Sulfur II Narrowband Filter

$198 ~~$275~~ In stock

Category: Filters

Description

SII filters isolate the emission from ionized Sulfur atoms, also common in nebulae. Emission is at two lines occurring as a doublet, at 671.6 and 673.1 nm.

Specifications

Parfocal for systems f/4.0 or slower
Transmitted wavefront better than 0.25 waves/inch
Parallelism: less than 30 arcsec
Made in America

Before you pay

Check the method and total at checkout.

When it ships

Allow for processing time as well as the journey to you.

Standard Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

Express Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

View policy

If you need a refund

Keep your order number and contact the store to start.

Please contact us for the refund processing timeframe before returning an item.

View policy

Delivery costs

Review the cost for your destination and chosen service.

Standard Shipping · United States: $0.00

Express Shipping · United States: $3.99

View policy

Returning an item

Check the return conditions before sending anything back.

United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

View policy

Customer Reviews (4.6 / 5 · 5 reviews)

George W. ★★★★★ Oct 21, 2026

I was worried about keeping focus across my whole imaging rig, but this filter being parfocal with my other gear made swapping between SII and Ha bands seamless. The doublet at 671.6 and 673.1 nm really pulled out those wispy sulfur structures in the Bubble Nebula.

Scarlett ★★★★★ Oct 20, 2026

My first test image showed crisp, clean detail in the Sulfur II lines, and the parfocal design meant I didn't have to refocus between filters. It locks onto those 671.6 and 673.1 nm wavelengths exactly as described, giving me a much cleaner separation of the nebula’s structure than my older filter.

Miles T. ★★★★★ Oct 18, 2026

Finally got clear skies to test this SII filter, and the parfocal design meant no refocusing needed between exposures. The doublet lines at 671.6 and 673.1 nm really brought out the sulfur detail in the nebula.