Anyone that can comment what lens for olympus mark em10 would be the best for the lights?
Yes, I can. However, user who excavated the tread from 2013 / 2018 is the golden shovel winner
Ad rem:
Any lens that is WIde Angle and fast. Note, it don't have to be UWA lens. Just WA and fast. It should have little coma fully open.
I personaly used P. 14/2.5 (not very optimal) in the past and O. 17/1.8 currently, as they were my usual lowlight travel primes (small and lightweight). P. 15/1.7 would have similar usability.
If You go for 100% dedicated aurora trip, You may think about something more sophisticated, at the cost of bulk (and usually price). My first choice here would be Sigma 16/1.4 - relatively low cost for such fast WA prime and excellent quality (I still think about buying it for Scandinavian trips...). There are also radical choices like these:
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Note, that Voigtlander 17.5/095 has serious coma up to F/2.0, so it has in fact little sense compared to relatively cheap Sigma, V. 10.5/0.95 is even worse so I didn't put it on the list at all. Generally, You may think about using F/0.95-1.2 glass in terms of very short shutter times to catch very fine aurora structures at the cost of little more ugly stars in the background, aspecially at the corners of the frame.
Some people use fisheye for auroras, but it's rather specific choice, for "almost whole sky" images. As generally going into UWA lens means sacrifying total aperture, the best choice here is O. 8/1.8 FE, though there are some options f/2.8-3.5 here. I don't know anything about their quality, excluding good, old Samyang 8/3.5 FE, which unfortunately is pretty slow.
Regards
-J.