Some of you know me well enough to have realised that my trustworthy CanonEOS 500N (SLR) was "sick" and had to go to "camera hospital", right? Well, as you can tell by my signature, it is back home with me. The problem it had - felt like "cardiac arrest" to me - is solved and it is back to taking photos. So far so good. But I am thoroughly unhappy with the outcome of most. And I realised something. For certain periods in time, something will happen. How can I describe what exactly that is? Some shutter-click sound can be heard while I am in the process of focussing and in the viewfinder everything becomes considerably much darker than it used to be. At first I did not really notice when and that it happened, only did I find out that the camera suddenly required a lot more light. I had shutter times of 1/15 and less on bright-sun-blue-sky days, without any filters on. At first I thought it was because I used the zoom lens pretty much, extended to the max. But the amount of light required THEN was ridiculous! While I was in Hamburg taking photos of industrial plants and typical port "sights" (containers, huge cranes, railroads, yes, the occasional ship, too), I felt this wasn't ok. Suddenly I heard a click, and everything went much lighter in the viewfinder. And the camera required the normal amount of light, the amount that I would have expected on a bright sunny day, even with the telephoto lens extended. Today I was taking "boredom photos" in the railway station of the town where my daughter takes ballet classes (I have to while away an hour of time then), happily snapping away, shhht-click. Viewfinder dark, camera slow. What is this? Will I have to wait for the next coincidence for it to click back to normal? I feel there is nothing much I can do. OK, I changed lenses from the 70-300mm to the kit lens (28-80mm) and everything looked fine. But then the kit lens is a 1:3,5, though the difference cannot be THAT big. Anyone familiar with the problem? Any ideas? Should I rattle and shake the telephoto lens? Or rather not? Help!