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.
View profile →instant
The Polaroid SX-70 Sonar OneStep (1978) is a pivotal variant of the SX-70 folding SLR, distinguished by its built-in sonar autofocus system — the first ever offered on a consumer camera. Where the original SX-70 required the photographer to manually twist the focus ring on the base of the camera body, the Sonar OneStep added a circular transducer module on the front face that emitted an ultrasonic pulse and measured the return echo to calculate subject distance, then automatically drove the focus motor. The entire sequence completed in milliseconds before the shutter fired.
Reference
Recommended film stocks for the sx-70 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.
View profile →Develop sx-70 film
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About this camera
The first consumer camera with sonar autofocus — a folding SLR instant camera that bounced sound waves off the subject to set focus automatically.
| Field | Value |
|---|
| Format | SX-70 integral instant film (ISO 100) |
| Lens | 116mm f/8, 4 elements / 4 groups, glass |
| Years | 1978–1981 |
| Shutter | Auto: ~10s – 1/180s, electronic leaf |
| Meter | CdS, coupled |
| Focus | Sonar autofocus (ultrasonic echo) |
| AF range | ~0.3 m – infinity |
| Body | Folds flat (~29 mm thick with sonar module) |
| Battery | In every film pack |
After the original SX-70 launched in 1972, Polaroid continued refining the line with the Model 2 (simplified front), the Alpha 1 (premium finish), and various promotional editions. The key engineering challenge the company addressed in the late 1970s was focus — the manual focus ring was a source of out-of-focus prints that frustrated consumers accustomed to point-and-shoot simplicity.
The sonar module idea emerged from Polaroid's Land Research Laboratory. Edwin Land himself championed the project; he saw autofocus as essential to fulfilling his vision of photography without barriers. The Honeywell SensAble technology was licensed and adapted to drive the SX-70's existing focus motor. Polaroid announced the Sonar OneStep at a major press event in 1978, and it shipped to retail that same year.
The Sonar OneStep was produced until 1981, when Polaroid pivoted the SX-70 platform toward the higher-speed 600-film architecture. The 680 SLR, launched in 1987, later brought sonar autofocus back to a folding SLR body using 600 film.
The Sonar OneStep's historical significance extends beyond Polaroid. By proving that consumer-grade sonar autofocus was manufacturable and reliable, it established the technical foundation for the autofocus camera revolution of the 1980s. The Honeywell partnership created a module that Konica, Nikon, and others could licence, leading directly to cameras such as the Konica C35 AF (1977, Japan only — an early parallel effort) and the Nikon L35AF (1983).
For Polaroid, the Sonar OneStep completed Edwin Land's vision of a camera that required no skill to operate — load a film pack, point, press. The camera knew where to focus, when to expose, and when to stop.
Lens is fixed (116mm f/8). Accessories compatible with the original SX-70: flashbar (10 disposable bulbs), Polatronic electronic flash, close-up lens kit, tripod adapter. As with all SX-70 cameras, shooting current ISO 640 600 film requires an ND filter cartridge to compensate for the camera's ISO 100 metering. Polaroid Originals sells a compatible conversion.
Polaroid SX-70 Sonar OneStep
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