Lens to Body Auto Focus Calibration

Spent the entire afternoon working on camera stuff. Focus calibrating all my lenses to be exact. And testing for lens performance issues. No lens is perfect of course, so its a matter of knowing how your lenses perform for a given body so you can squeeze every last bit of image quality out of it in every shooting situation.

And speaking of image quality, my Tamron 28-75mm 2.8 XR Di is actually quite a good lens. It performed horrendously on the 400D body and now it seems its down to AF calibration, which this not present on the 400D but present on the new Canon EOS 50D.

I found out that with the exception of the EF 50mm 1.4, all my other lenses need AF calibration. Most required between 5 to 10 steps of adjustment BACKWARDS. Does this mean it was front focusing? I'm not sure.

In my lens testing I found out to my pleasant surprise that the Canon EF 70-200mm 2.8 IS (my copy at least and my 2nd copy at that) at f2.8, 148mm as shown on the EXIF data is about as sharp as my Sigma 150mm 2.8 EX Macro HSM at f8.0. So thats very good consolation to me, especially since my 1st copy of the Canon was horrendous and clearly defective.

The Tarmon 17-50mm 2.8, which is another lens I own now performs up to expectations. AF calibrated with my brand new Canon EOS 50D, it now gives pretty good IQ, well worth the price I paid for this lens and IQ-wise, very much comparable to Canon L lenses costing several times more. Until Canon comes out with decent L lenses in this focal range which matches the image quality of the Nikkor 14-24mm 2.8 Nano coated lens, I will NOT be buying a wide angle L lens. Its just not worth it. The Nikkor in question by the way, absolutely trounces the Canon EF 16-35mm 2.8 Mark II. The Nikkor wide angle zoom even outforms Canon's EF 14mm 2.8 prime lens, which was a recent addition to Canon's lens lineup. Absolutely embarrasing for Canon in my opinion. Its time Canon lifted their game.

Anyways back to AF calibration...When AF calibrating your zoom lenses with your SLR body, make sure you calibrate the AF at the focal length that you will most likely use the lens at. Each Lens' focus performance vis-a-vis your camera body can vary at different focal lengths. And until camera manufacturers implement lens to body AF calibration at different focal lengths and different apertures for EACH lens you calibrate, you will just have to do this.

AF calibration at different apertures is important especially for highly expensive but what I would call "focus defective" L lenses that Canon currently churns out. One prime example (no pun intended) is the Canon EF 50mm 1.2 Mark II. Built without a floating lens element, focus actually shifts when you stop down to take the shot. Absolutely unacceptable for a lens costing so much. Canon really is shooting themselves in the foot by offering this supposedly top quality lens at a top quality price with a known and proven defect. A defect which strikes at the heart for which people buy this lens for - Image Quality. Real stupidity if you ask me. But that's another story for another day.

Well back to my AF calibration, all is now done and I'll be looking forward to some great landscapes and natural scenery to shoot this coming week. Look out for more postings when I get back.