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12/07/2006 02:50:05 AM · #1 |
I'm doing some studio portraits of ballet (I know, shocking, huh) and tonight wanted to do some jumps etc. Now I'll be the first to admit I don't REALLY know what I'm doing but the still portraits have come out really well.
My set up is:
An SB800 shot into a 48" silver umbrella
An SB600 from the opposite side as fill
An SB600 shot from behind a 10' wide roll of background paper (I put it behind because I put gels on it and it gives the background a nice soft pastel look).
I'm in a 40X50' room. The room lights are fluorescent so I keep them off and use a single daylight balance 60w light to light the room. This is to keep the ambient light low enough as to not affect exposure.
The problem I'm having is focus. On the still shots things are fine and the camera has plenty of time to focus before it fires. On the action shots I had a REALLY tough time nailing the focus though. I tried AF-C, AF-S and every type of auto focus I could but missed 90% of the shots. I tried manual focus but the girls are really flying and rarely hit the exact same spot from pre-focus to shot. Any suggestions? Is my ambient light wrong? |
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12/07/2006 07:37:20 AM · #2 |
I think you can "turn up the house lights" a bit without worrying too much about ambient light.
Remember this: For studio lights, the aperture sets your exposure. For ambient light, the shutter speed sets the exposure.
The reason this is true is that the strobe light is much faster than your shutter. So the shutter speed (any speed up to "sync speed") does not matter. But ambient light will diminish as the shutter speed goes up.
So, I believe your camera has a sync speed of 1/250th of a second. Let's say you've set your strobes for f/8. Now set your shutter to 1/250th and take a picture of one of your subjects WITHOUT turning on the strobes. What do you see? I bet what you see will be close to pitch black because your ambient light isn't going to be all that bright.
The more light you see in that frame (without the strobes being fired), the more you have to worry about turning down the ambient light. If you don't see anything, then don't worry at all, keep the ambient lights on so that you can get a good focus.
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12/07/2006 09:18:45 AM · #3 |
Dan - for the problem of focus... Set your camera at a fairly small aperature, like F8 (that will get you a pretty wide depth of field), now manual focus to a point in the middle of the DOF and have the girls jump through that area. Leave the camera in MF and fire away. Unless the girls move well ahead of or well behind your DOF, your focus should be good. Then all you have to worry about is tracking them.
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12/07/2006 02:15:30 PM · #4 |
| Thanks, I'll see what I can do about upping the ambient light and the aperture. I'm already shooting at 1/250th of a second so as to avoid as much motion blur as possible. I'll do some test shots though without the flash to see what the ambient is doing before the shoot though - good tip. Now hopefully this won't make my recycle times too much worse than they already are :( |
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12/07/2006 02:25:57 PM · #5 |
I agree with  dwterry
I think you can turn the house lights up ALL the way. At the speed/ISO you'll be shooting, and the power of the strobes, I don't think you'll get any ambient light from the fluorescents.
Good luck!
E
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