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Old July 9th, 2010, 02:08 PM   #1
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Setting Exposure for Indoor Sports...Help!

Hi everyone:

I'm getting ready to do an indoor shoot of a mixed martial arts event (like UFC). The event is going to be in a boxing ring under very bright stage lights. I want to make sure my line of thinking is correct as far as proper exposure goes. Would someone please check my plan to make sure I'm on track? Here's it is:

- Before the event and with all lights turned on, get a helper to hold an 18% gray card in the center of the ring.

- Point the camera at the gray card and fill the frame entirely.

- Set the camera to shutter priority and set the shutter to the camera's fastest speed.

- The camera will suggest a corresponding aperture (correct???). Write the shutter speed and aperture down.

- Switch the camcorder to manual mode and program in the shutter speed and aperature.

- White balance.

- Double check the exposure by repeating the steps above.

Is this correct? Any dangers? Any problems with using a super fast shutter speed? I realize that with a wide aperture I'll limit my depth of field, but that's actually desirable.

Thanks in advance,
Norm
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Old July 9th, 2010, 02:40 PM   #2
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Nope. There's lots wrong with that. Lots.

Are you shooting stills or video? What camera are you using?
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Old July 9th, 2010, 02:43 PM   #3
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I'm shooting video with a Canon XH-A1.
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Old July 9th, 2010, 03:33 PM   #4
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Hi, Norm...........

Quote:
Originally Posted by Norm Kaiser View Post
Any problems with using a super fast shutter speed?
The wheels fell off just about there, for a number of reasons.

1. Although you say "very bright stage lights", it is most likely not going to be all that bright as far as the camera is concerned, if you compare it to outdoors in bright sunlight. A high shutter speed may be totally impossible unless you crank the gain up to infinity and can live with the resultant signal noise (it's not a good look).

2. Those bright lights will, in all likelyhood, be some sort of gas discharge units. Such units "fire" once for every half mains cycle (60 Hz = 120 "fires" per second) and ramp up through each "fire" then ramp down again. As they do so they go through a colour shift.

Any shutter speed in excess of 1/60 second will not catch two complete fire cycles and will result in colour banding across the frame which will scroll up or down through the frame depending on just how much difference there is in the cameras multiples of 1/60 th and the mains 1/60th (this looks even worse than 1 above).

Ergo, in practise, 1/60 th is as fast as you can go.

As for colour balance, the camera should balance just fine by using the ring floor covering (if it's light coloured). As for getting the exposure, set to manual, set 1/60th shutter, adjust aperture to suit. If the aperture wants to head past 5.6 towards f 8 kick in a ND if possible.

At 1/60 th shutter such fast moving action won't be all that crisp but there's not much you can do about it except sticking with wider shots that keep the subject speed down relative to the frame size.


CS
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Old July 9th, 2010, 03:38 PM   #5
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Awesome! That's what I really wanted to know.

So that I understand, let me restate:

Set the camera to shutter priority and dial in 1/60. The camera will suggest the aperture. But should I be pointing the camera at a gray card or just at the ring itself?

And the ring canvas is blue, not white, so I'm thinking I should white balance against a white card?
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Old July 9th, 2010, 03:39 PM   #6
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I just deleted my post as Chris has covered all the same points. I will add you're best off asking questions about this camera here:

Canon XH Series HDV Camcorders Forum at DVinfo.net

The good guys and gals there will be able to give you tips specific to that camera.

Good luck.
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Old July 9th, 2010, 04:20 PM   #7
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Maybe..........

If you can get whatever you want to WB to onto the stage. If the contestants are wearing white you can just as easilly use that.

Leaving the A1 to do it's own thing for WB is no big drama, it's pretty good.

I prefer to shoot full manual rather than let the camera do it's own thing, as quite often I shut the aperture down half a stop more than the system indicates to get better saturation. In the circumstances you describe I don't think that will be necessary, so SP should be fine, with the proviso that ideally you don't want the aperture heading any smaller than 5.6.


CS
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Old July 9th, 2010, 04:29 PM   #8
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Thank you very much, Chris. This is very good information. I appreciate you taking the time to help me.
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Old July 9th, 2010, 06:01 PM   #9
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Don't forget that if you do any zooming that the lens will change the aperture. Video cameras like yours don't have constant-aperture lenses so zooming in will force the lens to close down. If you zoom wide without the aperture set manually, your exposure could change.
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Old July 10th, 2010, 12:54 AM   #10
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Ah, zooming................

What a minefield that is.

The first rule of video - do NOT zoom whilst shooting unless covering events where the closest subject distance and the furthest subject distance is so great that a zoom is the only way to keep comparative subject sizes "in frame".

The second rule: Never zoom whilst panning, it looks AWEFUL, unless you're following a subject and they are the point of the piece.

The rest is getting esoteric, but of note.

Imagine you're shooting your event in the ring and the average low light reflected illumination is say, 300 foot candles per square foot.

Now, at full zoom out, you're sensor coverage is approximately (say) 400 square feet. Total light into the sensor = 120,000 foot candles (actually considerably less due to distance, but let's not get TOO esoteric).

Now, you zoom in till the sensor coverage is only 50 square feet. Total sensor lumens are now 15,000 foot candles.

You've just dropped somewhere aroundabout 2 stops of lighting by going in close.

It gets worse!

Because there isn't a zoom lens made (that I know of) that doesn't drop stops as it closes in, your lens has also dropped anywhere from 1 to 2 stops as well.

Worst case - you've just dropped 4 stops of exposure!

This is the reason it's so easy to "toast" a subject when using a macro system, they just need so much light.

Bottom line, zooming in low light situations where you don't have light to burn is a serious no no.

Ergo, get in close, keep it wide and enjoy.


CS


PS: The above figures were plucked from nowhere (lost in the mists of time), the equation is, unfortunately, quite real.

The "rules" are mine (AFAIK) but hey, they work for me.

"Toast" = shooting an open mechanism carriage clock, on a turntable, from a range of 1 foot (or whatever a Canon XH A1 can focus to). Light used? Two 500 watt Halogen lamps, each (immediately) either side of the lens hood.

After 3 minutes it was, as Jim Carey would say, "Smokin!".

The lens hood (and clock) survived, but were never quite the same again.

The shot? Drop dead georgeous.
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Old July 10th, 2010, 05:54 PM   #11
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"Because there isn't a zoom lens made (that I know of) that doesn't drop stops as it closes in"

That may be one advantage of shooting with DSLR. Many photographic zooms have constant aperture. Of course, there are other problems shooting video with a still camera, but it might end up being an interesting choice to use a APS-C sensor with a constant aperture zoom for sports. Those manual lenses can zoom so fast that it could be a way to get two shots almost at the same time. Instead of a whip pan, it would be a whip zoom.

Anyway, that has nothing to do with the XH-A1. With the XH-A1, I would zoom in enough to get a medium shot of the ring and remember a good exposure. Most importantly, I would get somewhere I could get a good shot, with proper exposure, of the fighters. Full-body shots then medium shots of the fighters are the only important shots. A couple of establishing shots of the full ring with people getting started is important, but then the fight itself is all that matters. Make sure you can get decent exposure from where you will be situated. I would guess that this will be difficult unless there is a camera platform above the ring fairly close to the action. This would block the view in a larger arena so it would never be done, but maybe a smaller venue will have a riser available. In addition to the difficult camera angle, an important issue with exposure will be getting details of what happens when the fighters are down on the mat. The lights will be coming from above, so much of the action between the fighters will be in shadow. I would expose for whatever is the action and even let some things facing the lights overexpose in order to get the action. For exposure in a situation like this, the people are all that matters, and their faces and actions are all that matter. If a guys white clothing blows out in order to see the face of a guy pressed into the mat, so be it.
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