Pentax DA 40mm f/2.8 Lens

Ultra-thin pancake prime lens for Pentax K-mount digital SLRs and the Pentax K-01

  • Pentax DA 40mm f/2.8 Lens


Item #: 815DA40

Review Summary

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Our take on the Pentax DA 40mm f/2.8 Lens

by Woody Sherman

Milestones don't last for long anywhere in the world of photography. That being said, this is the single thinnest interchangeable lens we've ever seen, on any camera system (as of spring 2012). And even though it's a lens you could conceivably slip into a vest pocket, it's got optical properties that today's digital photography enthusiasts will find compelling. With its light-seeking f/2.8 aperture, this lens will make the most of the light in your environment. And with an effective 61mm focal length, it's ideal for snapshots and portrait photography.

This lens is a product of renowned designer Marc Newson's imagination, and it makes an artistic impression on the front of the Pentax K-01 camera.

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  • Pentax 40mm f/2.8 standard lens with 35mm equivalent of 61mm
  • compatible with Pentax K-mount digital SLR and hybrid cameras
  • low-profile lens is only 3/8" thin and less than 2 ounces
  • crafted by renowned designed Marc Newson
  • Pentax SP (Super Protect) coating on lens surface helps repel elements and aids in cleaning
  • constructed of 5 elements in 4 groups
  • minimum focus distance: 15-3/4"
  • minimum aperture: f/22
  • filter size: 27mm
  • lens is 13/16" thin, 2-1/2" in diameter
  • weight: 1.8 ounces
  • front and rear lens caps
  • warranty: 1 year
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
Brand Compatibility Pentax
Image Stabilization No
Focal Length 40mm
Maximum Aperture F2.8
Weight 1.8 ounces
Parts Warranty 1 Year
Labor Warranty 1 Year
Product Research
What's in the box?

Download owner's manual

  • Pentax-DA 40mm F2.8 XS lens (with front and rear lens caps attached)
  • Operating Manual
  • Pentax Worldwide Service Network sheet
  • Serial Number Card

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team — they open the box, verify contents, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.


Overview: The smc Pentax-DA 40mm F2.8 lens is a fixed focal length, pancake-style prime lens for Pentax D-SLR and interchangeable lens cameras. Its 35mm equivalent is 61mm, and is ideal for general photography in existing light, and for creative applications featuring depth-of-field.

Lens Mount: The lens has a KAF-mount, and can fit Pentax D-SLR and interchangeable lens cameras with KAF, KAF2 and KAF3 mounts. This includes the Pentax K-5 and K-01 cameras.

Marc Newson Design: The lens' aesthetic design comes from world famous designer, Marc Newson, who also designed the K-01 camera.

Super Protect: The Pentax-original SP (Super Protect) coating repels dust, water, and grease to help keep the lens clean.


  • Focal Length: 40mm
  • 35mm Equivalent: 61mm
  • Lens Construction: 5 elements in 4 groups
  • Mount Type: KAF-mount
  • Maximum Aperture: F2.8
  • Minimum Aperture: F22
  • Maximum Magnification: 0.13x
  • Angle of View: 39°
  • Minimum Focus Distance: 1.31' (15.72")
  • Filter Diameter: 27mm
  • Dimensions:
    • Diameter: 2.454"
    • Length: 0.813" (1.05" w/caps)
    • Weight: 1.8 ounces

Product reviews from the Crutchfield Labs (what are the Labs?)

Quick impressions from the Lab

Comment by Zak Billmeier Staff Writer - Creative,

Are you kidding me?

Written by Zak Billmeier, Staff Writer - Creative, on 4/30/2012 4:35:00 PM

How did Pentax do it? This lens is so thin, you'll think it's a lens cap. Pentax has long been known for their thin "pancake" lenses — but compared to them, this is a crepe.

All kidding aside, this lens turned out to be a fantastic performer. I tried it out for a couple weeks on the K-01 and was impressed. People will ask you about it, too.

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Pentax DA 40mm f/2.8 Lens Reviews

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4 out of 5

Shortstack and sweet

Written By Rob G, Charlottesville, VA on Monday, May 06, 2013
This lens is very useful, especially if you like to do candid or street photography. Because it barely sticks out from the camera body, it's easy to use one handed, it makes an SLR feel light like a point and shoot but gives you the all the options of a DSLR. Very quick autofocus response time, and very sharp and easy to use in manual mode, even if you have big hands. The picture quality has been very good, the large aperture allows for low-light photos, and though it is not a true macro lens, the details come out very sharp shooting in close. The small lens doesn't allow for screw-on, there might be an aftermarket adapter.
Useful, large aperture at low light, responsive, light and compact.
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