The lens cap that comes supplied with the Voigtlander Color-Skopar 20mm SL II does not fit when you have the LH-20 lens hood and a filter on. So what to do about it?
What a dumb design oversight. If you get a Nikon LC-52 52mm lens cap, that will fit right in there, no problem. Nice. I like the design of the Nikon caps better than the Cosina Voigtlander or Carl Zeiss ones anyway. Easy to grab and avoid getting my paw prints all over the lens.
I hope this helps any owners of the tiny high-performance Voigtlander Color-Skopar 20mm SL II. Enjoy!