot your particular subject.
6. Image Stabilization
Many cameras and lenses are now being released with different forms of image stabilization (IS) which won’t entirely eliminate camera shake - but can definitely help reduce its impact. I find that using IS will give me an extra two or three stops (ie I can use slower shutter speeds by 2-3 stops) when hand holding my camera. Keep in mind that IS helps with camera movement but not subject movement as it allows you to use slower shutter speeds (not good for moving subjects). Remember to turn off your IS when the camera is mounted on a tripod. Sometimes IS can have a panning mode which stabilizes shake only in the vertical direction, so use it if you are panning.
Perhaps the most obvious technique to work on when aiming for sharp lenses is focusing. Most of us use ‘Auto Focusing’ with our cameras but don’t assume that the camera will always get it right. Always visually check what part of the image is in focus before hitting the shutter and if it’s not right try again or switch to manual focus mode. This is particularly important if you’re shooting with a large aperture (small depth of field) where even being slightly out can result in your subject being noticeably out of focus.
8. Good lenses & Filters
This one is for DSLR owners - if you have the budget for it invest in good quality lenses & filters as they can have a major impact upon the sharpness of your images. Always buy the best lenses & filters you can afford. There is a direct relationship between price & image quality that you will probably notice if you upgrade. Generally, fixed focal length or prime lenses have better optics than zoom lenses, although in these days of computer aided design of optics, you would be hard pressed to tell the difference for any practical purpose.
9. Get your Eyes Checked
Since I was young I’ve worn glasses but in recent years my vision ha deteriorated significantly. Getting new glasses could improve your photography. Also connected with this is checking the ‘diopter’ adjustment on your camera (if it has one. The diopter is a little adjustment that you can make to how your viewfinder works - it’s particularly useful for people with poor eye sight - it’s usually a little wheel next to your viewfinder.
10. Clean equipment
I recently gave a talk at the club on the equipment & techniques to keep your lenses clean. This information is available on our website. Smudges, dust and grime that can impact your shots. Similarly - a clean image sensor is a wonderful thing if you have a DSLR as getting dust on it can produce noticeable blotches in your end images. I talked about techniques for cleaning your sensor at our last meeting.
11. Lens Sweet Spot
Lenses have spots in their aperture ranges that are sharper than others. In many cases this ’sweet spot’ is one or two stops from the maximum aperture. So instead of shooting with your lens wide open (ie where the numbers are smallest) pull it back a stop or two and you might find you get a little more sharpness in your shots.