Daystar Combo Quark Chromosphere Solar Filter

The Daystar Combo Quark: An All-in-One 6562.8 Å Solar Eyepiece

The Daystar Combo Quark simplifies Hydrogen-Alpha solar astronomy by integrating a Fabry-Perot etalon, blocking filter, adapters, and snouts into a single, compact unit the size of a large eyepiece. This design eliminates the need to assemble a complex and costly filter train. It inserts directly into a 1.25" diagonal, accepts a standard 1.25" eyepiece, and is optimized for the 6562.8 Å wavelength of H-alpha light.

This filter is designed for observers who already own a long focal ratio telescope and want to explore the sun without investing in a new, dedicated solar scope. If light reaches the filter at an angle it causes wing shift, so the Combo Quark needs the slow F/15 to F/30 light of these instruments.

Observing the Chromosphere with a Bandpass of ~0.5Å

With a bandpass generally 0.5Å or narrower, the Combo Quark Chromosphere model is built to maximize contrast on the sun's turbulent surface. This narrow window into the H-alpha line isolates features in the chromosphere, a layer of incandescent gas above the visible photosphere. Instead of a blank, white disk, you see a textured surface shaped by magnetic fields.

Through the eyepiece, you can expect to resolve a wealth of detail that changes daily, even hourly. Look for these key features:

• Filaments: These are vast ribbons of plasma held suspended above the sun's surface by magnetic fields. They appear as dark, snaking lines because they are cooler than the chromosphere below them. When a filament rotates to the edge of the sun, it is seen in profile against the blackness of space and becomes a prominence.
• Plage: Bright, blotchy regions that often surround sunspots, indicating areas of intense magnetic activity. They are hotter and denser than the surrounding chromosphere and serve as clear markers for active regions.
• Active Regions: Complex zones where sunspots, plage, and filaments are concentrated. These are the sources of solar flares and other energetic events.

It is important to note that granulation, the mottled pattern of convective cells, is a feature of the photosphere (white light) and is not visible in H-alpha.

F/15-F/30 Native Compatibility & 67mm Backfocus

The Combo Quark's optical design contains no integrated barlow or focusing elements; it is a pure filter assembly. This requires it to be fed a highly parallel beam of light, which is achieved with telescopes that have a native focal ratio of F/15 to F/30. This suits long focus refractors and Maksutovs. For Schmidt-Cassegrains, an off-axis Energy Rejection Filter (ERF) reduces the aperture, which raises the focal ratio from the native focal ratio to the preferred ~F/30 beam.

Because the filter assembly is placed between the diagonal and the eyepiece, it adds significant length to the optical path. You will need to move the focuser inward by 67mm to reach focus compared to a standard eyepiece. When using the included 2° wedge adapter for an off-axis ERF on an SCT, this backfocus requirement increases to 99mm. You will need to dial the focus knob quite significantly.

For faster refractors, Daystar offers optional 2.8x and 4.3x telecentric barlows (sold separately): the 4.3x for F/5 to F/9 refractors, showing the full disk at about 480mm focal length or shorter, and the 2.8x for F/5 to F/14, showing the full disk at about 720mm or shorter with a brighter, lower power image.

Chromosphere vs. Prominence: A Choice of 2 Solar Targets

Daystar does not specify an FWHM for its Quark filters. Prominence units are generally 0.6Å or above and Chromosphere units generally 0.5Å or below, so you choose by what you want to see.

• Chromosphere Model (This Product): With a bandpass generally 0.5Å or below, this model favours contrast on surface detail such as filaments, plage and active regions.
• Prominence Model: This variant has a slightly wider bandpass (generally 0.6Å or above). This favours prominences, the loops and eruptions of plasma seen at the sun's limb, with softer surface detail.

The choice between the two models is a trade-off. The Chromosphere model's narrower bandpass can make prominences appear dimmer, while the Prominence model's wider bandpass reduces contrast on surface features. Your primary observing interest should guide your decision.

Full Disk Views Under 1800mm Focal Length

The Combo Quark is compatible with a wide range of telescopes, provided the focal ratio and safety requirements are met. It has no aperture limit, meaning it can be used on large-aperture refractors for high-magnification views of specific solar features. However, whether you can see the entire solar disk in one view depends on your telescope's focal length.

It passes the full solar disk for focal lengths under about 1800mm, with a low power eyepiece such as a 32mm or 40mm Plössl. Longer focal lengths give higher magnification views of sections of the sun.

Energy Rejection Filters

The Combo Quark sits behind the telescope, so sunlight enters the telescope before it reaches the filter. To prevent damage, Daystar strongly recommends using an Energy Rejection Filter (ERF), and for apertures over 80mm suggests one. ERFs reduce the heat load on the filter assembly by absorbing or reflecting UV and/or IR light.

Daystar's guidance by telescope type:

• Schmidt-Cassegrains: SCTs must not be used in full aperture with this unit. They typically employ a front mounted ERF with an off-axis opening of reduced aperture, and the included 2° wedge adapter must be installed between the telescope and Quark, with its set screw on the same side as the ERF hole, or the transmission will be off-band.
• Maksutovs: Maksutov telescopes usually use a full aperture colored glass ERF.
• Refractors: For brief observing sessions with less than 80mm of aperture when not using a tracking mount, be alert for any rise in temperature of your telescope, diagonal or Quark. For telescopes under approximately 150mm of aperture, a screw in UV/IR cut filter can be employed in front of the diagonal. For highest safety, a red or yellow glass front mount ERF should be used.
• Tracking: All dedicated solar tracking applications should employ energy rejection.
• Important: Never use a Herschel wedge or a standard white-light solar filter with the Quark. Those filters block 99.999% of all light, including the desired H alpha light.

±0.5Å Wing Shift and 5-15 Minute Settling Time

The heart of the Quark is a Fabry-Perot etalon that must be precisely heated to pass the 6562.8 Å H-alpha wavelength. When you first power on the filter, the LED indicator will turn yellow, signifying it is warming up. This process takes approximately 5-15 minutes, after which the light turns green, indicating the filter is on-band and ready for observation.

A tuning knob allows you to "wing shift" the filter's center wavelength by up to ±0.5Å from the central H-alpha line, with detents at every 0.1Å. This lets you restore contrast if the image lacks it and observe Doppler-shifted features. Solar features moving towards you are shifted towards the blue end of the spectrum, while features moving away are shifted red. By turning the knob, you can enhance the contrast of these specific moving structures.

• Clockwise Turn: Shifts toward red. Enhances features moving away from you.
• Counter-Clockwise Turn: Shifts toward blue. Enhances features moving towards you.

After each adjustment of the tuning knob, the filter needs 5-10 minutes to re-stabilize at its new temperature before the change becomes effective.

5V, 1.5A USB Power for All-Day Operation

The Quark's precision heating system is powered by a standard female Micro-B USB port, requiring a 5V source capable of delivering at least 1.5A. Daystar includes a 90-240VAC wall adapter with interchangeable plugs for US, UK, European, and Australian outlets.

Away from AC power, use Daystar's optional 8-hour battery pack or another USB source rated for at least 1.5 amps at 5 volts.

Important: Do not power the filter from a computer or cell phone charger, as computer USB ports and cell phone chargers do not normally support this much power. A computer port makes the heater reduce its current draw, so the LED may stay yellow.

The 1.25" Format and Eyepiece Selection

The Combo Quark is designed for maximum compatibility, featuring a standard 1.25" male snout on the telescope side and a 1.25" female drawtube on the eyepiece side. The eyepiece holder has a brass compression ring to protect your eyepiece, and the sun-side snout has a safety indent.

Eyepiece choice is critical for good performance. At F/15-30 a high powered eyepiece can exceed Dawes' limit, giving a fuzzy disk without the ability to focus well, and Naglers, zooms, Radians and other fast eyepieces typically perform very badly.

Plössl eyepieces of 25mm, 32mm and 40mm are recommended, and best results come with 32mm or greater. In testing, fully multicoated eyepieces and blackened optical edges gave less internal scattering.

Why Only 1 in 4 Pixels See H-Alpha on a Color Sensor

While visual observation is the Quark's primary strength, it is also a capable imaging tool. For the best results, use a monochrome CCD or CMOS camera. Color sensors are less efficient in H-alpha.

A color camera sensor is covered by a Bayer matrix, a mosaic of red, green, and blue filters. Only the pixels under the red filters can detect the H-alpha light; the other 75% of the pixels (covered in green and blue) are essentially blind to it. This means a color camera has only 1/4 the sensitivity and 1/2 the resolution of a monochrome camera of the same size. Furthermore, many consumer DSLR cameras have an internal IR-cut filter that severely attenuates H-alpha light, reducing sensitivity even further.

Another common issue in H-alpha imaging is the appearance of interference patterns, or "Newton's Rings." The sensor and its cover slip form a small interferometer, and the sensor must be tilted to a minor degree to prevent the pattern. Daystar offers an optional accessory (MG-0408) to adjust the light angle.

The 5-Year Warranty and Twist-Case Storage

Daystar provides a 5-year warranty for the Combo Quark, ensuring it is free from defects in materials and workmanship. Components considered wear items, such as blockers and trimmers, are covered on a pro-rated basis over the five-year term.

Proper care and storage are essential for maximizing the life of the filter. The Quark ships in a durable Twist-Case for safe, dust-free storage. When not in use, store the filter with its end caps on in a climate-controlled environment; this extends optical filter life expectancy up to 2-3 times. Avoid touching any optical surfaces. A few specks of dust can be gently blown off with a squeeze bulb (never compressed air). Fingerprints and smudges must be cleaned off; the preferred method is factory cleaning at Daystar's laboratory. Never disassemble the filter assembly, as internal components are pressurized and opening it will damage them and void the warranty.