Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Jeremy Roussak on April 03, 2011, 04:59:01 pm

Title: Mystification
Post by: Jeremy Roussak on April 03, 2011, 04:59:01 pm
In his review of the Fujifilm X-100, Michael writes "My preferred way of working with just about any camera is to put AF on a rear button rather than on the shutter release".

Others have written this before and I have read learned articles which put forward the view that it's the only sensible way for grown-up people who really know what they are doing to use their cameras.

Now, I like to think of myself as a reasonably intelligent chap. Perhaps I flatter myself (but then, it's nice when someone does). However, I completely fail to understand the reasoning. What's the difference between a half-press on the shutter release and pressing a rear button? Why is the latter so much better than the former? Why are two buttons better than one? I've tried to understand; indeed, I've tried using my 5d2 in that way but it didn't make me happy.

Please help me. I feel fulfilled and contented when my education has been improved.

Title: Re: Mystification
Post by: fredjeang on April 03, 2011, 07:12:48 pm
Hi Jeremy,

This is indeed a better system and no surprise MR uses it.

Let's say you shoot in continuous AF mode. So now your shutter button only acts on your order and just has the shutter function.
On the other finger, having the AF control separatly, AF is on wether you take a pic or not so you can track the subject.
This is a much more powerfull way: track, track,, click...track,, see the difference? you control both, not the camera.

You follow your action with AF accuracy and you just press independently the shutter when you estimate. You can't loose focus if you just released your finger from the shutter button by mistake.
Ergonomically it is much more accurate and more efficient. Half-pressing for awhile tense the finger muscle after awhile and it is distracting. That way you are also more "into" the action.

At first it is normal that you ended to feel that weired because you are not yet used to it. But after awhile it's difficult to be back on the multifunction shutter.

One button=one function.

Title: Re: Mystification
Post by: Gary Brown on April 03, 2011, 07:31:20 pm
There's certainly not just one right way, and not all pros do that (e.g., Moose Peterson's D3 settings indicate that he leaves the shutter button enabled to do autofocus), but here's one rationale from Photographing Nature by Ralph A. Clevenger:

“Back-button auto-focus is used by many nature photographers, including me. It lets you activate AF by pressing a button on the rear of the camera with your right thumb. Most importantly, it separates focusing from picture-taking. The shutter release still wakes the camera and fires the shutter, but no longer activates focus.” He also has a “Why do you use that back-button to focus?” section where he explains a bit more, but that's his main reason — he simply prefers a separate button for focus.

One disadvantage of that approach vs. the shutter button (for Nikon DSLRs, at least), is that the button doesn't activate VR, and one might prefer that VR be active while focusing.
Title: Re: Mystification
Post by: leuallen on April 03, 2011, 09:58:48 pm
I use both. The menu selection to turn on/off back press focus hold is on My Menu on my GH2 so I can change it easily. If I am casually snapping away handheld I usually use the shutter button focus, seems quicker to me. On a tripod, I use the back button focus hold because I am often shooting panos and do not want the focus to change for every shutter press. By the way, the touch screen setting of the focus point on the LCD is really great when on a tripod. I don't need to raise the tripod to eye level because I can look down at the swivel LCD. I just touch the LCD at the point I want to focus and it is done.

Title: Re: Mystification
Post by: David Sutton on April 04, 2011, 12:23:12 am
Like Larry said. I put the camera on the tripod and select my focus point with the back button. Then I can use a remote release and watch the histogram and take a few shots to optimise the exposure knowing the focus hasn't changed with each press of the shutter. Or for moving subjects I can select the focus point and wait for the subject to hit that point and know I've nailed the focus. I could use the manual focus switch on the lens but it's never seemed as easy to me. For BIF I switch to focus on the shutter button. Then it's just the bird or the sky and usually the camera gets it right.
Title: Re: Mystification
Post by: Rob C on April 04, 2011, 03:30:03 am
Thank goodness I've eschewed all af, even on the single lens that boasts it!

Never felt manual a distraction in my entire life - indeed, it's an essential part of catching the 'feel' of a subject: that in/out of the ring at my speed makes it real, three-dimensional to the mind and far more interactive with my own vision.

I wouldn't (never have) thank you for af on anything involving people.

Rob C
Title: Re: Mystification
Post by: stamper on April 04, 2011, 03:50:25 am
In a normal set up the shutter button when pressed locks exposure, focus, activates VR and then the picture is captured. The locking of exposure and focus at the same place - a dark or light area -  in an image is mostly a disadvantage. Therefore separating not only the focus from the shutter function but also the exposure is - imo - a real advantage. On my Nikon cameras there are an exposure lock, focus lock and shutter release buttons. It makes sense once you get used to using them. :)
Title: Re: Mystification
Post by: Jeremy Roussak on April 05, 2011, 03:24:43 am
Thank you, all. I'm feeling more educated already.

Title: Re: Mystification
Post by: Clearair on April 05, 2011, 08:19:06 am
Strangely I use a 5D11 for wildlife photography including action.
My 40D focuses faster but I like the IQ of the 5D.
On both, the follow focus (servo) just works better for me if I'm using the back button rather than mid point balancing the shutter button.
Also I imagine there may be a shutter lag decrease if the focus (and also exposure ) is not happening at shutter press?

Go on someone, tell me I'm mistaken on the shutter lag which is not an issue anyway, even though some bitched about the Canon when the 5D11 specs first appeared.

Title: Re: Mystification
Post by: armand on April 05, 2011, 01:25:45 pm
Thank you, all. I'm feeling more educated already.


Me too!
Title: Re: Mystification
Post by: grzybu on April 06, 2011, 03:58:47 am
I've found focusing with rear button (AF/AE Lock button in Panasonic G1 case) is essential when shooting with pancake 20/1.7. This lens has slow AF but despite of this it's great for street photo.
So with sticky AF lock when using AF mode I can set and lock focus with single button press and it stays until I don't press AF/AE lock button again.
It works bit different than it other DSLRs I used to shot, where you work in MF mode and use rear button to force refocus with AF.
With sticky AF lock it's even better I think.