Help adjusting 17-40L

[GrantH]

I've been shooting with my 17-40 for a little bit now and it seems to be backfocusing a bit, or just plain soft. I know it's not the highest end of the L glass...but I expect it to be sharp none the less. Does anyone have a good how-to on adjusting for the lens, or how to verify exactly what it is doing?

 

[Dao]

AF Microadjustment Tips

 

[GrantH]

On a shorter zoom lens, like the 17-40, is it best to calibrate mid-range?

 

[CanonJim]

According to the linked article, lenses with a max aperture of 4.0 and above won't see as much 'benefit' from AF microadjustment - it's primarily those that can open to 2.0 or better, where the DOF is so narrow that mis-focus is apparent, that can be helped. But, again according to the article, you need to shoot multiple test exposures at multiple apertures and all the focal lengths. I have it on good authority that Santa is bringing me a 17-40 too, and I'm anxious to see how it does..