Shutter-speed - Aperture - ISO
The balance of the three is known as the 'exposure triangle - go google.
As one goes up, other has to come down, and you generally you want as low an ISO as possible to avoid 'noise', as fast a shutter-speed as possible to freeze motion and as small an aperture (high f-number) to maximise Depth of Field or front to back focus. Trouble is, you cant have all three, low ISO, high Shutter, and large aperture, at the same time, hence the art of photography starts with the art of comprise.
For Majorettes.. a high shutter speed would be helpful to freeze twirling battons.... B~U~T a picture that has the battons a bit blurry would tend to show they are moving so you might actually WANT a shutter speed slow enough to get a bit of blur,,,,, enter the art... how slow a shutter you may want will depend on how much blurr, and how far away you are from the majorettes, and how much zoom you are using.....
As a rough guide, I'd personally not be too fussed by the blur, I'd be more fussed to make sure the girls were properly in focus.. given the situation, and that majorettes tend to troop withe marching bands and they dont tend to march in typical UK grey-day winter weather... rule of thumb is f16-Sunny... and keep the Shutter over 1/Focal Length.. so, on a typical UK day... we are probably about two stops under f16-Sunny, so f8 grey-day; would suggest an 'Exposure Value' that would translate to something like 1/125th shutter, F8 aperture and ISO 100.
Up the shutter speed to 1/1000th, two stops, to freeze batons, you'd have to open up the aperture or ISO two stops, or one on each to 'balance' the exposure triangle and keep the EV the same. Now, at 1/1ooo th you could freeze the batons too much, and they look in the finished picture like they aren't moving at all. Open up the aperture to say f4, also two stops, and he same exposure, the DoF could get so shallow that whilst the batton tips were in focus, the hands trying to catch them aren't...
Depth of Field is not just dependent on aperture, its also dependent on the focus distance, and that on the length of lens or how much zoom you use.
Tip here would be to use LESS zoom, and don't try to so fill the frame with subject. The DoF will be greater whatever aperture you use, so you can use a wider aperture and higher ISO for the same light, and get more in focus... and have more tolerance on the majorettes marching 'in' to your focus zone past the point you focused on before pressing the shutter,,,,,,,, but its ALL down to that art of compromise, and circumstance dependent, we cant give yo a 'magic' one size fits all set of settings for everything and everything; that's why the camera HAS settings, and YOU have to pick the ones that are most suitable to what you want to do,, or leave it to an auto modes "best guess".
