Back button focus confusion discussion

[Mike Buckley]

MOD COMMENT: ~ This was the beginning of an off topic conversation which has now been moved to this new thread as it began to consume/dilute the original thread ~

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By the way, I also always use back-button focusing for handheld shots. So, I think using certain functions such as that one and Auto ISO has a lot to do with how our brain works; certain things are comfortable or not for each of us.

[AB26]

What I would like to know is WHY people are so obsessed with using BB focus. Is it a cool tool or do people actually know when to and why they use BB focus? I’ll bet you 90% of BB focus users won’t know what I mean (and they will dispute my statement) when I say BB focus should only be used when using continuous AF. It should not at all be used by anybody using the focus and recompose style of shooting.

[Dave Humphries]

Andre,

What I would like to know is WHY people are so obsessed with using BB focus. Is it a cool tool or do people actually know when to and why they use BB focus? I’ll bet you 90% of BB focus users won’t know what I mean (and they will dispute my statement) when I say BB focus should only be used when using continuous AF. It should not at all be used by anybody using the focus and recompose style of shooting.

I shoot BB with Continuous AF 98% of the time.
Using BB focus is a VERY quick way to separate focus lock (lift finger/thumb off) from exposure lock (half press with index finger).

So I can focus (and recompose) and even exposure set (and recompose), as two separate actions, before final composing and 'squeezing off' the shot.

[dubaiphil]

What I would like to know is WHY people are so obsessed with using BB focus. Is it a cool tool or do people actually know when to and why they use BB focus? I’ll bet you 90% of BB focus users won’t know what I mean (and they will dispute my statement) when I say BB focus should only be used when using continuous AF. It should not at all be used by anybody using the focus and recompose style of shooting.

Andre

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Regarding BB focusing - I wouldn't say I'm obsessed by it (!) but for me the merits are definitely there. I use it for tracking but mainly for focus and recompose shooting and pre focusing while waiting for a scene to unfold.

[Mike Buckley]

Regarding BB focusing - I wouldn't say I'm obsessed by it (!) but for me the merits are definitely there. I use it for tracking but mainly for focus and recompose shooting and pre focusing while waiting for a scene to unfold.

Same for me. Perhaps that's not an indication after all that neither of us has the slightest idea of what we're doing or why we're doing it.

[Venser]

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

Why?

[PhotomanJohn]

MOD COMMENT ~ discussion moved to this new thread ~

And to address the off-topic comment, I always use BBF for the obvious reasons that it allows me to instantly go between AF-S and AF-C and allows me to lock the focus between shots as desired without having to hold another button. IMO, BBF is ideal for focus and re-compose which is my normal mode of operation.

John

[rpcrowe]

Tony Northrup's YouTube video on back button focus is one of the most simple explanations of the advantages of BB focus.

https://www.youtube.com/watch?v=8PN9R0D3pF0

Speaking about Tony and Chelsea Northrup - this is a fun light-hearted video...

https://www.youtube.com/watch?v=ODIUaPooKGw

[Stagecoach]

What I would like to know is WHY people are so obsessed with using BB focus. Is it a cool tool or do people actually know when to and why they use BB focus?

I do

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

But by using the BB focus and recomposing for ALL my landscape work my results are PERFECT. If I revert to other methods and stop using BB focus and re-composing does that mean my landscapes will be MORE PERFECT?

Grahame

[AB26]

Why?

Because the results may be very dramatic:

All images are SOOC Jpegs. Shutter priority with Auto ISO on.

BB focus does not lock exposure like a half press does.
BB focus is primarily for action/fast moving object photography.

[Stagecoach]

BB focus does not lock exposure like a half press does.

Andre, to lock focus when using 'BB focus' you simply take your finger off it on a D300.

You are correct that it does not work in the same way as a half press of the shutter button does but it is certainly not primarily for moving subjects it works perfectly for static subjects where you re-compose as well.

Grahame

[AB26]

I do



But by using the BB focus and recomposing for ALL my landscape work my results are PERFECT. If I revert to other methods and stop using BB focus and re-composing does that mean my landscapes will be MORE PERFECT?

Grahame

Why do you re-compose when shooting landscapes? Does your camera not have focal points?

[Stagecoach]

Why do you re-compose when shooting landscapes? Does your camera not have focal points?

It certainly does have select-able focus points Andre but the only time I ever use these is for moving subjects, e.g. if I have a runner or car coming into frame and want to focus on them I do not want to use a centre point but one to the side.

For landscapes the chance of the target you wish to focus on (due to its distance) is very unlikely to line up with a focus point and I find it far easier and quicker to focus/re-compose using that center point than moving the selected ones around. You then of course have a second operation which is to move it back again.

Grahame

[AB26]

Andre, to lock focus when using 'BB focus' you simply take your finger off it on a D300.

The "problem" is not locking focus - that is locked when using AF-S - the "problem" is locking exposure when re-composing.
On a moving subject you do not want to "lock" focus in AF-C. Focus is locked on the subject when using AF-C.

Re-composing when using BB focus you need to lock exposure, focus, compose and shoot. Why not simply use half press focus when re-composing?

[Dave Humphries]

Tony Northrup's YouTube video on back button focus is one of the most simple explanations of the advantages of BB focus.

https://www.youtube.com/watch?v=8PN9R0D3pF0

Speaking about Tony and Chelsea Northrup - this is a fun light-hearted video...

https://www.youtube.com/watch?v=ODIUaPooKGw

Useful and amusing videos, thanks Richard.

Cheers, Dave

[Dave Humphries]

Andre, I have moved this discussion to its own thread for the improved clarity of both issues.

BB focus does not lock exposure like a half press does.

Correct.

BB focus is primarily for action/fast moving object photography.

I tend to disagree Andre, it can be equally useful for any type of photography since it removes the need to go into the menu (or use buttons) to change focus mode from AF-S to AF-C (and back).

However, there are occasions when I do change to 'normal (half press to focus) operation', your example above might be one such, although for me, these occasions seem to happen less and less often, as I get used to the speed and versatility that BBF allows.

Anyone is at liberty to use their camera as best suits them, so if BBF is not your 'cup of tea' then just don't use it.

Best regards, Dave

[Mike Buckley]

When using the back button to lock focus, there is no need to also program it to lock exposure.

The reason I prefer using the focus-and-recompose method when practical is that doing so allows me to use the center focus point, which is a cross point. Many (perhaps most) of the other points are not cross points and, thus, don't focus as accurately as the center focus point in certain situations.

[davidedric]

One word of caution. I mentioned in an earlier thread that on my camera lens combo (long zoom) press and release on the bb only brings in image stabilisation for a few seconds. Ymmv, but it is something to check. In the end I found bb focusing unusable for wildlife work.

[AB26]

Please, don’t get me wrong. I am not saying BBF does not have its merits, of cause it has its merits. Every button on a camera has its merits.

If for any reason you “only use” any specific feature on your camera you are restricting yourself form enjoying the full scope the camera offers. It is applicable to any feature like “I only use Matrix metering” or “I only shoot Manual mode”, “I only shoot RAW” is just as bad.

What I found is, BB focus works when shooting action, much better than a half press. When shooting a portrait I cannot see any merit in using BB focus.

How do you use BB focus and re-compose without affecting exposure, unless you have locked exposure before re-composing? I do not do this re-compose thing, so I do not know how you do it or why you do it. I set the focal point to where I want to focus – after I have decided on the composition.

When I anticipate I am going to shoot a portrait in portrait mode I set the focal point to the upper third of the viewfinder, there where I want the eye of the subject to be. If I need to re-compose, it will be very slight and my focal point will not leave the face of my subject. I often use the AE-L button to make sure I expose for the appropriate spot. Oh, yes – I use spot metering most of the time. Matrix metering can be easily confused whenever your subject does not fill the frame.

I just find it amusing that people with very expensive cameras tend not to use all the features on those cameras. Sometimes people even use a feature without knowing why, only because a Ken Rockwell told them to do so.

Of cause, your camera is yours and you can use it anyway you wish to. Like my sister in law said to me after attending a beginners course on using the D7100: “If I had not gone on that course, I would have been the proud owner of a very expensive P&S camera.”

[Mike Buckley]

The reason I never use the shutter release button to do anything other than to release the shutter is because I'm fundamentally uncoordinated. As a result, I find the requirement of half-pressing that button entirely unreliable. It's unbelievable from my point of view to be told that I'm doing something bad.