After looking through all 16 pages of this thread, it convinced me to search out a Summitar, to augment my 2.8 and 3.5 Elmars. Found an uncoated 1938 example, with the glass in surprisingly pristine condition. No haze, and only a few very fine 'cleaning marks' seen with a bright light on the interior surfaces. Was amazed the front element was essentially scratch free.
Not sure what hood, though. This lens doesn't have the 'groove' in the knurled ring at the front, as do the later versions. The dealer didn't have the SOOPD, but tried a couple of SOOFM, marked for use with the Summitar and Summicron. However, he said they just seemed a 'bit loose'. I opted to pass on those... Curious if these clamp behind the knurled ring, or there is a different hood that would be suited to the 1938 version?