The Lunt LS100MT with B3400 blocking filter is built for serious solar imaging. With a premium 100mm FPL-53 ED triplet at its core and a straight-through 34mm blocking filter, this configuration offers an unvignetted, high-illumination system ideal for full-frame cameras, complex imaging trains, and research-grade work.
Unlike smaller blocking filters that use a diagonal format, the B3400 is designed as a straight-through unit—allowing for the longest possible optical path and the cleanest light cone to reach your sensor. If your setup includes filter wheels, barlows, telecentric lenses, or off-axis guiders, the B3400 ensures nothing gets clipped or dimmed at the edges.
Why Choose the B3400 Blocking Filter?
Blocking filters are sized by the diameter (in millimeters) of their internal filter window. The B3400 offers a massive 34mm clear aperture, making it Lunt’s most capable option for large-sensor and high-magnification applications. When imaging the full solar disk with a full-frame sensor, or pushing the resolution with stacked optics, the B3400 provides the clean, vignette-free image circle advanced users need. The straight-through design also simplifies alignment in complex astrograph setups and helps reduce back-focus constraints.
Optical Excellence
The LS100MT is built around a 100mm f/7 FPL-53 ED triplet lens—offering crisp color correction and excellent contrast across the visual and hydrogen-alpha spectrum. This isn't just a great solar telescope—once converted for nighttime use, it becomes a high-performance refractor for general astronomy as well.
Solar Observing with Pressure Tuning
Lunt’s internal pressure tuning system shifts the central wavelength of the etalon evenly across the field, unlike tilt-tuned systems which can introduce uneven illumination. Pressure tuning allows you to bring out different features on the Sun by accessing various layers of the chromosphere—filaments, prominences, active regions, and granulation all stand out in greater detail.
Observing Tip:
When imaging the Sun with a full-frame or APS-H sensor, the straight-through B3400 eliminates the edge darkening common with smaller blocking filters. It’s also ideal if your setup includes barlows or telecentric systems where optical length adds up fast. For best results, ensure the telescope is thermally stabilized before observing or capturing data.
Important Safety Warning:
Never look at the Sun through this telescope—or any telescope—without the hydrogen-alpha etalon and blocking filter properly installed. Permanent eye damage or blindness will result. The telescope must be used exactly as designed for safe solar observing.
Engineered for Flexibility
The LS100MT is a true universal telescope. When solar observing is complete, the pressure-tuned module can be removed, and the included nighttime focuser installed in its place. You’re left with a 100mm f/7 apochromatic refractor—ideal for lunar and planetary detail, double stars, and wide-field deep sky work.
Mechanical Features
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100mm FPL-53 ED triplet optics
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714mm focal length (f/7)
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Internal pressure-tuned hydrogen-alpha etalon
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B3400 straight-through blocking filter (34mm aperture)
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Modular rear cell for solar/nighttime conversion
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Crayford or Feather Touch 2" focuser (nighttime use)
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Vixen-style dovetail and hinged ring assembly with solar finder handle
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Hard foam-lined case
What’s Included:
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Lunt LS100MT 100mm FPL-53 triplet optical tube
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Internal pressure-tuned etalon module
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B3400 straight-through blocking filter
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Rear focuser for nighttime use (Crayford or Feather Touch)
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Mounting rings, dovetail, and solar finder handle
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Foam-lined hard carry case
