I've read a few articles on various sites about this technique. I've not found these articles to provide an adequate explanation. I could not find anything on the tutorials here, either. Any good references? Thanks in advance.
I've read a few articles on various sites about this technique. I've not found these articles to provide an adequate explanation. I could not find anything on the tutorials here, either. Any good references? Thanks in advance.
My only references were various YouTube videos describing how to do it.
Try your camera manual...
I use back button focus (BBF) all the time. What it does for me is that it decouples the focusing of the camera from the shutter release function and that is good especially when doing certain types of shots where I don't want the focus to change in the slightest between shots, for instance when I do panos or shoot a static scene.
I typically use single point focus mode and do a focus and recompose shooting style much of the time, this technique works very well for me. There are no issues at all with losing focus if I do not continue to press down the shutter release or accidentally taking the picture because I have pressed just a tiny bit too much. With BBF I have set the camera to use continuous focus mode which means the focus locks in when I am no longer pressing the back button.
It takes some time to get used to using your camera this way, but once you get over the learning curve, it's hard to go back to the default focus method.
There have been several threads about it here over the years. It simply takes the focusing function off the shutter button and puts it on a back button. My cameras have had different menu options for doing this. On my Canon 5DIII, one sets the shutter button only to meter. If AF is turned on for the back button, metering is turned on there too. So the camera will focus and meter with the back button, but if you release that button, the a half press on the shutter will re-activate the meter but will not activate AF. If you want to focus and recompose, focus with the back button, release it, and recompose; the camera will change the metering if need be after you move the camera but will not change the focus.
I use it for bug macros as well, as I don't want the camera to focus at all most of the time. I focus by moving the camera. I just keep my thumb off the back button
It takes a week or two to get used to, but it becomes automatic quite quickly. I now rarely put AF on the shutter. I do it occasionally when I am shooting candids and when I ask someone else to use my camera.
Manfred, Dan, thank you for the explanation. I will give it a try.
Last edited by LePetomane; 9th January 2018 at 01:46 AM.
Manfred noted something I left out, because I usually shoot in single-shot mode. When you shoot in continuous mode (in Canon-speak, AF-Servo), back button focus is the only simple way to have control over when the AF starts and stops.
Try this link:
https://www.naturettl.com/back-butto...-game-changer/
Funny, I use my thumb to fix exposure and keep focusing to the shutter bottom.
When I remember well the back bottom focus doesn't activate the VR, that's still connected to the shutter bottom and causes a delay.
George
My link was to explain the principal - as might have appeared logical since the two brands the OP is using are not listed there. I would suggest to get specific information on the feature for each brand, refer to the manuals for the respective camera bodies. The feature has to identified there, surely.
If Paul has access to lynda.com there is a lesson of focusing including back button focusing and focus tracking at: https://www.lynda.com/Cameras-Gear-t.../489093-4.html - NO it isn't specific to his camera bodies (see above) but it might help...
I've a dedicated back focus button on my camera, D700 and a AE/AF button, but only 1 thumb on my right hand. And I use that thumb mostly for exposure lock. I'm not shooting birds in fly or something like that.
I don't know what the delay is when the VR is activated but in my remembering it's always activated by the shutter button. I'm speaking of Nikon. I just see TS has another brand.
George
Not on my Canons. The back button triggers image stabilization when back-button AF is on. On my 5DIII, if AF is not placed on the back button, the shutter button activates IS. If AF is turned on for the back button and turned off for the shutter button (they are controlled independently in the menu system), BOTH the back button and the shutter button trigger IS, even though the shutter no longer controls AF.
Last edited by DanK; 9th January 2018 at 12:53 PM.
On a couple of my Canons, and my Nikon Df, you can set it up so that you can use multiple points, and as long as you hold down the back focus button it will continue to track - which is really nice! However that is not consistent across all models by any means. I think that Paul needs to get some specific research on his particular cameras. Surely these features are in the manual, or maybe a 3rd party book?
I don't know of any reason why single-shot mode is preferred for BBF. At least on my Canons, AF works identically regardless of which button one uses. And if "3-D tracking" what is called in Canonspeak "AI-Servo", BBF is in some ways ideal for it. Canon has specifically noted the advantages of BBF for AI-Servo (http://www.learn.usa.canon.com/resou..._article.htmlp):
Even with a very animated subject that may be moving around, you can have your camera’s focus set to AI Servo AF (to track any movement), and just keep your right thumb on the back button to keep focus active, while your index finger can be ready to shoot with no worries about also preserving focus.