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It's not my usual practice to get worked up enough to write a story about a camera that's younger than I am, that has electronic controls, & that I don't know how to fix if it breaks. Throw in a plastic body, program shutter and the fact that the manufacturer is still In business....gee, I shouldn't even own one! But in the case of the Pentax Auto 110 I've made an exception, because this camera has characteristics that make it truly unique, and give it capabilities beyond other 110 or even larger cameras. The Pentax Auto 110 was the world's first and only subminiature SLR system. It wasn't the first subminiature SLR - that honor goes to the Narciss, a Russian 16mm SLR that debuted in the early 1960's, before the 110 cartridge was introduced by Yellow Box Inc. It wasn't even the first 110 SLR - that was Minolta's 110 Zoom, an aperture-priority autoexposure model of the mid-70's, following the horizontal arrangement of the Kodak Pocket Instamatics and fitted with a decidedly unpocketable, non-interchangeable f/4.5 zoom lens, and metering through a sort of miniature telephone dial on the front panel next to the lens. What the Auto 110 was, though, far outweighed its lack of chronological priority. It was introduced in 1978 as a system, the most thorough the 110 format would ever see: its modest but pocketable 24mm f/2.8 lens was interchangeable with an 18mm wide angle or a 50mm telephoto, both with the same f/2.8 speed; a 70mm tele and a 20-40 f/2.8 wide-to-tele zoom would follow, as well as a 1.7X teleconverter. In addition to optics, the Auto 110 was designed to accept a power winder, and its lack of a standard hot shoe (there wasn't room) was made up for by the provision of a proportionately teeny weenie dedicated flash that coupled mechanically with the body to set the camera at f/2.8 and 1/30 sec. All this was available, if desired, in a miniature aluminum attache that looked like a cross between a Halliburton case and a makeup kit. 
A system that fits in the palm of your hand: the Auto 110 with its 50mm tele lens mounted, 18mm wide angle, 24mm normal lens and nickel-sized 1.7x teleconverter in front. The Auto 110 focused to 14" (10" with the wide angle), without resorting to an internal swing-away closeup lens as the Minolta had done. Also unlike the Minolta, its TTL metering (a first for a 110 camera) allowed for filters without compensation, and a variety were offered in each of the tiny sizes. Auxiliary closeup lenses were also provided for those for whom 14" wasn't close enough. The Auto 110 was equipped with an electronically controlled, program automatic behind-the-lens leaf shutter and an instant-return mirror. More modest tasks than this had sent a number of previous attempts, even with a roomy 35mm body shell to put it all into, to early and unmarked graves. But it was a unique combination, and one which Asahi engineers deftly used to their advantage. Whereas in 35mm SLRs a leaf shutter between the lens and the mirror becomes a nightmare of complexity and the need to cross-couple it with a removable lens diaphragm would most likely have sent it far beyond any hope of redemption, the combination in the Auto 110 resulted in an extraordinarily simple design, made all the simpler by its autoexposure control requirements. The 110's automatic diaphragm and leaf shutter system contains neither a diaphragm nor a leaf shutter as we generally think oŁ them; the entire system consists of two V-shaped blades which form a square opening between them, similar to the diaphragm (but not the shutter) of any number of 70's-era 35mm compact viewfinder cameras. Having closed at the beginning of the mirror-raising sequence, these are instructed to travel in an opening direction for a given period of time (determined by the light intensity), at the end of which they close again. If the "given period of time" is less than, say, 1/60 sec., the blades will begin closing without ever having reached their fully open (f/2.8) position; hence, for speeds from 1/30 to the max. of 1/750, both the duration and distance of travel vary together for an effect which Canon (at just about the time the Auto 110 was being introduced) endowed with the pretentious title of "Program Operation". When done in this way, there's really nothing to it....as long as you don't have to know just what aperture and shutter speed you got for any given exposure. So the logical final touch is to just let the built-in meter handle everything on its own in automatic-only operation, with no indication of what it's doing other than a yellow light that comes on at all speeds allowing full aperture (1/30 sec. or longer). The other trick in a leaf-shutter SLR is the need for a light seal to protect the film when the shutter is open for viewing. In the Auto 110, this task is handled very elegantly by the instant-return mirror itself, which seals against a flange in front of the film plane when in the down position. Many of the mechanical arrangements which make the Auto 110 work could not be scaled up to 35mm size; they work only in the 110 size, for several reasons: first, while the Auto 110 is unquestionably the smallest SLR ever successfully marketed and among the smallest ever built, it is quite bulky in proportion to its film size, compared to larger format cameras of conventional design. If doubled in size to bring it up to a 35mm full frame, it would be 7 3/4" long, 4 1/4" high and 2 1/2" thick without lens, and using it would feel sort of like holding a sixpack in front of your face. Secondly, the mechanisms themselves are quite massive. In 110 size the blade shutter, mirror and light baffle work very quietly, but doubling their dimensions would increase their weight by 800% for every moving part, while in order to maintain the shutter speed range these massive parts would have to move twice as fast. The result would hardly be likely to meet wide acceptance. Another limitation imposed on the Auto 110 by its mechanical layout comes in the area of lens design. You may have noticed that all Auto 110 lenses have the same maximum aperture, from the normal lens (for which f/2.8 may be a tad slow) to the zoom (for which it's quite fast). This is because the diaphragm is built into the body and must work with all lenses. Another problem associated with this arrangement is that the diaphragm is located behind, rather than within, the lens. This has a decided effect on the optical design of the lens, especially in the longer focal lengths. The front element of the 50mm tele, for instance, measures 30mm across - - much larger than one would find on a 50mm f/2.8 normal lens for a 35mm camera. This is necessary to allow rays of light to reach the corners of the frame through the rear-mounted diaphragm. But it's more than just a matter of size: enlarging the front element of an f/2.8 Tessar wouldn't get you anything but extra glass. The design of the lens has to be changed so that the rays of light will converge near the rear of the lens rather than near the center as is usually the case. Further, the point of convergence should be about the same for all focal lengths. A lesson in how to qo about this had been given in the 1950's, with the interchangeable-front-cell lenses of the Retina and Contaflex cameras; the ancestor of these, in turn, had been the supplementary wide angle and tele attachments which went on the Contaflex I and II and the Rollei TLRs. Despite obvious differences, the basic problem, keeping the diaphragm in the same place, exists in all of these, and the basic optical approach is similar. Essentially, the rear portion of the wide angle and tele lenses resembles the normal lens. The front portion comprises a Galilean telescope with some degree of magnifying (in the tele) or reducing (in the wide angle) power. As in any Galilean optic the field of view becomes a function of the objective diameter; hence the increase in size as the lens varies in either direction from the normal 24mm. Even the zoom can utilize this approach, with a moving element in the forward section changing it from a magnifying to a reducing optic as it moves. Again, this succeeds only because of the small format: on a 35mm camera a 100mm f/2.8 tele with a front element nearly 2 1/2" in diameter would surely be found unacceptable, as indeed it was in the Contaflex series and the Canon EX. The question of optical attributes which are a function of this particular format size brings us to one of the Auto 110's most intriguing and significant features, and one which seems to have escaped the notice of the camera's own designers. The Auto 110's 24mm normal lens, particularly in combination with the camera's reflex viewing and through-the-lens autoexposure systems, is about as near an approximation of a human eye as you're ever likely to (or would ever care to) find in a photographic camera. It approximates both the focal length and the maximum aperture of the human eye, and its field of view corresponds to that typically provided in the eyepiece of optical instruments such as binoculars and microscopes. The net result of this is that the Auto 110 can photograph through the eyepiece of such instruments far more satisfactorily than any other camera ever made. Even the diameter of Its filter thread, at 25.5mm, allows the lens to nest snugly over a standard 23mm microscope eyepiece for a quick but steady shot. Proper exposure is nicely taken care of by the TTL meter, and the camera's small size and light weight don't jeopardize the steadiness of the instrument. 
One of the most fascinating ways to use an Auto 110 is to perch it on each of the eyepieces of a stereo microscope, as shown here. The camera's through-lens focusing and autoexposure systems give fool-proof results; an example is shown below. Another happy coincidence relates to lens speed. During the 1950's it was a fairly common trick to provide an otherwise limited SLR (such as a Contaflex, or an Exa) with long-telephoto capability by attaching a monocular to the front of the lens. The major problem was always that the diameter of the monocular objective was small relative to the resulting focal length oŁ the lens. Typically, binoculars and monoculars tend to be designed to provide a 5mm diameter exit pupil: the most common of these are 7x35, 8x40 and 10x50mm styles. These, when attached to a 50mm lens, provide an effective focal length of 350, 400 and 500mm, but in all cases the maximum effective aperture is f/10. That's pretty slow, and it shows in the dim viewfinder as well as the long shutter speeds, both of which one would just as soon do without when handling a supertelephoto lens. Mount the same device on the 24mm lens of the Auto 110, however, and it's a different story. The view through the finder looks much the same, but it's brighter - the 7x35 becomes a 168mm f/4.8, just 1 1/2 stops slower than the normal f/2.8 and over 2 stops faster than it could provide on a 35mm camera. That translates into shutter speeds over 4 times faster, which in turn means sharper pictures. Again the TTL meter compensates nicely for the 1 1/2 stop reduction in speed, but in this case there is a catch (albeit one that can be lived with): with a hand held monocular, unlike a telescope or microscope, there's a pretty good chance of encountering enough light to make the lens begin to stop down. At these higher exposure values the camera will tend to overexpose slightly, since the meter doesn't know that the light it's reading is all coming through the central 5mm (the exit pupil) of the 8 1/2 mm (lens aperture) that it thinks it's looking at. So if it sees enough light to require a reduction of, say, one f/stop to 6mm diameter, it only winds up closing off part of the unused edge area and allows the whole 5mm beam through unaffected. The result: a 1-stop overexposure, well within the capacity of most 110 films. One thing to watch for when selecting a monocular for this purpose is its angular coverage. The 24mm lens on the Auto 110 covers about 48 degrees across its 21.5mm diagonal; in order to prevent vignetting, the eyepiece of the monocular must cover at least as much. This means a 7x monocular must cover 48/7 or about 7 degrees minimum; an 8x, 6 degrees. Most modern glasses meet this requirement easily, but some older ones don't. Mine, a 7x dating from the early 50's, covers 6.5 degrees; vignetting is not visible with it at large apertures, but begins as the lens stops down in bright light. It is also important to get the camera lens as tight into the eyepiece as possible, just as it is with your eye. Other unique applications come to mind: it can be used to photograph the viewfinder display of another camera, through the eyepiece...... its light weight and low vibration level permit use with lightweight telescopes and instruments that could not support a larger camera, as well as those whose eyepieces cannot be removed...... It can even be used to measure the field of view of an instrument, by photographing through the eyepiece and measuring the diameter of the image on the negative. And finally, the apparent distance of a viewfinder or instrument display can be accurately measured by bringing the display to focus in the Auto 110 viewfinder, and then simply reading the distance off the footage scale on the lens. As price trends have indicated since the model was discontinued a couple of years ago, the Auto 110 is a classic design which is destined to be (indeed, which already is) a sought after collectors' item. More even than that, however, it is a uniquely practical machine, as useful as it is adorable, and one which, despite Pentax's gallant efforts to exhaust all possibilities, still has considerable room for future expansion at the hands of an adventurous amateur optician. THE PENTAX AUTO 110 SYSTEM Auto 110 camera Auto 110 Super camera 18mm wide angle lens 18mm Pan-focus w.a. lens 24mm normal lens 50mm telephoto lens 70mm telephoto lens 20mm - 40mm zoom lens 1.7x tele converter (by Soligor) Dedicated flash units Power winder Close-up lens sets Filter sets Various component and system cases Images Taken with the Auto 110: 
This one is hardly a fair example: it was taken with a 3 diopter closeup lens AND a 1.7x Soligor teleconverter on the normal lens, at a distance of less than 12 inches from the moving subject. Still, it's an example of a photo that could never have been taken with any other pocketable camera. 
Here's another one I'd like to see you take with your 35mm AF point&shoot: a herd of aphids on a stem, taken by placing the Auto 110 first on one, then the other eyepiece of an American Optical stereomicroscope... it's as easy as click, wind, click (aphids don't move very fast; they all register okay, though one was wiggling his little derriere in the left frame and blurred a little). To see this in 3 dimensions, print it out and place it in an antique stereoptican viewer (the right-hand image should be about 3 1/2 inches wide for proper spacing). Each of these bugs is about half the size of a small ant. 
A more conventional image, this one shows the resolution of the 18mm wide angle lens in Lindsay's hair and the upholstery texture, in spite of the grain in the ISO400 film. |
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