I'm torn... low light dilemma

I recently was taking pictures at a wedding reception. I was using my 24-105 4L and when they dimmed the lights after dinner, had a HELL of a time with AF focusing on ANYTHING. I've never had that problem before but I don't think the ambient has ever been quite that low in my experience. I was at the slowest shutter and highest ISO I was comfortable with, but had problems.

Here's my question. I also have a 70-200 2.8IS (LOVE IT) but at times it's too long for receptions. Not to mention it weighs a hundred pounds...

Anyway - should I be considering a 24-70 2.8L? Or should I just suck it up and use the zoom? Anyone wanna trade? :P

Why not try the 50 f/1.4?

Low light and needing AF? Tough situation. I doubt f/2.8 is low enough. How about a good prime? 50/1.4, 35/2, 85/1.8, etc.

Yeah, I've got the 50 1.4, too, and I like it a lot, but I really like the variety of shots I can get with some zoom at the reception without climbing all over people.

I guess, in retrospect, I don't NEED AF, I just really like it...

Maybe you just learned some things about AF and zooms. They can make a person a bit lazy sometimes.

Crap. That wasn't the answer I was looking for...

I was looking for someone to tell me that the 24-70 would solve all my problems so I could justify spending a grand on another lens...

You can use the focus assist beam (turn off flash) from an external flash like the 430ex or 580exII.

In those moments you can quickly put the 50f/1.4 on your 5D and purchase an 85 f/1.8 (light weight) or 85L and put it on your 40D for more reach with ambient low light photos.

Even in low light an f/2.8 zoom can struggle.

jlrichmond76 wrote in post #8443731
Crap. That wasn't the answer I was looking for...

Hmmmmmm,,,,sometimes you'll have to bite the bullet and learn the art of focusing manually.. There are situations when all lenses will fail to focus when lighting is less than ideal..

Maybe a 85mm f/1.2L in the near future? How about finding a used one?

Take Care,
Cheers, Patrick

jlrichmond76 wrote in post #8443731
Crap. That wasn't the answer I was looking for...

I was looking for someone to tell me that the 24-70 would solve all my problems so I could justify spending a grand on another lens...

You would be disappointed with the 24-70 in very low light. It is as good as a zoom can get, but it is still much slower than a prime.
I've taken tons of pictures with my 50mm 1.4 in low light situations where my 24-70 would have been useless.

You may have to use a flash once in a while too. I used to hate flash photography and then I realized that I just didn't know how to use a flash
I learned through this forum and other resources, and my low light shots improved significantly.

Put the camera in 'one shot' focus mode when it is that dark and the assist beam on your flash will make it function quite well.

I've limited experience in this field - five weddings, two engagement parties and two funerals.

But I quickly found that set-pieces (eg vows - no flash, or formal two-shots) are best served by an 85 1.2 on FF while 50 1.4 on second crop body covers the more spontaneous signing of the register and the aisle-walk.

For arrivals, speeches and general reception stuff, it's flash and mix'n'match 24-105 and 70-200 2.8. Everyone has their own way of working.

But, at base, you do need one fast lens. How long it needs to be is up to you.

jlrichmond76 wrote in post #8443699
Yeah, I've got the 50 1.4, too, and I like it a lot, but I really like the variety of shots I can get with some zoom at the reception without climbing all over people.

I guess, in retrospect, I don't NEED AF, I just really like it...

Well, you could say noone really needs AF - my old Minolta SLRs were MF only.... but I wouldn't want to go back to those days again! AF really makes it quicker to get bang-on perfect focus, and speed and convenience can make a big difference for those important moments. If your AF can't lock on in low-light, then maybe your eyes won't focus perfectly either?? You don't want get back to your laptop and find all the cake cutting shots were OOF...

Since you've got two bodies, you could put the 50/1.4 on the crop (for FL equiv 80mm) and the 24-105 with flash/AF assist on the 5D? that way you've got your zoom for some shots and your prime handy in case the zoom doesn't cut it.

What is the highest ISO and lowest shutter speed that you are comfortable with ?

I agree that a 2.8 is a weak solution. You need to go to faster primes otherwise you will be baxk here with the same post.

f4 in average lighting - use the AF assist of the flash - and while your at it - use some fill flash and drag the shutter... even shoot iso 1600... the flash will make it crisp and sharp while iso 1600 and dragging will make the shot more natural... its how you would be using the 24-70 anyways - and often at f4 for shots with 2 people in it... there you go - 1/3 the cost and a nice new flash