I know you've seen it a hundred times before but....
just got the poor man's pancake lens for my ist DS, so decided to look in. About 6 GB pounds on eBay, +2 for postage. A bargain. I really like the look and feel. Can't wait to see it performs well enough. If not great, least I have is a smart body cap that doubles up as an instant back-up manual focus lens. MF is most what I shoot with the ist DS anyway (Takumars, Tamron, Raynox, Carl Zeiss Jennar...Prinzflex, Derek Gardner i.e. a mix). I also have a Helios 44 (?).
Here's the industar pancake (industar 50-2 50mm 3.5) on my ist DS
Here's my 1st photo through it on the ist DS...be gentle...(evening, so with flash)
And thanks for all your soviet lens photos. They're great.