No filters, and I just use a microfibre cloth for dust. And keep the lens cap on when not in use.
For annoying bits that get stuck at the edges, particularly on lens rear elements, I keep my used sensor swabs for that (and other things). They pick out those awkward specks very efficiently and totally cure the OCD
DavidBM wrote: Sinasina wroteI despise cleaning my Loxia lenses and it's so easy to leave a fingerprint on those protruding front elements. My solution is to use a relatively good UV filter & just take it off for night time photography. UV filter ghosting is a very predictable endeavor, during the day my B+W filter doesn't have a ghosting problem in almost any situation. At night if you have strong leds or floodlights in the central area of the frame all hell will break loose though, but this is mostly true for all filters, since they are parallel with the sensor & 0% reflection is an unobtainable goal.
This is the absolute worst daylight ghosting I could produce with my B+W mrc nano uv filter, the decagon shaped ghost is almost never visible. This is a pretty abnormal photo in the sense that before cropping the sun was very near the center of the frame. (the bottom blob is the Loxia lens's own ghost)
https://i.imgur.com/cNg6sbh.jpg
Loxia21 @F13 with B+W mrc nano UV filterI would be surprised is the decagon had anything to do with the filter. Are you sure it wouldn’t have been there without the filter? The lox 21 does sometime produce ten sided aperture images without a filter being on.
The decagon shape is from the aperture blades. But the aperture blades don't generate reflections, they only limit their extend.