1D Mark IV Cross type or vertical type AF with 24-70 F4

I am trying to find out as to whether the 24-70 F4 is also one of the F4 max aperture lenses (along with the 17-40 and the 24-105 amongst others) that allow the body to utilise the cross type AF sensors even though they do not have a max aperture of F2.8?

The above two lenses are mentioned in the 1D Mark IV white paper as giving this capability, however the 24-70 F4 lenses came out a couple of years after and I have not been able to find anything anywhere that says it is or is not.

I am looking at a 24-?? walkabout lens to fill my current gap in focal length range, don't want the weight of the F2.8, and am leaning towards the 24-70 over the 24-105 for the better IQ ( mainly distortion at the wide end ) .

But, if it does not utilise the 39 cross point sensors I may well go for the 24-105 and deal with the distortion in post.

I don't see that it's significant if the 105 will use the 'better' AF. If your shooting conditions are that poor, and your demands that high, get the 2.8 v2...

Has nothing to do with the lens make. If it has max aperture that is listed then any lens that has that max ap will make it cross type sensitive if canon,sigma or tamron. It's about the amount of light that can get to the focus point to take advantage of the cross type.

05Xrunner wrote in post #17713888
Has nothing to do with the lens make. If it has max aperture that is listed then any lens that has that max ap will make it cross type sensitive if canon,sigma or tamron. It's about the amount of light that can get to the focus point to take advantage of the cross type.

Actually for Phase Detect AF it is not about the amount of light that reaches the sensor, it is about the angles that the light arrives at from either side of the aperture opening. That angle will be constant for the same f/number at any focal length. There are also minimum requirements for both level of illumination, and amount of contrast that is arriving at the PDAF sensor, but as long as that minimum level is reached the AF will work.

If it were just a matter of the level of illumination and contrast ratio to enable the PDAF system to work there would be no aperture limit. The CDAF system used during liveview relies only on the level of illumination and contrast level to achieve focus and has no aperture limits, so you could happily AF using CDAF in LV using an f/11 lens, such as any f5.6 with added 2× converter, as long as the subject illumination was bright enough.

Alan

skid00skid00 wrote in post #17713381
I don't see that it's significant if the 105 will use the 'better' AF. If your shooting conditions are that poor, and your demands that high, get the 2.8 v2...

Good point; but I was trying to avoid the weight of the 2.8, plus the IS on the 4 is appealing as most of my lower light photography foes not require action to be captured.

05Xrunner wrote in post #17713888
Has nothing to do with the lens make. If it has max aperture that is listed then any lens that has that max ap will make it cross type sensitive if canon,sigma or tamron. It's about the amount of light that can get to the focus point to take advantage of the cross type.

Actually in this case it does as Canon have somehow engineered the 1DIV to somehow be able to utilise the f2.8 sensitive cross points on some lens and lens/ converter combos that have a max aperture of f4. However the 24-70 f4 lenses came out after the white paper was published so it is not listed in there as one of the lenses that works this way.

I have not been able to find anything anywhere that states if the cross points are active or not with this lens.

Oh never didn't know they did that on the 1d4 to make specific lens use cross type even if was for 2.8. Thought was like most other bodies that if the lens met the fstop then it was activated no matter what lens or brand.

05Xrunner wrote in post #17713930
Oh never didn't know they did that on the 1d4 to make specific lens use cross type even if was for 2.8. Thought was like most other bodies that if the lens met the fstop then it was activated no matter what lens or brand.

The X is even crazier with it's list of 8 lens groups (A-H) and what will focus where! For example, the 100/2.8L IS is in a different group than the 100/2.8 USM... despite both of them being 2.8 and pretty much the same optics.

The IS is in Group C, where the center 3 columns is cross-type and the edge rows of the outer group is only sensitive to horizontal. The center two columns of the egde group are also cross-type, but less sensitive.

With the USM, the lens is in Group E, where the center 3 columns are cross-type, but all of the outer groups are only horizontal sensitive.

The 24-70/2.8 is another pair arrangement: the v1 lens is similar to the 100L IS, but the center of the center column is dual-cross. With the v2 lens, the whole center column of the center group is dual-cross.

one of these days I will own a 1DX but I dont think that will be till they are in the $1500 range

As more lenses are introduced, even more AF groups are established. For the 1DX, lenses are now arranged in groups A-I, or a total of nine different groups, all with different AF performance.

apersson850 wrote in post #17714681
As more lenses are introduced, even more AF groups are established. For the 1DX, lenses are now arranged in groups A-I, or a total of nine different groups, all with different AF performance.

When did they add group I? And what lenses are in it? The last I saw was Group H!

05Xrunner wrote in post #17714496
one of these days I will own a 1DX but I dont think that will be till they are in the $1500 range

It's a great camera. I have a 1D3 and 1Ds3 also...never thought there'd be as much difference (that I'd use or notice) until I started shooting with it. The low light performance is great, especially with something like the 35/1.4L and Otus 55/1.4! Once you use one, you'll never want to go back to the 1D3!

docholliday_sc001 wrote in post #17714903
When did they add group I? And what lenses are in it? The last I saw was Group H!

When the 200-400 zoom was introduced. It's the only lens in that group so far.

apersson850 wrote in post #17718098
When the 200-400 zoom was introduced. It's the only lens in that group so far.

Oh, yeah, I completely forgot about seeing that!