Lens Test: Pentax 70mm f/2.4 Limited

The category’s most compact short telephoto lens and Pentax’s lightest digital-only tele/portrait optic, this ultra-shallow “pancake,” the 70mm f/2.4 Limited AF ($540, street), delivers the 35mm equivalent of a 105mm’s field of view. One of Pentax’s elite “Limited” family, it has all-metal construction, engraved barrel markings, and “SP” (Super Protect) coating to guard against moisture and finger oils.

Hands On: This lens is well built: extremely compact and light, beautifully finished in matte black, and engraved with distance (meters, yellow; feet, blue) and depth-of-field scales. It’s all-aluminum alloy, including the velvet-flocked lenscap and telescoping sunshade. The bright green ring signifies a DA, or digital-only, lens. We found its manual-focus turning action was even and very well-damped. AF action on the *ist DS was reasonably fast, accurate, and quiet. Its “Quick Shift” AF feature enables manual focusing in the AF mode.

In The Lab: SQF tests showed sharpness and contrast in the Excellent range at all apertures and magnifications. DxO Analyzer 2.0 tests found Imperceptible pincushion distortion (0.09%), a superior showing. Light falloff was gone from the image edges by f/3.5, about average. Its maximum magnification ratio of 1:8.14 at 27.25 inches was somewhat disappointing.

Conclusion: A good choice for portraiture, landscapes, and general snapshooting, this is an enticing piece of glass, especially for anyone wanting to travel light. For more speed, look into Pentax’s 77mm f/1.8 full-framer ($690, street). For ultralight globe trotting, pair up the 70mm and 21mm pancakes.

Specifications

70mm (67.50mm tested), f/2.4 (f/2.46 tested), 6 elements in 5 groups. Focusing turns 130 degrees clockwise.
• Diagonal view angle: 23 degrees.
• Weight: 0.31 lb.
• Filter size: 49mm.
• Mounts: Pentax AF.
• Included: Lenshood, softcase.
• Street price: $540.