Solar Filters

No. An unfiltered telescope aimed at the Sun concentrates enough energy to cause permanent eye injury in a fraction of a second, and it can destroy an eyepiece or a camera sensor just as fast. Every product on this page exists so that the Sun is filtered before the light is concentrated, not after.

A white light filter such as the Lunt White Light Solar Wedge cuts the intensity across the whole visible spectrum. You see the photosphere: sunspots, granulation and faculae, in a crisp neutral image. A hydrogen-alpha etalon set isolates one extremely narrow wavelength and shows the chromosphere instead: prominences on the limb, filaments and flare activity across the disk. They show two different layers of the Sun, so many observers eventually own both.

The etalon at the front of the telescope narrows the light to roughly the hydrogen-alpha line, but it also passes several secondary bands. The blocking filter sits at the focuser and rejects everything except the one band you want. Without it you get a washed out image and an unsafe amount of energy reaching the eyepiece. An etalon and a blocking filter are two halves of one system and neither works alone.

The number is roughly the clear aperture of the blocking filter in tenths of a millimetre, so B600 is 6mm and B3400 is 34mm. A larger blocking filter passes a larger fully illuminated field. B600 suits visual use on smaller apertures. B1200 is the common choice for visual work at 100mm and for imaging with small sensors. B1800 and B3400 are for full disk imaging with larger sensors and for the biggest instruments. If you are unsure, call us with your telescope and camera and we will tell you which one clears your sensor.

The sets are sized by the aperture of light they pass: 50mm, 60mm and 100mm. They mount on the front of a refractor. If your refractor is larger than the set, the set simply stops it down to its own size, which is perfectly usable. Reflectors and most catadioptric telescopes are not suitable because of the heat load on internal optics. If you would rather not adapt an existing scope, our solar telescopes arrive already filtered.

Double stacking puts a second etalon in the light path. That roughly halves the bandwidth, which raises surface contrast noticeably: filaments darken, active regions gain structure, and the disk stops looking flat. The tradeoff is a dimmer image and a significant increase in cost. Most people single stack first and add the double stack etalon later once they know they want it.

Calcium K sits in the near ultraviolet at about 393nm and reveals the chromospheric network and bright plage around active regions. It looks nothing like the hydrogen-alpha view. Because the wavelength is at the edge of human sensitivity, many observers find it more rewarding as an imaging target than a visual one. The Calcium K Blocking Filter Module is the way in.

Yes, and that is where much of this equipment earns its keep. For imaging, pay attention to two things: pick a blocking filter large enough to illuminate your sensor fully, and consider a pressure tuner or double stack if you want maximum surface contrast. Our accessories range includes the adapters and tuning hardware that go with a solar imaging train.

It is a variable brightness control. Two polarizers rotate against each other so you can reduce image intensity smoothly rather than in fixed steps. At under fifty dollars it is the cheapest way to make a bright solar or lunar image comfortable to look at for long sessions.

The full aperture etalon sets are designed to mount to a range of refractor tube diameters and are the most adaptable items here. The blocking filters use standard 1.25 inch and 2 inch fittings. The double stack modules and the high resolution glass upgrade are matched to specific Lunt bodies and are listed with the models they fit. When in doubt, tell us the exact telescope you own before ordering.

Keep it capped and dry, and treat the etalon like the precision optic it is. Do not disassemble it, and clean the outer surfaces only when genuinely necessary using proper optical technique. Inspect any solar filter for pinholes, scratches or delamination before every single session. If you find damage of any kind, do not use it.

Then start with a purpose built instrument instead. Our solar telescopes collection runs from the LS50THa at $995.99 to the LS230THa at $39,995.99, with the safety filtering engineered into the telescope rather than added to it. If you are weighing the two paths, our buying guide walks through the decision.