Is there any focus assist product available for 5D3 in lowlight situations?

EDIT: sorry just realised.. wrong section.. can mods please move this to the camera section instead of lenses

Ive come across this problem many times now.. always on the dance floor / extremely dark environments.

My 5D3 + 600ex-rt hunts for focus forever.. and most of the time it doesn't find it.. I do manage to shoot the event eventually.. but with a lot of missed shots from the dance floor due to focus not being fast enough to capture what I want to half the time.

Just wondering if there are any products available out there which can solve this problem?.. perhaps an LED focus assist type of a product which I can connect to my camera somehow and velcro it onto my 600ex-rt which sends out a strong beam towards the subject allowing me to focus even in pitch dark?

i dont really have a problem getting fast AF in really low light/no light situations with a 430 exII - never used the 600 exrt on my 5dmk3. a lot of people have had success with Yongnou flashes and the remote transceiver 622. You may use any one of them.

Do you have the focus assist turned on for the 600ex-rt?

Edit: Maybe it does not actually work welll for some reason.
http://www.canonrumors​.com/forum/index.php?t​opic=10275.0

I believe the 5D3 manual advises that you use single point AF (NOT "spot single"), and to stick with the middle focus point for best results with flash. Not sure if you're doing that or not, but thought I'd mention what the manual says...

Dave

Now that I think of it, my 5diii and 500exii has not been assisting focus even when turned on.

Dumb question, have you tried without the on camera flash? I can focus fine with 5dmk3 in very low light, like ISO25600, f2, 1/30. This with 135L. 35L was harder. Not using any flash.

I am thinking there is some camera/lens issue as this has been brought up by multiple folks.

25600 ISO is not useable for events.. I try to stay under 6400 ISO at max when doing events and 5d3 with 600ex-rt struggles to lock focus in darkness at 6400 ISO.

Also I need 1/125+ shutter speed to freeze action for dance floor shots, otherwise the pics end up being blurry and unusable. I usually shoot f/2.8 (70-200) for dance floor shots.

5W0L3 wrote in post #15397007
25600 ISO is not useable for events.. I try to stay under 6400 ISO at max when doing events and 5d3 with 600ex-rt struggles to lock focus in darkness at 6400 ISO.

Also I need 1/125+ shutter speed to freeze action for dance floor shots, otherwise the pics end up being blurry and unusable. I usually shoot f/2.8 (70-200) for dance floor shots.

I was just saying those settings to show my low light was really low. Compare 1/125 f2.8 to f2, 1/30 is 3 stops. ISO from 6400 to 25600 is 2 stops so I was shooting in 5 stops lower light (if I got my math right) than your case. No flash on my camera.

OK, did some testing with older 550ex and I see no issues. Dark room no light, only little street light coming from the window and camera had no problem locking focus. Lens was 35L. Tried with flash off and camera took just a little more time.

Maybe something with newer 600ex flash.

bobbyz wrote in post #15401877
OK, did some testing with older 550ex and I see no issues. Dark room no light, only little street light coming from the window and camera had no problem locking focus. Lens was 35L. Tried with flash off and camera took just a little more time.

Maybe something with newer 600ex flash.

Hmm my main issue is with 70-200 II lens... when I tried focusing with 35L it did focus quite easily.. but that could be because its a wide lens and focusing 35mm at f/2.8 is a totally different ball game to focusing 100mm+ at f/2.8 because of how much thinner the DOF is, but I could be wrong.

5W0L3 wrote in post #15401900
Hmm my main issue is with 70-200 II lens... when I tried focusing with 35L it did focus quite easily.. but that could be because its a wide lens and focusing 35mm at f/2.8 is a totally different ball game to focusing 100mm+ at f/2.8 because of how much thinner the DOF is, but I could be wrong.

It has more to do with the distance of the subject that you're trying to focus on. How far are your subjects that you're trying to focus on using the 70-200; compared to the 35L?

Keep in mind that the focus assist light puts out the same amount of light and is also subject to the inverse square law, which means the focus assist light reaching the subject you're trying to focus on gets exponentially weaker to the point that the 5d3 may not be able to pick up anymore due to its distance.

Maybe switch to a 6d with its -3EV center focusing point

emdzey01 wrote in post #15402196
It has more to do with the distance of the subject that you're trying to focus on. How far are your subjects that you're trying to focus on using the 70-200; compared to the 35L?

Keep in mind that the focus assist light puts out the same amount of light and is also subject to the inverse square law, which means the focus assist light reaching the subject you're trying to focus on gets exponentially weaker to the point that the 5d3 may not be able to pick up anymore due to its distance.

Maybe switch to a 6d with its -3EV center focusing point

haha yeah possibly.. that is probably one of the main reasons why I struggle to focus in low light.. I try to shoot from a fair way back.

Maybe I should stick to more 70mm shots and try to come in a bit closer instead of shooting further back at 100mm+.

Either that.. or find a new way of focus assisting.. maybe some sort of a bright light hmm.

What about usin a cheap wireless trigger like the Yongnuo YN-622 Wireless TTL Flash Trigger to assist the focus?
I got have these triggers as I missed the wireless trigger from my 60D and these also fire out quite a strong AF target to help the AF system, even without a flash attached. It works really well and I also use one for night shooting.

Maybe use a IR light intended for surveillance cameras? They can be mighty strong, intended to light up objects 20-50 meters away. Yes, they need a separate power source so a reasonably large battery pack, but you should be able to auto-focus like a boss

I will try with 135L and flash but that thing didn't needed no assist when I tried last time. I nailed focus easily in no light IMHO. Don't have my 70-200mm f2.8 IS II to try any more.