A lot has been told about the Back Button Focusing in the past and there are people who are staunch supporters of it and people who completely ignore it. I have been using the back button for a decent amount of time now and believe that I feel more comfortable using it than otherwise.
This does not mean that those who do not use it consciously, are wrong. It just means that they are not comfortable with it. For those of you who do not know what it does, let us dig deeper.
The AF-ON button that sits on your cameras right where your right thumb might find its most comfortable slot functions as a focusing button. As long as you have the button pressed, the cameras auto-focus engine is engaged. The moment you release the button, it stops the AF engine. This is the default setting.
What people mean by using BBF is that they disengage the Shutter button from focusing. This can be accomplished as follows
- Canon : Go to Custom Controls and change the shutter button to ‘Metering Start’ only from ‘Metering + AF Start’
- Nikon : Go to Custom Settings – Autofocus and select AF-ON only under the ‘AF Activation’
A lot of people use BBF in place of ONE-SHOT/AF-S as well because with BBF once you remove your thumb from the AF-ON button the AF engine is dis-engaged, thus giving you almost similar functionality as ONE-SHOT/AF-S
The proponents of BBF say that by making the shutter button do one function less the camera has a better chance of latching on to focus and staying precise as there is a separate dedicated button taking care of it. True or false, there is no documentation of it.
People who do not like the BBF have one very pertinent point. If you are using the Back Button Focussing method, it takes a step more to change the focus point. Normally, your thumb is free and can do the job of changing focus point in the field really quickly. If you switch to the BBF method, that becomes slightly more difficult.
I use the BBF a lot in the following situation : When I am out in the forests clicking tiny forest birds under low light situations.
Birds are creatures of habit and quite often they repeat perches and that’s where the BBF comes in handy. It allows me to pre-focus on to a perch that the bird is likely to land on again and wait for the bird to come and click without being bothered about the AF being fast enough or not. When the light is great it is probably not much of an issue but when we talk about low light, the pre-focusing really helps a lot.
This also helps people who are not using the fastest of lenses and cameras in obtaining some good images of tough subjects.
Following are a few examples of the same. Very low light, not too much contrast, ideal situation for a lens to start hunting for focus. The pre-focusing helps here.
It finally boils down to having your fundamentals right and knowing the down-sides of each mode. Pick what works best for you. Don’t bother about what people say as long as it works for you guys.