Chroma SHO (S-II, H-a & O-III) 3nm f/3 Imaging Filter Set - 1.25", Mounted
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This set of three Chroma 1.25" round mounted 3nm filters is optimized for f/2.8 to f/3.6. Each filter has standard male filter thread (M28.5x0.6 thread specification) and can be attached to any astronomy accessory that has a standard 1.25” female filter thread. The cell height is 7mm so it will fit inside virtually all filter drawers/holders and filter wheels on the market. However, please verify this with your accessory before purchase.
Chroma's f/3.0 filters are designed to minimize spectral shift and hold their shape better in an f/3.0 beam.
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).
H-alpha filters are essential for imaging nebulae and other objects which are rich in ionized hydrogen. At 656.3nm, a narrow-band emission filter is required to separate H-alpha from the SII doublet (671.6nm and 673.1nm).
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.
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.
Useful Resources
Filter Cell Specifications
D = Filter Cell Diameter = 31.0 mm / 1.22 in
T = Total Filter Height = 7 mm / 0.28 in
C = Filter Cell Height (Excluding Male Thread) = 5.25 mm / 0.21 in
M = Male Thread Length = 1.75 mm / 0.07 in
F = USABLE Female Filter Thread Length = Not threaded, so you cannot stack additional filters
S = Glass Substrate Thickness = 3 mm / 0.12 in for all Chroma filters, except LoGlow filters which are 1.1 mm / 0.04 in thick
CA = Clear Aperture = 26.5 mm / 1.04 in
Other Information
- Country of Manufacture: United States
This set of three Chroma 1.25" round mounted 3nm filters is optimized for f/2.8 to f/3.6. Each filter has standard male filter thread (M28.5x0.6 thread specification) and can be attached to any astronomy accessory that has a standard 1.25” female filter thread. The cell height is 7mm so it will fit inside virtually all filter drawers/holders and filter wheels on the market. However, please verify this with your accessory before purchase.
Chroma's f/3.0 filters are designed to minimize spectral shift and hold their shape better in an f/3.0 beam.
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).
H-alpha filters are essential for imaging nebulae and other objects which are rich in ionized hydrogen. At 656.3nm, a narrow-band emission filter is required to separate H-alpha from the SII doublet (671.6nm and 673.1nm).
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.
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 set of three Chroma 1.25" round mounted 3nm filters is optimized for f/2.8 to f/3.6. Each filter has standard male filter thread (M28.5x0.6 thread specification) and can be attached to any astronomy accessory that has a standard 1.25” female filter thread. The cell height is 7mm so it will fit inside virtually all filter drawers/holders and filter wheels on the market. However, please verify this with your accessory before purchase.
Chroma's f/3.0 filters are designed to minimize spectral shift and hold their shape better in an f/3.0 beam.
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).
H-alpha filters are essential for imaging nebulae and other objects which are rich in ionized hydrogen. At 656.3nm, a narrow-band emission filter is required to separate H-alpha from the SII doublet (671.6nm and 673.1nm).
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.
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.
Useful Resources
Filter Cell Specifications
D = Filter Cell Diameter = 31.0 mm / 1.22 in
T = Total Filter Height = 7 mm / 0.28 in
C = Filter Cell Height (Excluding Male Thread) = 5.25 mm / 0.21 in
M = Male Thread Length = 1.75 mm / 0.07 in
F = USABLE Female Filter Thread Length = Not threaded, so you cannot stack additional filters
S = Glass Substrate Thickness = 3 mm / 0.12 in for all Chroma filters, except LoGlow filters which are 1.1 mm / 0.04 in thick
CA = Clear Aperture = 26.5 mm / 1.04 in
Other Information
- Country of Manufacture: United States
Chroma SHO (S-II, H-a & O-III) 3nm f/3 Imaging Filter Set - 1.25", Mounted