How to dismantle ef 35-105 3.5-4.5

Dario,

Dismantling the lens is easy - just undo all the screws on the base and/or front. The challenge is putting it back together! Seriously, dismantling a lens (other than removing the rear base which is sometimes possible) is not generally a reversible progress as there are several cogs and springs inside which are the devil's own job to put back and the electronics have to be removed (and are not designed for end user removal) to get at the lens elements/groups themselves.

People sometimes say you will never be able to realign the elements correctly, but actually this isn't the main issue since they are generally fixed in carriers that ensure correct positioning. Its the mechanical bits like the AF motor and associated mechanical connections and the electronic connections that are just going to be so much fun to deal with.

I recently took apart a 35-105 f4.5-5.6 USM that was broke ... and now its even more broke! I just wanted to see what it was like inside - will post some images later.

Images of an EF lens dismantled ........

Don't.

Whatever is on the element now is nothing compared to what's going to get in there if you open it up. Not to mention the problem of reassembling it...

I say do it, if you dont really want that lens anymore. To learn from your mistakes is one of the few great experiences in life, and who knows? maybe this dude is some electronics and micro enginerring wizard who just dont know how to take a lens apart.

Also I wonder, how much the canon service center charges for cleaning the inside of a lens.. hmmm.

If this is the same version of this lens that I have, and it looks to be, you have nothing at all to lose by taking it apart. It has less than sterling optical qualities. I had thought about trying to sell mine, but you have given me pause to reconsider. I have a perfect educational opportunity laying there right before my eyes. Now if I can just find the right size screwdriver.

Dario,

Some things are best left alone! Trust me on that, as I usually have an irresistible urge to disassemble broken things and try to fix them myself. However, your lens is NOT broken, just a little dirty inside. For a simple cleaning, you will be doing more harm than good since it is damn near impossible for an amateur to disassemble and reassemble a lens properly. If your lens is VERY dirty, and you like the lens, then a cleaning quote from a pro repairman is called for.

Thanx guys. I work with 1D and 17-40,70-200,85. There are some situations whan 35-105 would be nice, But mine has dirt circle on second lens from back side. That is first lens element that moves whan zooming so it's possible that air movements during zooming in long period can produce this dust problem.

DEREK, please two steps before,,, please :)

I've never disassembled this or any other lens, so I'm going on hearsay. From what I understand, many consumer-grade lenses have some of their inner bits glued together; i.e. they're not designed to be replaced individually. If the dirt you want to clean happens to be inside such an assembly, then you may end up taking the thing apart only to discover that you'd have to break open a glued assembly, hoping not to snap any cheap flimsy plastic parts in the process, and then glue it back together later.

Bottom line: if the lens is worth something to you, don't attempt to repair it yourself; get a professional to do it. If the lens is essentially without value (you can no longer use it due to the dirt, for instance, or you're planning on replacing it anyway), then go ahead and have some fun opening it up.