The initial 21mm may have been made in screw thread with a M adapter fitted at factory. Not seen one they are rare.
The type 2 summilux 5cm was made in LTM about 500 off for Ja market.
If you want to take photos the old Leica lenses are junk unless you are shooting period style shots like citizen kane... When a Canon LTM is just as good.
I see now that Tapatalk turned "Summilux" into "Summitar". Sorry for not spotting that as I posted. The Summilux 50mm pre-asph is of course the one I meant. Here it is on my Leica II:
I respectfully disagre, though, with the quite categorical statement that "old Leica lenses are junk" (sorry). I have a 1950 Summitar (correct, this time) which is a great lens, not only for b&w but also for colour. I also have a 1934 9cm Elmar which is in good condition and takes nice, if low contrast, photographs. It is true, of course, that also old non-Leica/Leitz screw mount lenses are good. I used to own a rather old Nikkor 8,5cm/2 which, though very beat up cosmetically and with some marks on the rear element, performed well enough. As with all lenses, it is a matter of condition.
I've long been an advocate for Leica releasing their newer lens designs also in LTM but I don't think that will ever happen. For that reason it is great that there are the Cosina Voigtländer lenses in LTM. It's quite spectacular that one can use ancient screw mount bodies with modern lenses for very reasonable cost.
br
Philip