I just got back from a week in Iceland. Among the three lenses I have the one that got the most use was the Sigma 10-20, most of the time at the widest focal length as the landscapes are so wide that you want to have them all in the frame.
Weather sealing is an issue: I got lucky with mostly sunny days but when weather was bad, rain was so spiky that each time I got out of the car to shoot pics I had to bring a towell with me to wipe the lens (I shot with a K30 so no problems there).
As a matter of fact the Sigma 10-20 started to squeak a little when focusing after a few times it got some water...now that I'm back home with 25°C looks like the small humidity that probably got into the HSM motor has dried and all is fine.
But it definitely brought the weather sealing issue to my attention.
Other lenses I used were the Sigma 17-50 (20% of the time for walkaround and for shots where I wanted a shorted panorama with a front subject or portrait) and the Sigma 70-200 (30% of the time, for some portraits, still life, animals and whalewatching boat trip).
Think about a polarizer which will be very usefull with all of the water you are going ton see, from waterfalls, to lakes, to rivers. I also used an ND 10 stop filter sometimes. Tripod is a must.
You are on to a fantastic experience, I fell in love with it, got to see some breathtaking ladscapes and nature phenomenons like the aurora borealis, it really feels likke being on another planet at times, the landscape changes so quickly and dramatically that it's a continuous rollercoaster ride...and people are so few (except in the most tourist friendly, overcrowded spots) that you really feel the sound of silence and you get into your thoughts about solutide and peace.
Good luck and have fun.
Hope this helps
Last edited by gerax; 09-08-2016 at 02:12 AM.