12.500 Nkr (or 1535 USD) is a lot of money for a 2nd hand camera. At the same time we have to take into consideration that Norway has probably the highest pricelevel for camera equipments globally. Due to that; congratulations. I cross my fingers and hope you will be satisfied.
Regarded the K5, perhaps the dark stripe has something to do with your location - and the season? Not many other members of this forum knows that Tromsø, your city, is quite far north; 69°39′N. Same as
the North Slope region of Alaska.
Sunrise 09:14 and sunset 13:41 today,. And then at noon the black night descends. By the Exif I can see that your picture was taken at 17:25, eight weeks ago. Perhaps you just snapped the the winter curtain coming down from above.....
The norwegian singer Åge Aleksandersen most well known song is about this; "Når mørket nå har senka seg"... (As the winter curtain has lowered...) Two weeks forward you'll have to say goodbye to the sun for the rest of this year.. Completely
Northern Darkness.
In such case, keep you K5 until the springtime and see what happen when the stage curtain are lifted and the sun climb above the horizon.....
In the meantime try out K1's high iso capabilities. Why not use the occasion and grab the opposite of the
Northern Darkness? According to Tromsø Geographical Observartory you had a lot of
Northern Lights (Aurora) last night at 9 PM. Indicated by the blue line on this useful
graph (I'm at Dønna these days and acc. to the similar
magnometer down here it's no sign of aurora).