Pentax 100mm f/2.8 SMC D FA Macro Autofocus Lens for K-Mount {49}

Pentax's weather-sealed 100mm macro with 1x magnification

The SMC D-FA 100mm f/2.8 Macro WR is a full-frame prime built around a 9-element, 8-group optical formula that delivers true 1x magnification at a minimum focus distance of 0.3 meters. Eight rounded aperture blades produce smooth out-of-focus rendering across the aperture range from f/2.8 to f/32, which matters as much at portrait distances as it does when you're working close. At 340 grams and 81mm long, it's a compact enough package that it doesn't upset the balance of a mid-sized Pentax body.

Weather sealing is the specification that separates this lens from unprotected macro alternatives in the Pentax ecosystem. Paired with any of Pentax's weather-resistant bodies, you can work in rain, dust, or humid field conditions without pulling back. Autofocus runs off the camera's screw-drive motor, and full-time manual override means you can fine-tune focus mid-shot without switching modes. A depth-of-field scale is engraved on the barrel, a practical detail that's genuinely useful when shooting stopped down for macro work. The 49mm filter thread keeps accessory costs low, and a hood ships in the box. For Pentax shooters who want a single lens that handles macro, portrait, and outdoor work without a weatherproofing compromise, this is a proven and choice.

Who It's For

Nature and field macro photographers working with weather-resistant Pentax bodies get the most direct benefit, since the WR sealing means conditions that would sideline an unprotected lens are no obstacle. Portrait shooters will find the f/2.8 maximum aperture and 8 rounded blades produce subject separation at normal working distances. Product and still-life photographers gain from the 1x magnification and full-time manual focus override for precise control. Hikers and travel photographers carrying a single prime appreciate the 340-gram weight and compact 81mm length.

Key Features

• 100mm focal length with 1x magnification at 0.3m minimum focus
• 9-element, 8-group optical design with 8 rounded aperture blades
• Weather-sealed construction for rain and dust resistance
• Full-time manual focus override with screw-drive autofocus
• Depth-of-field scale engraved on barrel for macro work
• 340g body with 81mm length balances mid-sized Pentax cameras
• 49mm filter thread with included hood

FAQ

Does this lens work with all Pentax bodies?

It mounts to any Pentax KAF mount body, but autofocus requires the camera's screw-drive motor - older film bodies and some entry-level DSLRs lack this. Manual focus works on everything with the mount.

How close can you focus?

Minimum focus distance is 0.3 meters (11.81 inches), which gives you the full 1x magnification for true 1:1 macro work.

Is weather sealing adequate for outdoor field work?

Yes, the WR designation means the lens is weather-sealed for rain, dust, and humidity. Pair it with a weather-resistant Pentax body and you have a sealed macro system.

Can you manually adjust focus while autofocus is active?

Yes, full-time manual override lets you fine-tune focus without switching modes or turning off AF. Just rotate the focus ring during or after autofocus acquisition.

What's the filter size and does it come with a hood?

49mm filter thread. A hood is included in the box.

How does the depth-of-field scale help in macro work?

The engraved DOF scale on the barrel lets you see at a glance how much of your subject will be sharp when stopped down - critical for macro where depth is thin even at f/16 or f/22.

Does the lens have an aperture ring?

No, aperture is controlled from the camera body. This is standard for modern Pentax lenses.