Pentax Lens Codes

Pentax (now owned by Ricoh) has one of the longest-running lens mounts in history.¹ The K-mount has been around since 1975, meaning you can technically mount a 50-year-old lens on a brand new K-3 Mark III.

However, just because it fits doesn’t mean it works perfectly. Pentax uses a complex series of letters (DA, FA, D FA) to tell you whether the lens covers a full-frame sensor and whether the aperture is controlled by a mechanical lever or an electronic motor.

1. Lens categories (sensor size & series)

• D FA: Full-Frame Digital.
  • The Tech: Optimized for modern high-resolution full-frame DSLRs (like the K-1). They also work perfectly on APS-C cameras.
• DA: APS-C Digital.
  • The Tech: Designed specifically for crop-sensor cameras (K-3, K-70, KF).
  • Warning: If you use these on a Full-Frame K-1, the camera will automatically crop the image (reducing resolution).
  • Pro Tip: Some DA lenses actually cover a Full Frame sensor with minimal vignetting (like the DA 55mm f/1.4 or DA 200mm f/2.8). Pentaxians often use these on the K-1 to keep their kits light.
• HF: Half Frame.
  • The Tech: Introduced with the Pentax 17, “HF” indicates optics designed specifically for the 17x24mm half-frame film format.
  • The Philosophy: This is a modern code for Pentax’s film revival, focusing on “character” and compact size rather than clinical sharpness.
• FA: Full-Frame Autofocus (Legacy).
  • The Tech: The autofocus lenses from the film era (1990s). They are fully compatible with digital cameras and are often prized for their compact size.
• A: Manual Focus (Auto-Aperture).
  • The Tech: Manual focus lenses that have electronic contacts to allow the camera to control the aperture from the body.
• M / K: Manual Focus (Manual Aperture).
  • The Tech: The original vintage glass. They have no electronic communication. You must use “Stop-Down Metering” (the Green Button hack) on modern DSLRs to get exposure.

2. Premium series badges

• ★ (The Star Series): The Gold Standard.
  • The Philosophy: Pentax’s equivalent of Canon’s L-Series. These are weather-sealed, large-aperture optics designed for maximum resolution.
• Limited: The “Soul” Series.
  • The Philosophy: Unique to Pentax. These are ultra-compact, machined aluminum primes designed for rendering “character” and tactile feel.
  • HD vs. SMC: Newer Limited lenses have the HD coating (red ring); older ones have SMC (green ring).

3. Autofocus motors (the KAF4 trap)

KAF4 (electronic aperture) compatibility table

Lenses marked as KAF4 or PLM use an electromagnetic diaphragm. If you put these on an incompatible body, the lens will always stay at its smallest aperture (f/22 or f/32), making the image dark and unusable. Check your camera below:

Support Level	Camera Models	Note
Fully Compatible	K-1, K-1 II, K-3 III, K-3 II, KP, K-70, KF	Native support for all electronic aperture lenses.
Needs Firmware	K-3, K-S2, K-S1, K-50, K-500	Must be updated to the latest firmware to control the aperture.
Incompatible	K-30, K-5 series, K-7, K-r, K-x, K10D, K20D	Lens will fit physically, but aperture will stay stuck at f/22.

• PLM (Pulse Motor):
  • The Tech: A modern stepper motor. It is silent, instant, and great for video.
• SDM (Supersonic Direct-drive Motor):
  • The Tech: Quiet and fast ultrasonic motor.
  • Warning: Early-generation SDM lenses (such as the legacy 16-50mm f/2.8) were prone to motor failure. If buying used, ensure the AF is snappy.
• DC (Direct Current): A smooth, quiet motor found in mid-range lenses.
• Body Screw Drive: (No Code)
  • The Tech: Relies on the mechanical motor inside the camera body. FA and Limited lenses typically use this.

4. Weather sealing & glass

• AW (All Weather): Heavy-duty sealing against dust and rain, typically found on Star (★) and D FA lenses.
• WR (Weather Resistant): Standard sealing using a rubber gasket at the mount.
• HD / SMC: Lens coatings. HD is the modern coating; SMC is the legendary Super Multi-Coating.
• ED: Extra-Low Dispersion glass to reduce chromatic aberration.
• AL: Aspherical Lens elements to reduce distortion and keep lenses compact.
• RE: Retractable design to save space when not in use.
• SP (Super Protect): A fluorine coating that repels water and grease from the front element.
• IF: Internal Focusing. The lens does not change length during focus.

5. Mount abbreviations

• K-Mount: The standard bayonet mount for all Pentax DSLRs.
• 645: Medium Format lenses (for the 645Z and 645D).
• Q-Mount: Tiny lenses for the discontinued Q-series mirrorless cameras.

Related

• Pentax Lens Filter Size & Lens Hood Chart

Notes & References:

1. The Pentax brand is owned and operated by Ricoh Imaging Company, Ltd. Ricoh acquired the Pentax camera division in 2011. Today, Ricoh uses the “Pentax” name for its SLR and film camera systems, while marketing compact cameras (like the GR series) under the “Ricoh” brand. [↩︎]