Back button focus confusion discussion

[Mike Buckley]

Yeh, i use the D4 as a paper weight... must swap them around as the D4 is heavier and then i would be utilising both to their maximum potential ...

May I suggest that you get a lighter door so you can effectively use a P&S?

[HaseebM]

Haseeb,

My thinking is that you're probably better off reading the details in your user's manual explaining the options pertaining to the use of the back button rather than trying to follow this thread.

This made me go through the manual again but do not find any mention of BB?

[Mike Buckley]

This made me go through the manual again but do not find any mention of BB?

Conduct a search of the name of the button that you use. I'm a Nikon user, so I would search on "AF-L." I don't know the name that Canon uses for their corresponding button.

[Dave Humphries]

This made me go through the manual again but do not find any mention of BB?

Try looking for "AF-ON" Haseeb - that may be what Canon call it, especially if your camera has a button labelled with that tag (or even if it doesn't).


Being serious for a moment (with regard to paperweights and doorstops) for the benefit of those that don't know - on DSLRs that don't have an AF-ON button, almost all can achieve back button focusing, by means of assigning one of the other buttons.

The AE-L/AF-L button is most commonly used, since this is located top right on rear of camera, where the AF-ON button is traditionally.

That said, on my D7100, I have actually programmed the AF-ON function to the Fn button, located on the front of the camera below the lens. I did so because I wear glasses, even when shooting, and I found my thumb knuckle collided with them. However, my third finger can reach (and rest on) the Fn button far more easily. After the acclimatisation period, muscle memory soon kicks in and it works great for me - and might for other spectacle wearers.

[Mike Buckley]

Being serious for a moment (with regard to paperweights and doorstops)

Why in the world would we want to do that?

[Dave Humphries]

Why in the world would we want to do that?

I know - dunno what came over me, apologies Mike

[Stagecoach]

Andre, you seem to be digging a deeper hole with every post

Graham,

It is all about exposure when re-composing. It has nothing to do with locking focus.

There you go again.

You cannot lock exposure by using the back focus button only.

I'm fully aware of that and can not see any post here suggesting that others are not aware of that.

If you use BB focus you need to use another button to lock exposure before re-composing.

IF, but put more accurately, you need to use another method of setting exposure.

AND, a statement that totally ignores the fact that you may not wish to lock exposure before re-composing.

AND, a statement I suspect based upon an assumption of locking exposure and focus at the same instant, which is an operational option if wished.

If you are using half press to lock exposure before re-composing you might as well use half press to focus and lock exposure before re-composing.

IF, and as with everything these options are available to us all if we believe they better suit the shooting scenario.

BUT, BUT, BUT, a statement that ASSUMES that you wish to lock exposure at the same time as locking focus.

You cannot “re-compose” a moving subject, it is only effectively done for static subjects.

I suspect this is something most photographers understand.

Half pressing the shutter release button locks focus and exposure, in spot metering mode. Pressing the back focus button, only activates auto focus. The shutter release button, half press, activates focus, exposure lock and focus lock. It is a four in one button.

UM, I would suspect most people conversant with their cameras are aware of this but as it's a learning forum there may be some that find this information useful.

Have you noticed how exposure is affected when re-composing?

I certainly have, it's one of the first things I noticed and learnt to address with my photography many years ago. Over the years I have also learnt to adapt my methods to different shooting scenarios using more and more of those wonderful options the manufacturers give us.

What amazes me is that one of the least areas I have concerns with is acquiring good exposure with my photography subjects whether static, moving, dim light or macro, now I wonder if that is due to my camera or my knowledge of its use?

So, in summary Andre, after your initial statement that BBF should not at all be used by anybody using the focus and recompose style of shooting followed by I do not know how you do it or why you do it your continued backpedaling attempts to support this have simply been based upon ONE VERY SPECIFIC LIMITED SCENARIO.

WHICH IS, If you wish to shoot an image and lock exposure + focus at exactly the same time using one finger you COULD use the shutter button to do this as an option to other methods.

WOW I wonder what page in my manual refers to that method

[chauncey]

According to the dates on my CR2 images, my first picture was taken in 2008, have been shooting
totally in manual mode for 3 years...I don't have a clue as to where my BBF button resides.

[Glenn NK]

I use the BBF method on both bodies exclusively and understand the limitations and usefulness.

What I can't seem to find is the "hide" button. Oh, we don't have one. Darn.

[DanK]

According to the dates on my CR2 images, my first picture was taken in 2008, have been shooting
totally in manual mode for 3 years...I don't have a clue as to where my BBF button resides.

That's easy, since you have a Canon: right under your thumb.

[Stagecoach]

According to the dates on my CR2 images, my first picture was taken in 2008, have been shooting
totally in manual mode for 3 years...I don't have a clue as to where my BBF button resides.

William,

I can only assume you are looking for yet another diversion to this thread so we can all be told that using your camera in manual mode is not ideal or efficient for producing images

Grahame

[Dave Humphries]

Here are a few examples when I find BBF easier than the alternatives:

Shooting a distant stationery subject through waving grass, other foliage or fence mesh - once focused, why risk mis-focusing on the grass if the wind blows as you take subsequent shots?

With BBF:

you focus once by pushing the button you have set up for AF-ON, then simply lift your pinkie off it (focus is now locked), frame up and shoot as often as necessary, you only need to re-focus if you, or the subject, moves.

Without BBF:

you could refocus each time you take another exposure (and curse when the wind blows),
or try to keep your thumb depressing the AF-L button (be ready to curse if/when your thumb slips off)
or you could try to carefully switch the lens or camera to MF (manual focus) without losing sight of the subject hidden behind the foliage

Similar benefits to the above apply if you are shooting in low light or have an extender fitted, when AF may well struggle, or just have a lens which is slow to focus and/or likes to exercise itself from end-to-end each time you AF.



Focus and recompose, especially when using a tripod - once focused, why risk accidentally re-focusing on what happens to be under the focus point on subsequent shots?

With BBF:

you focus once by pushing the button you have set up for AF-ON, then simply lift your pinkie off it (focus is now locked), compose and shoot as many as you like, you only need to re-focus if you, or the subject, moves.

Without BBF:

you could repeat the focus and recompose actions each time you take another exposure, but you risk slightly different views each time and you may have to release tripod pan/tilt (or ball) locks to do so,
or you could try to keep your thumb depressing the AF-L button (be ready to curse if/when your thumb slips off)
or you could carefully switch the lens or camera to MF (manual focus)

Removes the need to change focus modes between AF-C (aka AI Servo) and AF-S (aka AF Single or AF One shot) via menu or multiple button pushes.

You leave the focus mode set to AF-C/AI Servo permanently, which means;

When you want auto focus to track a moving subject; you keep your pinkie on the button configured for AF-ON.
When you want AF-S (aka AF Single or AF One shot); you press and release that button
When you want Manual focus; don't press it all, just focus the lens manually (assuming that is OK for your lens, which it is for most Nikon lenses when set "M/A")

The choice of Continuous or Single (one-shot) is always instantly available.


BBF isn't always the right method, but it suits far more situations than you might initially expect, especially once your fingers/thumb/brain have got used to it.

Persevere, I'd be surprised if you don't find it worthwhile, especially if you recall doing the things listed in the "Without BBF" sections, as many, but not all, genres of photography entail.

Happy shooting, Dave

[AB26]

But:



And:



And then my personal Fave:



Seriously?

For someone who admittedly never uses BBF or re-composition techniques or even knows how or why its done you seem to be a leading authority somehow. One of the main advantages of BBF has everything to do with locking focus.

90% of BBF users don't have to dispute your statement(s). You do a perfectly fine job of handling that yourself!

Must be a Nikon thing! Glad I shoot Canon!

For Canon shooters who would like to get reliable information regarding the subject here is a pretty good summation of some of the advantages/settings Canon BBF offers.

And from someone who is a leading authority.

Terry,

Oh me oh my, should I explain it in Afrikaans.
LDDDFD

Read my words “ I do not do the re-composing thing” it does not mean I do not use BB focusing!

Action Photographers insist on using BB Focus and Portrait Photographers insist they never use it. Do you perhaps know why?

“Even dedicated supporters of back-button AF will change back to standard camera operation from time to time.”
From: Back Button Auto Focus Explained – By Rudi Winston.

This one is a little laughable:
"Less risk of focus errors with moving subjects
For sports photographers and others taking action pictures, back-button AF lets you stop focus whenever something might interfere with the moving subject you’re tracking — without requiring you to stop shooting. In sports, for instance, it’s common for a referee or another player to come between the camera and an athlete being photographed. With back-button AF, it’s easy to momentarily pull your thumb off the rear button, and you can still keep shooting by pressing the shutter button fully. The camera instantly stops focusing when your thumb comes off the back button. Once the obstruction is out of your way, you can immediately pick-up your primary subject by pressing your thumb on the back button again."

I guess he has never shot action sport. A referee moves into the frame and out of the frame long before your brain can tell your finger to release that AF-ON button. (Do you know how far a man can run in 2 seconds?) But it must be a Canon thing because with a Nikon you need not take your finger off the AF-ON button, you simply set up your camera not to respond to objects temporarily moving into the frame.

"Easier macro and close-up focusing
Many times, you’ll find that it’s actually easier to get consistently sharp close-up pictures of small objects by pre-focusing, and then moving yourself forward or backward until you see the critical sharp focus appear in your viewfinder. Once again, with back-button AF active, you can use the AF to get within general range (press the rear button with your thumb, then take your thumb off the button), and move a little bit to get things critically sharp. Most important, you can then shoot freely, without AF trying to re-focus each time you touch the shutter button. Finally, touching-up focus with the full-time manual focus feature on certain Canon lenses is simple and quick, and the autofocus never fights you by trying to un-do what you just adjusted."

I would think you got plenty of time when shooting Makro and close up shots. Simply turn off AF by switching to MF. Can actually be done on all Nikon cameras. Moving yourself forward and backward to get sharp focus? Is that how Canon shooters do it – focus with your feet?

[AB26]

AF-ON: the facts,

The AF-ON button on the back of most cameras is exactly what it says: Auto Focus ON.

In the menu system of the camera the half press focusing function of the shutter release button can be deactivated to allow the AF-ON button only, to activate Auto Focus. Deactivating the AF function from the shutter release button does not deactivate exposure lock from half pressing the shutter release button.
The focusing function is now activated by the AF-ON button only. Pressing the button, the system will focus on the object in the focal point(s) selected. Focus is locked by releasing the AF-ON button. Half pressing the shutter button will have no effect on focusing but it will still lock exposure. If your subject moves for any reason, focus will still be locked at the point where you released the AF-ON button. If you need to re-focus you need to activate AF by pressing the AF-ON button again.
To lock exposure on any selected area in the frame you can half press the shutter release button or lock exposure by using the AE-L button.

When the AF-ON only function is not selected in the menu, the AF-ON function is still activated by pressing the AF-ON button. The half press focusing function, on the shutter release button, is then overridden by the AF-ON button until the AF-ON button is released and the AF function returns to the shutter release button.

When continuous AF is selected, with the AF-ON function active, focus should be maintained if the subject moves and exposure will be compensated for if any sudden change in lighting conditions occur, until such time as the shutter release button is half pressed. If the AF-ON function is not activated focusing should be maintained on the subject if the half press is used but exposure will also be locked at the moment you half press the shutter release button. If for any reason the lighting suddenly changes you will have an incorrectly exposed image if the shutter is released.

[Stagecoach]

Andre, you made this statement regarding BBF in post No 2

It should not at all be used by anybody using the focus and recompose style of shooting.

Are you going to give this any credible backup or are you going to continue steering away from it?

[DanK]

"Easier macro and close-up focusing
Many times, you’ll find that it’s actually easier to get consistently sharp close-up pictures of small objects by pre-focusing, and then moving yourself forward or backward until you see the critical sharp focus appear in your viewfinder. Once again, with back-button AF active, you can use the AF to get within general range (press the rear button with your thumb, then take your thumb off the button), and move a little bit to get things critically sharp. Most important, you can then shoot freely, without AF trying to re-focus each time you touch the shutter button. Finally, touching-up focus with the full-time manual focus feature on certain Canon lenses is simple and quick, and the autofocus never fights you by trying to un-do what you just adjusted."

I would think you got plenty of time when shooting Makro and close up shots. Simply turn off AF by switching to MF. Can actually be done on all Nikon cameras. Moving yourself forward and backward to get sharp focus? Is that how Canon shooters do it – focus with your feet?

Maybe that's what you would think, but you are wrong on both counts. Do you actually do any macro photography? This suggests you don't. I'll answer both of your questions. The advantage of not using the MF/AF switch is that you don't have to move your hands, and hence the camera, to change. I have shot thousands and thousands of macro shots, and I would never even consider doing what you suggest. For the second, yes, moving the camera is a standard technique for focusing among macro photographers. In fact, with one common macro lens, it is the only way one can focus. Do some reading on macro forums, and you will learn why people do this.

[Loose Canon]

I’m going to choose not to address your doubts about Mr. Winston’s expertise and experience Andre. I am comfortable in my belief that his experience and work directly with one of the major camera manufacturers in the world far outweighs your experience and knowledge. I will choose to take his word over yours if I have any doubts. Here’s a little bit of a bio if you are interested and it seems that he did shoot action sports for a number of years.

AF-ON: the facts,

The AF-ON button on the back of most cameras is exactly what it says: Auto Focus ON.

In the menu system of the camera the half press focusing function of the shutter release button can be deactivated to allow the AF-ON button only, to activate Auto Focus. Deactivating the AF function from the shutter release button does not deactivate exposure lock from half pressing the shutter release button.
The focusing function is now activated by the AF-ON button only. Pressing the button, the system will focus on the object in the focal point(s) selected. Focus is locked by releasing the AF-ON button. Half pressing the shutter button will have no effect on focusing but it will still lock exposure. If your subject moves for any reason, focus will still be locked at the point where you released the AF-ON button. If you need to re-focus you need to activate AF by pressing the AF-ON button again.
To lock exposure on any selected area in the frame you can half press the shutter release button or lock exposure by using the AE-L button.

When the AF-ON only function is not selected in the menu, the AF-ON function is still activated by pressing the AF-ON button. The half press focusing function, on the shutter release button, is then overridden by the AF-ON button until the AF-ON button is released and the AF function returns to the shutter release button.

When continuous AF is selected, with the AF-ON function active, focus should be maintained if the subject moves and exposure will be compensated for if any sudden change in lighting conditions occur, until such time as the shutter release button is half pressed. If the AF-ON function is not activated focusing should be maintained on the subject if the half press is used but exposure will also be locked at the moment you half press the shutter release button. If for any reason the lighting suddenly changes you will have an incorrectly exposed image if the shutter is released.

This is a decent post regarding some of the technical facts of how it works on the camera body Andre. Neither I, nor as far as I can tell anyone else involved in this thread, doubt you have knowledge of the technical aspect of how your particular camera functions as regards BBF. This camera specific information can be found all over the internet and varies for different cameras.


My main concern is your consistent posting of inaccurate misinformation and “absolutes” on when, where, how this technique should be used and by whom. It is simply not true and therefore can’t be substantiated that:

“…Portrait Photographers insist they never use it.”

“It should not at all be used by anybody using the focus and recompose style of shooting.”

“…BB focus should only be used when using continuous AF.”

“It is all about exposure when re-composing. It has nothing to do with locking focus.”

“Neither Nikon D610 nor the D750 has a back focus button.”

In his explanation of BBF Mr. Winston clearly cites logical and convincing reasons why BBF could be a distinct advantage in these as well as other scenarios. That he states that the traditional half press technique works perfectly well in some cases and that even dedicated supporters will change back to standard operation indicates to me that he, as well as the dedicated supporters to whom he refers, have an open mind and are interested in the best technique for the given circumstances.

This rather than stating only when, only where, only how, and only by whom absolutes such as you have. This kind of close-mindedness does not serve to educate or encourage education and exploration to my way of thinking.

Hopefully those interested in this topic and with less experience with it will recognize the difference and understand that the BBF technique can be used with great success under a variety of circumstances and for a variety of genres and is not just to be used for a very limited use as you seem to believe.

[PhotomanJohn]

This discussion absolutely amazes me and reminds me of the lengthy discussions about RAW versus JPG. In both cases it is very straight forward to describe the differences between the two options along with the benefits and limitations in the various situations they could be used. Being a technically minded sort I would assume that would be the end of the discussion and now, armed with all the information, each person would decide what makes most sense for them and go forward. To me discussions about the facts are always worthwhile. Long discussions about opinions are generally of less value.

Back-button focus, shutter-button focus, RAW and JPG are what they are. There is no mystery here. Choose which one you like to use and worry less about justifying and convincing others why your decision is the "best" which is generally just a demonstration of ones insecurity about their decision.

John

[Glenn NK]

This discussion absolutely amazes me and reminds me of the lengthy discussions about RAW versus JPG. In both cases it is very straight forward to describe the differences between the two options along with the benefits and limitations in the various situations they could be used. Being a technically minded sort I would assume that would be the end of the discussion and now, armed with all the information, each person would decide what makes most sense for them and go forward. To me discussions about the facts are always worthwhile. Long discussions about opinions are generally of less value.

Back-button focus, shutter-button focus, RAW and JPG are what they are. There is no mystery here. Chose which one you like to use and worry less about justifying and convincing others why your decision is the "best" which is generally just a demonstration of ones insecurity about their decision.

John

I'd rate this as the best post ever about the topic of BBF (and JPEG/RAW).

Glenn

[Tony M]

I'd rate this as the best post ever about the topic of BBF (and JPEG/RAW).

Glenn

Agreed. Anyone who wanted to inform themselves of the subject have long since left the room.