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Pentax 300mm f/4 SMC Lens

The Pentax 300mm f/4 is a 300mm f/4 lens designed for Pentax K mount cameras. Check GearFocus for current availability, with buyer protection on every purchase.

Pentax 300mm f/4 SMC Lens

Pentax 300mm f/4 SMC Lens

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Lens Overview — Pentax 300mm f/4

The Pentax 300mm f/4 SMC is a manual focus, full-frame telephoto prime lens built for the Pentax K mount. With a fixed 300mm focal length, it delivers a consistent telephoto perspective well-suited to subjects like wildlife, sports, and portraiture at distance. The maximum aperture of f/4 provides a reasonably bright view through the finder and enables meaningful subject separation at telephoto distances.

As a prime lens, it offers a straightforward optical design without the mechanical complexity of a zoom mechanism. Autofocus is not available on this lens — operation is entirely manual, which suits deliberate, methodical shooters who prefer direct control over focus placement. The 77mm filter thread is a common professional size, making it easy to pair with filters you may already own.

Weighing 925g, this is a substantial but manageable telephoto prime. Image stabilization is not present, so steady technique or a tripod is advisable at 300mm. Designed for full-frame coverage, it will also work on APS-C Pentax K mount bodies without vignetting concerns.

This lens is a practical choice for Pentax K mount shooters seeking a dedicated 300mm prime with manual focus operation.

Key Features — Pentax 300mm f/4

300mm Prime Focal Length: Fixed telephoto perspective with no zoom trade-offs, well-suited to wildlife, sports, and distant subjects.

f/4 Maximum Aperture: Provides a reasonably bright viewfinder image and meaningful subject separation at telephoto distances.

Pentax K Mount: Designed for the Pentax K mount system, compatible with both film and digital Pentax K mount bodies.

Full-Frame Coverage: Covers a full-frame image circle and can also be used on APS-C Pentax K mount bodies without vignetting.

Manual Focus Operation: Entirely manual focus design suits deliberate shooters who prefer direct control over focus placement.

SMC Optical Coating: Super Multi-Coated glass helps reduce flare and ghosting for improved contrast in backlit or high-contrast situations.

Lens Specifications — Pentax 300mm f/4

Pentax 300mm f/4 full specifications
SpecDetail
Use CasesWildlife, Sports, Birding
Lens TypePrime
FormatFull Frame
Zoom/PrimePrime
Focal Length300mm
Maximum Aperturef/4
Camera SystemDSLR
Lens MountPentax K
AutofocusNo
Focus TypeManual
Image StabilizationNone
Filter Thread77mm

Description — Pentax 300mm f/4

The Pentax 300mm f/4 SMC is a 300mm telephoto prime lens designed for the Pentax K mount, offering full-frame coverage suitable for Pentax K mount DSLRs. With a maximum aperture of f/4, it delivers a bright enough image at telephoto distances for a range of subjects including nature, sports, and distant portraiture. Focus is entirely manual, appealing to photographers who prefer hands-on control and deliberate shooting.

The lens weighs 925g, making it a solid but portable option in the 300mm telephoto prime category. A 77mm filter thread allows straightforward use of common professional filters. There is no image stabilization, so technique and support equipment become important considerations when shooting handheld.

As a prime lens, the fixed focal length keeps the optical path simple and consistent. This lens is a focused, no-frills option for Pentax K mount shooters who want a dedicated 300mm manual focus telephoto.

Pros — Pentax 300mm f/4

  • ✓Fixed 300mm focal length provides a dedicated telephoto prime with no zoom compromise
  • ✓Full-frame coverage on Pentax K mount bodies, usable on APS-C as well
  • ✓Maximum aperture of f/4 offers a reasonably bright image at 300mm

Cons — Pentax 300mm f/4

  • ✗Manual focus only — no autofocus support, which limits use in fast-moving or action scenarios
  • ✗No image stabilization, making handheld shooting at 300mm more challenging
  • ✗Pentax K mount compatibility limits use to Pentax K system bodies without an adapter

Resources & Downloads — Pentax 300mm f/4

Manuals & Guides

Frequently Asked Questions — Pentax 300mm f/4

Does this lens support autofocus?+
No. The lens is manual focus only. There is no autofocus motor or electronic AF drive of any kind, so focus must be set entirely by hand.
What camera mount does this lens use?+
The lens is built for the Pentax K mount. It is designed for use with Pentax K mount DSLR cameras.
Will this lens cover a full-frame sensor?+
Yes. The lens is specified as full-frame format, meaning it provides sufficient image circle to cover a full-frame sensor without vignetting. It will also work on Pentax APS-C bodies.
What filter size does this lens accept?+
The lens has a 77mm filter thread, which is a common size among professional telephoto lenses and compatible with a wide range of filters.
Does this lens have image stabilization?+
No. Image stabilization is listed as None in the specifications. Handheld shooting at 300mm will require careful technique, and use of a tripod or monopod is advisable for sharp results.

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