Hi Neil,
I am not a professional video guy. I just acquired some experience with video over the past 3 years. Recently I recorded a little bit of raw video now working to get a efficient workflow with it. Occasionally I worked (as a sound engineer) together with a group of indie film makers at some little concerts. So I got some additional information by just watching.
If you want to go for 1280x720 anyway and have to record a rather long show with just one camera without experience I would suggest the following "safety first attempt":
Do not consider RAW video.
Use the built in h264 video capabilities and 1920x1080 resolution. No sharpening or Sharpness 1. The footage will be soft, but as you are going to downsample it to 1280x720 you will gain some sharpness. In post production you can sharpen to taste, resulting in a sharpness that was satisfying my personal needs most of the time.
Use full stop ISOs or the pulled ones (160, 320). ISO 100-1600 do almost have the same quality on 5DIII
Restart the recording after each performance (!).
You can use the All-I function if your camera and card support it (test it before)
Use for example the "Flaat10" picture style or (if really needed!) Flaat11. If the scene is not high dynamic range you may be able to just use Neutral with contrast -3 or Flaat9 or Marvels Cinestyle.
Make sure the exposure is right and your white balance is optimal. In such a controlled environment you even could set the white balance beforehand with a grey-card on stage.
Speak to the lighting engineer (if any) to keep the front illumination at a reasonable level (i.e. bright enough that you can get a proper exposure at no higher ISO than 1600).
The advantages (compared to RAW video) are:
- You can record single performances of up to 12minutes without having to stop and restart the recording.
- You do not have to buy 2x 1000x 64GB memory cards (each lasting for only ~12mins of footage) and swap them for dumping files to the computer after each performance.
- You end up with files that are compatible to every computer. So even without post-production the farmers can view your videos. This reduces pressure and you can take some time to edit the video.
- your workflow is A LOT faster!
The disadvantages are:
- The footage is a little soft (even compared to designated video cameras at about half the price point of the 5DIII)
- You can only capture 8-10 stops of dynamic range depending on your picture style settings
- You can not use Adobe Camera Raw to grade your footage (fill lights / shadow recovery)
Possible applications for ML in your case:
You could use the MagicLantern tools like ETTR and Histogram / Vectorscope to make sure the exposure and white balance is right.
If you have Firmware 1.1.3:
You can have a look at the Alpha 3 (
http://www.magiclantern.fm/forum/index.php?topic=2602.0) which will (to my knowledge) at least support you with a live video histogram. It can be loaded like a firmware update and not alter your camera. So it is safe to play around a bit. If anything strange happens just pull the battery and your camera is like before. (But of course there is no guarantee by any means). Please note that this Alpha has a strongly reduced feature set compared to full ML.
If you would consider installing the bootflag and full ML be aware that the boot flag is not yet removable and your Camera will be about 1-2sec slower in powering up!
Despite your question: 2:30 of video can get quite boring without additional camera angles / different framings.
If this is a "just for fun" work and you want to get into video it should be ok. If they rely on it maybe get some help of an advanced video guy. I suppose for a nice media coverage it would take at least 3 camera angles (one of them being a mobile camera).
I hope I could give some starting point for reseach ;-)