<p>Hi Philipp,<br>
sounds as if the shutter in the lens is stuck. This happens often if it isn´t used for a long time, as the lubricants thicken over time.<br>
It is quite easy to disassemble the lens and clean the shutter/aperture-mechanism, I´ve done it several times.<br>
Alles Weitere lieber auf deutsch...<br>
Gruß<br>
Christian</p>