Pentax HD 40mm f/2.8 PENTAX-DA Limited Autofocus APS-C Lens for K-Mount, Silver {49}

Pentax's pancake prime: 40mm f/2.8 in 15mm of metal

At 15mm long and 80 grams, the HD DA 40mm f/2.8 Limited turns any Pentax APS-C body into a pocketable kit. The 40mm focal length, equivalent to roughly 61mm on APS-C, sits in that slightly-long-normal sweet spot that works for street shooting, casual portraits, and travel without telegraphing 'serious camera' to everyone in the frame. The silver finish on this version pairs with silver-bodied Pentax bodies and has the kind of machined-metal feel that's become a signature of the Limited lineup.

The optical formula is five elements in four groups, coated with Pentax's HD multi-layer coating, which cuts ghosting and flare compared to earlier SP-coated versions of this lens. Nine rounded aperture blades mean out-of-focus backgrounds don't render as harsh polygons at mid-apertures. Autofocus runs via screw drive from the camera body, and full-time manual override is available without switching modes. The 49mm filter thread is compact and shares sizing with other DA Limited lenses, so one set of filters covers multiple primes. At f/2.8 with a 0.40m minimum focus distance, this isn't a macro tool, but for a lens that disappears into a jacket pocket, the optical quality-to-size ratio is hard to argue with.

Who It's For

Street photographers who want a discreet Pentax kit will appreciate the pancake form factor, at 15mm long, it barely extends past the mount. Travel shooters benefit from the 80g weight and the fact that it pairs with weather-sealed Pentax bodies for outdoor use. Portrait photographers working at short distances will find the 40mm field of view on APS-C flattering for environmental work. Film-influenced shooters drawn to the Limited series' metal construction and refined rendering will recognize this as the lens that defines the series' pancake identity.

Key Features

• 40mm f/2.8 prime with HD multi-layer coating
• Five elements in four groups for optical quality
• 15mm length and 80g weight fits jacket pocket
• Nine rounded aperture blades render smooth bokeh
• 0.40m minimum focus distance with 0.13× magnification
• Screw-drive autofocus with full-time manual override
• 49mm filter thread shared with other DA Limited lenses
• Silver finish matches silver-bodied Pentax bodies

FAQ

What's the equivalent focal length on a Pentax APS-C body?

40mm on APS-C is roughly 61mm equivalent, putting it in long-normal territory for street, casual portraits, and travel work without the conspicuousness of a longer telephoto.

How does autofocus work on this lens?

It uses screw-drive autofocus powered by the camera body, so AF speed depends on your camera's motor. Full-time manual override is available without switching modes.

Can I use this lens for macro work?

At 0.13× magnification and 0.40m minimum focus distance, it's not a macro lens, but it focuses close enough for product work and tight portraits in a pinch.

What coating does it use and why does that matter?

The HD multi-layer coating reduces ghosting and flare compared to older SP-coated versions. You'll notice cleaner contrast in backlit and high-contrast scenes.

Does the silver version match my camera body?

Silver finish pairs with silver-bodied Pentax bodies like the K-5 II or K-7. If you have a black body, Pentax also makes a black version.

How do the rounded aperture blades affect bokeh?

Nine rounded blades keep out-of-focus areas smooth and circular at mid-apertures rather than rendering harsh polygons, which matters if shallow DOF is part of your shot.

Will my existing 49mm filters work with this lens?

Yes. The 49mm filter thread matches other DA Limited primes, so if you own filters in that size, they're compatible.