Shooting from the Boat - Focussing Strategies

Hey guys, I've been shooting sports/wakeboarding for a few years now and have been getting decently consistent results. ...but I'm definitely still learning and still improving.

40D / 70-200 2.8 IS
(Usually I strive for 1/1000 with f/4 or so; lately I've been turning the IS off but am still on the fence in this debate.)

Over my numerous outings on the boat, I've tried various AF techniques and to be honest I've still not really latched onto one.

A few that I've tried:

- switching to MF after autofocussing on the rider's head and sitting directly under the tower, centered on the boat (with the idea that the focal/rope length never should change)

- using Canon's * button to set a focal length at the rider's head and then using the shutter to just fire away (logic similar to above); this I've tried with AI Servo, AI Focus, and One Shot

- using AI Servo and center point AF

- using AI Servo and multi-point AF


I guess there are a few variables to consider:

1) the AF drive mode
2) the AF point selection
3) the method of applying the AF (i.e. independent of shutter or not)
4) the notion of a "never changing" focal length


I guess I'm just curious what you guys (pros and amateurs) use for shooting from the pull-boat.


On another note, what is the DOF at f/4 vs. f/2.8 on a 1.6 crop body at, say, 140mm? Save me the math!


Thanks in advance for the answers/discussion guys/gals.

(Message edited by Notreknip on July 02, 2008)

DOF is pretty thin at f2.8 from the boat I would imagine, I've always shot at f4-f5.6.

Leaving the IS on/off is up in the air as well, I turn it off on my f4 L IS but I've never seen any bad results due to it being on at those shutter speeds.

As far as the AF mode goes I use AIServo with either CP or a point on the outer rim but I do switch my AF activation back to the shutter button from the dedicated Af button on my 1D3 because it seems quicker to me for some reason. I've used all points before but found no real benefit (after shooting birds in flight a ton tracking a wakeboarder is easy.)

Whether your 40D/70-200 is performing up to it's potential is hard to say, you'd have to compare your results with other 40D owners. You won't get 100% keepers from any camera, there always seems to be an oddball frame here and there.

Hmmm the age old question to AF or not to AF. I generally AF with a CP on the riders head then switch to MF making sure as to not touch the focus ring. I know other guys that will focus once then put gaffers tape on it so they are sure it doesn't move. Usually i run AF Servo if tracking a subject with different shutter speeds but normally AF One-Shot if i plan to switch to manual. Not sure if that helps.

I am also quite curious about the IS or not to IS debate. I recently took a F4L non IS and a F2.8L IS to the last PWT stop and took a number of pics from both lenses to see if the IS really matters. I personally didn't see a huge issue with the non-IS and the weight savings was appreciated.

I'll admit i'm no pro but i sure do enjoy taking pics so this topic is quite interesting

+1 on the interesting topic. Great thread starter Devon.

I'm definately interested in hearing more about focus methods from WW's more seasoned shooters so hopefully more will chime in.

Walt? Ryan? Riley?

IS or VR isn't a factor when your shutter speeds are so high. Drop below 1/125 or so and you will notice how IS/VR helps

Also kind of my thought for this sport as well as needing a F2.8 as how many times are you shooting late in the day. Most of time I shoot in the bright daylight

I only use * and AI SERVO. I also use a single focus point that I move around when I want to change the composition of the shot.

This was shot at 1/1000th, f4. ISO3200, +.7EV.

An f2.8 lens would have helped a bit, I could have not pushed the exposure or dialed the ISO backto 2500 with f2.8. It was really dark at the time, more so then the image shows.

I'm all for fast lenses but realistically I don't feel f2.8 is a huge requirement for outdoor shooting in general.

Walt, do you use full mash the whole time on the * when you in AIServo? I've found pumping it on and off gives a little better result with my cam, which I find easier with the AF back on the shutter. I use the dedicated AF button for shooting everything else though.

Rich,
It sounds like we use * the same way.

Thanks for the help so far guys. I'm glad to hear that I wasn't the only one thinking about this.

Regarding my DOF query in my original post, check out this: http://www.dofmaster.com/dofjs.html

At 140mm (fairly tight framing) on a 1.6 crop body with a rope length of 80' (quite average)...
f/4 DOF = 15.2'
f/2.8 DOF = 10.7'

...even with 2 feet of rope slack/stretch and a 6' rider f/2.8 should provide enough DOF for the entire subject.

Don't forget usable depth of field does not extend 10'7. It's not like there's an invisible line right there at the edge where everything goes from being sharp to blurry. I think you'll find parts of your rider a bit Oof at f2.8 at 80' but there's only one way to find out, maybe someone can post up a 100% crop shot from the boat at f2.8.

Yeah, parts of the rider will be noticeably soft (mainly the board) if you're shooting at f2.8 and the rider does a raley or off axis spin of some sort. It's not a huge deal, but it is noticeable. I'll see if I can find a pic...

I've used a lot of these techniques as well. I think from the boat setting the focus with AF then switching to manual can work well if you are at certain points in the boat (like Randy mentioned). Anywhere else I tend to use AI Servo with a specific point. I haven't tried the * button switch yet, How long did it take everyone to get used to using it separate from the shutter release? Do you leave it on for all shooting or just action shots?

It takes a very minimal adjustment for most to start with * focusing. (Maybe a week or so on average.)

Personally, I use it for just about everything, there really is no downfall once you train your fingers/brain to work quickly together.

AP is right about the IS or VR on your lens. Image stabilizer should only be used in low light conditions. Otherwise its useless and can cause images to be out of focus.

As far as the DOF goes...that link is really cool and can be a good tool. But my real life experiences do not agree with what that site is telling us. I wont go into detail but test it yourself.

I also use the star for my AF. It took me about 2 days to get used to it and I don't know if it's better or not.Tapping it does work better for AF but only in certain conditions. I use A1 Servo for numerous reasons. The main reason is because it can do the same job as "One Touch" only better. If I want to focus like one touch I just touch the star button once and it does the same thing. If I need to track my subject, my AF is already on servo so I'm ready to go.

On another note...if you guys get a chance to shoot from a chase boat, do it! The tricks look better, its a great angle and the girls have more room to layout without all those boards laying around.

I've thought about leaving my cam in AIservo all the time as well but it bothers me not having the FP light up and hearing the confirmation beep, a lot of guys do that though.

Isn't it hard to use AI Servo and track the rider the entire time with a single focus point selected? I figure you would end up hitting the spray, rope, background, etc. if you missed the rider. I assume you guys are tracking the rider the entire cut say if you wanted to hit them at the peak of their jump/trick?

I just got a camera that does AI Servo so I'm interested to hear the advantages of using it for in boat shooting. Auto focusing and switching to manual seems ideal and the most consistent, but I guess you might have to worry shooting wide open for when riders and spinning (advancing themselves toward the boat) and tricks that bring them closer to the boat.

I just tried the auto focus on the rider just before the boat pull him out and then switching to manual for the first time last weekend, seemed to work pretty well for me, I got a lot more quality shots then I normally get.

Ken Rockwell says that you should always keep you VR/IS on...


I have been shooting a lot with my IS (28-135) off in AV mode with AI Servo with changing ISO depending on light. I probably need to try some other stuff. I am just starting out with the whole photography thing.

this has been a great thread..

just switched to manual focus and i got a lot more shots than in AF..