OIII 3nm Bandpass optimized for f/2.8-f/3.6

$391 ~~$575~~ In stock

Description

Chroma’s OIII filters isolate the 500.7nm primary emission line of doubly ionized oxygen. After H-alpha, this is the next most common emission when imaging nebulae. Chroma’s f/3.0 filters are designed to minimize spectral shift and hold their shape better in an f/3.0 beam.

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Customer Reviews (4.6 / 5 · 5 reviews)

Edward ★★★★★ Oct 21, 2026

Shot a couple of emission nebulae last night at f/3 and the contrast against the sky background was noticeably better than with my old filter. The 3nm bandpass really isolates the OIII signal without cutting too much of the star field.

Ruby Q. ★★★★★ Oct 20, 2026

The 500.7nm line comes through so clean on my f/3 scope that the background sky just falls away, even with a nearly full moon up. The bandpass is tight enough that I don't get that washed-out haze on the edges of the image. Worth every penny for narrowband work.

Thomas P. ★★★★★ Oct 18, 2026

I’ve been running this OIII filter on my f/3 scope and the contrast on the Veil Nebula is noticeably better than my old 6nm filter, especially with the narrow 3nm bandpass. It’s sharp even at the edge of my field, which I didn’t expect. Definitely worth it for narrowband imaging.