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28mm Diameter OIII Filters

  • 27500

This item is out of stock but you can place an order now and we’ll ship when it becomes available.


  • AR: Durable AR coatings on both exterior surfaces over applicable transmission range
  • Scratch Dig: 60/40 or better (max scratch width 0.006mm, max dig 0.40mm)
  • Transmitted wavefront better than 0.25 wave/inch
  • Parallelism: Better than 30 arcsec
  • Thickness: 3.0 +/- 0.05mm
  • Designed for f/4.0 or slower


The FLI high transmission filters are manufactured in the United States with the highest quality fabrication techniques available. We offer a full line of filter types and sizes. Complete sets are available as well as individual filters in both round and square shapes.These filters are A/R coated Johnson/Bessell filters that are blocked up to 1200nm


FLI Research Grade filter sets are par focal to F4.0 (individual filters are also available)
Size: 28 mm
Shape: Round
Thickness: 3mm +/-0.05mm
Bandwidth: 8nm, 5nm, 3nm available

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