The Pentax auto 110 is a relative latecomer in the generations of pocket cameras that use the type 110 cartridge film. It is not the first miniature SLR either. However, as far as I know, it is the only system camera that uses the 13x17 mm picture format. Available accessories include a battery powered winder, two automatic flash units, six interchangeable lenses, filters, and close-up attachments. Quite impressive, really.
I remember when my father bought his Pentax auto 110 in the early 1980s. He really liked it and could be seen busily clicking away with it at family gatherings in those years. When he passed away in 2001, I found a whole lot of narrow film strips from that camera in his drawers. Pity no-one makes prints from these anymore. One day I will digitise them somehow to recover a bit of family history.
The Pentax auto 110 was often sold as a boxed set. I know of two different kinds of sets - one is presented below. The other one comes with a transparent lid, and includes a whole lot of filters - something that the below set doesn't have.
With my collector's hat on, I can proudly say that this set is complete. The included card lists the major components:
There are a couple of small bits, that can easily go missing, so make sure you check for these when you purchase a Pentax auto 110 set. Here I am referring to the battery holder and the little protective cap for the flash socket. This is normally on the camera, and when you attach the flash, there is a storage place for the cap on the side of the flash unit.
The camera works off two 1.5 volt button cell batteries (LR44 or equivalent). You need two AA size 1.5 volt batteries for the winder, and the same for the flash unit. All these batteries are easily obtained today. (The film cartridge is another matter.)
The operation of the camera is easy, as some things are automatic. It takes two strokes with the film advance lever to advance one frame and cock the shutter, but with the power winder attached this is taken care of automatically. You won't find an aperture dial on the lenses - exposure is fully automatic and the camera will decide what shutter speed - aperture combination to use. The slowest shutter speed is 1 sec., and the fastest is 1/750 sec. At 1/30 and below the camera always uses the largest aperture (f/2.8), so the depth-of-field is shallow at slow shutter speeds (i.e. in dim light). Should the light level reach EV-17 (with 100 ASA film), the aperture closes down to it's smallest, f/13.5 opening. When the flash it attached, it sets the camera to operate at 1/30 sec and f/2.8. In this case the amount of light is controlled by the flash - it has a simple light sensor.
The viewfinder is surprisingly big and bright for such a tiny SLR. There is a fairly large split-image field in the middle to aid focusing. (Focusing is manual.) At the lower right corner of the viewfinder a little lamp lights up when the shutter release button is pressed half way (provided there are healthy batteries in the camera). The lamp glows green in good light, and yellow when the shutter speed drops down to 1/30 sec. or below.
The beauty of the camera's through-the-lens light metering system is that it automatically compensates for light loss when filters and close-up lenses are used. The meter is of the silicon photo diode type, not the less desirable CdS cell. (CdS meters suffer from the 'memory problem' - they tend to 'remember' the recently made measurement, and so, can give an inaccurate reading.)
The aperture blades, which at the same time serve as the leaf shutter, are behind the lens in the camera. This is a simple and quite ingenious solution, but not without limitation; the shutter speed and aperture cannot be controlled independently. In effect, the camera implements program mode without program shift.
This is what happens when the user presses the shutter release button: 1.) when the button is half-way down, the light meter measures the light and determines the amount of exposure needed, 2.) when the button is fully pressed, the two L shaped blades move in and close the opening, 3.) the mirror goes up, 4.) the blades start to move outwards gradually increasing the opening and letting in light, 5.) the extent to which the blades open has been determined in step 1., and as soon as that is satisfied, the blades close in again, 6.) the mirror lowers and the blades open again to allow viewing through the viewfinder.
The camera is not much larger than the film cartridge that goes into it, which is itself pretty small. There is no frame counter on the camera, instead, the number of shots taken can be checked on the back of the film cartridge (where now the white arrow is) through the back-door window. The cog wheel visible on the left hand side is responsible for advancing the film. On the opposite side, near the battery compartment, there is a little pin that was designed to tell the camera about the sensitivity of the film loaded. The two settings are: 'high' (about 400 ASA), when the pin is pushed in by a lip on the cartridge, and 'low' (about 100 ASA), when the pin is left alone.
In 1982, four years after the introduction of the original model, the Pentax auto 110 Super was brought to the market. The Super is somewhat more advanced with features like self-timer, shutter release lock, and a +1.5 f-stop compensation button for back-lit subjects. Film wind was reduced to a single stroke. The focusing aids in the viewfinder also changed. As in many 35mm SLRs, there is now a somewhat smaller central split-image spot surrounded by a microprism collar.
Asahi also modified the automatically selected shutter speed-aperture combinations for bright lighting conditions. For instance, the limit at the high end in the Super is 1/400 sec. at f/18. Personally, I don't think this is much of an improvement. A small camera is hard to hold steadily, so a faster shutter speed made more sense at the not so crucial expense of shallower depth-of-field.
The L, A, and S markings for the Mode switch near the film advance lever may be misleading, because the latter two have other meanings than what we are used to. A just means normal (program) operation, and S means self-timer. The red light above the PENTAX logo is for the self-timer.
Here, the two Pentaxes are shown with the additional lenses that usually come in a kit. The larger is the 50 mm long focus lens and the smaller is the 18 mm wide angle. The three remaining lenses, that I don't have, are the 20-40 mm zoom, the 70 mm telefocus, and the 18 mm fixed focus lens. All auto 110 lenses are f/2.8.
Finally, here is a comparison between the tiny Pentax SLR and a typical 35mm SLR, both with motor drive and flash attached:
(Have you noticed, that in camera instruction manuals the person demonstrating correct camera holding always has his or her visible eye open? You can't focus like that, because - save a very few cameras - the viewfinder projects a reduced image! I suppose, they do it for looks. I, on the other hand, don't care about my looks, so I wink, as we all normally do in this situation.)