Pentax Auto 110
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The Pentax Auto 110 and Pentax Auto 110 Super are single-lens reflex cameras made by Asahi Pentax that use Kodak's 110 film cartridge. The Auto 110 was introduced with three interchangeable lenses in 1978. Three more lenses were introduced in 1981, and then the Super model was released in 1982. The camera system was sold until 1985. The complete system is sometimes known as the Pentax System 10, apparently for its official Pentax name, although most Pentax advertising only uses the camera name or Pentax-110. This model represented the only complete ultraminiature SLR system manufactured for the 110 film format, although several fixed-lens 110 SLRs were sold. The camera system also claims to be the smallest interchangeable-lens SLR system ever created.
The cameras and lenses were very small (the camera fits in the palm of a hand easily) and were made to professional SLR standards of quality.
Auto 110 
The Pentax Auto 110 featured fully automatic exposure, with no user-settable exposure compensation or adjustments. Metering was TTL (through-the-lens) and center-weighted. Unlike 35 mm SLRs, the system's lenses did not have a built-in iris to control the aperture. Instead, an iris was mounted inside the camera body, and functioned as both an aperture control and a shutter. This mechanism was capable of programmed exposures between 1/750 second at f/13.5; and 1 second at F/2.8. To ensure that light travelling past the diaphragm blades could not get through to the film over time, the camera's mirror system also functioned as a light-tight seal when in the viewing and focusing position. Since the iris was part of the camera, all of the system's lenses had to be constructed with an f/2.8 aperture. The lens' designs, based upon the film dimensions, resulted in the 24mm lens being the 'normal' focal length, while lenses of wider angles or longer focal lengths were larger.
The camera detected the film speed by the presence or absence of a ridge on the cartridge, as specified in the Kodak 110 film standard. Since there was no official specification of what the film speeds should actually be—they were just "low" and "high"—film and camera manufacturers had to decide for themselves the meaning. Pentax chose 80 and 320 ISO as their settings, but commercially available films at 100 and 400 ISO are close enough to work in practice. A film with a 200 ISO speed would result in either under-or-over-exposure. The exposure latitude of the then existing color print films was about 2 f/stops (meaning that a photographer could expose either 2 f/stops under or 2 f/stops over the exposure set by the camera). Unfortunately, some recently produced 110 film is rated at 400 ISO, but is packaged with the ridge indicating 100 ISO. If this is the case, the ridge must be removed (by filing or cutting with a sharp blade) for the camera to expose correctly. Since only a few 110 cameras ever supported the ISO auto-selection, this does not affect the majority of cameras using the format but does affect the Pentax Auto 110. In 2012/13 100 ISO film has been produced and marketed under the Lomography label, and gives excellent results, without the need to modify the cartridge casing.
The camera was offered in a special edition "Safari" model, identical to the Auto 110 except for the brown-and-tan color scheme.
Auto 110 Super 
Introduced in late 1982, the Super was identical in basic shape and size to the previous model and accepted the same lenses. Many improvements and changes were included to make this model arguably a better camera than the previous Auto 110. Film winding was improved with a single-stroke film advance lever that advanced the film and cocked the shutter in one winding (the Auto 110 took two strokes to advance the film). A switch around the shutter release button enabled a new ten-second self-timer mode and a shutter lock; the self-timer activated a red light on the pentaprism housing, which flashed during the 10-second shutter release count-down. A button on the front on the user's left hand side gave a +1.5 EV (exposure value) backlit scene exposure compensation.
More subtle changes include a revised top shutter speed of 1/400. The optional winder offered an improved battery cover, a well-known weak component in the first generation form. The shutter button is protected from accidental tripping by an altered casing around the button. The flash synchronization socket cover on the Super was permanently attached to the camera in an attempt to prevent loss, though many still go missing when the plastic tether break.
The viewfinder screen has a split image rangefinder center, surrounded by a microprism collar, whereas the Auto 110 had the split image rangefinder center only. The low light warning activated at 1/45 second (the Auto 110 activated at 1/30 second).
The line of lenses consisted of these three at launch:
- 18 mm f/2.8 wide-angle lens (equivalent angle of view to a 35 mm lens on a 135 format camera).
- 24 mm f/2.8 normal lens (Equiv. 50 mm). The optical design meant that this was the smallest lens on the system.
- 50 mm f/2.8 telephoto lens (Equiv. 100 mm)
In 1981, three more lenses were included:
- 18 mm "Pan Focus" lens was a compact lens of fixed focus set to the hyperfocal distance; the short focal length and wide aperture meant that its depth of field stretched from 1.75 m (5.7 ft) to infinity. The camera aperture needed to be set at F/6.3 for this lens to work as intended.
- 70 mm f/2.8 telephoto lens (Equiv. 140 mm)
- 20–40 mm f/2.8 zoom lens (Equiv. 40–80 mm). This lens extended for wider focal lengths and shortened towards the telephoto end.
The three later lenses are much rarer.
Lens hoods were available for all of the lenses, and Pentax sold add-on close-up lenses for macro photography and a range of filters.
Two models of motor winder were produced. The original 110 Winder took 2 AA batteries and with a set could wind through 100 cartridges of 110 film. It worked only in single-shot mode. It took about 1.5 seconds to wind a frame. The 110 Winder II, introduced in 1982, added a continuous shooting mode and improved the battery cover door, which was rather fragile on the original. (However, it was still fragile.)
A custom electronic flash unit, the AF130P, was part of the original Auto 110 system, and was produced until the camera ceased being manufactured. Pentax responded to criticism that this electronic flash unit was too large by introducing the smaller AF100P electronic flash unit in 1980. This unit, however, was never part of the Pentax camera kits and became rare.
Other accessories 
Pentax produced a range of various camera-carrying cases and also a belt-clip for the cameras.