Vintage Nikon Nikkor Extension Ring Set K stacked macro tubes showing K3, K5, K4, and K2 rings on suede background

Nikon SLR Lens Extension Ring Set K (5-Piece Macro Tube Kit)

$58.00 CAD
$58.00 CAD

WHAT CONDITION THE CONDITION IS IN: 88-Day Confirmed Operation Warranty. Clean and pristine. Some very minor wear marks, only noted for full disclosure. Scroll down if you want to learn about the design, performance, and story behind it. Or don’t. It’ll be here either way.

Somewhere in a Tokyo camera shop in 1968, a Nikon engineer looked at a perfectly good lens and thought, what if we made it worse, but on purpose, and in five interchangeable pieces? Thus was born the Extension Ring Set K, a deceptively modest collection of metal tubes that contains absolutely no glass, performs no optical wizardry, and yet manages to transform ordinary lenses into macro instruments of surprising capability.

The K-set's genius, if we're being generous, and why not, it's Tuesday, lies in its hybrid identity. With a Nikon F bayonet on one end and 52mm screw threads on the other, it has the rare distinction of being useful in at least three different ways: as an extension tube, a deep lens hood, or, combined with a reversing ring, a "poor man's macro" solution that would make any cheapskate beam with pride.

Ranging from 5mm to 20mm of extension across five rings, the set lets you creep closer to your subject while simultaneously robbing you of working distance, depth of field, and light. It's a transaction that feels a bit like getting a raise and discovering your taxes went up.

The K-set has very firm opinions about who it will and won't associate with. Modern Nikon DSLRs with an AI tab, your D850s, your D750s, the whole respectable lot, risk actual mechanical damage if they so much as flirt with these rings. However, Z-series bodies, the D3000, the D5000, and any vintage F mount camera that remembers the Nixon administration are perfectly welcome at the table.

There's no autofocus, no automatic diaphragm, and no digital hand-holding of any kind. You stop down manually, you meter manually, and you think, which is either a meditative return to photographic fundamentals or an inconvenience. The K-set is a relic that refuses to behave like one: still useful, still versatile, and still capable of making you work for something beautiful.

Technical Specifications
  • Manufacturer: Nippon Kogaku K.K. / Nikon (Tokyo, Japan)
  • Product Model: Extension Ring Set K (5-Piece Modular Macro Ring Set)
  • Production Era: Introduced circa 1968 (Pre-AI Nikon F era)
  • Optical Construction: None (hollow metal mechanical extension spacers; zero optical glass / zero image degradation)
  • Mount & Thread Standards: Nikon F Bayonet mount & standard 52 mm × 0.75 mm screw thread

Individual Ring Specifications & Thread Configuration

  • Ring K1: Female Nikon F Bayonet to Male Nikon F Bayonet — 5.8 mm extension (can be used as a standalone bayonet tube)
  • Ring K2: Female 52 mm thread to Male Nikon F Bayonet — 5.0 mm extension
  • Ring K3: Female Nikon F Bayonet to Male 52 mm thread — 5.8 mm extension
  • Ring K4: Female 52 mm thread to Male 52 mm thread — 10.0 mm extension
  • Ring K5: Female 52 mm thread to Male 52 mm thread — 20.0 mm extension

Extension Combinations & Macro Performance

  • Extension Range: Provides 9 distinct extension steps from 5.8 mm to 46.6 mm
  • Alternative Uses: Screw-in deep lens hoods, 52 mm filter spacers, and reverse-lens macro configurations (paired with Nikon BR-2 / BR-2A reversing rings)

Operation & Mechanical Interface

  • Diaphragm & Metering: Fully manual operation (stop-down metering required; no auto-aperture diaphragm lever coupling)
  • Focusing: Manual focus only
  • Interior Finish: Matte anti-reflective internal ridging/flocking to eliminate internal flare and ghosting
  • Chassis Construction: Machined solid brass and aluminum alloy with satin black finish and engraved white lettering