1DmkIV vs 7DMkII - Low light AF

I know this is starting to be done to death but I have a bit of a different spin on the question that I would like to get some opinions on....

I have a 1DMkIV and a 5DMkIII that I use to shot figure skating with. The light is usually pretty terrible so I am at ISO3200, F2.8, and 1/500sec. The quality of the images that I get is pretty good on both cameras (5D is slightly better though) but I am getting a lot of issue with OOF shots.

I am shooting with a 70-200 F2.8L Non IS lens which is really sharp normally so I don't think there is an calibration or adjustment issues. The AF issues are only happening on on AI Servo at the low light levels I get in the rink. I am also using a monopod and with the 1/500 shutter I shouldn't be getting too much motion blur. I can see some on extended hands during a spin but when the AF locks on the faces are sharp.

I am considering a couple of options to try and help improve my hit rate:

1. Sell the 1dMkIV for a 7DMkII - I know IQ will be a little worse but if my hit rate goes up then it would be worth it. The 7D mkII would also give me more reach which would be useful as 200mm on the 1.3 crop is just a little short sometimes.
   
2. Sell the 70-200 F2.8L for a 70-200 F2.8L IS II - I have read that this is supposed to give a better AI Servo performance on newer cameras
   
3. Buy a Sigma 120-300F2.8 OS S - Not sure that this will help with the AF (maybe it will) but it will give me some greater reach on both cameras which will be useful.
   

In a spin the face will not be rotating as fast as the hands. My guess is you need to be up at 1/800 to 1/1000 for spins - especially with older kids. For hockey as an example I'm at 1/1000 for any game involving kids over 10. I can shoot at much lower SS but I have settled on 1/1000 at 2000 to 3200 for most arenas - there are some brutal old rinks where 5000 is required.

I'm guessing you are at around 80ft to pick a distance - that gives you 2 meters of DoF at 200mm and 2.8 - in a spin if you hit an extended hand and your lens is front focusing significantly (on its own or potentially with florescent light shift) you might need to push the focus rewards - I have done this with my 70-200 II using w=+8 and T=+8.

Up your SS to 1/1000 and see how it goes as a first test.

Heya,

Rent a 7D2 or 6D, for the -3 EV autofocus piercing (center point only) and see if it helps. If it does, then you have a good idea of what to expect before you sell good equipment and get the same results.

Very best,

Thanks for the replies. The 1/500 shutter speed is ok for what I need as I get pretty good results when it is in focus. I am getting OOF shots on some MIF movements and things like spirals etc. which should be sharp at my shutter speed. Even spins a good except for the hands which are slightly blurry. I think this is probably preferable than going to ISO6400 and 1/1000. I have a show coming up so I might try IS6400 and 1/1000 during a dress rehearsal just to see anyway. You never know..

My issue is that the focus is not being consistent. If it was always front or rear focussed then I would know what the issue was and micro adjust. What I am getting is a sequence of say 5 shots with 2 or three in focus. This could be say during a spiral which should be pretty easy for the camera to track.

The lights are a mixture of fluorescent and mercury vapour so it is interesting that you mention that. I see a significant colour shift and intensity between frames. I wonder if this is possible a cause of the OOF? This is also something that I was wondering might be improved on the 7D mkII as this is supposed to sense light changes and hold back the shutter to give consistent lighting.

As for renting one, that would be great but options in Australia are particularly limited. It would be nice to have a lens rentals here...

The 1d4 wasn't great for low light AF, and in fact several needed sent in to canon for repair. The 1d3 was great for low light AF, as is the 6d. The 7d2 should be in the same league as those 2, and be better than the 1d4.

With the settings used, you aren't near the low limit for AF in any of Canon's EOS cameras. They all manage at least around EV 0, and you are at EV 7.

But Canon's improvements done to better handle low light when using Servo AF in the 1DX does indeed show that there is more to it than just the design of the AF module.

I understand you don't want to spend that much money, but if you get a chance to try one out, preferably with the EF 300 mm f/2.8L IS II USM, and that doesn't work either, then no other camera will help. You don't know one with that equipment closer to you than most of us are, so you could try?

Have you tried playing around with the AF settings in the 1D IV?

Doing some adjustments in CF settings might be able to help. What do you have it set on?

1/500 is tooooo slow for figure skating. Forget about it on a spin.