We are shooting a Christmas concert tomorrow night using a Canon XH-A1s, res. 1080i. The camera will be about 100 feet from the stage, and the lighting is not the best. We tried shooting with the gain at 0, 1/48 sec. and iris at 1/8-3/4 (depending on the zoom). Is there a problem with going down to 1/24 sec., so we don't have to boost the gain? Any help is appreciated!
Well to start with, I wouldn't be too afraid to boost the gain a little. Im assuming you are fearing grain/noise from the boosted gain... but with that particular camera you should be able to gain up to +6 without really degrading the image.
But to your question... yes, you can drop your shutter to 1/24th to get a better exposure, but it will come with a price. That shutter speed is obviously quite slow... exposure for each frame is twice as long as "normal" if you are shooting 24fps, and almost three times as long as normal if you are shooting 60i. The end result is that you will be getting a lot more motion blur than normal.
Now, that might be alright. You said it was a concert, so I'm assuming it's just people standing and singing. If there is any dancing, choreography, movement, etc., then the motion blur is going to show up fairly noticably. You may also notice what appears to be a slower than normal frame rate, although the camera will actually be recording at the frame rate you set it to.
IF it's more or less a static concert without movement, you might get away with it ok. But keep in mind, that YOU can't move much either. ANY camera moves (pans, tilts, zooms) must be very slow and smooth or the motion blur will appear like crazy.
The easiest and best thing would be just to conduct a test. Shoot some footage at 1/24th under similar lighting conditions and see if it looks acceptible for your needs.
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