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Baader Planetarium Semi-APO Filter 2"

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Baader Planetarium FSAPO-2: Picture 1 regular $147.00

About Baader Planetarium FSAPO-2

The Baader Planetarium Semi-APO filter 2" delivers an amazingly neutral view, while cutting most of the annoying and contrast-robbing violet fringe that plagues all achromats. The Semi-APO filter 2" combines a stronger Fringe Killer coating formula with the Moon & Skyglow Neodymium substrate. The result is similar performance to the Fringe Killer plus Moon & Skyglow combination, but with a slightly stronger violet cut and at an even greater value.

It's high efficiency and neutral coloration make it practically disappear in use, while making most of the violet fringe disappear! The effects on sharpness, contrast and aesthetics are remarkable, even with small refractors. The RGB enhancement of the Neodymium substrate actually boosts color contrasts, particularly for Jupiter and Mars.

Baader Planetarium FSAPO-2 Features

  • The Baader Planetarium Semi-APO Filter combines the stronger Fringe Killer coating formula with Moon & Skyglow Neodymium glass
  • This combination results in a stronger violet cut when used with all refractors, but also blocks out skyglow from light pollution & the Moon, providing views with better contrast & sharpness
  • The Baader Planetarium Semi-APO Filter RGB enhancement boosts color contrast, particularly on Jupiter and Mars
  • A great Mars filter for all telescopes, including SCTs and Dobsonians

Baader Planetarium FSAPO-2 Specifications

Filter Size
2" / 50.8mm
Mfr #

Baader Planetarium FSAPO-2 Reviews Powered by TurnTo®

Reviewed by 1 customers


Works better than expected!


I got this to use with a short-tube achro refractor I use for wide-field astrophotography with either a stock Canon DSLR or a CCD astro camera. I've tried other filters (e.g. UV/IR cut) to reduce the purple fringing around bright stars, but none performed well. This Baader semi-APO does the job, almost eliminating the false color and purple halos around even the brighter stars. Short of getting a triplet apochromat you can't do better (and for a lot less money).

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