In 1978, the moment had arrived: the Japanese manufacturer Pentax introduced the smallest and most compact analog SLR camera with interchangeable lenses, the Pentax Auto 110 was born. And the light it captured was recorded onto pocket film, also simply known as 110 film. ​ You can still use this camera today, as brand-new pocket film is still available for purchase (as of 2021). I’ve even had great results shooting with film that expired over 20 years ago. Personally, I don't mind the color shifts or heavier grain at all :-) ​ Shutter speed and aperture cannot be adjusted manually; the camera handles everything completely automatically. The 110 film cartridge itself communicates the correct ISO speed to the light meter. All you have to do is slightly half-press the shutter button. An LED is visible in the upper right corner of the viewfinder: if it lights up yellow, the shutter speed is at 1/45 of a second or slower, warning you of potential camera shake. A green light signals that you’re good to go and there is plenty of light. Now, you just have to focus, which is just as easy as using a standard 35mm SLR. ​ Press the shutter all the way down, and the shot is in the bag—or rather, in the cartridge. Advance the film lever twice, and you're ready for the next frame!

There are a few suppliers online offering adapters to use your Pentax Auto 110 lenses on an MFT camera. Crucially, you need to choose an adapter that features its own built-in iris diaphragm. Why? Because the lenses for the Pentax 110 system do not have an internal aperture mechanism! To fully leverage the optical performance of these lenses, I highly recommend stopping them down by at least 1 to 2 f-stops.

These adapters typically offer stepless aperture control. By monitoring your camera's shutter speed, you can easily calculate the approximate aperture you’ve set. The beauty of this system is that almost all of these lenses share the exact same maximum aperture of f/2.8!

Here is a practical example of how it works:

Example:

Adapter completely open 1/500 sec. / F / 2.8

now you turn the shutter lever and the times change too

1/250 sec. - this would now correspond to aperture 4 ... keep turning ...

1/125 sec. - this would now correspond to aperture 5.6 ... keep turning ...

1/60 sec. - now you have set an aperture of 8 ... and so on ...

More information is available here.

About two years later, Pentax improved the Auto 110 and introduced the Auto 110 super model.

In contrast to the first model, Pentax made the following improvements:

- the quick release lever only had to be operated once

- The camera has been given an exposure correction button (+1.5 f-stops)

- She received an on / off switch and a self-timer.

All accessories can be used on both cameras. In addition to the lenses, this includes the winder with a handle; it offers a serial speed of 1.5 frames / sec. as well as the two flash units:

AF 100P as well as the somewhat larger and more powerful AF 130P.

Lens hoods, filters, bags, lens pouches and carrying handles rounded off the system and are still used today.

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The lenses are really tiny and light  - but because of their performance they are actually suitable for adapting to mft cameras! Here they completely distinguish the image format! I myself use these lenses on an Olympus OM D 10 MKII.

Pentax offered a total of six lenses for this camera system:

• PF 18mm f/2.8 Pan-Focus: Fixed focus from 1.75 meters to infinity, with no manual focusing capability.

• 18mm f/2.8: Wide-angle lens (approx. 35mm equivalent in 35mm format).

• 24mm f/2.8: Standard lens (approx. 50mm equivalent in 35mm format).

• 50mm f/2.8: Telephoto lens (approx. 100mm equivalent in 35mm format).

• 70mm f/2.8: Long telephoto lens (approx. 140mm equivalent in 35mm format).

• 20-40mm f/2.8: Zoom lens (approx. 40–80mm equivalent in 35mm format).

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Check out my YouTube video for more details. In it, I’ll walk you through the camera itself, and toward the end of the video, I’ll showcase the various adapters as well.