08-11-2015 03:42 PM
I have a Canon 16-35mm f/2.8 lens, it was working verygood and I got amazing photos with it.
but recntly I noticed that there is no focus in my images and I tried using the manual mood but I faced the same problem.
I think one of the guys hit it on the ground or a wall I'm not sure.
what do guys think? shall I try open it myself and see what's going on? or take it to a lens repair and pay at least $125 to get it fixed!
08-11-2015 04:26 PM
I don't know what your skill in repairs is, but I am guessing if you are asking the forum it isn't at a 10 level.
$125 is a small fraction of the lens cost and it might save you from an expensive paperweight.
08-12-2015 01:01 PM
I do not recommend opening it yourself. That's an expensive lens and I wouldn't suggest you let anybody (including yourself) work on it unless they have expertise in servicing lenses.
When you rotate the focusing ring, does the focus distance change (visible in the window)?
The focus collar on that lens is (like most USM lenses) on a clutch which is delerately designed to allow it to slip (this is so so you don't damage the lens if you are trying to manually focus the lens while the motor is *also* trying to focus the lens.) But if something has jammed the focusing mechanism, you might notice that you can rotate the focusing ring but the focus distance visible through the window doesn't really change (it would not matter if the lens is in AF vs. MF mode.)
If the lens focus mechanism is jammed, then it needs service.
It's also possible that it will move, but wont focus correctly. This can happen if someting has happened to one of the elements within the lens. I've seen images from lenses where one side of the image is focused but the other side is not.
Imagine if you were to tape a sheet of newsprint to a wall and take a photo of it (so that the newspaper fills the frame) with the camera imaging sensor being perfectly parallel to the newspaper (be careful not to let the camera angle tilt up, down, left, or right). If it focus isn't reasonably even across the flat surface (it's normal to be fractionally less focused in the corners than in the center since the focus plane usually isn't "perfectly" flat) then it could mean that a lens element is askew.
Either way... if the focus mechanism is jammed or fails to produce a reasonably flat focus field then the lens would require service beyond what an end user can do. It's time to send the lens to a professional.
08-12-2015 08:36 PM
I don't know if it's the case with the 16-35 in particular, but several Canon lenses are "fly-by-wire", which means that there is no direct, manual focus... It's done electro-mechanically instead. With that type of lens, there must be power to the lens via the electronic contacts in the front of camera, for it to be able to focus. Check that the contacts on the rear of the lens are clean and, if needed, wipe with a clean, lint free rag lightly dampened with a few drops of isopropyl alcohol ("rubbing" alcohol).
Also operate the AF on/off switch a dozen times or so. If you usually just leave it in the on position, sometimes a switch like that will get oxidization inside the breaks the electrical contact. Most of those switches are "self cleaning" though, will wipe away the oxidization themselves if operated occasionally.
Both the above are only remote possibilities, but are free and easy to try yourself.
More likely though, if it is a fly-by-wire type lens, is that a flex cable inside the lens has broken or come loose. If the above ideas don't help, I would highly recommend putting the lens in the hands of an experienced, trained, professional repair tech. I agree with other repsonses.... Don't try fixin' it yourself.... Or, if you do, thers's a good chance of it ending up an expensive paperweight!
08-12-2015 09:03 PM
I don't know if it's the case with the 16-35 in particular, but several Canon lenses are "fly-by-wire", which means that there is no direct, manual focus... It's done electro-mechanically instead.
All "STM" lenses are electronically focused (the computer senses the direction of motion on the focus ring but nothing directly links the gear to the focus elements other than electronics.)
But all "USM" lenses I've ever encountered will focus even with the lens off the camera (power is not required.)
08-27-2015 02:38 AM
08-27-2015 09:32 AM
"But all "USM" lenses I've ever encountered will focus even with the lens off the camera (power is not required.)"
The EF 85mm f1.2L USM will not focus off the camera. It won't even manual focus in AF mode. In fact the focus ring feels like it is broken when off the camera.