Lensalign help

I have a LensAlign MK2 that I just got to try and tune my AF on my 5D2.

Just now trying it out with my 24-105 I got this:

-7 at 105mm

0 at 24mm

So, I don't know what to think. Bad lens? Try to split the difference? Try more focal lengths and average it? I'm doing it wrong?

Trying to go by their calculator for distance. 2 feet at 24mm, 8.5 feet at 105mm. I can see the red target in the center. I don't know.

-K

If you are sure your results are accurate... I would send it to Canon for calibration. I just wouldn't try splitting the difference between 0 & -7. Now if you had said -5 & -7 it might have been worth a try.

Sorry,

John

Gah. Well, This is my first time trying to do anything with this. I've been suspecting I needed to do some micro adjustment. I tried repeatedly doing different settings, snapping pictures and using live view. Each time manually refocusing to infinity or so and letting it AF back to the target.

If I had no intention of sending it in for calibration, I'd go with the longer focal length adjustment and let the apparent increase in depth of field at the shorter focal lengths cover the focusing errors.

Lens Align confirms that you will get a differnt result on zoom lenses at each end...and therefore you'd need to select a "usual" focal length to test with. on a 24 - 105, i'd suspect its more necessary to "test" at 105 than 24 (obvious reasons). So you may have no problem at all.
the toughest part of using lens align is getting the little red "dot" perfectly concentric where it should be. I'd be curious to see a 100% crop from the 105 end...

MA is useless on zooms, most of the times AF at different focal lengths is all over place. Had the same issue with 24-70, repeat the test, collect test images with detailed description of the problem and send to Canon, they can fix it. Be as specific as possible, request to test and calibrate AF at *ALL* zoom positions.

I wouldn't say that MA is necessarly useless on zooms. In an instance where a lens needs -7 on one end and 0 on the other end it doesn't really help much.... but I have a 24-70mm that is good with a MA of 0 at both ends and very very good with a MA of +4. It helped me fine tune the lens to the camera.

I would adjust it for the long end. That is when your depth of field will be shallowest and would show any focus miss.