Mark3 AF with 400mm F5.6 Lens Question

Any answer to this, please

Maybe I'm missing something, wouldn't be the first time (+:

Tell me, if I mount my 400mm F5.6 lens on my new to me Mark3,( it's at Canon now for fixes, only had it 3 days, mirror Lock-Up Error 99 so can really test )

Using manual center point selection, AI servo, Inner RoF, How many AF points are cross-point sensitive?? and what point has to initiate focus? And are the RoF points active with F5.6??

My understanding, center point has to nail initial focus lock and then the RoF can assist, but it seems, from the manual, that because the lens is not F2.8, the RoF is not available and the center point is not even X point unless at least an F4 lens is used???

It would seem that it would be horizontal sensitive only!!!

Kind of a bummer, if so, cause I can't afford a 300 F2.8 or 500 F4

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I don't have 1dmk3 (only 1dmk2) so can't directly anwser your question.

But I wouldn't sweat too much. Put your 400mm f5.6 and use center point and you will be amazed at the AF speed. If you shoot something against clear sky then enable sorrounding assist points. 400mm f5.6 is as fast as 300mm f2.8 IS and it could be hait faster than 500mm f4.

bobbyz wrote in post #9694262
I don't have 1dmk3 (only 1dmk2) so can't directly anwser your question.

But I wouldn't sweat too much. Put your 400mm f5.6 and use center point and you will be amazed at the AF speed. If you shoot something against clear sky then enable sorrounding assist points. 400mm f5.6 is as fast as 300mm f2.8 IS and it could be hait faster than 500mm f4.

Thanks Bobby, that's what's confusing, I have seen soo many fine captures with both the Mark11 and n, Mark111, using the 400 F5.6, I could not understand how it could be so, after reading the manual!!

Also trying to draw a conclusion compared against how the 7D's AF is configured. Can't do much till I get it back ( Mark111) from Canon and the 7D is sold Thanks again, still find it a confusing AF configuration

Put it on the center point and expand the points and have fun clicking away

A 5.6 lens will not provide any cross-type sensors.

When using ROF and Servo AF you must first begin tracking with the center point, the camera will then hand-off to other points from there if necessary. If you use any AF point with point expansion and Servo AF you must begin tracking with your chosen point. I hope that all made sense!

equetefue wrote in post #9694437
Put it on the center point and expand the points and have fun clicking away

Thanks ,will do

FL PHOTO wrote in post #9694608
A 5.6 lens will not provide any cross-type sensors.

When using ROF and Servo AF you must first begin tracking with the center point, the camera will then hand-off to other points from there if necessary. If you use any AF point with point expansion and Servo AF you must begin tracking with your chosen point. I hope that all made sense!

Thanks so much, so I am reading this right Seems, from results I've seen over the years that I shouldn't be concerned as the AF nails it, even if the AF points are just horizontal sensitive !! Click on and be well