Having trouble getting sharp focus on a moving subject

[ilzho]

Ok, I have been taking pictures of horse racing, some good, some not so much.

I am using Rebel Xsi, usually in a creative mode, AV or TV or just starting manual mode as well.

I am in AI servo, using center af point, continuous shooting mode.

I have not tried Back button focusing (yet).

These pictures where taken in later afternoon, early evening, (6-7 pm) so the ISO is a little higher, just trying a few different things.

One thing that is common is that I am getting more pictures out of focus than in sharp focus, so clearly I am doing something wrong.

Either I'm not getting the center af point on my subject, or camera shake, or too slow of a shutter speed. Or I need more practice 🙂

My post processing is pretty bad as well as I am only using what Iphoto has to offer.

I am panning my shots, either to freeze the motion or to try a little motion blur.

I realize it will be very hard for you all to give me any concrete advice as you are not with me, but as always, you have giving me sound advice.

This one is in focus.

This one, not so much.

Some others......

[ilzho]

Well, I will certainly keep trying and playing around with everything.

As the horses are coming down the track, they are coming towards me and then crosses my parallel plan and then they get further away as they head to the finish line.

Granted they aren't moving around like a basketball or football player, but I'll keep trying.

I'm going to the track in a few hours to try again........

[Waddizzle]

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@ebiggs1 wrote:

"This rebel only has 9 points, so I try to use the center one."

That is what you should be doing.

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With only 9 points, that is exactly what you should be doing.  You do not have AF assist points in AI Servo mode.  What you have is the camera frequently making undesireable decisions for you,.as it chooses an AF point to use.

I get the best success with my T5 using just the center, and pre-focusing [using back-button focus] in One Shot mode.  I have never tried to photograph horses, but I would begin by knowing my distances to the subjects so that I can know what depth of field to expect.  By knowing what my depth of field will be, I can get a handle on what to expect to be in focus when the action moves into my "focus zone."

I have gotten great results by pre-focusing on an area where I expect action to be.  I try to "focus low", by that I mean that I angle the camera downward focus at the ground, and then recompose the shot by moving the camera to a level position again. 

[jrhoffman75]

Definitely shoot in raw unless there is some reason you want immediate images for sharing, and in that case shoot raw+JPEG. 

DPP can take advantage of all the settings you set on the camera, including Picture Style, but like Waddizzle said its UI is a little tough. 

If you are currently comfortable using iPhoto/Photos on the Mac switching to shooting in RAW will be seamless. It will open the RAW image and you won't notice any difference other than better image adjustment capability. 

[ilzho]

Awesome. Thanks.

I thought there would be visual change upfront in shooting in Raw.

Guess I need to do it.

Would shooting in Raw slow down the burst mode?

I can shoot 3 fps and get about 9 bursts before the camera buffer needs to clear itself.

[Waddizzle]

I am not familiar with Iphoto, but the images you posted seem to have had the metadata cleared out of them.  I cannot determine your focus points, nor see how far away the subject may have been from the camera.

[ilzho]

hmmmm. I think the dirt track is about 85 feet wide and I'm along the railing.

I use the center af point, just not getting it on the right place.

[Waddizzle]

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@ilzho wrote:

Awesome. Thanks.

I thought there would be visual change upfront in shooting in Raw.

Guess I need to do it.

Would shooting in Raw slow down the burst mode?

I can shoot 3 fps and get about 9 bursts before the camera buffer needs to clear itself.

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Shooting RAW may slow down burst mode.  Would you rather have a burst of 9 out-of-focus shots, or a burst 3-6 shots that were in focus? 

I use Back Button Focus for action shots with my T5.  When using One Shot mode, and the center AF point, I have found separating AF from the shutter switch to be very useful.  I can press the shutter, and the camera immediately takes the shot.  the subject is in my "focus zone", and I don't have to wait for the camera to re-acquire focus. 

I have also found that if I put the camera into AI Servo mode when using BBF, that I can briefly press BBF and lock focus just as if I were in One Shot mode.  As John Hoffman has pointed out, it is not as fast to acquire and lock focus as One Shot.  It is as if I have the camera in AI Focus mode, except I decide when it tracks and when it doesn't, instead of the camera.

[Waddizzle]

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@ilzho wrote:

hmmmm. I think the dirt track is about 85 feet wide and I'm along the railing.

I use the center af point, just not getting it on the right place.

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From about 85 feet away from the opposite rail, with a 100mm lens you should have a depth of field between 10 feet and 30 feet, or more, depending upon your aperture setting.

http://www.dofmaster.com/doftable.html

What lens are you using again?  Does it have Image Stabilization?

[ilzho]

It's canon macro lens EF 100mm 1:2.8 USM.

[jrhoffman75]

AI Servo is a good tool, but it has limitations. Even the 1D X won't deliver 100% of the time.

I wouldn't spend anytime reading it, but Google 1D X Auto Focus guide and just look at all the adjustments that camera has for improving AI Servo response. And that camera has several (maybe many) times the computing power of the Rebels we have.

The other thing you might try is bumping focus. I don't know the timing involved, but if you've got the camera locked in using AI Servo and the subjects suddenly stop moving towards you and now move parallel the camera needs to compute a new speed (close to zero) and readjust the focus correction.

If you release BBF and then reapply it will start the process over; I don't know which will respond quicker, but its something you could try.

The beauty of digital is we can practice at no cost.