Jim, the reflections off the aircraft speak of artificial light of some sort, and the background is mostly dark, but the depth of field suggests that the aperture at which the picture was taken was not the largest. I don't think all that many screw mount Summicrons were made. Also, I recall reading that the first few (or many?) were Summitars with a star after the name. It's probably enough to keep in mind that, for about a decade, the Summitar was the fast normal for the Leica.
Thanks for the link, Blakley. Should serve as education.
[EDIT] Bob, at f/2 the Summitar does give distinctly ring-shaped out-of-focus highlights -- but then some of the other lenses you tested do that too, not including the Noctilux.
Michael, if your Zorki holds film flat, has the correct flange to film distance, no light leaks, and shutter speeds within the latitude of the film or films you use, there's no hurry to look at the other pasture. A good option is to make do with what you have, learning along the way. Many have done that with success, while damned few have dug up philanthropists who give people what they already have.