Ha 6.8nm Filter

$227.4 ~~$379~~ In stock

The IDAS Hydrogen-Alpha family of filters allows astrophotographers to select an Hα filter optimally tailored to their equipment.

Features include:

6.8 nm bandpass (measured value 6.5 +/- 0.1 nm)
98% transmission (measured value)
IR blocking out to 1200 nm
2.5mm and 3.0mm filter thickness options
Configurations:
- 50.8mm for filter wheels (QHY/ZWO/Atik)
- 48mm and 52mm mounted
Each filter is individually measured and inspected for quality
3 classes* available: STD, HS, UHS
Made in Japan

The IDAS Ha-6.8 family includes 3 options - STD (Standard), HS (High Speed) and UHS (Ultra High Speed) with bandpasses adjusted to accommodate the f-ratio of different speed astrographs. In addition each class comes in two different glass thicknesses - 2.5 mm & 3.0 mm.

STD - recommended for most regular scopes
HS - ideal for the optics between F2.0 and F3.5 such as Takahashi Epsilon Series, RASA11, and standard camera lenses
UHS - highly optimized for the optics for F2.2 or faster such as RASA8 and HyperStar Series

Prices are the same across the filter family regardless of the option selected. Filters are designed to fit in 50.8mm QHY, ZWO and ATIK filter carousels.

Reflection Test Sample:

This test (200 second exposure) shows clean images of bright stars in the field, indicating good anti-reflection (AR) design.

(Enlargement)

Another set of photos from the Orion belt region demonstrates the lack of reflection artifacts around bright stars.

Sigma 105mm@F2 + IDAS Ha 6.5nm HS 52mm + ASI 2600MM, 30 x 5 minutes (gain 0), Bortle 8 sky

Closeup shot including bright belt stars Alnitak and Alnilam.

Examples from Bortle 8 skies (5-minute exposures):

Cygnus wide-field.

Also from Bortle 8 skies - Simeis 147

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Customer Reviews (4.4 / 5 · 5 reviews)

Madison ★★★★★ Oct 20, 2026

Finally got this 6.8nm filter dialed in on my rig, and the sharp contrast on those faint nebula details is exactly what I was hoping for. The tight bandpass really cuts through light pollution without losing signal.

Sofia ★★★★★ Oct 19, 2026

The 98% transmission really makes a difference in capturing those faint hydrogen-alpha details. I paired it with my fast scope and the 6.8nm bandpass kept the background sky nice and dark. My first test shots had noticeably sharper nebula contrast than with my old filter.

Andrew ★★★★★ Oct 18, 2026

I finally got my hands on this 6.8nm Ha filter, and the measured 6.5nm bandpass is incredibly tight, cutting out nearly all the light pollution from my backyard. The 98% transmission really makes those faint nebula details pop in my images, even on my stock DSLR. It’s a huge step up from my old broa