This is more of a rant than any thing. Sure you can adjust your lens with the microadjustment. But is it not possible to make a $4500 camera and a $2300 just play together on there own without tuning it?

I bought the 70-200mm F2.8L II a week and half ago. I thought when I took it out to the Zoo it felt like it was Back Focusing a little.

So today I decided to test it out. I started with the lensalign at 200mm. With the 1D Mark IV it was back focusing quit a bit. I ended up at minus 7. Then tested my main 5D Mark II with it and it was almost dead on, maybe a very very slight back focus and it was left at zero.

Then things get interesting. I set it up at 70mm. Now at minus 7 everything is front focused. I take it all the way back to zero, and I end up with a very slight front focus at 70mm. I test the 5D Mark II and it has a very slight front focus at zero, so I call it good at zero and put it up.

So now I test the 1D Mark IV at 135mm, at zero it has a slight Front Focus. So at this point I am wondering what the heck is going on at 200mm.

So I reset up the 1D Mark IV at 200mm with the setting zero. Again everything back focuses at 200mm.

So to size it up, at setting zero at 70mm it front focuses a bit, at 135mm it front focuses a bit and at 200mm it back focuses quit a bit.

I was puzzled by this, but from what I can tell the 5D Mark II does the same thing only to a less amount. Maybe the 1.3 crop factor magnifies the results on the 1D Mark IV.

Thing is there is no setting that would be an acceptable average with the 1D Mark IV. You either realize it does this at 200mm and go with it, or correct the 200mm end and end up with the rest of the range front focusing. Of course at a fair distance with your aperture stoped down you will not notice it. Only real close tight wide open shots will it start to matter.

I would be curios if any one that has this lens with say a 7D has noticed this, if the crop factor does make it more pronounced it would be even worse on the 7D.