Ektar not Ektanon. 44mm F2.8 Ektar. SN# is RM693 which makes it 1953. I've seen a SN# _ _693 before on a production camera so it's not unusual. It's quite far in, though. There must have been quite a few cameras made with this Ektar branded lens.

I can't find a 44mm 2.8 Ektar camera.

I contacted Prarielist about 2 years ago ..John Wallen? I can't remember his name. He didn't know.
But protoypes were not numbered like that.

Anyone seen one? This is just the front element that I have. Found it loose in a box of small junk camera stuff and Ektar and 44mm seemed a good combination