Manual focus and when to use it
Autofocus has been a standard feature on mainstream cameras for decades, so why would anyone want to focus manually any more? There are situations, however, when manual focus is actually better, both from a technical point of view and for a stronger feeling of engagement with the photographic process. Here’s how it works, and why.
Practically every modern lens or camera will have a manual focus option. When this is engaged, you can turn a focus ring to see the image go in and out of focus in the viewfinder or on the rear screen. Some cameras offer a magnified view to aid precise focusing which is activated as soon as you turn the focus ring, or via a button on the camera.
But why would you want to focus manually when the camera can do it for you?
1. Preventing unnecessary refocusing
With AF, the camera focuses for every shot, whether you need it to or not. Sometimes this is useful – when your subject distance keeps changing or you’re taking lots of different shots as you walk around. But if you’re photographic a landscape, a building or a still life and trying a few different angles and compositions, or just waiting for the right moment, you don’t want the camera to keep refocusing. It’s a distraction, it adds a momentary delay, it may even refocus on a different spot. If your subject and your distance aren’t changing, you don’t need this constant refocusing.
- See Autofocus basics
2. Proper depth of field control
AF systems can only pick one thing to focus on. They have no concept of depth of field, zone focusing, hyperfocal focusing or any technique that exploits a range of sharp focus in a scene. In effect, a whole area of creative control is closed down. Using depth of field means focusing between the key subjects in a scene, not on one or the other, and then using appropriate lens aperture or focal length settings to keep them both sharp. You can persuade your AF system to focus between two subjects but honestly, it’s so much easier with manual focus. And, once you’ve made your calculations, you won’t have to worry about your camera’s AF messing it up.
3. Still life and macro
These are two photography genres in particular where manual focus will be both quicker and more consistent. In both cases, you’ll know exactly where the focus point needs to be and you don’t want the camera’s AF to be changing it or fighting you over every shot.
4. Panoramas and HDR
These are two specialized techniques that involve blending a whole series of images, and it’s essential that the focus point does not change throughout. Panoramic ‘stitchers’ are assembled from overlapping images and HDR ‘merges’ are carried out using a series of different exposures of exactly the same subject and framing.
5. Simplicity and physical engagement
Modern autofocus systems are highly complex and demand a lot of the user’s attention. There will often be features you don’t use, don’t fully understand or don’t work in the way you want them too. And for a lot of photography genres and styles, it’s just overkill. If you want to make your picture taking (and your camera) simpler, just switch to manual focus. You turn a ring until the thing you want is sharp, and that’s it.
Why old or ‘dumb’ lenses are better for manual focus
Autofocus lenses have manual focus rings, but they use fly-by-wire electronic control to move the focus groups within the lens that the AF would normally control. They have an ‘electronic’ feel not a mechanical one. Most will also lack a distance scale, or offer one so short it has no precision at all, and even if there is an aperture ring there are no depth of field markers to help you exploit zone focusing, for example. They will offer some of the advantages of manual focusing, but not others.
Older vintage lenses and many modern ‘dumb’ lenses are better for anyone who wants to use manual focus techniques fully. This is what they offer:
- Smooth, long-travel mechanical focus rings
- Long, precise (and hopefully accurate) distance scales
- Index markers to help estimate depth of field at different lens apertures and focus distances
Manual focusing can be hard to adapt to for anyone raised on AF, but while it requires a little more effort and may lack the accuracy of autofocus, it brings creative and technical advantages that are often overlooked.
