Problems with Mark II auto focus

[Craig_Hartley]

I own two Mark II’s that both hit focus erratically when shooting at 8.5 fps; they’re fine at single shot. It doesn’t seem to matter what lens I use. It’s a real pain when shooting CEO’s doing the “Enron scuttle” when exiting the courthouse here in Houston.

I asked around and discovered that the problem appears widespread. (Check Sportshooters.com). This was never an issue with my old 1D cameras.

Are there others out there having auto focus problems, and will Canon ever have a firmware upgrade to fix the focus issue?

[Paul_Rogers]

I also find that high ISO for football matches using autofocus provides very erratic results that don't appear at lower ISO.

ISO above 800 + 8.5fps + autofocus = Very soft images!! And peculiar dof!

[Peter_Galbavy]

Could this "high ISO" issue be rather related to shutter speed ? i.e. the shutter is automatically faster when ISO is higher. Of course aperture changes too, but it appears that the Program mode tends to vary the shutter more than aperture.

[Ian_McLaren]

No No Guys

This post is very misleadsing.

Last week I took about 100 images of a Hyabusa travelling towards at about 240kmph using a mark 2 and a 500 4.5 at 8.5fps. Some of the images were taken about 20m away at F4.5. At that distance the DOF is about .5 of a meter. All the shots were perfectly in focus.

Auto focus is dependent on contrast and also a decent quality lense.

I suspect that the error is caused by poor light and possibly a less than decent lense.

I have noticed that the mark 2 can struggle to auto focus in poor light. I dont know if that can be improved but that may be a technology limit.

Regards

Ian

[Paul_Rogers]

Afraid Not. My problems occur with a 300mm F2.8 (IS off) and a 70-200mm F2.8 (IS off). So the poor lens suggestions hold no water. Obviously poor light otherwise I wouldn't be using ISO over 400!!! Incidently the firmware is also the latest.

[billmurphy]

Ian...i'm glad you're having such success.
some of us are not.

[Paul_Rogers]

Also if I use the same settings and lenses with the 1DsmkII, the focus is spot on!! It is so frustrating