Cleaning inside Canon 50mm /f1,8 II

Have a look here

http://www.canon.co.uk/support/consumer_products/product_ranges/cameras/eos/error_codes/#err01

Seems to be a connection problem Clean to connectors on both the lens and camera with a pencil eraser.

Turn camera off, remove lens
Replace lens, turn camera on.

To help prevent it from happening again, you can try cleaning contacts on both camera and lens.

Can you still switch AF/M?

The 50mm f1.8 lens is not a macro lens. If you attached a close up filter, it should just screw off. Try not to squeeze the ring too tight as that may make it harder to remove. Also "righty tighty - lefty loosey"

No. There is no easy way to remove them, to do so requires an expensive strip down and overhaul in a clean dust-free environment.

Unless you have the dust equivalent of boulders in there, then they are highly unlikely to show on your images and you can ignore them. Even if they do show occasionally you can usually easily correct the faults using commonly available processing software.

Make sure you're holding down the lens release button, which is located on the front of the camera, while turning the lens. Sometimes a little bit of force is needed, I've found new lens' can stick a little bit. If it still won't come off, contact Canon.

Get a quote first for the repair as this lens is the least expensive Canon lens and it could be that the combined cost of postage and repair will exceed to cost of a brand new replacement.

You can. But do you have a lens collimator and other equipment needed to ensure proper alignment when you put it back together again? Without such gear, the resulting pictures will probably be worse than they are now.

I don't think so. the lens is held by 3 or 4 internal plastic hook clipping type . send it to canon cost about 30 bucks. one clip breaks, you can say goodbye to your lens.

Maybe that's why it was for sale on Ebay.