Lunt Double Stack Etalon Filter for MT Telescopes
Narrow The Bandwidth On Your MT Telescope
A double stack etalon puts a second filter in series with the etalon already in your Lunt MT telescope. Single stack gives you 0.7 Angstrom or better. Adding the second etalon takes the system to 0.5 Angstrom or better, and Lunt reports tighter figures near 0.28 Angstrom on current internal modules. Contrast on the disk climbs sharply.
Choose the version that matches your telescope. The LS50FHaP and LS60FHa front mount on the LS60MT and LS60THa. The internal SFPT module drops inside the LS80MT and LS100MT. The LS130MTP module serves the LS130MT. The LS100FHa front mount covers the LS100MT and LS100THa. Each one leaves the night sky configuration untouched.
At the narrower bandwidth you see filaments resolve into dark cores and multiple strands, plage boundaries sharpen into cellular networks, and active regions show more magnetic structure. The trade is brightness, so plan on lower magnification or longer exposures. Pressure tuning shifts the passband on and off band without tilting the etalon, and the internal modules install without a factory return.
Key Features
- Second Etalon In Series - stacks a second precision etalon with the one already in your telescope to cut the combined bandwidth.
- 0.5 Angstrom Or Better - takes a 0.7 Angstrom single stack system down to 0.5 Angstrom or better, with Lunt quoting under 0.28 Angstrom for the current internal modules.
- Front Mount Or Internal - arrives as a front mounted filter for 60mm and 100mm class systems, or as an internal module for the 80mm, 100mm and 130mm tubes.
- Doppler True Pressure Tuning - shifts the passband on and off band without tilting the etalon, and the internal SFPT adds a second independent tuning knob.
- Customer Installed - fits without a factory return, so the double stack can be added at purchase or at any point afterward.
- Night Sky Unaffected - leaves the telescope in its night configuration once the solar module comes out for deep sky use.
| Specifications | |
|---|---|
| Model / SKU | LS50FHaP, LS60FHa, DSII/SFPTP, DSII/LS130MTP, LS100FHa |
| Type | double stack hydrogen alpha etalon filter for Lunt MT and THa telescopes |
| LS50FHaP 50mm | front mounted 50mm etalon, fits the LS60MT and LS60THa |
| LS60FHa 60mm | front mounted 60mm etalon, fits the LS60MT and LS60THa |
| DSII/SFPTP Internal | small format internal module, fits the LS80MT and LS100MT |
| DSII/LS130MTP Internal | internal module, fits the LS130MT |
| LS100FHa 100mm | front mounted 100mm etalon, fits the LS100MT and LS100THa |
| Clear Aperture | 50mm, 60mm or 100mm on the front mounted versions with no central obstruction, matched to the host telescope on the internal modules |
| Bandwidth | 0.5 Angstrom or better combined, with Lunt publishing under 0.28 Angstrom for the current SFPT and LS130 internal modules |
| Single Etalon Bandpass | 0.4 Angstrom on the LS50FHa, LS60FHa, SFPT and LS130 modules as published by Lunt |
| Tuning | Lunt Pressure Tuning on the internal modules with dual independent knobs on the SFPT, tilt tuning on the front mounted etalons |
| Blocking Filter | required at all times, sold separately |
| Mounting | threads or clamps to the front cell on the front mounted versions, installs inside the optical path on the internal modules |
| Weight | LS50FHa 10 lb shipping, LS60FHa 11 lb shipping, SFPT module 7 lb shipping, LS130 module 7 lb shipping, LS100FHa Not published |
| What's Included | etalon filter assembly and aluminium hard case with fitted foam on the front mounted versions |
| Warranty | 5 years from date of purchase against manufacturing and workmanship defects |
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