I tried it as well, but, like you, was very unhappy with it at wider apertures. The Voigtlander Ultron 75/1.9 + M mount adapter is a safer choice if you want a solid all-arounder. It's not the bargain the 7A is, but it's a nicely solid lens in a small package. When I go out with just two lenses these days, it's usually the 7A 35/1.4vIII and the Ultron.