Question about 5D Mk3 AF for prom pictures

I have always used single point or 4-8pt expansion.
When I am taking my sons prom pictures and it is just him and his date I planned on using the single point (not spot single) and slightly off center so I dont have to recompose and I will focus on his face. My question is when taking his group of friends...there will be 10 kids total all lined up. Do I use all the points available and let the camera focus or just use the same single point and focus on a kid in the center of his face?? I planned on shooting group at f/5.6 or even f/8 to make sure they are all in focus. I will be using the 70-200 2.8mk2 and flash on bracket with the 5Dmk3

I'd probably go with the single point and the narrow aperture. However, what you could do is experiment in advance. If you can get three people together under the conditions you expect to have (wife, son, and son's girlfriend, or son and a couple buddies), experiment with them. Put one in the middle and two as far out as you expect them to be at the ends when you have all 10 together. Take some shots and see how the focus is.

At f/8, my greater concern would be lighting them evenly, so you might play with that a bit too. If the light is uneven or insufficient, up the ISO. I'd have no problem going to 3200 or 6400 to get even lighting. I shoot sports and marching band, and am at ISO 12800 and higher all the time. A bit of touch-up in Lightroom gets rid of the noise.

Good luck! Hope this helps.

I'd use a single point, selecting the one that falls on the person positioned in the middle of the group, depthwise.

I shot a prom with that very same body. I like single point but expanded is fine. I find a this quick formula for group size. 5 people = f5.6. 8 people = f8. I don't go higher than f8. It may sacrifice some nice blured background but then I am sure about dof for the subjects.

agedbriar wrote in post #17558814
I'd use a single point, selecting the one that falls on the person positioned in the middle of the group, depthwise.

This is what I would do.

Left Handed Brisket wrote in post #17559624
This is what I would do.

Right. I do that with my formula.

Yeah, I like that idea, great way to think about it.

Got it from a pro at one of our local camera clubs. May not be fancy dof but you don't have to think so much when in a hurry.

digital paradise wrote in post #17559620
I shot a prom with that very same body. I like single point but expanded is fine. I find a this quick formula for group size. 5 people = f5.6. 8 people = f8. I don't go higher than f8. It may sacrifice some nice blured background but then I am sure about dof for the subjects.

That was exactly what I did...the pics came out great!!!

agedbriar wrote in post #17558814
I'd use a single point, selecting the one that falls on the person positioned in the middle of the group, depthwise.

I would also. Keep in mind that the more points you use, the more you are giving the camera the job of deciding where to focus. It will pick the place with the most contrast, not necessarily the place with the depth you want.

Back button focus would also help. you can focus at the depth you want and then not worry about the camera refocusing when you take multiple shots.

gqllc007 wrote in post #17560402
That was exactly what I did...the pics came out great!!!

Nice work.

Here is a f/8 Very hard to get everyone to look at me when all the parents are taking pictures! I didnt get to crop the bottom picture yet