A 5diii or d800 has no problem handling this.
Best light modifier for group shots.
No group placement relative to light.
In dark churches this may push your iso to 3 200 plus.
For our family shot the sun had just set behind the mountain in front of us which left us with nice open shade and indirect light as we faced the setting sun.
But for a really big group i just use bare speed lights and spread them out lots of them as i have several 560 iii s and i d rather just set them up and position them to light everyone.
Regardless of the light source that you regularly use in your photography daylight continuous or flash light modifiers can surely help you improve your work.
The key to creating even light across a large group portrait is focusing the light direction to control the spill as much as possible.
45 degrees to window aperture.
Indoors with clean window light.
Sometimes it s also great to place the group in their context like a sports team on the field hikers in the mountains or in our case the red mountains of southern utah symbolized.
Set up your two off camera flashes modified with the wescott shoot through umbrellas on light stands raised to about 5 6 feet to avoid campfire lighting and to get the best light spread.