Canon 24-105L collimation

[CometGuy]

Some of you might be interested in this link for collimating the Canon 24-105L lens:

http://canonrepair.wordpress.com/2013/01/01/adjusting-the-coaxiality-of-the-3-lens-group-in-an-ef-24-105-is-usm-lens/

I just tried the collimating my own copy of the 24-105L using the technique described above (except using the star Canopus rather than a artificial light source) and the improvement was stunning! My lens is now a great performer wide open and at all focal lengths as a result. Attached is a comparision at the 105mm f4.0 - the weakest setting for this lens - showing before and after. Both shots are near best focus possible and are crops at 100% from a 50d.

Dissassembling this lens is not for the faint of heart and requires some patience - it's not for everyone!

Terry

[iceman]

Wow what an amazing difference.

I don't know about taking my lens apart though :(

[White Rabbit]

Yeah me neither, I'm just not that game even though mine has a soft spot at the bottom right of the image. I'm sure ill talk myself into it though lol.

Thanks for posting.

Thanks

[DavidU]

Very cool Terry, I would try that.
Any luck with the surveys?

[leon]

Wow what a difference, yep i would be game to have a go at that if it were to improve with such clarity

Leon

[Dennis]

Thanks for the heads up Terry and great job on your lens, the results speak for themselves!

Cheers

Dennis

[Phil Hart]

I'm very impressed Terry! Is that example from the corner or centre of the frame? Been awhile since I used that lens for any astro work but I'm pretty sure mine doesn't look like that.

Phil

[pluto]

I'm very impressed with the difference! And your bravery ;)

But my 24-105f4L@105mmf4 gives results like your after image, looks like you had a bad one from the start :(

[Octane]

Likewise, mine's one of the sharpest lenses in my bag, as I've said often. :)

I would be interested to know, if that is the edge performance after collimation, how does the centre fare?

H

[CometGuy]

I've come to the conclusion that I had an exceptionally bad copy of the 24-105L lens. I believe most 24-105 owners would not need to go through this process.

Here is a centre crop and reduce fullframe at 24mm f4.0 using a 50D. This was a single 30 second exposure with cloud and moonlight interference. There is some minor coma at the edges, but IMO quite acceptable for nightscape shots. Comments?

Btw...the previous comparision was also done at the centre of the frame and at 105mm f4.0, but was slightly out of focus in the post shot. In the before shot the image was very mushy and this was the best I could do at the centre of the frame!.



Terry

[E_ri_k]

Looks a bit like what I get with my 24-105L, but not as bad, and only in the corners...Interesting. Huge difference, I bet you're happy with that!
Erik