why focus lock is important

[paulfish4570]

iso 3200 bw with yellow filter setting.
my youngest son and his girlfriend without locking focus on one of them at f2:



with focus locked on son:



auto contrast in photoshop; no other pp

[Roger Hicks]

Dear Paul,

All my M-series Leicas have focus lock...

Cheers,

R.

[paulfish4570]

you betcha, Roger, just like my barnack.
i have not done the manual focus thing yet with the x100 ...

[peterm1]

In general when I use a modern digicam of some sort, I much prefer to opt for a single central focus point and manual focus lock, rather than the "hocus pocus focus" offered by multiple focus points and an algorithm that lets the camera decide what to focus on.

Some of the latter work well enough (e.g. my Nikon D200) - but some seem not to (I have doubts about my Sony NEX in this regard as I see a lot of OOF images when I use this mode.) In either event I am never sure of what has been just focussed on when the camera decides and hence never know whether I have got the shot or not. LCD screens are seldom hi-res enough to be able to discern if critical focus has been achieved especially in bright sunlight.

To prove that I am not totally a luddite who craves for old technology and the "good old days" I have recently bought a Sony NEX which has spiffy "focus peaking" for manual focus. I must try that soon as its rather cool - on the LCD screen it places a bright colored overlay on the elements of an image that are in focus. Those who have tried it with a legacy lens say it works superbly. As stated above, I am less sure about the choices it makes about focussing when left to its own devices, till I turn on the single focus point mode and make my own choices.

[willie_901]

Paul,

On the X100 MF mode is similar to AF-S mode in that MF mode is (in practice) just a different way to autofocus. Focus is initiated with the AFL button. Then you can use the finder's focus scale and/or the focus zoom feature to check the focus. I rely on the focus lock audio beep too. In MF mode, the focus frame does not turn green. Small adjustments to focus can be made by manually rotating the lens collar. Focusing with only the lens collar is useful when using the rear LCD screen during macro work. Otherwise use the AFL button to initially set focus. Unlike AF-S mode, a shutter half-press will not change the focus in MF mode. Also, the focus frame size can not be reduced.

In the example you show, it is possible to focus and recompose in AF-S mode without using focus lock. Just focus on the face. When focus is confirmed, press the shutter half way and keep it pressed. Then recompose and press all the way to take the photo. This method also locks exposure when you are in AE or S exposure modes.

Using the focus lock button does have an advantage. When the AFL button is set to lock focus only, the exposure is not locked in AE or S mode.

[DNG]

Many cameras (Non-DSLR) have "Face-Detection", which, with people as your subject, it can do a pretty job.... but, I have used a smaller f/stop, like f/8 with face detection...cheating maybe, or extra insurance...

I like the idea of focus peaking.... maybe Sony will license it like the Face Detection...

[paulfish4570]

thanks, Willie. i had figured out the half-push lock, but didn't think to use it on the first shot.

[Keith]

These little things become easier as you go for sure Paul. I quite liked the suggestion ^ of using manual as a different way of auto focusing because that way it keeps your exposure more accurate. I wish they had made the focus window the same size and the green frame confrmation the same as well in manual mode though. I don't 'get' why they have to be different!

[celluloidprop]

Close-ish (across a table, similar distances), my X100 in OVF mode tends to focus on the distance. But I've pretty much switched to the EVF all the time, and with the center point at its smallest I rarely run into this issue.

[gavinlg]

Originally Posted by celluloidprop

Close-ish (across a table, similar distances), my X100 in OVF mode tends to focus on the distance. But I've pretty much switched to the EVF all the time, and with the center point at its smallest I rarely run into this issue.

Turn on 'AF close focus indicator' in the shooting menu, and it will turn on a parallax corrected AF box so you can see exactly where your AF box is at close distance. No more missing.

[redisburning]

Originally Posted by peterm1

In general when I use a modern digicam of some sort, I much prefer to opt for a single central focus point and manual focus lock, rather than the "hocus pocus focus" offered by multiple focus points and an algorithm that lets the camera decide what to focus on.

I thought everyone did this.

It's like a dubble clutch transmission versus an automatic. Neither is a full on manual but with one you are not making the fatal assumption that a computer knows better what you want.

A computer can't read your mind. What it CAN do is do exactly what you tell it very, very quickly. So I focus-recompose on the rare occasion that I use autofocus whether it is in single shot or continuous focus.

My 40D has a button just for focus lock (and AE lock) not to mention the half press on the shutter. Just about the only thing I like about the camera.

[GaryLH]

Originally Posted by fdigital

Turn on 'AF close focus indicator' in the shooting menu, and it will turn on a parallax corrected AF box so you can see exactly where your AF box is at close distance. No more missing.

I wished they had made this the default setting... Every time a new firmware update need to find that setting again.

This new feature works really well. U get the normal focus box plus a one for the close focus, and a green confirmTion which shows where it actually focus at, close, normal or somewhere in between.

Gary

[bhop73]

Originally Posted by fdigital

Turn on 'AF close focus indicator' in the shooting menu, and it will turn on a parallax corrected AF box so you can see exactly where your AF box is at close distance. No more missing.

I don't see that option anywhere in the menus..

edit: Nevermind.. it's in the set-up menu under 'AF Corrected AF Frame' unless you're talking about a different setting..

[paulfish4570]

willie, i tried the settings you suggested. very easy and quick and simple: just the way i like. ken rockwell suggests the same thing.