1DX and 100-400 Focus Points

On the 1DX the 100-400 lens only displays 21 useable points and then if you install a 1.4x converter it drops to 4 useable points.

The documents I have read indicate I should have 21 useable points with the 1.4x extender but that all 64 points are available?

Trying to flush all this out and help is appreciated.

Thanks

Have you tried mounting another 100-400mm onto your 1Dx? I would try that and see if you are still getting the point reduction.

I can use all 61 points on mine w/ the 100-400 installed. I don't have a 1.4x so I can't tell you how many off hand.

Are you sure you didn't limit your 1DX AF to just X-type only?

I don, t have access to another 100-400 and how would it be limited to X type?

Do you have in settings to only use cross-points? If you do, the available points may be non-cross therefore not showing up.

Where in the menu would this be, I am looking at this now....

On my 5d3 it is in the 4th tab of the AF menu under "Selectable AF point".

Jwcdds

Are you seeing all 61 points solidly lit or are points flashing, there may be a communication issue in thar I only see 21 points solidly lit

The other points are "flashing", but doesn't mean you can't use them. (w/o the TC that is)

The limitation to cross-type points will give you 21 only, with the EF 100-400 mm f/4L IS USM lens mounted. Otherwise you can select all 61, but the other 40 will be limited to linear only.

When I add the Extender 1.4X III, then I can only select the center point, although it's possible to expand it with the four nearest points.

I thought I was seeing things and yes 21 points with the 100-400 4.5-5.6 lens and no more than 4 with the 1.4x added

Canon's docs are then accurate.