Canon 24-70 2.8L Mk1 Focus Problem Only At Certain Focal Lengths

I purchased a Canon EF 24-70mm 2.8L Mark 1 lens from B&H around 2010 / 2011. This lens is certainly a problem lens when compared to my other Canon L lenses. Sometimes it works great, and other times the focusing just does not match up to my other Canon L lenses. I have found that it sometimes works better on my 5dmk2 than my 1dmk4, while still shooting at F2.8 on both bodies. On the whole it is just plainly unreliable.

I have done several tests (on both bodies mentioned) and tried micro-adjustments, but that only solves the problem to a certain extent. In my bodies (1dmk4 and 5dmk2) micro-adjustment can only be set for the full range of focal length of the particular lens. With the new 5dmk3 you can set different adjustments at different focal lengths. On my problem lens I can get it to focus properly (after making a micro-adjustment of only 1 increment) from 70mm down to about 40mm. In the range from 24mm to about 40mm, the micro-adjustment made for 40-70mm does not work at all.

I have no idea to what extent this lens needs technical attention.

Does anyone know if the latest firmware for the 1dmk4 and 5dmk2 might have a greater range in micro-adjustment, like the 5dmk3 has?

Any suggestions are very welcome.

This is fairly common with the mk I. There is a collar which guides the lens elements during focus/zoom; after a certain amount of use the guide pins wear and the focus becomes inconsistent at the long end. I have to MA mine at 24 and at 60, because 70 is way off. Luckily I rarely use it at the long end.

As far as I know, Canon has never changed the MA range in firmware updates for those bodies; that was one reason I chose the 5D3 over the 5D2.

Read the following thread. I've seen very positive comments about TF Camera Repair in a number of threads.

https://photography-on-the.net/forum/showthre​ad.php?t=861971

Thank you for you response. At least now I know what is wrong. I plan on sending mine in for repair.

I have had this lens for a short while compared to some of my other lenses (Canon EF 80-200mmF2.8L since 1992) and I really have not used the 24-70 that much in the time that I have had it. I would have expected these malfunctions from a non-Canon product. I am the only person that has used the lens and I take very good care of my gear. It really seems as if this lens with its technology and hardware never got off to a good start.

Did you ever send in your 24-70 for repair, or do you continue using it in the restricted configuration.

Thank you for the details of the recommended repair center.
I shall get in touch with them.
Hopefully they will be able to repair it.

CanonGuyCapeTown wrote in post #17595188
Thank you for the details of the recommended repair center.
I shall get in touch with them.
Hopefully they will be able to repair it.

If you do, come back and relate to us your experience.

I called T F Camera Repair in NJ today.
Their answering machine says they are on vacation from June 11th through June 25th.
Just missed them by 2 days I guess.
I shall try them again after their vacation.

Mine was probably used a fair amount before I bought it. I am using it mostly under 70mm but plan to send it in for service as soon as I renew my CPS membership.