Lunt 40mm Center Obstructed H-Alpha Filter Set
Turn Your Refractor Into A Solar Scope
This 40mm center obstructed H-alpha set from Lunt mounts over the centre of your existing refractor objective, converting a night sky instrument into a solar telescope in seconds. The 40mm etalon delivers a bandpass below 0.65 Angstrom at 656.28 nm, so prominences, filaments, active regions and chromospheric texture all come into view without a dedicated solar tube.
Tuning is by tilt, so you angle the housing to centre the hydrogen alpha line and start observing. There are no pressure systems, no air pumps and no external controls to manage. A centre mounted foot supports the etalon, which means the filter carries a central obstruction; plan your aperture and contrast expectations around that design choice.
Each set ships with your choice of a B600 or B1200 blocking filter and one machined adapter plate sized to your telescope, included in the set. The plate is matched to the outside diameter of your dew shield, so to measure for your adapter plate take a measurement of the outside diameter of the dew shield on your refractor telescope. Nine plate steps run from 55 to 60 mm up to 95 to 100 mm, covering objective housings up to 4 inches. Removal takes seconds when the refractor is needed for night use.
Key Features
- Front Mounted - etalon sits over the centre of your existing refractor objective and lifts off in seconds
- Bandpass - rated below 0.65 Angstrom at the 656.28 nm hydrogen alpha line
- Tilt Tuned - wavelength control by angling the housing, with no pressure or pump hardware
- Blocking Filter Choice - supplied with either a B600 or a B1200 blocking filter
- Adapter Plate Included - one plate machined to the outside diameter of your dew shield, from 55 mm to 100 mm, comes with the set
- Centre Obstruction - a central support foot holds the etalon, so the clear aperture is obstructed at the middle
| Specifications | |
|---|---|
| Type | Front mounted center obstructed hydrogen alpha etalon filter set |
| Etalon Aperture | 40 mm, center obstructed by the support foot |
| Wavelength | Hydrogen alpha, 656.28 nm |
| Bandpass | Less than 0.65 Angstrom |
| Tuning | Tilt tuned |
| Blocking Filter Options | B600 with 6 mm clear aperture, or B1200 with 12 mm clear aperture |
| B600 Suitability | Lunt lists the included B600 for focal lengths up to 540 mm |
| B1200 Suitability | Lunt lists the B1200 for visual use to 1080 mm and imaging to 540 mm |
| Adapter Plate | One plate included with the set, chosen at checkout |
| Adapter Plate Sizing | Measured on the outside diameter of the dew shield on your refractor, ranges 55-100 mm |
| Adapter Plate Sizes Published | 55-60, 60-65, 65-70, 70-75, 75-80, 80-85, 85-90, 90-95 and 95-100 mm, taken on the dew shield outer diameter |
| Adapter Plate Codes | LS40-CO-AP5560 through LS40-CO-AP95100 |
| Objective Cell Limit | Objective housings up to 4 inches |
| Use | Visual and imaging |
| Model / SKU | LS40F-CO-B600 and LS40F-CO-B1200, plus adapter plate codes LS40-CO-AP5560 through LS40-CO-AP95100 |
| Storefront Listing | Published as Lunt LS40F Hydrogen-Alpha Front-Mounted Etalon System B600 and B1200 |
| Shipping Weight | Not published |
| Warranty | 5 years from date of purchase, original purchaser, manufacturing and workmanship defects |
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