Actually with such low f stop you are going to have less in focus.
Yes, but lens aperture is only one of several factors that affect depth-of-field (DOF). Focus point distance is also important.
If the table was pretty wide, using a 50 mm lens means the camera wasn't very close to the table, so everyone at the table would be in the shot. As distance from the focal point to the camera increases, so does the depth of the DOF, even if the lens is wide open.
Using a 50 mm lens on a Nikon DX body, with the aperture set to f/1.8 the total DOF is 0.21 feet (about 2.5 inches) with the focal point just 5 feet in front of the camera (actually the image sensor). At 20 feet of focal point distance, with the same aperture, the total DOF increases to 3.5 feet, easily the width of a rectangular restaurant table.
If you use supplimental lighting, you don't need to use a wide aperture.
Using bounced light can be problematic for several reasons:
- the bounced light is coming almost straight down giving everyone dark eye sockets (Raccoon eyes) if the ceiling is flat. You can however use a 'bounce card' to somewhat mitigate the issue. If the ceiling isn't flat the light gets distributed unevenly. (see the Inverse Square Law referred to below.)
- bounced flash will take on a color cast if the ceiling isn't white, and what looks white may not actually be white because our eyes and brain work together to meet our expectations.
- bouncing the light effectively doubles the distance it has to travel and the Inverse Square Law applies. Inverse-square law - Wikipedia, the free encyclopedia
Softboxes don't work to good on groups, unless you have some good sized ones, and there are not many restaurants that will let you setup light stands and softboxes unless you have made prior arrangements. A single hot shoe type light is not often sufficient for a group of people.
