topic Re: AI Servo, AF point selection question for close moving objects in EOS DSLR & Mirrorless Cameras

AI Servo, AF point selection question for close moving objects

ilzho — Sat, 11 Jun 2016 22:33:47 GMT

Hello:

I just came back from the horse race track and looking through some of the photos, the camera/lens (of course not the photographer 🙂 ) couldn't get the horses in sharp focus when they were bunched together racing by.

I have a Rebel XSI (2008) and the manual stated to keep the automatic AF point selection (all 9 points) when shooting in AI servo.

I would like to know your thoughts?

I tried the center only AF point and it worked good as long as I kept it on the horse as it raced by 🙂 even in bunches.

Thanks,

David

Re: AI Servo, AF point selection question for close moving objects

diverhank — Sat, 11 Jun 2016 23:27:46 GMT

For cameras such as yours that have only 9 points, I think you should have only the center point. Having all nine points will mean that the camera will choose a random one for you. When you have a bunch of horses and you wish the lead horse to be in focus...the camera will most likely choose the one in the middle or at the end...

As you have seen, tracking moving objects with only one point is difficult. Cameras that have more than 9 points will generally allow you to use the center point plus several more around the center to make tracking the target a bit easier.

Re: AI Servo, AF point selection question for close moving objects

ilzho — Sun, 12 Jun 2016 00:04:29 GMT

Thank you.

Yeah I knew better than to use all 9..... Sometimes it tracked the **bleep** railing, hahaha......

Just goes to show you it's not the equipment, it's the photographer 🙂

I'm going to buy a good camera as this is my brothers and he eventually wants it back.

Re: AI Servo, AF point selection question for close moving objects

cicopo — Sun, 12 Jun 2016 00:36:08 GMT

Depending on what the camera allows (Rebels likely don't offer this) use center point or expanded center point & put it on the horse that you specifically want as the main interest in the photo. IF the camera offered picking an expanded point other than the center area you might want to use the one opposite the centre point from the direction they are heading so the lead horse is the main focus but you have more horses in the frame behind it. When I frame an R/C model with the smoke on I want the plane on 1 side of the frame with the smoke trail going across to the other side rather than 1/2 the smoke trail because I had the plane in the center of the frame.

Re: AI Servo, AF point selection question for close moving objects

jrhoffman75 — Sun, 12 Jun 2016 00:41:04 GMT

The correct technique is to use the center point first on the subject to acquire focus. Then, if the camera moves away from the center point one of the other points will pick it up and focus. If you don't have AF Point selected, I.e. only have center point, if the subject leaves the center point the camera will choose the next thing the center point sees.

If if you move the camera to keep the center point on the subject then center point only is OK.

Re: AI Servo, AF point selection question for close moving objects

ilzho — Sun, 12 Jun 2016 00:48:14 GMT

Yes, I previously had the center point on and panned the horse/s and it seemed to work fine, then reading the manual (I'm a newbie still learning) I decided to use the AF automatic ponits... bad choice, haha.

Here's a bad example, but you get the idea.

Yes I was far away and I only have a 100mm prime lens, but here you see the brown railing in focus, the horses, no way. It's a throw away.

Re: AI Servo, AF point selection question for close moving objects

jrhoffman75 — Sun, 12 Jun 2016 01:11:26 GMT

For subjects like this, where subject is moving parallel to camera, I get better results with One Shot Continuous. No need for camera to refocus since distance isn't changing.

AI Servo benefit is predictive focus based on subject motion changing distance between camera and subject.

Re: AI Servo, AF point selection question for close moving objects

ilzho — Sun, 12 Jun 2016 01:19:53 GMT

To be honest I have never used one shot continuous. I have always used AI servo, continuous (center AF point), usually.....

It's easier when the subjects are separated.

Not the best pic, overcast day.

100mm, f/6.3 1/1000, 200 iso. TV mode

Re: AI Servo, AF point selection question for close moving objects

jrhoffman75 — Sun, 12 Jun 2016 01:21:51 GMT

Nice shot.

Re: AI Servo, AF point selection question for close moving objects

ilzho — Sun, 12 Jun 2016 01:23:55 GMT

Thank you so much....

I have a greater appreciation for all of this....

It's not easy

Re: AI Servo, AF point selection question for close moving objects

cicopo — Sun, 12 Jun 2016 02:26:15 GMT

If it was easy everyone could do it & no one would really care about a better than average photo. As for that nice long lens you'll need to get a big bank account to move up to one of those. Work on your technique & think about just what you'll need in gear as you do that.

Re: AI Servo, AF point selection question for close moving objects

ilzho — Sun, 12 Jun 2016 02:37:05 GMT

Yes, that's way out of my price range and honestly I don't need anything like that.

I'm a beginner, learning the dslr, functions, etc.....

Going out and doing and trying is fun and frustrating... It's trial and error.

My attempt with motion blur. ISO 200, f/7.6 1/60

Re: AI Servo, AF point selection question for close moving objects

Waddizzle — Sun, 12 Jun 2016 11:37:54 GMT

@ilzho wrote:
Yes, that's way out of my price range and honestly I don't need anything like that.
I'm a beginner, learning the dslr, functions, etc.....
Going out and doing and trying is fun and frustrating... It's trial and error.
My attempt with motion blur. ISO 200, f/7.6 1/60

Nice shots. I think you could take even better shots with a tripod, especially on panning shots like the one above. The IS circuitry in the lens will reward you for it. You will really be able to freeze the riders in sharp focus.

What type of head to use is a personal preference thing. I have ball heads, and pan/tilt heads. I mostly use "video" tripods, which means I'm using gear with a 100mm bowl, or a flat mounting plate, instead of a center column. I haven't settled on what type of head I like the most. I can switch from one type of head to another by swapping ball adapters, or mounting plates.

Like lenses, each type of tripod head shines in specific scenarios. Ball heads are fast, quick and easy to re-adjust to a new target in various directions. Pan/tilt heads are slower to adjust, but great for when your shots will mostly be along a constant horizontal plane, like panning on horses as they run by. Better ball heads have horizontal panning controls. With either type of head, a well leveled tripod is a must.

Horizontal panning on a tripod minimizes up/down camera shake. In fact, Canon's professional grade, telephoto lenses have Image Stabilization modes that are optimized for horizontal panning, and will actually ignore side-to-side camera shake because you're panning.

Once again, nice shots. You seem to be using shutter speed creatively, and most effectively I might add. Follow the advice about using just the center point. Don't let the camera choose what to focus on. I mgiht also add that pre-focusing [one shot mode] on a specific distance, area, or zone, and waiting for subjects to enter it works well for me.

[EDIT] For a shot like the one above, I would use Back Button Focus to lock focus on the ground where the horses will run across. Once focus is locked, I can press the shutter without the camera re-focusing. With enough depth of field and continuous shooting mode, you just might be able to get capture some great shots of the whole herd of riders in focus, instead of just the one.

Re: AI Servo, AF point selection question for close moving objects

ilzho — Sun, 12 Jun 2016 12:03:23 GMT

Thanks so much for the comments/advice. I appreciate it.

As far as a tripod is concerned, my brother gave me one, but the horse race track will NOT allow tripods at all 😞 nor lens over 15". Except for the official track photograhers which one is below.

Yeah, I'm still kicking myself for not using the center AF point. I guess that's one way to learn 🙂

I need to learn/look up the back button focus.

Here's another motion blur photo.

Re: AI Servo, AF point selection question for close moving objects

Waddizzle — Sun, 12 Jun 2016 12:23:47 GMT

Back Button Auto Focus.

http://learn.usa.canon.com/resources/articles/2011/backbutton_af_article.shtml

I have found BBF useful. I'm not good at holding the shutter halfway down, and moving the camera at the same time.

--------------------------------------------

A 15 inch lens is pretty long. I hope that doesn't include the hood. If you're using a 100mm lens, then a 70-200mm might be the most that you need. From what I have seen so far, your 100mm seems to be doing a pretty good job of covering it.

Re: AI Servo, AF point selection question for close moving objects

ilzho — Sun, 12 Jun 2016 12:32:28 GMT

Awesome.

I never tried it. I'm already in the creative mode (TV & AV) shooting, so now I will figure out how to custom that function.

I will practice on the cars passing by in may area and see what I can get.

Thanks.

Re: AI Servo, AF point selection question for close moving objects

ilzho — Sun, 12 Jun 2016 13:15:34 GMT

By the way here is the tripod my brother told me I can borrow. Too bad I can't take it to the track.