5D markII can't lock focus on low light places

In a lowly lit places like club house, I found out that even using a center focus point with fast lens(f2.8) failed to lock the focus.

I try to get a better contrast to lock the focus but the focus subject on overall has low contrast. The nearest higher contrast object i.e backlight, neon light is not really near that subject or at least on the same focusing plane.

As of my understanding, in order to lock a focus, the subject must have contrast. But to my surprise why even a 40D with 24-105 could lock the focus on the same environment where the 5D mark II failed to?

Theoritically the behavior of the AF should be at least the same as 40/50D and 7D since they share the same AF working range: -0.5 - 18 EV.

Thus, is there anything wrong with my copy?

Otherwise would installing a third party focusing screen on this situation would help?

Any ideas?

i.e is it practically to manually focus using Eg-S stage performance in the club?

lannes wrote in post #10681089
Are you using the center AF focus point or the edge points. The center is the most sensitive.

Yes. As I've said initially I thought it's due to low contrast subject but when the 40D could lock a focus on the same situation, that's the part where I can't understand.

The autofocus on the 5DII is not that great. The 40/50D have better AF. Do you have a Canon flash? If you mount one it will emit a focusing beam from the flash to help the camera focus in low light. If you don't want the flash to fire, you can set it in the custom configuration menu I think.

Jmoney, I had mounted the 580EXII to it. But doesn't really help much on lowly lit and low contrast subject.

Would manual focusing screen i.e Eg-S would help?

Can you use a higher f/stop and higher ISO, so that focusing on the neon area will get more things at different distances in focus?

danielyamseng wrote in post #10681312
Jmoney, I had mounted the 580EXII to it. But doesn't really help much on lowly lit and low contrast subject.

It should. That's one of the purposes of the red beam it emits. You can't use AI Servo though. With a Speedlite and the focus assist beam active, even the dino of a 10D becomes an unstoppable AF machine.

The focusing screen won't help the AF. Cleaning the mirror might, if there is haze or anything else on it. The focus system is below the mirror. The mirror has a spot where it's not completely opaque and that is where the light passes to the focusing system.

What are your typical settings when you are shooting, ISO, shutter and aperture. I'm trying to get an idea what you mean by lowlight.

I agree that the best solution is to mount a flash for the assist beam.

tvphotog wrote in post #10682210
Can you use a higher f/stop and higher ISO, so that focusing on the neon area will get more things at different distances in focus?

Focusing is always performed wide open and is not dependent on the main sensors so unfortunately none of your suggestions will help.

Main differences are usually ONE SHOT or AI SERVO, lens itself.

The focus screen won't help either for AF, but an S screen can help with manual focus on a fast lens.

I think the EG-S would make your life harder under low light conditions. Which F/2 lens are you using? I find mine to work very well in low light.

danielyamseng wrote in post #10681165
Yes. As I've said initially I thought it's due to low contrast subject but when the 40D could lock a focus on the same situation, that's the part where I can't understand.

When I had my 40D, I never had a situation where it could focus in lower light than the 5D/5D2 when using the same lens. This is center-point AF only. The 5's peripheral AF points are not as good in low light.

Are you comparing with the same lens?

danielyamseng wrote in post #10680899
In a lowly lit places like club house, I found out that even using a center focus point with fast lens(f2) failed to lock the focus.

Did you try turning ALL focus points ON?

danielyamseng wrote in post #10681312
Jmoney, I had mounted the 580EXII to it. But doesn't really help much on lowly lit and low contrast subject.

Would manual focusing screen i.e Eg-S would help?

I shoot in a club setting also. I never have a problem locking focus unless I have an outer focus point selected. Even then, its not usually an issue.

Please post examples of your settings used. Or even a sample picture with EXIF info attached.

subscribed... as i'm getting mine next wednesday.. was hoping the 5D2 would help with my natural and low light photography over my 30D... hope i made the right choice. will have to test it out when i get it..

EOS mE wrote in post #10684548
subscribed... as i'm getting mine next wednesday.. was hoping the 5D2 would help with my natural and low light photography over my 30D... hope i made the right choice. will have to test it out when i get it..

5D + 30D will be pretty similar focusing in low light. 5D might win out a bit, but I wouldn't expect much of an increase.

timnosenzo wrote in post #10684648
5D + 30D will be pretty similar focusing in low light. 5D might win out a bit, but I wouldn't expect much of an increase.

but the high iso capability will.