[TomTextura]

I've heard plenty of people say that focusing then recomposing works well for them but I'm starting to have serious doubts as to the validity of this method. Using center point AF seems to typically go along with this technique but I don't believe it's a requirement and think that using one of the other AF points is entirely possible. I've tried the technique many times now and have been left disappointed 90%+ of the time.

As an example... The other day I was taking a picture of a cute teenage couple that were nice enough to give me permission. I wanted to be quick so as to minimize any possible bother, which is part of the reason I didn't try manually focusing; that usually takes me longer. The composition I wanted didn't line up with any of the AF focus points so I gave the old focus and recompose trick yet another try. I was at f/4.5 so figured I had enough tolerance to make it work. Well, the picture turned out soft. I can't guarantee that the reason for the softness was the use of this technique since I was also at a slow 1/15 shutter speed, but I'm willing to bet it was. The 1/15 should have been okay in theory since I was using a 31mm lens and had SR on. I took two pictures of the couple: The first was taken with the same exact settings and was sharp but not composed quite the way I wanted and the expressions weren't as nice as in the second soft shot. This particular photo might have been out of focus for some other reason but please don't get hung up on this one example.

What I'm really curious about is:

• Are there secrets to focusing and recomposing that I don't know about?
• Is this technique of much use or is it flawed?
• What are your experiences with it? Successful or unsuccessful?

Thanks for any input!

[normhead]

Here's what I find. I focus on the place i want to focus...when I recompose I lift my finger off the button and it refocuses before it takes the picture. Sometimes I've had to try 3 or 4 times before I got it right. For me, for this to be effective, there needs to be clicks. One click with resistence to focus, and another when I let go of an acquired focus. Without mechanical or auditory feedback, and without a little mechanical help to hold the focus, in my experience it is more trouble than it's worth. Maybe others have better motor control than I do, I don't know.

But also at 1/15 s, anything can happen. SR can work or not. I can shoot 1/15 without SR, but not dependably, When I have to, burst mode is a wonderful thing. 5 exposures in a second, one of them might be good.

[Medium FormatPro]

Ah the K-5 the flagship of the Pentax non medium format models... But there is an issue here... 1/15th of a second with that focal length lens?

Sure it is possible, but I would not want to count on it for a number of reasons. First theres the mirror movement inside of the camera.Even with SR it would be a gamble with the K-5 without some additional support. It also would depend upon the actual person taking the pic. You'd almost have to have a bit of above average control over items like breating and even heart rate; and also holding the camera bracing it effectively against ones body and all. Then there's also stance and a whole bunch of other factors. At that speed even a slight bit of wind could throw it all off.

With that speed I would be using some kind of support even for the camera, but also noting... That shutter speed also not ideal even if the subject were holding reasonably still. I would also try to get the shutter speed up higher; either by iso settings or by lighting of some sort.

As for the focus lock issue; or focus and recompose... It works better with in camera settings; such as (example only)... Having focus set for spot versus average; and the same for metering. for some it may take a bit of practice; some others able to get it right the first time - it just depends.Still for others that may have the time to experiment a bit (or for tactfully stating please - more skills in the manual settings - not that there's anything wrong with automatic under some circumstances) why not go full manual??

[Anvh]

Normhead it's simple, move the AF away from the shutter release half press and use the dictated button for it, problem solved for you =]

@TomTextura the problem is this.
Why Focus-Recompose Sucks

[RioRico]

Some options (hope I don't sound too negative):

* Don't re-compose in-camera. Shoot the shot, then crop as needed for composition.
* Don't shoot wide-open. Stop-down for thicker DOF. Ultra-thin DOF takes tight control.
* Don't AF. Use MF. Better yet, zone-focus, with thicker DOF and good distance guesses.
* Don't be in a hurry when using a slow shutter. Use a tripod or a faster shutter speed.

As mentioned, this last is VERY important. With SR on, use the 1/FL rule for SHARP shots. With SR off, use the 1/(5*FL) rule. 2/FL or slower are fine... for thumbnails or artistic blurs. To be artistic, use the old drop-your-Lomo technique. Tres hip!

[StephenHampshire]

Here's what I find. I focus on the place i want to focus...when I recompose I lift my finger off the button and it refocuses before it takes the picture. Sometimes I've had to try 3 or 4 times before I got it right. For me, for this to be effective, there needs to be clicks. One click with resistence to focus, and another when I let go of an acquired focus. Without mechanical or auditory feedback, and without a little mechanical help to hold the focus, in my experience it is more trouble than it's worth. Maybe others have better motor control than I do, I don't know.

But also at 1/15 s, anything can happen. SR can work or not. I can shoot 1/15 without SR, but not dependably, When I have to, burst mode is a wonderful thing. 5 exposures in a second, one of them might be good.

Agree with you re shutter speed - at 1/15th, 50/50 soft/sharp is about par for the course, also check using PhotoMe if the SR had actually kicked in, a still moving sensor at 1/15th of a second is definitely trouble. One question though, why do you release the half press when you recompose?, Once you have the green hexagon/beep to confirm focus just leave your finger where it is! Just prctised again on my K5 and K20D, I find it hard to let mey finger relax enough to lose the focus lock in the 1 or 2 seconds to recompose. As a left-eye shooter, the AF button is a real no-no for me when looking through the viewfinder.

[TomTextura]

But also at 1/15 s, anything can happen. SR can work or not. I can shoot 1/15 without SR, but not dependably

But there is an issue here... 1/15th of a second with that focal length lens?

I admit, the 1/15 shutter speed was much slower than ideal. It was evening so the lighting was dim, I was working quickly trying to not be too much of a bother to two strangers, and with the ISO limit and f/4.5 aperture I already had set, Av mode gave me that speed. The thing is, the previous shot with the exact same settings worked fine. Now, I could have easily not held the camera in place as well on the second shot, SR may have not done it's job, or the AF locked on a different spot than what I thought. But to me, the main problem seemed to be focusing and recomposing. Whatever the case, I didn't do the best job. I should have not worried about working so fast, actually taken the time to change my exposure settings, and maybe even tried manual focus. Maybe this was a bad example but I used it because it is my most recent experience with trying to focus and recompose, and it was yet again unsuccessful, even with what I thought would be a forgiving enough aperture.

[TomTextura]

One question though, why do you release the half press when you recompose?, Once you have the green hexagon/beep to confirm focus just leave your finger where it is!

I don't have a problem with that and that wasn't the issue in this case. I think the sensitivity for holding AF lock is pretty good on the shutter release of the K-5.

[jaytee]

Try doing it this way a few times and see what you think....just try it. First put your camera in manual mode ( AF will still work in manual!) Set your ISO as low as you can get away with. When you look through the view finder you will see the light meter scale and can very quickly adjust for a good exposure on your subject with the front or rear dial. Front dial for motion control rear for DOF. Now your exposure won't change unless you change it and you can concentrate on composition. Set your AF on the rear AF button NOT the shutter release. Set focus mode too Center...Focus the subject with your thumb on the back AF, frame your shot and shoot. If I haven't left something out of my explanation you will find this works best in most situations. A mix of old school and high tech !

[TomTextura]

@Avnh Thanks for the link! That explains what I figured was the main problem with this technique. The part that really stuck out for me was that: "The error introduced by focus-recompose is greater with shorter camera-to-subject distances."

Don't re-compose in-camera. Shoot the shot, then crop as needed for composition.

I do this quite a bit already and will continue to whenever I have the extra space around the edges.

[pezmaker]

As has already been said, focus and recompose is best with manual focus; however, it's not difficult to do with auto focus as long as you're not in AF-C. Focus, keep the button in half press as it has AF lock, then recompose, then finish the button press as usual. If you release, it's going to refocus when you press again.


Another thing to consider is the radial focal plane you create as you recompose. This is going to be difficult for me to explain, so if I lose anyone on this, it's not their fault... Consider yourself the center of a circle with the radius being the distance of you to your focal plane, thus you have radial focal plane when you turn (as long as you don't move your feet ). If you focus to the left of your subject on the plane tangent to your circle, you'll actually be focused at a point past your subject when you rotate to it for recomposing. The amount of affect this will have will depend on the distance between where you focused and your subject on recomposition, and the size of your depth of field due to aperture. a few inches of rotation may be enough at F1.7 to cause this back focus if you're close enough. It may afford you several feet if you're further away or have a smaller aperture set, like F8.


Try not to laugh too hard at my ascii diagram below....

\o/ - the person with the camera
o - the subject
| - the plane of focus when pointing directly at the subject
) - the radial focal plane

There are two radial focal planes below. The one between the subject and the shooter is where the focus needs to be prior to recompose, the one to the right of the subject is where the radial focal plane occurs if you focus on the same plane as the subject and recompose.

---- EDIT ----
my filler spaces were edited out. Drat. nothing like a compressed ascii image to really emphasize your point. I'll try something better. albeit paint, so not much better, haha.

--- re-edit ---

In this diagram, center square is the photographer, square on the right is the subject, outer circle is if you focus on the same plane as the subject, and inner circle is where you should find something to focus on if possible.

[Anvh]

@Avnh Thanks for the link! That explains what I figured was the main problem with this technique. The part that really stuck out for me was that: "The error introduced by focus-recompose is greater with shorter camera-to-subject distances."

Sorry that i was so lazy for not writing it down
You've enough focus point to select a focus point you want to use without recomposing so use that.
With portraits i often use focus point one above the middle one so that the focus is closer to the eyes.

[todd]

Thanks Anvh for that link.. good info!

[RioRico]

I admit, the 1/15 shutter speed was much slower than ideal. It was evening so the lighting was dim, I was working quickly trying to not be too much of a bother to two strangers, and with the ISO limit and f/4.5 aperture I already had set, Av mode gave me that speed.

When you run into aperture+shutter limits, boost the ISO even more. High-ISO noise can be fixed in PP. Motion blur and missed focus can't. My basic rule for isolated subjects (not thick-DOF 'scapes): Nail the focus; *everything* else can be fixed.

[TomTextura]

My basic rule for isolated subjects (not thick-DOF 'scapes): Nail the focus; *everything* else can be fixed.

I think I'll be adopting that rule and making it my own because my experience tells me the same; motion blur and missed focus are just too hard to fix with much avail. I have installed a S-type focusing screen and O-ME53 magnifying eye cup to help with my manual focusing as well as with verifying that the AF locked on correctly. I'm not doing myself any favors though by using slow shutter speeds or attempting to focus and recompose.