I have a problem with, i think, the contact between the lens and the camera. I hope someone might have a simple solution, rather than a lenghty repair or having to replace my lenses.
I have the problem with both my lenses, which makes me think that this might be something to do with the camera rather than the lenses:
1. The lens appears to be loose on the mount so that the lens is sometimes not recognised (display asks for manual input of focal lenght, or the top display shows "F - - "), with this the autofocus also goes out the window. Pushing the lens into the body, or sometimes twisting it slightly, helps to make the contact and the lens is then recognised by the camera. Camera: Pentax k-5
Lens: Sigma 28-70mm 1:2.8 EX DG
2. The lens has a similar problem as above, but also has a very soft focus when it works (much like a softfocus filter, or vaseline on the lens)Camera: Pentax k-5
Lens: Sigma 17-35 1;2.8-4 DG
More info: The problem appeared after a while, so probably not a manufacturing problem. Is intermittent, so it is a slight problem, nothing major (but something I can't have when taking pictures...). The problem of focus occurs in good and bad lighting conditions. And finally, as I have not found a similar problem being described elsewhere I do not think that it is a software problem.
Any advice, or ideas, as to how to fix this would be welcome.