Diving tomorrow! What focus to use?

[Coll]

Quick, simple (I hope) question.

I have a Canon SD630 and have always used the "Evaluative" focus mode, it does get frustrating sometimes though because I have to pre-focus multiple times to get the camera to focus on my subject and I often lose the shot. My other options are center-weighted avg and spot focus, I'm guessing center weighted just focuses at whatever is in the center of your frame and I'm not real clear on what spot does? Which one is best for underwater shots? Specifically macro in low vis. Thanks as always and happy diving!

 

[mofongo_max]

You're probably already out diving but...

The modes you're talking about are for metering (measuring light), not focus. Evaluative has the camera taking a reading from several points in the scene before deciding on an appropriate exposure. Spot and center-weighted are metering more so on the center of the frame (with spot being very concentrated on the center).

 

[Larry C]

For macro, use spot focus, and center your spot over the critters eye if possible. Otherwise, the camera will continue to hunt and try to focus on all the green crap floating around in front of it. It will do enough of that anyway. If you can't get a good hard focus, find an object at as close as possible to the same distance that has a strong focus, half-press to lock focus and then move the camera back to your desired focus point.

 

[Kukuisa]

Larry,

When shooting from 3 to 4 feet distance after a macro shot, would you set the measuring back to center-weighted for a non-macro shot or just leave it on the spot focus?

 

[Larry C]

I use spot focus for everything except wide angle. I don't know about the Canon, but my Oly allows four "MyModes" and I have it set up for a single button to switch between them. I have one mode for Super Macro, with much faster shutter speeds (1/125-1/500) and aperture at f8, one for normal macro (usually about 12-18") with 1/60 f5.6 (I like to see more background, not black it out) and two for wide angle, one with strobe and one for ambient light. Lately, I've been trying 1/30 f5.6 for wide angle strobe shots, and getting nice results with good overall lighting. YRMV-Most of my diving is between 60-100' in dark green water.