Questions about a 1d MK IV auto focus system.

[Apop]

Hey, I have been reading and trying out with the 1d mkiv.

I have some questions regarding the auto focus system,

I only have f4 lenses ( 300 f4/ 500 f4), while the auto focus is fast, i do wonder if there are people who have tested several other lenses , like the 70-200 f2.8 / 300 f2.8 / 400 f2.8 ?

Those lenses use 39 cross types opposed to 19 , and maintain those 39 when using a 1.4 converter ( resulting in 280mm f4/ 420mm f4 / 560mm f4 ), is there anyone who have compared the auto focus accuracy/speed between the lenses mentioned?, and is the tracking capability much better when using the 2.8 lenses?

Also, which 19 cross types are used on f4 lenses? ( are these the ones http://media.the-digital-picture.com/Images/Other/Canon-EOS-1D-Mark-IV-Digital-SLR-Camera/AF-Point-Options/19.gif) , or others?

I want to get the most out of the auto focus system and if there is a big difference between the focussing (tracking) capabilities of f4/f2.8 lenses I would need to sell the 500 f4 and get a 300 f2.8/400 f2.8 with a 1.4 converter.

In theory i would think if you use the expansion setting (45 points , bottom left image of the link below) with a 2.8 lens could give much better tracking capabilities opposed to a f4 lens, but it depends on which are the 19 cross type used on a f4 lens and

http://media.the-digital-picture.com/Images/Other/Canon-EOS-1D-Mark-IV-Digital-SLR-Camera/AF-Expansion-Points.jpg


Thanks in advance for replies/advice/information/suggestions.

sources used:

http://www.learn.usa.canon.com/resources/articles/2011/whats_new_eos1dmarkiv_auto_focus_article.shtml

http://www.the-digital-picture.com/Reviews/Canon-EOS-1D-Mark-IV-Digital-SLR-Camera-Review.aspx

[Jan van Holten]

When you put a 1.4 converter on your lens, you can be sure that the autofocus is a bit slower.
Buying a 400 mm F2.8 and combining it with a converter does not help you much I guess.
If you want to spend money, buy a new 500 mm or 600 mm. With a 600 mm you have more reach and it' s even fast with the new converters type 3. What about a 1Dx?? It has an amazing fast autofocus.
Possibilities enough.

Jan

[Apop]

Well, it is more about the autofocus accuracy

19 cross types on the 500 f4, or 39 on a 400/300 f2.8 (even with 1.4 converter)

I wonder how big of a difference it makes, if at all when using center point with expansion.
But I still don't know which are the 19 cross type sensors for f4 lenses

[Harry Muff]

Just out of interest, how does the Mk IV autofocus compare to the 1DX?


Just wondering.

[Apop]

It will probably be a lot better,

But I would love to know how much difference it makes between the 19/39 cross types in the 1dmkiv :

Auto mode
Center with 45 surrounded

I am not really able to buy a  f2.8 lens to test it out, and renting neither for the moment.

[Jan van Holten]

First, in real world what I experience is the autofocus from the 1Dx observable better / faster then the MARK4. Recently I did shoot on a subject with the MARK4 and the 1Dx and had about 25% more keepers with the 1Dx.
The subject was a very fast moving bird that stood not still for a half a second. The autofocus of the 1Dx is really amazing, without a doubt. What I like about the MARK 4 is the larger area with autofocuspoints. It is more easy to select an autofocuspoint which match with the composition you create in a picture. Sorry for my English, but I hope you understand what I mean. Still, autofocus of the MARK4 is also very good.
I shoot very often with a converter mounted on my ''old'' 500mm F4.

With the MARK4 autofocus is a bit more slow, so therefore misses some more shots. But whe you have enough time, the MARK4 does also a very good job.

Jan