Posts Tagged ‘Autofocus’

Autofocus is a feature included on almost all cameras, and it has been that way for decades. We expect our cameras to be able to automatically focus on our subject quickly and accurately.

However, sometimes autofocus can fail. It might be that the camera just doesn't seem to want to focus at all. Or it might attempt to focus, but give up. Or it might tell you that it has focused, but the focus is actually somewhere else than where you wanted it.

In this article we'll look at ten reasons why autofocus may not work correctly, and what you can do to avoid / fix these problems.

Modern cameras offer a plethora of autofocus options to help you get the best focus performance possible, whether you're photographing a fast moving sports car or a static still life subject. In this article we'll look at the various different modes and options, what they mean, and when you might want to use them.

Back button or Rear button focusing is a method of autofocusing used by many photographers. It decouples the autofocus from the shutter button, so a separate button on the back of the camera is used for focusing, while the shutter button is just used for taking photos.

In this article we'll look in more detail at the back button focus method. We'll cover why many photographers prefer this method over the standard half-press of the shutter button for autofocus. And also cover some situations where it doesn't work so well.

Something that you may come across when browsing photography forums, or reading camera or lens reviews, is the mention of the camera or lens 'Front focusing' or 'Back focusing'. This means that the camera / lens focuses in front or behind of the subject, rather than where it should have focused. Obviously not a desirable trait.

In this article we'll look at what causes back and front focusing, how to check if your camera / lens suffers from it, and what you can do about it if it does.

In the previous article we looked at examples of when you might want to use manual focus instead of autofocus. In this article we'll cover how you can focus manually, with some tips to help you make sure that your focus is accurate.

The autofocus systems in modern cameras can usually focus a lot faster than we can focus the camera / lens manually. But there are some situations where using manual focus may be preferable. In this article we'll look at some examples of where using manual focus can give better results than autofocus. (Tips on the actual process of focusing manually will be covered in a separate upcoming article).

cannon ball by fRandi-Shooters on flickr (licensed CC-BY)

The most obvious situation when you'd want to use manual focus is when autofocus isn't working. When the camera can't autofocus correctly, or is finding it difficult to autofocus, you'll often find that the autofocus will 'hunt'. This is where the focus is racked back and forth between infinity and the closest focus of the camera, in an effort by the camera to try and find the point where the subject is in focus.

Most cameras will flash the active focus area in the viewfinder or on the LCD and beep when focus has been successfully achieved. If your camera is having trouble autofocusing, then switching to manual focusing would be advisable.