Focus and DOF while shooting boxing

[cotfessi]

I shot my first boxing match last week. It was an amateur event, and the lighting wasn't quite what you'd see in a professional fight. I was shooting with a Canon 50mm f/1.8 lens, open all the way, with ISO at 1600. I was able to get some great shots, but I was frustrated with the percentage of shots that were just out of focus, or partially in focus due to the shallow depth of field given the f/1.8. For instance, a boxer's body might be in focus, but with his arm fully extended in a punch, his glove was out of focus.

As i understand it, the f-stop controls the depth of field. It is also one of the factors that controls the shutter speed. If i increase the f-stop to allow for a great amount of the shot to be in focus won't it slow my shutter speed down?

I can't figure a way around this short of introducing a flash in the mix, but I don't believe I'm allowed to use one.

Anyone have any tips?

[sk66]

You have it right. Only thing you can do is increase ISO in order to use a smaller aperture. You are up against the limits of your gear.

You could work from further away to increase the DOF, but that will result in harder cropping and more apparent noise.

[inkista]

You could also push in post. And that will increase your noise, but might get you closer to what you want. You have to judge.

Basically, shoot RAW, use iso 1600, underexpose by a stop or two to use a smaller aperture setting and get more DoF, and then adjust the exposure to be brighter in post. That's effectively like using iso 3200 (for one stop) or iso 6400 (for two stops), and is similar to what the extended iso settings are doing in-camera.

When I had a Canon XT, which maxed out at iso 1600, I'd occasionally do this to avoid motion blur.

[ZafarSami]

Thanks inkista, for the hint about what extended ISO setting do in camera; so the Lo settings overexpose while the Hi settings underexpose? I assume it is better to shoot at the settings between the extended ones unless forced by the light?

Finally what good is it to set extended Lo ISO and overexpose?

[wulf]

You do have a challenge on your hands there, particularly as high ISO = ugly digital noise, especially if the end result is still underexposed. A few further ideas to consider:

1. Pay close attention to the lighting. Perhaps there is an area of the ring that is better lit and that could be your main target zone? Remember that our eyes are brilliant at adapting and levelling out light differences. Try taking fast shots of the whole area before the action starts and gradually dialling down the shutter speed. The areas that start showing up first are the ones where the light is brightest.

2. Depth of field sounds too limited. Since you can't open up the aperture any more, try stepping back and exploring wider views of the match. The scope for doing this will vary with the room but even a few feet further away and using slightly wider framing might make all the difference.

3. Don't despise slower shutter speeds. Sure, some of the action will be blurred but you are capturing a fight after all and not posed statues. You didn't mention what shutter speed you are using but I wonder if you have room to slow that down significantly and thus ease the pressure on ISO and aperture?

Wulf