Having a hard time focusing at receptions, any tips?

I have been shooting as a second/assistant with a wedding photographer who uses nikon, but every once in a while I get a chance to shoot with my 50d and 24-70 2.8. Usually during the receptions and I have noticed that it is extremely hard to auto focus on anyone during the reception. I also use my 580ex II on camera. This is kind of concerning because I do have my own wedding as a primary coming up in a few months. Any tips?

Yes,
If you wear glasses make sure that the diopter is set exactly where it needs to be so you can focus.
Use f8 as your primary aperture, that should get you very close to sharp if the focus is a bit fuzzy.
If need be use manual focus to get close or even spot on, instead of AF. Train yourself to move fast with either, or both. I used to sit in the living room and just focus on several different targets until I knew the lens backwards forwards and inside out.
Remember to focus on the eyes, not the body of your subjects.

LBaldwin wrote in post #12625662
Yes,
If you wear glasses make sure that the diopter is set exactly where it needs to be so you can focus.
Use f8 as your primary aperture, that should get you very close to sharp if the focus is a bit fuzzy.
If need be use manual focus to get close or even spot on, instead of AF. Train yourself to move fast with either, or both. I used to sit in the living room and just focus on several different targets until I knew the lens backwards forwards and inside out.
Remember to focus on the eyes, not the body of your subjects.

Really...f/8 you say? If the reception venue is dark as most are then f/8 will give you an unusable shutter speed...

Im having trouble just locking the focus, it just keeps going in and out of focus but usually wont lock.

I would also try manual focus, just curious what shutter speeds are you aiming for? F8 seems too small, Id open it up more.

http://www.flickr.com …iscuss/72157594​481100009/

Take a look at this, maybe the lens needs an adustment

Bheims wrote in post #12625720
I would also try manual focus, just curious what shutter speeds are you aiming for? F8 seems too small, Id open it up more.

http://www.flickr.com …iscuss/72157594​481100009/

Take a look at this, maybe the lens needs an adustment

Mine is only about 2 weeks old though, but from reading that I guess it is possible that it could have a problem.

Chrisnuge13 wrote in post #12625698
Im having trouble just locking the focus, it just keeps going in and out of focus but usually wont lock.

Yeah, b/c the AF assist beam doesn't work in Servo mode, this is often times challenging. I would try to focus on something that has better contrast, which would be other than the person's face. Depends on how close/far you are.

I would also stick with the center AF point only as that is typically the strongest and most sensitive.

What kind of lighting levels are we talking about here? I know this is at receptions, but what readings were you getting?

Is your 580EX AF Assist on?

Mike wrote in post #12625776
Is your 580EX AF Assist on?

I have recieved complaints about yhe AF assist beam so I tend to keep it off.

nicksan wrote in post #12625767
Yeah, b/c the AF assist beam doesn't work in Servo mode, this is often times challenging. I would try to focus on something that has better contrast, which would be other than the person's face. Depends on how close/far you are.

I would also stick with the center AF point only as that is typically the strongest and most sensitive.

What kind of lighting levels are we talking about here? I know this is at receptions, but what readings were you getting?

The lighting is pretty dark, during the dancing I cant lock a focus, in daylight I can easily get a sharp focused image but during the dancing AF wont even lock. I always use my center point as well.

Chrisnuge13 wrote in post #12625802
I have recieved complaints about yhe AF assist beam so I tend to keep it off.

Received complaints from who? The couple? Some over-sensitive guest?

nicksan wrote in post #12625887
Received complaints from who? The couple? Some over-sensitive guest?

Both unfortunately

Chrisnuge13 wrote in post #12625807
The lighting is pretty dark, during the dancing I cant lock a focus, in daylight I can easily get a sharp focused image but during the dancing AF wont even lock. I always use my center point as well.

What's "pretty dark"? You ask 100 people that question and you get 100 different answers.

The camera will always have limitations. If it gets dark enough and there's lack of contrast, it'll have a very difficult time. This is not just limited to your 50D.

If you are shooting in single shot mode, then I would turn the AF assist beam back on. You need to get the shot right?

Chrisnuge13 wrote in post #12625893
Both unfortunately

Really? Odd. Never, ever had any complaints with my AF assist beam.