C41
Kodak Portra 400
Kodak Portra 400 is a professional C-41 color negative film known for flexible exposure latitude, natural skin tones, and fine grain.
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slr-35mm
The Asahiflex I, introduced in 1952, was the first single-lens reflex camera produced in Japan and the direct ancestor of the Pentax line. Made by Asahi Optical Co., Ltd. - the company that would eventually rebrand as Pentax - it used a waist-level finder, a 24x32mm half-frame-adjacent exposure format on standard 35mm film (later models moved to the standard 24x36mm), an M37 screw mount, and a fully mechanical focal-plane cloth shutter. It had no light meter, no instant-return mirror, and no eye-level pentaprism. Despite these limitations by modern standards, it was a genuine SLR at a time when that design was rare outside Germany.
Reference
Recommended film stocks for the 35mm format your camera takes.
C41
Kodak Portra 400 is a professional C-41 color negative film known for flexible exposure latitude, natural skin tones, and fine grain.
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Kodak Tri-X 400 is a classic black-and-white film known for strong tonality, visible grain, and documentary character.
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Kodak Gold 200 is a daylight-balanced C-41 color negative film with warm color, moderate grain, and a classic consumer-film look.
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Labs in our directory that process 35mm film.
Before you buy used
The Asahiflex I is a collector piece rather than a shooter:
About this camera
Asahi Optical's first SLR and Japan's first domestically produced single-lens reflex camera.
| Field | Value |
|---|
| Format | 35mm |
| Mount | M37 screw |
| Years | 1952-1954 |
| Shutter | Cloth focal-plane, 1/25s - 1/500s + B |
| Meter | None |
| Viewfinder | Waist-level |
| Focus | Manual (matte screen) |
| Battery | None required |
Asahi Optical Company was founded in 1919 as a lens manufacturer. After World War II, the company turned to camera production. The Asahiflex I debuted at the 1952 Osaka Trade Fair as Japan's first 35mm SLR. Its M37 lens mount (37mm diameter screw, 1mm pitch) was unique to the Asahiflex series - not compatible with the later M42 "Pentax" screw mount adopted from Contax S/Praktica.
A key limitation was the lack of an instant-return mirror: after the shutter fired, the mirror stayed up, blacking out the viewfinder until the film was advanced. The Asahiflex IIa (1954) introduced the world's first quick-return mirror mechanism, solving this problem. The Asahiflex line gave way to the Asahi Pentax in 1957, which introduced an eye-level pentaprism and the "Pentax" brand name.
The Asahiflex I is a founding document in Japanese camera history. Japan's camera industry in the early 1950s was dominated by copies and derivatives of German designs; the Asahiflex demonstrated that Japanese manufacturers could produce an original SLR rather than simply adapting rangefinder or TLR forms. The lineage runs directly from the Asahiflex I through the Asahi Pentax AP (1957), the Spotmatic (1964), and eventually the Pentax LX (1980) and modern Pentax K-mount bodies.
Its significance is primarily historical. As a user camera, it is cumbersome by any modern measure: waist-level viewing only, mirror stays up after each shot, no meter, a proprietary lens mount with limited glass options. But it represents the starting point of an unbroken line of SLR development that spanned five decades.
The M37 mount is proprietary to the early Asahiflex series and is not the same as the M42 mount used by later Asahi/Pentax, Praktica, or Contax cameras. Very few lenses were made for M37:
M37 to M42 adapters exist and allow use of the vastly larger M42 lens library, but this is a later collector workaround. Accessories for the Asahiflex I were limited; the system was not designed for expansion in the way later Pentax bodies were.
BW
Ilford HP5 Plus is a flexible ISO 400 black-and-white film with classic grain and strong push-processing tolerance.
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Kodak Ektar 100 is a fine-grain C-41 color negative film with saturated color and high sharpness.
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