Lunt H-Alpha Blocking Filter
Choose The Right Blocking Filter Aperture
A Lunt blocking filter is required with every Lunt hydrogen alpha etalon or telescope. It is not just a stop; the housing carries an additional filter stack that makes the package safe and gives the final image its contrast. Lunt only warrants safety and performance when one of its own blocking filters sits in the optical path.
Clear aperture sets how much of the light cone gets through. B600 gives 6 mm, B1200 gives 12 mm, B1800 gives 18 mm and B3400 gives 34 mm. Larger apertures hold a fully illuminated field at longer focal lengths, which is what full disc imaging with a bigger sensor needs. Match the size to your telescope focal length.
Housings come in three styles. The s versions are 2 inch straight through tubes with T2 and 2 inch connections. The d1 versions are star diagonals with a 1.25 inch eyepiece holder and a T2 connection, and the d2 versions are star diagonals with a 2 inch eyepiece holder and T2. For imaging, step up one size from the visual recommendation.
Key Features
- Safety Critical - required in the optical path of every Lunt hydrogen alpha etalon or telescope
- Four Clear Apertures - 6 mm, 12 mm, 18 mm and 34 mm to suit different focal lengths
- Straight Through - the s housings are 2 inch extension tubes with T2 and 2 inch connections
- Star Diagonal - d1 and d2 housings add a star diagonal with a 1.25 inch or 2 inch eyepiece holder
- Imaging Headroom - step one size up from the visual recommendation to allow for extra back focus
- Full Disc Imaging - the larger apertures keep the field fully illuminated for big sensor full disc work
| Specifications | |
|---|---|
| Type | Hydrogen alpha blocking filter module |
| Wavelength | Hydrogen alpha, 656.28 nm |
| B600 | 6 mm clear aperture, visual to 600 mm focal length, imaging to 400 mm |
| B1200 | 12 mm clear aperture, visual to 1200 mm focal length, imaging to 600 mm |
| B1800 | 18 mm clear aperture, visual to 1800 mm focal length, imaging to 1200 mm |
| B3400 | 34 mm clear aperture, visual to 3400 mm focal length, imaging to 1800 mm |
| Straight Through Housing | 2 inch extension tube with T2 and 2 inch connections, suffix s |
| 1.25 Inch Diagonal Housing | Star diagonal with 1.25 inch eyepiece holder and T2 connection, suffix d1 |
| 2 Inch Diagonal Housing | Star diagonal with 2 inch eyepiece holder and T2 connection, suffix d2 |
| B3400 Housing | 2 inch straight through extension tube only, no diagonal option published |
| Compatibility | Lunt hydrogen alpha etalon filters and Lunt solar telescopes |
| Additional Sizes Published | A B400 4 mm and a B500 5 mm filter, both in 1.25 inch diagonals, also appear on the Lunt storefront |
| Storefront SKU Format | Straight through options are listed as B600s2, B1200s2 and B1800s2, and the 34 mm filter as B3400 |
| Model / SKU | B600s, B600d1, B600d2, B1200s, B1200d1, B1200d2, B1800s, B1800d1, B1800d2, B3400s2 |
| Shipping Weight | 2 lb, published as 907 grams for every variant |
| Warranty | 5 years from date of purchase, original purchaser, manufacturing and workmanship defects |
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