Chroma S-II (3nm) Imaging Filter - 31mm Round Unmounted
Stock count is accurate & shown in real time.
- This item is out of stock.
- Sign up for back-in-stock alerts to be notified when this item becomes available (account login required).
- This item is out of stock.
- Sign up for back-in-stock alerts to be notified when this item becomes available (account login required).
Contiguous US / Lower 48:
Free shipping applies to orders over $50 using our chosen carrier/method. Faster paid options are available at checkout.
Alaska, Hawaii & US Territories:
Free shipping applies to many—but not all—products. Enter your ZIP code in cart or upon checkout to confirm options and costs.
International:
International orders do not qualify for free shipping. Shipping, duties, brokerage, tariffs, and taxes are the customer’s responsibility. Some items may be restricted due to export, size, or manufacturer limitations.
This Chroma 31mm round unmounted 3nm SII filter will fit inside virtually all filter drawers/holders and filter wheels on the market. However, please verify this with your accessory before purchase. The glass substrate thickness is 3mm.
SII Filter for Narrowband Imaging
SII filters isolate the spectral emission of singly ionized sulfur atoms, also common in nebulae. Emission is at two lines occurring as a doublet, at 671.6 and 673.1 nm. This filter also separates sulfur emission from H-alpha emission (656.3nm).
About Chroma Filters
Chroma manufactures the highest quality astronomy filters with durable, sputtered hard coatings using single substrates of the best glass, eliminating the need for laminations. All primary filter coatings are applied on the front surface and anti-reflection coatings on the rear surface to prevent ghosting and to maximize transmission. Highly precise and accurate, the passbands of Chroma filters remain spectrally stable and do not drift in response to extreme temperature fluctuations or changes in humidity. All filters may be used with focal ratios of f/4 or slower.
Cleaning, Handling, and Orientation
Handle Chroma filters by the edges only. Clean gently only if necessary. Loose particles should be removed with a bulb puffer or filtered, pressurized air cleaner. If necessary, gently wipe surface using anhydrous alcohol and lint-free lab towels. Use new surface of towel with each wipe.
- AVOID TOUCHING OR WIPING A/R COATED OR METAL MIRROR SURFACES
- AVOID HANDLING EXPOSED COATINGS WITH BARE FINGERS
Proper orientation of the filter is recommended for maximize performance. These filters should be mounted with the coated surface toward the light source and the AR-coated side towards the camera sensor. The AR-coated side can be easily identified because you can look right through the AR side into the filter. The front side, on the other hand, is highly reflective to prevent unwanted light from passing through.
Other Information
- Country of Manufacture: United States
This Chroma 31mm round unmounted 3nm SII filter will fit inside virtually all filter drawers/holders and filter wheels on the market. However, please verify this with your accessory before purchase. The glass substrate thickness is 3mm.
SII Filter for Narrowband Imaging
SII filters isolate the spectral emission of singly ionized sulfur atoms, also common in nebulae. Emission is at two lines occurring as a doublet, at 671.6 and 673.1 nm. This filter also separates sulfur emission from H-alpha emission (656.3nm).
About Chroma Filters
Chroma manufactures the highest quality astronomy filters with durable, sputtered hard coatings using single substrates of the best glass, eliminating the need for laminations. All primary filter coatings are applied on the front surface and anti-reflection coatings on the rear surface to prevent ghosting and to maximize transmission. Highly precise and accurate, the passbands of Chroma filters remain spectrally stable and do not drift in response to extreme temperature fluctuations or changes in humidity. All filters may be used with focal ratios of f/4 or slower.
Cleaning, Handling, and Orientation
Handle Chroma filters by the edges only. Clean gently only if necessary. Loose particles should be removed with a bulb puffer or filtered, pressurized air cleaner. If necessary, gently wipe surface using anhydrous alcohol and lint-free lab towels. Use new surface of towel with each wipe.
- AVOID TOUCHING OR WIPING A/R COATED OR METAL MIRROR SURFACES
- AVOID HANDLING EXPOSED COATINGS WITH BARE FINGERS
Proper orientation of the filter is recommended for maximize performance. These filters should be mounted with the coated surface toward the light source and the AR-coated side towards the camera sensor. The AR-coated side can be easily identified because you can look right through the AR side into the filter. The front side, on the other hand, is highly reflective to prevent unwanted light from passing through.
This Chroma 31mm round unmounted 3nm SII filter will fit inside virtually all filter drawers/holders and filter wheels on the market. However, please verify this with your accessory before purchase. The glass substrate thickness is 3mm.
SII Filter for Narrowband Imaging
SII filters isolate the spectral emission of singly ionized sulfur atoms, also common in nebulae. Emission is at two lines occurring as a doublet, at 671.6 and 673.1 nm. This filter also separates sulfur emission from H-alpha emission (656.3nm).
About Chroma Filters
Chroma manufactures the highest quality astronomy filters with durable, sputtered hard coatings using single substrates of the best glass, eliminating the need for laminations. All primary filter coatings are applied on the front surface and anti-reflection coatings on the rear surface to prevent ghosting and to maximize transmission. Highly precise and accurate, the passbands of Chroma filters remain spectrally stable and do not drift in response to extreme temperature fluctuations or changes in humidity. All filters may be used with focal ratios of f/4 or slower.
Cleaning, Handling, and Orientation
Handle Chroma filters by the edges only. Clean gently only if necessary. Loose particles should be removed with a bulb puffer or filtered, pressurized air cleaner. If necessary, gently wipe surface using anhydrous alcohol and lint-free lab towels. Use new surface of towel with each wipe.
- AVOID TOUCHING OR WIPING A/R COATED OR METAL MIRROR SURFACES
- AVOID HANDLING EXPOSED COATINGS WITH BARE FINGERS
Proper orientation of the filter is recommended for maximize performance. These filters should be mounted with the coated surface toward the light source and the AR-coated side towards the camera sensor. The AR-coated side can be easily identified because you can look right through the AR side into the filter. The front side, on the other hand, is highly reflective to prevent unwanted light from passing through.
Other Information
- Country of Manufacture: United States
Chroma S-II (3nm) Imaging Filter - 31mm Round Unmounted