When centre focussing doesn't quite work

Left the GX-10 on centre point focussing, then sat at the local sailing lake and took some snaps. Just got home and uploaded them, found that several are way out of focus (and sod's law it's the better photos it happened to!).

Is this just a case of the object I thought I had focussed on being too small in relation to the whole image? And any suggestions on how to improve my technique, I was trying to aim at the sail, but also did a few aiming at the people in the boats which is where it must struggle.




At least the trees look nice

draw an x from corner to corner.
are there trees dead center? that seems to be what you focussed on.
possible you had your af set to af-c instead of af-s? that would mean if you focused on the sail then recomposed, your af (being on Auto Focus-Continuos) would refocus on the trees in the center of the frame.

The thing is, it's not way out of focus - it's really just a bit out.

And the Laser, and even more so the Fireball, are moving towards you quite fast.

You really don't have much time between having the AF lock, and pressing the button, if you want it to stay in focus.

How much of the frame is this? It's obviously a crop, but of how much of the original? The EXIF suggests the focal length was 160mm, so you'd have had to be reasonably close to get them this size in the frame. So with a crop, the tolerance is even finer.

Then, you have the camera set up at max sharpness. Did you process a camera-sharpened JPEG by reducing for the web? Hard to say, but you might lose some definition there too.

Looking at that image is it a focus issue or lack of sharpness - could it be the boats moving has made them less clear. What was the shuuter speed?

Mike

How do you know the Fireball is going faster?

Not quite so hard on the wind?
Heeling more, despite the extra ballast?
Sheeted harder?
Number two must try harder?
Other?

G

I don't know for sure, in all honesty, but it looks like it's trying to get up on the plane, with an awful lot more weight aboard, whereas the Laser very much isn't.

Neither one is going that fast (the Fireball crew isn't out on the trapeze), but the Laser guy isn't working at all... In my Laser days, on a good day, I used to be out so far, with the bow so far out of the water, that I'd be looking under the hull through clear air. Abs of steel I had, then...

So I'm surmising (not much more than that, really) that the Fireball is catching up.

Am I right, AF?

Just looks to me (at this size) that the camera's focused on the trees, so as Don says, probably just missed the target, which would have been just to one side of centre, and got the background instead.

Unfortunately, if we're honest, it happens to us all now and again.

Dan

Do you really think the trees look all that sharp?

Mostly again, in my case.

More sharp than the boats are. I think they are, but it is hard to say for sure at this size.

And the only embarassment with missing the focus point is when it's not a moving target.

Dan

Shutter speed was 1/500 i think, so should be fast enough to freeze the boats (they weren't going that fast). It was set on AF-S, and I was generally targetting the sail or the people and then recomposing slightly. The image I posted is a crop, probably just over a 1/3 of the orginal (shot landscape). It's just been a useful lesson to me that you can't always trust the auto focus options! The camera isn't set to max sharpness, it's +1 on the settings screen and I added a small amount in Lightroom afterwards. I realised that saying the focussing was 'way out' is a bit of an overstatement, but it's still a long way off the crisp image with a blurred background that I was after

Yeah, well this reinforces what I thought.

It's a third of the frame, so it's pushing the limits already - the slightest degree of OOF-ness and you really pay the price with an aggressive crop.

And it's focused and then recomposed, presumably with focus lock. In the time it takes to reframe and press, they've moved quite a few feet.

I think the trees are a red herring myself - they don't look particularly sharp to me.

Started typing this a couple of hours ago, then got distracted by the telly, so here is what I initially thought!

It does appear that the centre is in the trees, so it's all down to technique!

In this situation where they are moving towards you, there a a few options:-

1) Focus on the front of the front boat, and very quickly reframe and shoot, it takes practise, but speed counts, you have very little time for composition.

2) Focus on a point that the boats are going to sail into, keep your finger half pressed on the trigger, and when the boat hits the spot, let em have it!

3) Use a higher (or is that lower?) F stop for greater depth of field so more will be in focus.

I've used these techniques with varying levels of success, basically take some time out to practise some skills, try both AFC & AFS see which works best for you

Quick calc

Assuming you were shooting with your DA50-200 at the long end and guessing the rest (worst case ?), aperture at f5.6, distance to subject 150ft, subjects doing 10mph (or should that be knots = 14.6ft/sec.

The depth of field at these settings (front to back acceptable sharpness) works out at 39.3 ft, divide that by 2 (or 3) then you really don't have much time to recompose and still be within the limits.

If not, it jolly well should be

Thanks for the insights and calculations everyone. When I posted the image I thought the camera had got confused by the relatively small thing I actually wanted to focus on and had aimed at the trees instead, but from what you're all saying (which I do agree with and makes sense) it's mainly due to me taking too long to compose the shot after locking the focus where the boats used to be.

Will try and be quicker next time! Thanks again.