What criteria to consider to match cameras and lenses for shooting people at parties?

Question

I normally don't like shooting people that much, because I like to experiment with settings, lenses etc. to get a result that I like, so it helps when the subject doesn't move (Mountains and buildings are especially good at that).

Now I have been asked to shoot my moms wedding (not with brides dress or anything fancy), and I can use what equipment they have there.

I have available a Canon 5DMKIII and a 6D and in order to not have to quickly switch lenses on one body (after which I am sure the subject of the photo I am going to take is gone), I was planning to take both with different lenses.

The available lenses are (well, there are some more, but I don't think a macro or tilt shift will be of much use there):

EF 24-70mm f/2.8L II USM
EF 70-200mm f/2.8L IS II USM
EF 50mm f/1.2L USM

I will want to cover several situations and locations, first the ceremony is in a not so well lit room where no flash is allowed. I am planning to use the 50 prime for the ceremony part, some portrait and close ups of maybe fingers with ring or signing the papers or whatever will happen (I am trying the "invisible photographer" approach, people should just ignore me, no "can you hold this a moment" stuff), mainly due to the bad lighting conditions.

Then for getting outside a bit I thought about the 24-70 being a bit more versatile (I am hoping for at least a bit light, although forecast says rain) and then for shooting small kids I like the 70-200 most, because usually when you approach them, it destroys the moment you want to capture (at least thats the way it works with my kids).

So I am leaning towards using the 5d+50 for indoors, and then the two bodies with the two zooms for outdoors and the bigger, more lit rooms.

tl;dr

But what are good criteria to match which of the bodies to use with which lens? 5d+24-70/6d+70-200 or 5d+70-200/6d+24-70? Or am I overthinking this and there will be no real difference?

Answer 1

As for which lens to use on which body, I do think you are over-thinking it. Both cameras are full frame cameras, and all your lenses are L series lenses. So, with any matchup, you have L lenses on full-frame bodies.

As for which camera/lens combination to use where, I suggest you use the body that performs best in low light for indoor shots. All the lenses you have are pretty fast, so the difference btwn the two full frame bodies may be negligible.

Personally, I think trying to manage 3 different lenses on 2 separate cameras is too much for a fast moving wedding. If you are taking 3 lenses, then that means you are going to try and change lenses on one of the cameras at some point. I suggest you simplify things and put the one 50mm prime on one camera, and the 70-200mm on the other - and call it a day. Those two lenses will provide you with more than enough coverage for the various situations that may pop up.

And don't forget to turn on your "silent shutter" if you intend to be discrete as possible!

Answer 2

Which body should you put the general purpose lens on, and which body should you put the telephoto on? The answer is: It doesn't matter

The only difference between the two bodies is that the 5DMkIII has a great number more AF points, so I would lean towards putting the lens you plan to use the most on that body. But really, it doesn't matter. They are both capable cameras and much more similar than they are different, especially for wedding photography.

Answer 3

I just checked the ISO performance comparison of Mark III and 6D, and they're nearly identical. This would have been the biggest consideration wrt camera bodies in your situation. See here: http://www.dxomark.com/Cameras/Ratings/Sports

Some may be mildly helpful suggestions:

-don't go below f/1.8 or may be even 2.4 (if you set the aperture at increments) when you're taking pictures of people in this case, though you might be tempted to go with 1.2. You'll lose the sharpness.

-don't set the shutter speed slower than around 1/125, especially if there's movement. Again you can take advantage of setting to 1/2 or 1/3 stop increments.

-the low light performance is great on your camera, but if you're still worried, increase the ISO, but at the same time slightly overexpose to avoid noise.