AF for dynamic fashion shots?

Started 3 months ago | Discussions thread
Paul P K
Paul P K Contributing Member • Posts: 647
Again: read beter

Boudewijn van der Drift wrote:

Paul P K wrote:

Nils wrote:

LOL

https://www.youtube.com/watch?v=WJ2DC2X1e5k

In reply to Paul P K • 4 min ago

Paul P K wrote:

What I wrote before about previously, and you clearly did failed to read, is 'BBF only with separate shutter release triggering', i.e. activating the AF with the BBF button only, and decoupling the AF from the shutter release button, which means that button is used only for triggering the shutter, useless for moving subjects

But on the other hand very useful when you are shooting a static subject with very critical AF for a specific area, and you don't want the AF to change whenever you touch the release button.

In the first scenario, using 'BBF only with separate shutter release triggering', you are one moment triggering the AF button with one fingering, and have to switch to another finger to take the shot when you see your subject in focus in the viewfinder (similar to the manual focus film shooting days when you would focus on a subject by turning the focus lens with your left hand till you had it in focus, and having to switch the next moment to your right hand to take the shot)

What you are describing is activating the AF with both the BBF button as well as the shutter release button, (which is doing the same thing simultaneously using the BBF button and the shutter release button, and obviously a bit redundant).

I.e. still having the AF activation linked to the shutter release button ( which means the camera will AF whenever the release button is touched), while doing the same with the BBF button at the same time ( and pretty much a waste of attention and energy).

In the old/early days of DSLR's, there was a small, but for fast shooting significant enough delay between the moment the AF found the subject in focus, and the camera taking the shot the next moment/split second you pushed the release button to take the shot. That delay would come on top of the shutter release that already was came with the the camera when taking a shot, a pretty deadly combination when trying to nail a shot in a very specific moment (eg when shooting catwalk, when catching a specific pose at the very moment it occurs will make or break a shot)

With modern DSLR's and mirrorless the delay caused by shutter release lag has indeed been reduced to negligible fractions of a second, no longer a real shot threatening problem (although of course there are plenty of 'experts' to find it something to still complain about when shooting under laboratory condition during 'tests').

But in my experience with DSLR's (reaching back to the D1/D1H/D2X days) and with the Z6, based on shooting fashion, catwalk, dance and surf, the delay between activating the AF by pushing the release button half way, and taking the shot when deciding to do, is so negligible that using the BBF button while already triggering the AF with the release button is unnecessary overlap.

Only time I use/have used that option is when I want to pick a point for the AF to start focusing from without risking to take an undesired shot (like as described earlier when a model takes a pose at the far end of the catwalk before taking the run down the catwalk towards the camera)

As far as the Dof is concerned, for creative purposes, as well as possible limitations to the fastest shutter speed possible to use in combination with the possible maximum aperture (eg bad/low lighting), especially when using long lenses (like eg in my case at times a 2/200VR wide or nearly wide open ) that DoF may sometime be simply not enough to keep the subject in focus while moving along in that split second, despite of the appealing theory, when using BBF AF with separate shutter release triggering.

In the case of having the AF linked to the shutter release button, means one will have to trust the AF, and the lack of significant shutter release lag , of the camera used, like I did with my Z6 in this shoot https://pbase.com/paul_k/20181209_mafb_tropenfest

See in particular shot https://pbase.com/paul_k/image/168520443 https://pbase.com/paul_k/image/168520444 and https://pbase.com/paul_k/image/168520445, from a series of 14 shots taken within 3 seconds of a model further away to close up. The result of what at that moment my 1st serious shoot with the Z6 late 2018 (with still only FW 1.0) were reason/impressive enough for get a 2nd Z6 within two weeks after that (not widely for sale at that moment yet) despite its at that moment still novelty status

So yes, you are completely missing my point, but that of course may also be due to not only not fully reading what I wrote, but also apparently never having shot a catwalk show in earnest

in the several reactions on the above post the specific details on how the BBF focus is set up (and consequently is used) are missing, and thus pretty useless to be able to judged upon on their merit.

Again, I'm talking about the usefullness/uselessnes of having AF on the BBF button only Practically speaking this boils down top: push the BBF button and the AF is triggered, push the shutter release button and the shot is taken without the focus previously set with the BBF changing.

This set up is useless for shooting fast moving subjects, but as said earlier ideal when shooting a static subject when perfect focus on a specific area is wished for, annd to be left unchanged when the shutter release button is pressed (eg to check exposure, or simply 'wake up' the camera from 'sleeping')

What however is generally used and incorrectly described as as BBF focusing (yes, also in sportsphotography, which I did in my early digital DSLR days shooting surf https://pbase.com/paul_k/surf_main) is having the AF linked to both the BBF button and the shutter release button, and probably is the BBF focus mode mentioned in several reactions to be used so successfully over the years (sorry, but referring to a video rather then having actual relevant experience with BBF focusing IMO really isn't relevant).

In this case the BBF button is used to adjust the AF on the subject while moving, but without risking to take an accidental shot, in order to have the focus as close to the subject at the moment the shot is to be taken by pushing the shutter release button (at which moment the AF activation is taken over by depressing the release button in the split second before the picture is shot)

To state the obvious, if you have focused on a subject nearby, and leave the focus there, to next focus on a subject further away, the camera/lens will have to adjust from near by to far/further away, which with a slow focusing AF lens and body will risk missing to lock on the subject in time reuslting in an OoF shot

With modern DSLR's and mirrorles the delay between switching focusing, and taking the image with the same release button is negligible, contrary to the early digital shooting days when shutter release and AF lag were always a standard topic mentioned in the camera reviews.

Since pictures say more then words:

I took this picture using BBF (pre)focusing in combination with shutter release AF activation

Kelly Slater Q Silver Pro 159 201001002 D3 4/600mm AF-I + TC1.4EII

View: original size

I started shooting the series using BBF to toggle the relatively slow focusing 600mm+ TC14EII combination to (pre)focus (and have the AF point as close to as possible) on Kelly Slater when I anticipated (and had the time to do so) he would start a run on the approaching wave

To then taking the several shots with the shutter release button taking over the AF activation while taking the shots, with AF tracking following him during his run, since obviously adjusting focus with the BBF button is/would have been impossible within the very few seconds between him starting his run down the wave and into the funnel .

But this shot however

Texel 175 20091016 D3 4/20-400mm VRI

View: original size

happened unexpectedly in a split second , leaving no time for BBF focusing, only allowing to next to instinctively aim the camera, and rely on the shutter release activated/coupled AF activation.

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