Alternatives to paying for lens focus calibration?

[bitwise]

So after letting my warranty expire on my 24L, and being frustrated with my own inability to take pictures in focus, I finally determined through focus testing that the calibration is beyond the limits of MFA. I would like to send my 50D and 24L to a Canon service center, as I've heard the results are excellent for this type of procedure. However, after spending so much money on the lens itself, it just seems like highway robbery for them to charge $250-$350 to correct this problem, even with it out of warranty. I'm just a hobbyist, and this lens has been babied through maybe 500 snaps, with absolutely no drops, no moisture, no dust.

Just wondering if there are any alternatives. Any DIY videos or tutorials on adjusting the lens myself? Or other shops to send the lens to? The focus is so unpredictable that I just don't use the lens anymore. I figure I don't have much to lose by taking an alternate route.

Dave

[neuroanatomist]

When Canon does lens calibrations, they physically calibrate it to a reference body of the type you have. I don't think this is something you can DIY, unfortunately.

[Black_Dog]

I've seen some videos on YouTube that show how you can do this yourself. It involves taking the dust ring off the front of your lens and manually adjusting the position of the front glass element (it is mounted on threads on the inside of the barrel and can be screwed in or out), which is basically what CPS would do if you send your body and lens into them. I have never tried it.

[neuroanatomist]

I've seen some videos on YouTube that show how you can do this yourself. It involves taking the dust ring off the front of your lens and manually adjusting the position of the front glass element (it is mounted on threads on the inside of the barrel and can be screwed in or out), which is basically what CPS would do if you send your body and lens into them. I have never tried it.

???

I don't think that's how CPS calibrates focus... The front element isn't generally the focusing element/group. Also, not all lenses are constructed that way - for some, the front element is glued in place, so 'unscrewing' it would be a bad idea.

[Black_Dog]

This video (http://www.youtube.com/watch?v=tOZRN2mxajk) shows how to make micro focus adjustments to an EF-S 17-55mm f/2.8 USM (in addition to how to seal dust out of the lens). This lens uses internal focusing, not a rotating front element. I would never put silicone on my lens like this, but it is a good look at the mechanicals of the front of a Canon lens and how the focus calibration works.

Here is another video (http://www.youtube.com/watch?v=vOjCiJN7T2E) that shows how to calibrate the focus of an EF 50mm f/1.8 by soldering the focus control board. This is a completely different methodology. Neither may work for bitwise's 24L.