5D Autofucus Mode

I have yet to use my 5D underwater but I expect to have the same autofocus problem that I had with the 10D, i.e.: autofocused shots were out of focus - specifically at close range with macro or WA lenses.

Every mode appears to be able to take an out of focus shot though I not always able to get it to do so. I can always get AI Servo to take out of focus shots and the 5D knows it's not in focus: no beep or confirmation light.

I'd like to hear from anyone that has determined the best autofocus mode to use or the situations in which to use which mode.

In One Shot AF mode, the camera will not take a photo unless autofocus has locked, indicated by the red focus point illuminating and accompanied by a beep (unless you turned that off).

If you move the camera after autofocus lock, and while depressing the shutter button half way, you can still take an out of focus picture. Also, if you are moving, or your subject is moving, and you have a slow shutter speed, then your shot will look out of focus.

Cheers

James

I like One Shot AF with AF on the * button.

This way you activate AF by pressing the * button, and as long as the * button is depressed the camera will not take a picture unless AF has locked.

And if AF will not lock you just release the * button and the camera will let you take a picture anyway.

Problem is the 5D will confirm autofocus occasionally even when it's not actually in focus.

Canon 5D and 10D consistently produces images that are in focus, maybe there was something floating in front of you that caused the AF sensor to lock on it. A blanket statement like that about both cameras would simply make most folks wonder if it was more operator error than equipment error.

My shooting modes for UW:

AI-Servo for fast moving fish and super macro (AF compensates for one's moving in and out due to bouyancy changes)

One-Shot, for everything else, especially on subjects where I focus say on a nudi's head then recompose to capture the entire critter.

Stu

In my experience which is limited to only one 5D body and one 10D body, I found the AF difference to be extremely significant. My 5D AF is both faster and much more accurate then my 10D, even after I sent my 10D and lenses to Canon for calibration.

All,

I didn't mean to imply that there was wrong with either the 5D or 10D.

I don't doubt at all that it was my fault to begin with and I'm working toward correcting both my technique and having everything set appropriately to begin with is a prerequisite. Generally I don't have focus issues u/w but I have had out of focus close-in shots, with both the 100mm macro and the 17-40.

I've done some additional land testing (with the 17-40) and found that both AI Servo and AI Focus will track the subject but, when getting closer than the lens' minimum distance, they will still take an out of focus shot.

When starting out to close to begin with, AI Servo will take an out of focus shot but One Shot and AI Focus will not.

Stu, can you elaborate on you choice of AI Servo rather than AI Focus ?

-Irwin

Irwin,

I've successfully used AI Servo tracking peregrine falcon in flight, so if the 10D can do that, I figure it would for being able to compensate for a diver's movement, specifically in the change in bouyancy as one breathes in and out.

Are you using a diopter with your 17-40? My CFWA shots using the 16-35 with a 6" dome are tack sharp. I have a BW +4 diopter mounted.

One Shot and AI Focus will try to acquire focus first before firing, AI Focus is then supposed to track the subject if the subject moves after focus has been attained. You could have had a focused subject at first but failed to properly track your subject. AI Servo will fire regardless of focus or not, it's up to you to keep your subject on the sensor.

Remember though, UW photographers are not in the forefront of the camera designer's minds.

Stu

Irwin, regarding your out of focus shots with the 100mm macro, you're not closer than the minimum focus distance are you?

I've seen people get in a little too tight with that lens and think the autofocus was to blame for the shot being soft.

I've also used a 10D and I agree the 5D's AF seems better than the 10D. The sharpness is unquestionably better, due no doubt to the better sensor.

Irwin, regarding your out of focus shots with the 100mm macro, you're not closer than the minimum focus distance are you?

Yes, I was using the 100mm macro I almost certain I was too close. I mistakenly believed that the shutter would only fire when focus lock was present. Not so.

This was with a 10D. The tiny viewfinder, multiplied by the housing optics, didn't allow me to see much of the image - definitely not enough to judge crisp focus vs. nearly focused.

The 5D is going to improve what I can see through the viewfinder, including the focus lock light.

I've successfully used AI Servo tracking peregrine falcon in flight, so if the 10D can do that, I figure it would for being able to compensate for a diver's movement, specifically in the change in bouyancy as one breathes in and out. 

Are you using a diopter with your 17-40?  My CFWA shots using the 16-35 with a 6" dome are tack sharp.  I have a BW +4 diopter mounted. 

A few questions on your 16-35, +4, 6" combination. Did you always use that combination or was the +4 added based on results obtained without it?

Would you expect the Ike 8" dome to provide me the same improvement with my 17-40 that you see with the +4 ?

What else will a diopter affect? DOF, focal length/distance, etc.

One Shot and AI Focus will try to acquire focus first before firing, AI Focus is then supposed to track the subject if the subject moves after focus has been attained.  You could have had a focused subject at first but failed to properly track your subject.  AI Servo will fire regardless of focus or not, it's up to you to keep your subject on the sensor.

As to keeping the subject in the AF point, for me the 10D viewfinder made that next to impossible. The 5D will improve what I see.

I have tested the 16-35 behind the Ike 8" dome and the diopters help corner sharpness a bit... but not enough. I'm still looking for ways to improve my results. I have not had a chance to test the 17-40. It would be interesting to see in water results with it. Scubastu seems to be getting better results with 16-35 behind the Subal 8" dome in his enclosure (is the Subal dome glass?).

I find the one-shot AF mode works best for macro. Once One-shot AF gets me close, I move the camera back and forth to fine tune the DOF range where I want it.

I am very happy with the 5D/Ike viewfinder combo.

Just getting back to this thread:

This image was shot with the 10D, Tamron 90, Woody's Diopter using AI Servo

This has been printed to 20"x30" and looks stunning.

Maybe I'm lucky that my (then) 37 yr. old eyes are still working OK...even using Toric soft contacts! So, I leave it up to you to decide if AI Servo works or not.

I posted some shots using the 5D, 16-35L with a Subal 6" Dome with my modified 10D housing.:

http://wetpixel.com/forums/index.php?showtopic=14205

Sharpness is very good at the corners as you can see. I expect to have a modified Aquatica 8" dome with the 15mm Sigma FE to try out in the pool in a week or so. So far, testing has shown that there is no vignetting with this lens/port combo in my housing.

I would expect that the 16-35L would perform better in the 8" dome but have yet to try it. I have had my 16-35L ever since it first came out and have always used it with a +4 BW diopter as recommended by Subal. I will likely try the 16-35L with and without diopter with my new 8" dome.

Stu