Auto focus is a win win in many cases due to its simplicity and accuracy. Unfortunately there are situations where the auto-focus fails, and you have to focus manually. Manual focusing is not as difficult as it seems provided you know the right way to go about it.
From Auto-focus to Manual Focus
Auto-focus (AF) is a great tool in many situations, but not always. For example, when there is little or no contrast between the subject and the background, and the auto-focus cannot find anything to focus on. Or the auto-focus persistently focuses on some objects in the foreground, instead of the imposing landscape behind it. In such cases, it is better to switch to manual focus. That’s called MF, from ‘manual focus’.
With a few exceptions, you mostly focus with the focus ring around the lens. Some lens have it in front of the zoom ring, while others behind it. Before focusing manually, it is highly recommended to set your camera and lens to the M or MF position. This prevents any damage to your camera and lens. With older and / or cheaper lenses, the focus ring sometimes turns on the AF position.
You can switch to manual focus with a switch on the lens and / or the body or via a menu option.
You don’t always have to choose between AF and MF. With some camera-lens combinations, you can manually adjust the focus with the focus ring after the autofocus has focused, then you use autofocus, as it were, for the big line and the focus ring for the finishing touch. Please note that the lens must be suitable for this, otherwise you might damage the lens. Also, this only makes sense with single AF. If you counter throttle with continuous AF, the camera immediately focuses the other way and then it becomes a tug of war.
Manual focusing is much easier if you enlarge the image on the screen or in the electronic viewfinder.
Focus And Check Sharpness
With manual focus, how can you see whether your image or is really sharp? This is where the kind of camera you use come into play. With most cameras you can of course review the photos you have taken on the screen, and zoom in considerably to check the sharpness at detail level. This is essentially the safest way, but not always the most practical.
With SLRs, you usually focus via the optical viewfinder. It contains a frosted glass on which you can focus. A bright focus point gives a signal that the image at that location is sharp, but not everyone is adept at using such a frosted glass image. If you use a telephoto lens, the difference between sharp and just not sharp is usually still visible, but with a wide-angle lens it is more difficult.
Many photographers prefer the electronic viewfinder or the screen of a mirrorless camera. The image that comes with such is not always that resoundingly sharp, but you can zoom in on the image and see exactly what is sharp and what is not. You can move the focus frame to the desired location and magnify it up to ten times at the touch of a button, making focusing a breeze. With some cameras, you can set that magnifying function to automatically activate as soon as you turn the focus ring.
With focus peaking, sharp parts are also accentuated. Contours that are sharp really stand out. The more they ‘shimmer’, the sharper they are. Often you can also set the desired color of this accentuation in the camera menu, so that the sharp parts stand out most clearly.
If you regret staring at your SLR now, many SLRs have comparable options in the live-view mode, so you use the screen instead of the optical viewfinder. This can be very useful, especially when photographing a stationary subject from a tripod.
With sufficient depth of field, you can also safely focus manually with portraits.
Depth Of Field
By depth of field we mean everything that comes in sharp focus from front to back. The depth of field will increase as the distance to your subject increases and if you use a shorter focal length (so a wide-angle instead of a telephoto lens) and / or a smaller aperture (higher F-number). In principle, you have more depth of field with a landscape photo than with a macro shot. The same applies to a full-length group photo compared to a close-up portrait. The greater the depth of field, the less small focus errors are noticeable. You can of course take advantage of that!
Practice makes perfect
You will automatically learn to focus better by hand the more you do it. So practice as much as possible before you start the ‘real work’. A point to note is how the focus ring works exactly. With some brands you turn it clockwise from close to infinity, and with other brands it works the other way around. If you make a mistake and initially turn in the wrong direction, focusing naturally takes more time. That can mean the difference between a missed photo opportunity and a successful photo. This is especially something to keep an eye on when you mix equipment from different brands. System cameras also have an advantage on this point. For lenses where the rotation of the focus ring is not transmitted mechanically but electronically,
If you do work from a tripod, it is often better to focus manually once.
In macro photography with an extremely shallow depth of field, manual focusing helps.
Just like typical AF subjects, you also have subjects that lend themselves to manual focus. Macro and landscape photographers often focus manually, especially when their subject is not moving and they are shooting from a tripod. In this way they have the greatest influence on the exact focus point. And if your object isn’t moving and neither are you, it doesn’t do much to get the camera to refocus for each shot. Preferably use live view while focusing. With this you can zoom in and you can see better than through an optical viewfinder whether you have focused properly.
Even when subjects such as architecture, products or food (‘food photography’) are among your favorites, you are often better off focusing manually. This way you can better determine exactly where the sharpness will be, and also to make optimal use of the depth of field. And if you are not only a fanatic photographer, but also an avid filmmaker, you will notice that with some lenses, using the autofocus leads to choppy results, in which the sharpness jumps in an annoying way. In this case also, a manual focus would be better.
All in all, you can see the usefulness of a manual focus, and it should be a pretty easy thing to do if you follow the guidelines in this post.