What is a photograph?
A photograph is reflected light from a scene focused onto a light-sensitive surface, i.e. Negative Film or a digital cameras sensor.
So we can see that the focus of an image is a critical part of photography, Without good focus you will have “soft” images. Nobody wants that. So let’s get cracking with some ways you can improve the focus in your photographs.
Set your camera to centre spot focus, and learn to use it.
Most cameras these days are equipped with multi spot auto focus (AF). This means that the camera will have anything from 9 to 61 focus points spread around in the viewfinder. Most cameras allow manual selection and activation of individual “focus points”, as well as automatic selection which can evaluate different lines of contrast in the scene and use special algorithms to determine which part of the image to focus on using as many points as it sees fit. This can be very unpredictable, slow and problematic in certain scenarios and I tend to avoid using multiple AF points at all costs. (Although there is always an exception)
If anything, as the photographer you should at least pick what you focus on, even if you leave the rest of the image capture process to the camera. To do that, get your camera to have one single focus point, right in the middle of your viewfinder. This is known as centre spot focus, and if you have never used it before you are about to have your world explode with possibility.
Once you have one centre focus point enabled its time to learn how to compose the shot you want. To do this, align the part of the image you wish to be in focus in the center of your viewfinder. Half depress the shutter button and lock the focus (usually a beep is heard and the AF point flashes red once locked) you can now keep the button half depressed and re compose the shot, this will keep the focus locked and allow better composition of the image. Once you are happy with the composition depress the button all the way allowing the camera to capture the scene focused as you wanted it.
Generally lenses are sharpest in the middle, this means you get much faster & sharper focus using the centre point.
Look for contrast to help with focus
Cameras use horizontal and vertical lines of contrast to attain focus(even when using one point). This means if you try to focus on a flat low contrast object, such as a wall, the camera might not be able to use AF. Try to find an area with some contrast to allow the camera to focus properly. Maybe a darker patch of paint on a wall, or the horizon when shooting a landscape.
Cameras can’t see in the dark
Turn on AF assist beam, this will either send out a beam of light to allow the camera to ascertain focus, or it will pop the flash and burst pulses of light to allow the camera to focus. sometimes this may be a bit slow, be patient. A hot shoe flash can speed things up dramatically and allows for better exposures as well. If you are shooting in very dark conditions try shine a light on your subject to attain focus, or if shooting landscapes maybe the moon or a distant street light.
Servo mode allows the camera to track movement (and focus) of a subject as it moves either towards or away from the camera. This is quite useful when shooting wildlife, sports or any other moving subjects. This mode can be combined with multi or single AF points depending on what you need to shoot, and the servo mode can also be responsable for bad focus. If used with spot focus(unintentionally), it will never lock and as you recompose your shot the focus might shift, leaving you with some very random results.
Shoot for the eyes
When shooting portraits, engage your viewer by focusing on the eyes, for wider portraits the face of the subject will do.
Infinity and beyond
Infinity focus isn’t the only option for landscapes, try drop a point of interest close to the lens and add some shallow depth of field for something interesting.
Shallow depth of field requires more time to focus
When using lenses at a wider aperture than f/2.8 expect focusing to take a bit longer. Some of the better canon lenses have ultra sonic motors (USM) which are pretty quick, but if you’re using something like the 50mm 1.8 give it some slack when fully open.
Invest in glass
Good lenses are sharper and focus faster. Fact.
And sometimes generic brands are as good as original (In my opinion anyway), Do your homework before purchasing fresh new glass.
Shutter speed could be the culprit..
check your shutter speed is adequate for hand-held shooting.Camera shake can sometimes cause blurry pictures. The general rule of thumb is that if you use Xmm lens then your shutter speed shouldn’t go below 1/Xth of a second.
E.g. With a 200mm lens, your shutter speed shouldn’t drop below 1/200th of a second. 50mm = 1/50th. Get it?
You can sometimes go a bit slower depending on the steadiness of your hands and if you have stabilised lenses or not. If you find your shutter speeds are too slow try increasing your ISO or opening the aperture a little wider. You could also lean against a sturdy object and try to take the picture at the end of a slow exhaled breath. (seriously)
Still having focus problems?
Could be that the lens calibration or camera focus screen might be out. Did you drop it?.
If it is a minor focus problem some camera body’s allow specific lenses to be calibrated allowing absolute pin sharpness when paired to each other.
So that concludes my points on image sharpness. Time for bed.
Questions & Comments welcome.