Sony 1018 or Voigtlander 15

Hrmm very hard decision, I have both and if I had to give one up it would be the 10-18.  But my reasons may not be similar to yours...I have had great results from the little CV15 on both my 5N and 7 bodies.  It's tiny, you can zone focus easily when there is enough light - and you end up with around a 22mm field of view which on our sensors works out great as a wider but not too wide lens for even some street and casual shooting.

That being said the 10-18 on the wide end is a 15mm equivalent and that is very wide indeed so you might just make your decision on what you will be shooting.  The stabilization is pretty great, you can even walk around carefully in video mode and you get what looks like a shoulder rig setup.  Picture quality wise I haven't put the 10-18 to its full paces yet but I already prefer the smaller CV from what I see so far.  The 10-18 does have more light so that's great, it is stabilized, and it can go from 15-28mm or so in 35 equiv.  Both are great lenses, but I will be using the CV15 for what I would consider "important" photos and using the 10-18 for video and when I need super wide.  Here are a few examples I've posted before from both the 5N and 7 using the CV15:



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