Back Button Focusing?

Started 11 months ago | Discussions thread
dsjtecserv Veteran Member • Posts: 3,700
Re: Add one more reason:

Eliot Kramer wrote:

No need to switch to manual mode when I am doing long/multi exposures.

I can leave the camera in AF-C but use it as AF-S if needed without changing modes.

As has been said before, it is not for everyone. However, there are definitely advantages to BBF. I can't think of any disadvantage, unless of course you don't have enough buttons on the back of the camera for other tasks.

Your statement about AF-C and AF-S is NOT correct.

When you are in AF-C and you take the finger off the BBF it does not magically "convert" to AF-S. All it does is STOP the AF-C function at your last point of focus.

The point is that one can focus continuously until there is a need to lock the focus, and releasing the back button does that, just as if single focus was in effect at that moment. This is not reproduced when focus is on the shutter button, because while releasing the button stops focus, before you can take a picture the button must be pressed again, which will initiate another round of focusing, whether you want it or not, effectively canceling your focus lock. That doesn't happen when using the back button and releasing it to lock focus.

The termination of AF-C is NOT the same as being in AF-S mode. Otherwise, what really is the point of having AF-S at all if all you could do is just lift the finger off whatever button you are on and voila, you got yourself another focusing method.

And furthermore, if you are using the shutter button in AF-C and you lift off the finger the same result is accomplished, it stops focusing at that point in time.

This is the key difference: before you can then take a picture, you need to press the shutter button again, which will initiate a refocus, whether you want to or not. If the focus point is not on the spot you want to focus on (such as if you had recomposed), you will lose your preferred point of focus as it refocuses on something else.

With back button this is not an issue. Once you release the back button, focus remains unchanged, regardless of how many times you press the shutter button or where the camera is aimed. That is a key difference, if you choose to take advantage of it. You aren't required to use it, but that doesn't mean it doesn't exist!

I think we need to finally acknowledge that all BFF does is change how and when your fingers activate and terminate the focusing process. The fact that it is decoupled from exposure is not an intrinsic advantage, it just happens to help some people in some situations when they are trying to focus on one thing but expose for another that is located away from their point of focus. Which admittedly is not that common.

The ability to decouple focus, exposure and shutter initiation is quite useful and really is not reproduced by the conventional configuration, as described in the example above. It may or may not be of value for the type of shooting done by different people, or it simply may not suit their preferences, but the differences are real and many of us find them useful.

I bet if a rigorous test was conducted and people were shooting with both methods the ones with regular focusing will get more shots in focus more rapidly due to the time wasted playing with two fingers on two buttons.

There really is no waste of time, as both actions can be taken at the same time; once you get into the habit it becomes second nature. Kind of like walking and chewing gum!

Just my two cents, LOL

And mine!


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