well your large group is not going to be standing all on one plane....side by side, are they....NO...You will probably have them arranged in 3-4 rows...
Therefore, you will want to shoot with a small aperture for sure (small being a higher humber.....11 will likely be good.
use a tripod. depending on the lighting conditions, getting to f11 might require reducing your shutter speed more than you thought you would need to.
why would you even be thinking of 10 for an aperture?
apertures run 2.8, 4, 5.6, 8, 11, 16, 22
each of these numbers means either a doubling or a halving in size of aperture....
10 is just a third of a stop somewhere between 8 and 11
