SOURCE: lens canon 28-135 IS
This lens opens from the rear. The trim ring inside the mount must be removed and the electronic connector separated from the mount by removing the 2 small screws at the mount edge. You can then remove the mount itself. The electronics board is the next item to remove. Make careful notes on the connections as the can get reversed easily. Not sure how far you need to get into this piece, but this will get you inside.
SOURCE: side out of image
I'm assuming in what follows that you've tried other lenses and only get the problem with this one lens. If you haven't, then it's essential to do this first unless the lens is obviously the problem. If it happens with other lenses then you have a damaged image sensor mounting within the camera body which will need professional attention.
This is a common problem on this particular lens. Normally it's due to the front element of the lens being slightly skewed on the lens barrel and most commonly occurs after the lens has been dropped.
Turn your lens to manual focus and focus to the shortest distance. Set the lens upright on a table and carefully view all around, if the problem is the front element it will lean slightly to one side like a miniature leaning tower of Pisa. If it doesn't, then check again with greater precision using a ruler to measure the distance s between the lens barrel and the focussing ring and a number of opposite points around the circumference. If they're anything but identical then the lens is skewed. If they are identical then the skewed element is buried deep inside the lens and will need professional repair as it's most likely a fault with the moving element used for image stabilisation.
If the tests confirm that the front element is skewed then if you're really careful and lucky you can often jiggle the front element using a firm twisting action back into place. It does take a bit of judiciously applied brute force and if unsuccessful you can make the problem worse, but either way if you don't try then the lens needs professional repair and new internal parts.
I've had this problem on about one of these lenses every month or so for the last year. The brute force repair works in about half the lenses I try it on and normally lasts. On the others a strip down repair usually shows the same range of broken/worn parts as I find on those lenses which clearly are too far gone to attempt the brute force method.
The difference is cost: the brute force repair costs nothing. The proper repair is often economically unviable as it often costs 50% to 70% of the cost of a brand new lens with a warranty.
SOURCE: I have not banged or
Check this article which will lead you through how to identify and solve the problem.
http://www.richardsnotes.org/archives/2005/04/29/50mm-lens-contact-points/
132 views
Usually answered in minutes!
×