The 1960s Olympus Pen F half-frame film SLR had a modest range of lenses. I've written about the 25mm f/2.8, the 40mm f/1.4, and the standard 38mm f/1.8 before. The system majored in normal primes and telephoto zooms, with a big gap at the wide end. With the 1.4x crop factor of half-frame the system's ultrawide, a 20mm f/3.5, was only really a 28mm, and furthermore there were no fast telephotos, no fisheye, and no tilt-shift.
Fortunately Olympus sold a range of adapters that could fit other lenses onto the Pen F lens mount. The adapters had some limitations - there was no aperture automation, so you had to use stop-down metering, and the intriguing M39 Leica screw mount adapter was macro only. Judging by eBay's listings the most popular was M42, but there were also T-Mount, Canon FD, Nikon F and Minolta models, even one for Olympus OM lenses. In this respect the Pen F was a distant ancestor of the modern Micro Four Thirds system; the two camera mounts are unusually flexible.
The Nikon F adapter is particularly interesting because the Nikon F mount is still used today, and until relatively recently the lenses had mechanical aperture rings. I point this out because modern G-type Nikon lenses don't have aperture rings, so although they will mount on a Pen F adapter, the aperture will be perpetually stopped down to f/22 or something equally silly (unless you use blu-tak to hold the aperture pin open).
The lens looks massive; in reality the Pen F is small.
Luckily I have some manual-everything Nikon lenses. For this post I used a Samyang 14mm f/2.8, which becomes a 20mm on a half-frame SLR. Optically it has a lot of barrel distortion and is difficult to focus on an original Pen F, because the camera doesn't have a split-image viewfinder and everything looks far away.
On a physical level it looks silly, and on a practical level the great bulk defeats one of the Pen F system's raisons d'être; it was supposed to be compact. On the other hand, if you want to go wider than 28mm with a Pen F (or faster than f/4 at the longer end) there aren't many other options, and the Samyang 14mm is not unusually large for a 14mm full-frame lens.
Also, off to the Tate Modern, which has grown since I was last there. The last exhibit, Abraham Cruzvillegas's Empty Lot, was a dismal load of cobblers. It has now been replaced by a choir and a twisty building which has grown from one of the Tate's corners. If the intention was to pay homage to 1960s public architecture, they succeeded. There is a viewing platform on the top, a restaurant just beneath that, and exhibition spaces all the way down.
There was a small exhibition of works by Louise Bourgeois. They say that you should never stick your dick in crazy, but arty chicks are often right goers, and I imagine that Bourgeois would have been into kinky sex. I would however sleep with one eye open in case she tried to tattoo my penis or put rubber bands around my testicles or cut open my stomach or something.
The top of the Tate affords a view into the living rooms of all the posh flats that surround the gallery. People want to own property next to the Tate Modern because it feels good. The living rooms looked unlived-in; they were empty and extraordinarily clean, with magazines and furniture dotted around as if they were show homes. I wondered how many of the posh flats were real homes, and how many had been bought as investments. The area around the Tate Modern is essentially empty of all the things that support human life.
The exhibits included some people handing out ribbons, plus some thin intense-looking Europeans making music with air pumps, and if you think about it aren't we the exhibits in some strange way? As we peer at the art, security cameras peer at us; in a control room somewhere there are banks of monitors overseen by operators who ponder our meaning. At least it's nice to imagine that someone is pondering our meaning. The alternative - that no-one is observing us - is too horrible to contemplate.