courtland43 Loc: Central Florida

My 2 cents: If it was me I wouldn't think of doing this without first taking some prep/practice shots using the actual location and equipment and ironing out any bugs before the big day. Discover any problems (you're dealing with a bunch of kids so there will be some) while you still have a chance to mitigate.

easy8

the 16-35 would be my choice. allow you to get close an still have everyone in shot. Also go buy a flash at best buy can get the insignia brand there for 65.00 bounce it off ceiling or back wall. should be able to shoot at at least 600 iso. If you are shooting on a stage ask them to turn on all lights

aellman Loc: Boston MA

You have focused on equipment, but that's only half the "battle". Taking photos of a group of 20 or 30 people
presents a number of challenges that go well beyond your stated experience. Although I'm sure there may be a lot of suggestions of
various complex forms of supplementary lighting, you don't really need a lot. The fluorescents would be sufficient but for one exception:
Because their light comes mostly from above, they create dark eye socket shadows. This can be addressed with the right amount of fill
light coming from slightly above the camera or possibly even just the on-camera flash to fill eye sockets. Just be sure you don't overfill, which will
make the flash the primary light source creating what I call the "deer in the headlights" effect. One more challenge is to make sure every kid's face is visible.
To the extent it works, I tell the kids first to make sure they can see the camera clearly. Then you eyeball the group to make sure everyone is shown. Lastly,
you don't want the kids to look like their dogs just died, the default. Do what you can to get some smiles. Crack a joke; do something silly;
Have a rubber snake jump out of a can; whatever it takes. Shoot a bunch of exposures of each group, because the possibility of getting closed eyes is significant.
I have done a lot of this stuff. If you have any questions I can help with, you are very welcome to send me a private message.
Good luck! >Alan

Burtzy Loc: Bronx N.Y. & Simi Valley, CA

Agreed. Also, kids are often camera shy and tend to hide behind the ones in front of them. Remind the children directly but nicely that if they can't see you, the camera can't see them.

dsmeltz Loc: Philadelphia

You might want a ladder for the group shot. The FF 6D and the f4 L lens will do what you need.

gvarner Loc: Central Oregon Coast

If you're saying individual portraits with your FF camera, the 50 would be a good choice or one of your better zooms set at 70 to 135mm or so. If you're looking at a large group photo, take a wider zoom to the room and see what works for the subject distance limits you have. If you can't do that, use a photography calculator like the one at tawbaware.com to get an idea of the field of view limits you will have at different focal lengths and group sizes. With no flash, you're stuck with white balance issues in post processing so shoot RAW.

jackm1943 Loc: Omaha, Nebraska

I think the hardest part will be just getting all the kids to look into the camera, show their faces, and not hide behind someone else. And, take plenty of photos because there will always be someone looking off in some direction, yawning, eyes closed, etc.

barryb Loc: Kansas

I would not use your wide angle any greater than 35, because of distortion on the edges, and the focus can get soft on the edge. Back up enough so the children aren't too close to the edge of the frame, and use larger f stop, greater than 8 at least, so the people at the edges aren't in soft focus.

dsmeltz Loc: Philadelphia

Make it a game. "Everybody close your eyes real tight and when I count to 3 everybody open your eyes and smile! 1 - 2 - 3 SMILE!"

Or something more clever than that.

sippyjug104 Loc: Missouri

CHG_CANON gave you very good advice and his work is quite accomplished and he surely knows the Canon line-up. My tip would be to be sure to have the group stand forward from whatever may be behind them for it is they that you want the viewers eye to be drawn to. By having some distance between the group and the background, it will soften the background making a more pleasing image.

Enjoy your venture!

Architect1776 Loc: In my mind

I have had great success with the 24-105 and a 7D doing portraits.
I don't know your budget but renting a couple of studio lights and stands would work wonders.
Otherwise if you can do it outside might be better than dealing with the existing lights. Open shade outside.

TriX Loc: Raleigh, NC

👍👍 Yep - that’s what I’d take.

bittermelon

Tripod is a must.

Ali Rizvi Loc: NYC

So much information and good advise guys. My main concern is lighting and the shadows that will come with the overhead light. I can borrow / rent a flash and maybe an umbrella but that would be my first time using them. Hope it all works out. I will shoot in RAW and can do post in Photoshop to adjust the white balance if needed. Thank you so much for all the great advise.

JFCoupe Loc: Kent, Washington

If you are doing a group shot, the most important thing is to make sure each student is clearly visible in the photo. So if there are two or more rows of students, make sure they are staggered so that each student is visible. Even if the class sizes are small, I would suggest having two rows of students rather than all of them in a straight line.
I learned with my grandchildren that if you ask them to pose nicely and that you will also take a shot of them doing whatever they want (a silly, funny shot) you will gain cooperation of the students. Also, as mentioned earlier, shot in RAW format for more PP options. Try shooting at F8 or higher so that you have plenty of depth of field and each student in good focus.
Have fun.

I would suggest you shot your 6D with the 24-105 lens and have the 16-35 available if you need the width.