In 1959 Olympus released the first of a series under the Pen labelling. By using the half-frame format, Olympus was able to reduce both the weight and size of the Olympus Pen. It featured a simple rear-winding mechanism, a D-Zuiko lens for superior photographic quality, and an attractive design that also made the camera extremely easy to use. The Pen was a compact mix of innovative ideas that triggered the half-frame camera boom of the 1960s and 1970s. Cumulative sales of Pen Series cameras exceeded 17 million units. The highly original concepts embodied in the Pen Series would eventually lead to the creation of the legendary Pen F Series half-frame single-lens system.

In a teaser presentation Olympus have released a series of small online videos with more still to come. So far there are small videos each for 1959, '61 and '62 with June 9 listed for the next installment. View the videos here: http://asia.olympus-imaging.com/products/dslr/special/pen50th/pen_d/

Olympus Pen        (1959)
The first-generation Olympus Pen camera appeared in 1959. The design process began with the concept of creating a camera that could be sold for ¥6,000 yen. The Pen combined the superb photographic performance of the D-Zuiko lens with excellent portability, and it was also used by professional photographers as a secondary camera.

Olympus PenEE        (1961)
With the Olympus Pen EE, the emphasis was on efficiency. Features included fixed focus, a shutter speed of 1/60 sec., and automatic exposure adjustment. Anyone could take beautiful photographs simply by pushing the button. The camera was priced at ¥10,000 yen. Olympus eventually introduced eight models in the Olympus Pen EE series, which became a driving force for the popularity of the Pen cameras.
           
Olympus PenEES       (1962)
Launched in 1962, the Olympus Pen EES was the world's first camera with a programmable EE shutter. The shutter speeds were 1/30 and 1/250 sec. The shutter speed changed automatically according to light level, thus increasing the appropriate exposure range. A three-zone focus system was used to adjust the focal point. The Olympus Pen EES heralded the start of the programmable EE camera boom.
         
Olympus PenD       (1962)
The Olympus Pen D was introduced in 1962 as the top model in the Olympus Pen range. Many professional features were packed into its compact body, including a high-performance F1.9 large-aperture lens, a high-speed 1/500 sec. shutter, and a built-in exposure meter that allowed direct reading of the LV.

Olympus PenEM       (1965)
The Olympus Pen EM went on sale in 1965 with three new features: an electronic shutter, automatic film advance, and automatic rewind. The electronic shutter allowed an exposure range from 30 sec. down to 1/500 sec. according to the brightness of the subject. Power for the shutter, film advance and rewind systems was provided by two built-in AA batteries. While the Olympus Pen EM had a major influence on the future of electronic technology and automation in cameras, there were manufacturing problems that could not be overcome with the technology then available. Sadly, production ceased after just one year.

Olympus PenF       (1963)
The Olympus Pen F was the world's first and only half-frame system single-lens reflex camera, released in 1963. The camera featured a porro-prism finder and was the first to have a rotary titanium shutter. It could be used with a highly versatile range of 20 exchangeable lenses. The Olympus Pen F was a revolutionary camera packed with innovative features. The rotary shutter, which combined speed with durability, was reportedly perfected only after long and hard effort by Olympus engineers.

Olympus PenFT       (1966)
The Olympus PEN FT went on sale in 1966. Though identical to the Pen F in external appearance, it had a built-in TTL exposure meter. When the camera was pointed at a subject, the TTL number exposure control system displayed an aperture number in the view-finder according to the shutter speed setting. There were many other enhancements, including a single-action film advance system, and a built-in self-timer.