Back button focus

[SquarePeg]

Can someone explain the advantages/disadvantages or point me toward a good resource on back button focus? Using a 7100...

specific questions

How to set it up?
When/why to use it?
Is it just a more advanced process of focus/recompose?
Can you opt back and forth with standard focus on the fly?

I'm sure I'll have more questions once I give it a try. Thanks!

 

[JacaRanda]

Here you go: Back Button Focus: What it is, why you want it & setup guide

Scroll down far enough and it shows some specifics for the D7000 (hope it's close enough).

 

[SquarePeg]

Here you go: Back Button Focus: What it is, why you want it & setup guide

Scroll down far enough and it shows some specifics for the D7000 (hope it's close enough).

Great!!! Thank you so much.

 

[Overread]

How to set it up?

Varies from camera to camera and I can't say for your Nikon but should be easy to google that info or find it in the manual

When/why to use it?

Honestly I'm hard pressed to think of situations where you don't want to use it unless you've got:
1) An older camera that doesn't have a dedicated back-button for the AF (some twinned it with the pre-flash fire button)

2) If you're handing the camera to someone who doesn't know how to use backbutton (although sometimes for those groups just clicking it into auto mode - which doesn't support back button AF - at least in Canon - can work).

Is it just a more advanced process of focus/recompose?

No; in fact its not really anything to do with focus and recompose. Backbutton AF is about separating the act of metering and taking the photo from the act of focusing the photo. This means that with backbutton AF you can enable the metering (half press of the shutter) and take a shot (full press of the shutter) without the AF motors engaging at all.

This is powerful because it means that you can pre-focus and leave the focus fixed; focus and recompose; focus once and lock the focus etc... It also means you can take meter readings without the AF trying to do anything.

Can you opt back and forth with standard focus on the fly?

Yes and no and Yes.

Yes because, as said, if you enable auto-mode you get normal focusing back on the shutter button; but you also then have to deal with auto mode doing everything else too.

No because you honestly won't need to. Once you get used to backbutton AF you likely won't go back; you can just shift the menu options back and forth as you need, but most find no need to do it.

Yes because when you have a lens with full-time manual focusing you can shift into manual focusing without doing anything. You just turn the focusing ring and focus the lens whilst in AF mode on the lens; because the AF on the camera won't engage until the backbutton is pressed, so you just don't press it. And because its not on the shutter the act of taking the shot won't suddenly engage the AF for a split second to try and focus.

Of course any lens without fulltime manual focusing will have to have the AF switched changed (to allow the focusing wheel to move and affect focus); but otherwise this allows you to swap between auto and manual focusing on the fly without having to hunt over hte lens body to find the AF on/off switch.

 

[480sparky]

..........Honestly I'm hard pressed to think of situations where you don't want to use it ...........

I don't use it when I'm shooting fast action like sports or moving wildlife. My D600s are set to BBF as I usually am shooting landscapes, architecture etc. So BBF makes sense to me for that.

But my D7100/200-500/1.4TC Stack is not because that's what I use to shoot BIFs, sports etc.

 

[NancyMoranG]

Peg, I am using it based on suggestions on TPF. I didn't even know the stuff overead posted (zheezs :{ )
But I think a lot of people in the Nature forum use it. SCraig and Jaca come to mind. You might wander over there...
Sorry I can't help much.

 

[pjaye]

All of your questions were answered, but just wanted to add, I use it. Took a couple of days to get the hang of it, but I love it. I have a Nikon D7000 & D7100. I shoot mostly wildlife.

 

[Derrel]

BBF is not a panacea. The biggest danger with it is forgetting to re-focus when you shoot quickly...it's easy to end up with multiple OOF images. Not every situation is best with the shutter actuation and the focusing step "segregated" into two, distinct operations. In situation s where you have a large, heavy lens, or when you have really shallow depth of field, or you are using the 4-way controller to move the AF point to start with, it really is dumb to use it, since it takes away your thumb as an actual TOOL to manipulate the camera. The second biggest danger is that it can VERY easily lead you into the habit of focus-once and never-refine, never-reset the focus over a sequence of shots.

How BBF is implemented depends too on the specific camera, and its control options. I've been shooting the pro Nikons for 15 years, and they have two buttons on the horizontal shooting mode: a separate AF-ON button, an a combination AE-L/AF-Lock button right next to one another. In vertical mode, there is just the AF ON button. There are several permutations on how the buttons actually function....AF os active when the button is held in? AF is active and then locks once the button is released. Light meter reading tied to the AF lock position, or light meter free to adjust but focus locked? etc.etc..

I seldom use back button focusing, but I do use the AF-Lock quite a bit. I know imagemaker46 does not use back-button focus, so it's not that one needs to use BBF, even to shoot action spots, or to be an accomplished shooter.

I personally think that linking the focusing operation to the trigger in AF-C, and having my right thumb free to move the AF point to the desired area trumps BBF.

It depends on how you want the camera to work...and how you want to use the AF system: wither with one AF point, or with a group AF point like 9-point, 11-point, or 21-point, or all 39 or all 51 points. I think for a lot of continuous action, BBF is misguided....for some things like baseball, where you might easily want to set the AF to a specific base and hold the camera on a monopod and wait for the play that you KNOW MUST be to a specific base under a specific base runner and pitch count or strategic situation, BBF can be handy.

Still, I prefer to have the camera in AF-Continuous and to RE-focus for each and EVERY frame, so to me BBF makes little sense for people work...it's just way,way too easy to set a focus and then leave it there. The higher the magapixels, the shallower the depth of field, the longer the focal length, the more I want a NEW focus established for every single press of the trigger, and I want it all done in one step...with the trigger.

I think BBF is often way over-touted on-line. it appeals to people who distrust their AF system, or who typically want to use it as if it's a one-AF-area camera, using just ONE, single frame of reference to focus, and they to stay with that one-point AF lock. I distrust that idea...I ant the focus to be NEW for each frame, and want to use my thumb to move the AF area at any and all times, and to have my THUMB free for gripping the camera and for moving the shutter speed wheel...

Part of this might also be body-dependent; on a camera with a weaker AF module, the focusing system is often not the best, and with a slower lens (say f/4.5~5.6), or with wide-angle lenses that have low magnification, I totally,totally,totally DISTRUST using one, single AF lock for more than one or two frames.

 

[Overread]

I just leave backbutton focusing on and hold the button down for continual refocusing.
Gives me the same grip on the camera; although I do back that up with a battery grip and wrist strap.

That's when shooting anything; - landscapes, macro*, wildlife, showjumping, people etc....

To my mind the mode lets you do everything the shutter button AF does and more because the functions are split. To me it makes focusing easier.

*Yes for macro. Because I don't use AF for macro it means that I can just put the lens on and shoot; and if I want to use AF for a further off shot I just press the button; no hunting for switches on the lens body. I only have to hunt for a switch on my 35mm because it hasn't got fulltime manual focusing.

 

[Derrel]

Back Button Focus: What it is, why you want it & setup guide

Okay, let's take this fellow's first instance of why one would want to use BBF.

"EXAMPLE NUMBER ONE

First, suppose you are shooting portraits. The person who you are shooting is standing still and you want to take several different shots of the person. You take your first shot, and then change your composition and need to move your focus point to be on the person’s eye. If your camera has 40+ focus points like many DSLRs do, you have to use the four-way selector to tediously move the focus point to the correct spot, focus, and then take the photo. How annoying!

You can use back button focusing to solve this problem because the distance between the photographer and the subject stays the same between both shots, but the composition changes. With back button focusing, the photographer activates focus for the first shot, and then is able to recompose infinite times as long as the distance between the camera and the subject remains exactly the same.

You’ll note that there are other ways to solve this problem, such as focus and recompose (equally tedious, but sometimes it’s your best bet), or holding the AF-L, AE-L button, but that is just plain annoying. Back button focusing is superior in this instance as long as the photographer is careful not to change the distance between the camera and the subject (which would throw off the focus) when using shallow depth-of-field."

******
A great example of THEORY clashing horrifically with the actual practice of portrait or model or lifestyle photography.

1) Here's a steel-tape FACT. Focal plane at 90.25 inches to X of gaffer tape on wall. Twenty-five degrees to left of the lens-to-target axis, the measured wall-to-focal plane is 97.00 inches distant. That is a 6.75 inch distance disparity. More than the depth of field will cover at wide aperture. Focus and recompose with a 35mm lens will throw the focus off by almost seven inches. The author of this piece suggests that instead of taking .25 seconds to use the jog wheel on the back of your camera, to just skip placing the AF point properly, and instead using using focus and recompose! Wow...how newbish.

And the wording: "recompose infinite times as long as the distance between the camera and the subject remains exactly the same". I wish the world were that simple and perfect.


2) Steel tape fact #2: I set up a tripod with the camera plate a measured 47 inches from the floor. With the camera framed in "tall" mode, the center of the frame was a measured 91.25 inches to the wall. The distance to the ground wall/floor joint, at the ground? 103.25 inches. That means an 11.75 inch focus discrepancy. Very dicey. At wider apertures, this one is a loser.

The guy who wrote the piece above is not a very experienced photographer. But he did figure out how BBF works. And he wrote a nice excited piece about it, but his portraiture technique and knowledge utterly sucks.

He's basically saying, WTF, lock the focus somewhere between 7 inches and a foot off, and fire away. Uhhhh...no. Never. Ever. Photo technique articles that use faulty examples spread misinformation. And that is exactly why so many noobs shoot portrait sessions with EVERY FRAME out of focus, even at 15 feet, with their 35mm and 50mm lenses, even when they had stopped down to f/2.8. Bad advice from people who try to teach stuff they really have no business "teaching". Focus and recompose is a HORRIBLE method if one is so,so lazy as to use the center AF point, then to let go of the button and just blaze away? Just so,so,so wrong on multiple levels.

 

[JacaRanda]

It's very much a YMMV scenario. As in all things camera and photography related, use what works for you and your camera.
My camera is pretty much always set to AI-Servo for continual focus update. For a flying bird or any other fast or slow moving subject, I hold my bbf thumb down while tracking and pressing the shutter. Even when a bird is wading (not moving distance at all), I simply BBF and release it (focus once and done) and again release the shutter as often as I want. At that point my thumb is free to change anything else it would normally be used for. Since I have gotten used to using BBF, I don't think I have ever forgotten to refocus. It simply becomes habit or second nature - just like using the shutter button.

All it is, is a way to use your camera differently.

 

[JacaRanda]

I just leave backbutton focusing on and hold the button down for continual refocusing.
Gives me the same grip on the camera; although I do back that up with a battery grip and wrist strap.

That's when shooting anything; - landscapes, macro*, wildlife, showjumping, people etc....

To my mind the mode lets you do everything the shutter button AF does and more because the functions are split. To me it makes focusing easier.

*Yes for macro. Because I don't use AF for macro it means that I can just put the lens on and shoot; and if I want to use AF for a further off shot I just press the button; no hunting for switches on the lens body. I only have to hunt for a switch on my 35mm because it hasn't got fulltime manual focusing.

Dang, you beat me to it.

 

[SCraig]

Peg, I am using it based on suggestions on TPF. I didn't even know the stuff overead posted (zheezs :{ )
But I think a lot of people in the Nature forum use it. SCraig and Jaca come to mind. You might wander over there...
Sorry I can't help much.

Don't know about JacaRanda, but I never use it. I've never seen any reason to push two buttons when pushing one will do the same thing. To each their own though.

 

[Derrel]

I'm still laughing about the portraiture scenario where, "the photographer activates focus for the first shot, and then is able to recompose infinite times as long as the distance between the camera and the subject remains exactly the same."

Gotta love that kind of a scenario! That surely exists in the world where all the women are 7's and I am a sold, gold-plated 10.

 

[robbins.photo]

Don't know about JacaRanda, but I never use it. I've never seen any reason to push two buttons when pushing one will do the same thing. To each their own though.

I tried BBF - wasn't really my cup of tea. Maybe if I'd had Jaca there to hold the button for me.. hmmmm...