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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The Spotmatic SPF (1973) was Asahi Pentax's final iteration of the Spotmatic line and the most technically capable M42 body they ever made. Its key advancement over previous Spotmatics was the switch from stop-down TTL metering to **open-aperture metering**, working in conjunction with the new SMC Takumar lenses that carried a mechanical coupling tab on the mount. The SPF also replaced the CdS cell of earlier models with a faster-responding **silicon photo-diode**, giving more accurate readings in low light and eliminating the cell's slow dark-adaption lag.
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.
Develop 35mm film
Labs in our directory that process 35mm film.
Before you buy used
About this camera
The last and most refined Spotmatic: open-aperture metering finally arrives for M42.
| Field | Value |
|---|
| Format | 35mm |
| Mount | M42 (Pentax universal screw mount) |
| Years | 1973-1976 |
| Shutter | 1s - 1/1000s, mechanical horizontal cloth |
| Flash sync | 1/60s |
| Meter | TTL open-aperture silicon (with SMC Takumar) |
| Modes | Manual |
| Battery | 2x SR44 / LR44 (1.5V) |
| ISO range | 20-3200 |
The SPF appeared in 1973 alongside the rationalised SMC Takumar lens line. Earlier Spotmatics (SP, SPII) used stop-down metering because there was no coupling mechanism between body and lens to communicate the set aperture. When Asahi introduced open-aperture Takumars with the necessary coupling pin, they revised the body to add the reading circuit that could interpret it - and the SPF was the result.
The SPF shares its production window with the Electro Spotmatic ES II (also 1973), which offered aperture-priority automation on the same M42 platform but with an electronic shutter. The SPF was the strictly manual choice for photographers who wanted open-aperture convenience without electronic dependence.
Production ended in 1976 when Pentax launched the K-series (KX, KM, K2) with the new K bayonet mount. The M42 Spotmatic family - SP, SPII, SP500, SP1000, SPF, ES, ES II - ended together.
The SPF is the definitive Spotmatic for a photographer who wants to use the SMC Takumar lenses as Asahi intended. Open-aperture metering means you compose and meter wide open, then the lens stops down automatically at the moment of exposure - the same workflow modern shooters take for granted. Earlier Spotmatics required manually stopping down before reading the meter, then reopening to compose: an extra step that slowed shooting and made the bright viewfinder go dark when metering.
The silicon cell also ages better than CdS. Many surviving SPFs have meters in better calibration than equivalent Spotmatic II units, all else equal.
M42 screw mount. The SPF meters open-aperture only with SMC Takumar lenses carrying the coupling tab. Older Super Takumar and Takumar lenses work stop-down (the SPF falls back gracefully - meter works, but you must stop down manually). Third-party M42 glass (Helios-44, Industar, Carl Zeiss Jena Pancolar, Flektogon, Mir) works stop-down.
Notable lenses for SPF use:
Accessories: Asahi Auto winder (late M42 era, uncommon), M42-to-K bayonet adapter allows SPF lenses on later Pentax bodies (stop-down only).
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.
View profile →Pentax Spotmatic SPF
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