I've known about half-frame 35 mm for many decades, but only recently picked up and overhauled a Universal Mercury II, an odd and interesting camera that got me hooked on the generous number of exposures that half-frame makes possible. The contact sheets contain so many images in chronological order that they serve as a visual diary of each of the weeks that I typically take to get through a roll of film. I especially like the way that panorama series look on the filmstrip, plus I can use expensive film like Portra without fretting too much about the cost per shot. Manual exposure and zone focus take some time and concentration, but that's my current preference after years of being frustrated by automatic cameras.
The Mercury is fun to use and quite the conversation piece, but it's big and heavy, so I looked around for something smaller and settled on the viewfinder style Olympus Pen. I ended up with a Pen-S, with 6 speeds and f2.8 lens, but the standard f3.5 Pen would have been fine too. I like the super-quiet shutter, bright-line viewfinder, low-profile lens with simple controls, zone-focus click stops, compact body and hefty construction. There's no light meter, but I carry a hand-held for indoors and use Sunny 16 outdoors. I suppose a metered Pen-D would be nice, but I'm not interested in the automated Pen-EE variants.
I considered the Pen-F SLR, but they're pretty expensive, not very small and increasingly hard to service. I found a Canon Demi at an estate sale, but the light meter didn't work and without that the Demi seemed confusing to adjust manually because the mostly unmarked shutter speeds are mechanically linked to the lens openings in a rigid exposure program. The Demi had a very clear viewfinder, but overall didn't seem as solid as the Pen.
If I came across a Samurai or Konica Auto Reflex convertible full/half-frame SLR, those would be interesting, even though they're auto exposure. Too bad there are so few half-frame rangefinders.
