[jon]

I have 2 pentagon lenses from my old 35mm camera, I have bought a 42mm to canon adapter ring so that I can use these on my 650D.
Unfortunately it is very difficult to focus, I have seen chipped adapter rings on ebay, has anyone tried these? do they work?
Is there any possibility of them causing damage to my camera?

[vlad]

The chipped adapters allow you to have focus confirmation. You still turn the focusing ring on the lens, but you get a beep to confirm the maximum sharpness.