Back Button Focus.

[Braineack]

Yep. Three things I forgot. I've used all three.

 

[zulu42]

You guys are making sense but I'm still not convinced. I don't really understand the advantage of BBF over AF-L for pre-focus or focus and recompose situations.
For manual override of focus, I can see that benefit.
for metering without changing focus, AF-L...
Finger fatigue? Get outta here.

 

[Derrel]

Finger fatigue...that one left me at the border town called Credulity...AF-L has served quite well for two decades for me.leaves the right thum free to grip, select focus points withe the D- pad. Run the shutter speed selector.

With a large and heavy lens on the camera the thumb serves a pretty important part of gripping the camera. when you add on a 7 lb 200 or 300mm lens, the thumb as a gripping point is not to be compromised.

 

[TWX]

Tried it, don't like it, now do not use it. It makes what is a 1 step process into a two-step process. Some cameras have a focus lock button on the back and if you have this control, then you will see very little need for back button focus.

I tried it in-part because I have a lens whose AF/MF switch is busted and I left it in the AF-mode, so BBAF allowed me to selective use AF.

I found that the traditional BBAF with the shutter-button not doing any AF simply didn't work well for me on my 77D. I've been slowly retraining myself to use my right eye, but I've traditionally been a left-eye shooter, and that makes it harder to reach the AF-ON button. Likewise, even when I use my right eye, the 77D body, like the Rebels, is small enough that my face still makes it awkward to reach the BBAF button.

What I instead do is use the AF-ON button as an AF-OFF button. This allows me to use the shutter button to achieve focus, then hold down AF-OFF when I don't want subsequent shots to use AF while pressing the shutter button. This has the advantage of allowing a novice like my wife be able to use the camera with traditional half-press AF as well.

 

[JBPhotog]

I guess one might want to ask from a R&D perspective, if there was no value to BBAF then why do manufacturers design cameras with them? The answer is rather simple, it is the preferred method of focusing by the majority of professional (i.e. working) photographers. As Steve Perry says in his eBook mentioned earlier, "BBAF once again separates AF from the shutter release - the way the camera gods intended." And for those who have been around before AF was invented, these two functions where separated, the shutter did its job, the focus ring did its job the two were not married to each other.

Here's a great video explaining BBAF.

 

[TWX]

I wish that the lock switch on my camera would allow me to enable or disable AF on the shutter button. If that could be configured in that fashion that would make it a lot easier to just use BBAF or not at-will.

 

[Braineack]

You guys are making sense but I'm still not convinced. I don't really understand the advantage of BBF over AF-L for pre-focus or focus and recompose situations.

You don't accidentally forget it's engaged/locked, or accidentally let go, depending on your settings.

 

[JBPhotog]

Finger fatigue...that one left me at the border town called Credulity...AF-L has served quite well for two decades for me.leaves the right thum free to grip, select focus points withe the D- pad. Run the shutter speed selector.

With a large and heavy lens on the camera the thumb serves a pretty important part of gripping the camera. when you add on a 7 lb 200 or 300mm lens, the thumb as a gripping point is not to be compromised.

I have not encountered any issues with BBAF operation with my thumb with either the AF-S 300mm F2.8 or the AF-s 500mm F4 even with TC's included.

 

[Braineack]

Finger fatigue...that one left me at the border town called Credulity...

Back when I was doing lots of panning for an entire day, it became an errand to try to track the subject, half-press track focus, then release the shutter, and continue to focus, and release the shutter again, maybe 3-4 shutter releases per pass. I don't experience that using AF-ON

 

[Derrel]

It's time for a T-shirt that proclaims, "I Shoot Back Button Autofocus", similar to the , " I Shoot RAW" shirts that Fro Knows Photo popularized. Say it loud, say it proud, wear it on a T-shirt.

 

[TWX]

It's time for a T-shirt that proclaims, "I Shoot Back Button Autofocus", similar to the , " I Shoot RAW" shirts that Fro Knows Photo popularized. Say it loud, say it proud, wear it on a T-shirt.

Problem is that's too much.

On the front it will say, "I shoot back" and on the back it'll say, "button autofocus"

 

[Derrel]

Brilliant suggestion!

 

[Derrel]

Finger fatigue...that one left me at the border town called Credulity...

Back when I was doing lots of panning for an entire day, it became an errand to try to track the subject, half-press track focus, then release the shutter, and continue to focus, and release the shutter again, maybe 3-4 shutter releases per pass. I don't experience that using AF-ON

But every time you half-press the shutter, the system autofocuses.... I have shot perhaps only 10,000 panning photos and I don't know what you are talking about.

If you use the direction pad and your right thumb to set the focus Point once, every Nikon made since at least the d2x will use RGB tracking to follow the subject anywhere it goes across the frame. So for about the past 10 years or more we have had a system to automatically track your subject at computer speed much faster than you can do it with your slow human reflexes. I think your rationale here is underutilizing the system. Perhaps you are not that familiar with 3D RGB tracking. Any Nikon has over 1,008 sensors (the number used in the low-end Nikons) dedicated to analyzing the scene as far as RGB values and luminosity, and as I said, it can track a subject based upon its RGB values wherever that subject goes, anywhere in the frame, but this is dependent upon you using your thumb to select the initial Focus point and Target. Nikon and their teams of engineers have used decades ' worth of camera engineering and you are relying upon a method that introduces the slowness of the human reaction as opposed to utilizing the camera's multi-bit computer.

This kind of reminds me of people who are using the Nikon metering system as if it were a dumb,color blind 18% reflected meter from the 1960s.... the camera does both RGB_and_Luminosity analysis for both metering and focusing, and this is what makes the Nikon D5 such an incredible auto focus camera. There is no need to make compensation for what the light meter sees... by combining RGB analysis with reflected light readings the metering system can tell with extreme certainty what the exact color is of an object. It can differentiate between a white car and a gray car and a black car. The system can _track_ a subject effortlessly. The focusing system can track a subject easily, but only if you allow it to.

If you want to go by slow human reaction, then go ahead, but do you think that you can out-think a microcomputer in terms of speed and reliability? In my experience,no. It's like using Centerpoint only focus with a camera that has 51 auto focus points. If you take the time to understand how the Nikon autofocus system works then there is very little advantage to using the slow human brain and body to try and out think the camera.

 

[JBPhotog]

AF systems are truly amazing however, they are not infallible. There are caveats to all modes such as Single point, Dynamic, 9, 21, 51 etc. 3D, Group and Auto AF. Each mode uses different determinations as to what you want to keep in focus, Single being the most particular of the bunch.

The subject matter can play a huge roll as to what AF mode you employ and there is no nirvana to all scenarios, they all fail to nail focus at times. It is incumbent on the photographer to decide which AF mode best suits the subject and whether it is static, in a predictable motion, how fast and of course the direction in relation to the photographer it is moving. BBAF lets you decide when the AF system engages and since it sits right under the pad of the thumb when holding the camera, is a logical use of said feature but it doesn't change the AF mode just when it is on or off. This determination is made by visual cues through the viewfinder, is the image sharp or not, is the focus indicator a 'O' or '> <'.

Even with this amazing technology, I have bin of OOF images the camera couldn't make the right decision on.

 

[Derrel]

Learn what your system was designed to do and seek understanding. Today's autofocus systems are extremely complex. Noted Nikon Authority Thom Hogan has a series of books that will help gain a more complete understanding of Nikon autofocus systems and controls. There are also a couple of other authors who have written entire books on getting the most from particular Nikon models. Using today's modern and sophisticated cameras as if they were models made in 1990 is not my idea of getting the most out of the technology. For example the United States Air Force has developed very sophisticated computer tracking and lock on technology which far outstrips the ability of mere mortals.

And speaking of "lock on", Nikon uses that terminology in what I would consider to be backwards English. Most people have lock on set to "fast.... when in reality what they would be better off with is a much lower level setting. lock on should more properly be called "new Target Focus acquisition timing delay".