Preachdude Loc: Geneva, OH

Most digital cameras are set up (default) to focus when you press the shutter release part way. What are the advantages or disadvantages of disabling this and setting up one of the custom buttons with which to focus?

twowindsbear

Ah - 'remembering to press the focus button berfore pressing the shutter release button' comes to my simple mind.

Dngallagher Loc: Wilmington De.

More control of WHEN the camera focuses....

I find that for some shots, setting up Back Button Focus provided me with more "keepers" right away because instead of the camera mistakenly focusing on the enclosure, I was able to focus on the animal inside the enclosure ....

Removing the half shutter press focus also can speed up action shots simply because the camera no longer is refocusing BEFORE taking the shot.

There are many videos on the internet that fully explain Back Button Focus technique and the benefits of using it, as well as articles that explain how, when and why....

http://improvephotography.com/4552/back-button-focusing/

http://www.learn.usa.canon.com/resources/articles/2011/backbutton_af_article.shtml

http://digital-photography-school.com/back-button-focus/

http://www.clickinmoms.com/blog/how-to-use-back-button-focusing-tutorial/

kd7eir Loc: Tucson, AZ

This is a very good read on this subject -

http://www.nikonusa.com/en/learn-and-explore/article/hxlkcpoz/benefits-of-using-the-af-on-button-for-autofocus.html

Mac Loc: Pittsburgh, Philadelphia now Hernando Co. Fl.

Less chance of releasing the shutter before you're ready to.
A firmer hold on the camera body to lessen camera shake.

rwilson1942 Loc: Houston, TX

What you are referring to is Back Button Focus.
For me one of the big advantages is you get instant focus lock when you release the back button and the camera doesn't try to refocus if you re-frame and then press the shutter. It takes a bit of getting used to but I prefer it to half-press shutter button approach.

mborn Loc: Massachusetts

Once you get used to BBF you will not go back to focusing with the shutter button

OnDSnap Loc: NE New Jersey

Check this out...
http://www.youtube.com/watch?v=FzqQskGoURE&feature=youtu.be&list=UUhUi5Gm8w-S_d6dS31cFCnQ

jerryc41 Loc: Catskill Mts of NY

For me, it's being able to focus on the exact spot I want and then reframe, if necessary, without any loss of focus. Using the back button is a definite, separate action - getting the focus right. With the shutter button, if I press too fast or press too hard, I get a picture before the focus is right. So, using BBF is almost like taking a separate step of rotating the lens barrel to focus.

Carl D Loc: Albemarle, NC.

I only use back button focus.

NoSocks Loc: quonochontaug, rhode island

I tried it and went back to the shutter button. I just couldn't get used to it.

NoSocks Loc: quonochontaug, rhode island

Just can't teach an old dog new tricks.

jerryc41 Loc: Catskill Mts of NY

That reminds me of a cartoon. A dog was looking at his owner. The caption said, "Spot was aware of two things: he was an old dog, and this was a new trick."

amfoto1 Loc: San Jose, Calif. USA

I've been using BBF with all my cameras for many years.

To me the main advantage is that it allows me to leave the camera in continuous focus mode all the time (Canon: AI Servo. Nikon: AF-C. Etc.) This has several benefits.

When using the shutter release button to control AF, you wouldn't want to use continuous focus at times and need to switch modes more often. For example, with the shutter button AF setup you can't use a focus and recompose technique, without first resetting the camera to the non-continuous focus mode (Canon: One Shot. Nikon: AF-S. Etc.)

With BBF and the camera set to continuous focus, I'm pretty much ready for anything: Stationary subjects, moving subjects, focus and recompose, etc.... without any need to stop and change the AF mode. I can simply start and stop AF as needed, by pressing with or releasing the button under my thumb.

Now, I do occasionally reset a camera to non-continuous focus mode temporarily for certain types of shots (maybe landscape, portrait, macro).... Sedentary stuff where I'm working more slowly and want the most precise focus possible. However BBF works just fine for this, too. And most of the time my default mode is continuous focus.

Using continuous focus mode also will auto-correct for the fact that many modern autofocus zooms are varifocal... meaning that they don't maintain focus when you adjust the zoom and change the focal length. (This is done to allow for lower cost, smaller, lighter and less complex zooms... as compared to parfocal designs.) If using a non-continuous mode with a varifocal zoom, you have to remember to re-focus after any change in focal length. If you don't, you'll have a focus error. But, when instead using a continuous focus mode the camera will automatically maintain accurate focus as you zoom the varifocal lens. No extra steps to remember to take.

BBF makes it possible to use continuous mode more full time... And, in turn, continuous mode makes it pretty much a non-issue whether a zoom is varifocal or parfocal.

Yes, BBF takes a little practice at first... And using it requires me to do my job as the photographer. But BBF solves several focus problems, soon becomes second nature, and puts me in more full control of exactly when and where the camera and lens focus. Now if there are any focus errors, I only have myself to blame!

Dngallagher Loc: Wilmington De.

I know that feeling - it took me two attempts to get used to BBF... now it is easy ;)