I always love this film combination – the Argus C3 with Tasma Mikrat 300 microfilm. I think much of it has to do with this specific C3. When I picked this one up in Iowa for $15, it came with filter threads on the 50mm f/3.5 Cintar lens. It took a Kodak Series IV retaining ring (which, I think was 16.5mm). You could then put a small Tiffen series 4 drop-in filter inside of it. The filters themselves are not threaded.
This is all weirdly complicated as it was well before any kind of standardization. Fortunately for me, the camera came with the filter.
The 85 filter is strong enough to darken the sky a bit, but because of the retaining ring, I do get a lot of vignetting. I’d probably be better off just holding an 85 filter (or whatever) over the lens while taking the photo. But it’s much easier to not do that.
Camera: Argus C3 (1953)
Film: Tasma Mikrat 300 (x-06/1974); 6iso
Process: HC-110B; 6.5min
Othello, Adams County, Washington