LS60THa 60mm f/8.33 refractor, 12mm blocking filter, Pressure Tuning

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This Lunt LS60THa/B1200CPT 60mm solar refractor with 12mm blocking filter represents an economical new approach to serious high resolution Hydrogen-alpha solar viewing and imaging. It has a True Doppler Tuning (Pressure Tuning) system that allows you to shift the scope's passband to either side of the H-Alpha band. This emphasizes features that are moving either towards or away from you, adding a 3D-like component to your viewing. 

Pressure tuning has a minimal effect on prominences, due to their being at the edge of the disk, but it clearly improves your view of filaments and active regions on the surface. While looking at a filament at the center of the Sun, for example, you have the ability to Doppler shift from the base of the filament to the tip. You can follow the filament thru its structure toward you and away from you. This allows for enhanced visual and imaging capability for the observer as well as a research tool for the avid hobbyist. 

This Lunt LS60THa/B1200CPT consists of a 500mm focal length 60mm aperture f/8.33 refractor with an integrated Hydrogen-alpha solar filter. The two-part filter uses an internal etalon behind the objective lens and a 12mm blocking filter built into the standard equipment 1.25” star diagonal. There is also an infrared reflecting window (Energy Reflecting Filter or ERF) in the optical path to remove unwanted heat from the system. A turn or two of the Pressure Tuning mechanism built into side of the system lets you center the passband precisely on the H-alpha line for maximum contrast, as well as quickly perform off-band observations of Doppler-shifted disk features.

The scope’s singlet objective lens is fully multicoated. It is not necessary to use an achromatic doublet in a small solar scope to correct for chromatic aberration in the violet end of the visible spectrum. Solar scopes are designed to observe only a single wavelength of red light at the opposite end of the spectrum and all other portions of the visible spectrum are filtered out. Why pay for two lenses to cure a problem in violet light that a solar scope is incapable of showing you in the first place? In addition, the front singlet lens design reduces the stray light of a two-lens achromat by half. With the matched collimation lens set built into the scope, it also fully corrects for on-axis coma, astigmatism, and de-centering aberrations and provides a spherically corrected flat-field image.

The filter has a <0.75 Ångstrom passband, centered on the 6562.8 Ångstrom H-alpha line. The sub-Ångstrom passband width gives you balanced views of feathery prominences and low-contrast surface detail alike. The filter is thermally stable, so there is no drifting off the H-alpha line as the filter heats up during use.

In addition to superb visual observing, the 12mm clear aperture of the blocking filter portion of the H-alpha system in the star diagonal is ideally suited to DSLR imaging of the approximately 4.5mm diameter prime focus image of the Sun. This 12mm diameter blocking filter is also well suited for binoviewer use. However, for those who are interested primarily in visual observing, with little or no imaging, the smaller 6mm aperture blocking filter used in the Lunt #L60TP will provide identical visual results at a lower cost.

This Lunt LS60THa/B1200CPT uses a dual-speed Crayford focuser with a 10:1 reduction ratio for precision focusing on the smallest of solar details. Large ribbed focusing knobs make it easy for you to reach a precise focus, even if you are observing in the dead of winter while wearing gloves or mittens.

You can use virtually any 1.25” eyepieces with this 60mm Lunt solar refractor. A typical 20mm 1.25” Plössl will give you a magnification of 25x and a little over a 2° field of view compared with the 0.5° diameter disk of the Sun. A 15mm Plössl will give you 33.3x and about a 1.5° field, giving you plenty of dark sky background around the solar disk to show off the prominences.

This Lunt LS60THa/B1200CPT comes with a clamshell-type mounting ring with 1/4”-20 thread holes that will let you mount the scope directly on a photo tripod for a quick peek at the Sun. You can also mount the clamshell ring on a dovetail plate and install it on an altazimuth or equatorial mount with slow motion controls for easier extended observing and tracking of the Sun. A foam-lined hard case is standard equipment for transporting and storing your Lunt scope.
Focal Length:
This is the length of the effective optical path of a telescopeor eyepiece (the distance from the main mirror or lens where the lightis gathered to the point where the prime focus image is formed). Focallength is typically expressed in millimeters.

The longer the focallength, the higher the magnification and the narrower the field of viewwith any given eyepiece. The shorter the focal length, the lower themagnification and the wider the field of view with the same eyepiece.

500mm
Focal Ratio:
This is the ‘speed’ of a telescope’s optics, found by dividing the focal length by the aperture. The smaller the f/number, the lower the magnification, the wider the field, and the brighter the image with any given eyepiece or camera.

Fast f/4 to f/5 focal ratios are generally best for lower power wide field observing and deep space photography. Slow f/11 to f/15 focal ratios are usually better suited to higher power lunar, planetary, and binary star observing and high power photography. Medium f/6 to f/10 focal ratios work well with either.

An f/5 system can photograph a nebula or other faint extended deep space object in one-fourth the time of an f/10 system, but the image will be only one-half as large. Point sources, such as stars, are recorded based on the aperture, however, rather than the focal ratio – so that the larger the aperture, the fainter the star you can see or photograph, no matter what the focal ratio.

f/8.33
Resolution:
This is the ability of a telescope to separate closely-spaced binary stars into two distinct objects, measured in seconds of arc. One arc second equals 1/3600th of a degree and is about the width of a 25-cent coin at a distance of three miles! In essence, resolution is a measure of how much detail a telescope can reveal. The resolution values on our website are derived using the Dawes’ limit formula.

Dawes’ limit only applies to point sources of light (stars). Smaller separations can be resolved in extended objects, such as the planets. For example, Cassini’s Division in the rings of Saturn (0.5 arc seconds across), was discovered using a 2.5” telescope – which has a Dawes’ limit of 1.8 arc seconds!

The ability of a telescope to resolve to Dawes’ limit is usually much more affected by seeing conditions, by the difference in brightness between the binary star components, and by the observer’s visual acuity, than it is by the optical quality of the telescope.

1.93 arc seconds
Aperture:
This is the diameter of the light-gathering main mirror or objective lens of a telescope. In general, the larger the aperture, the better the resolution and the fainter the objects you can see.
2.4"
Telescope Type:
The optical design of a telescope.  Telescope type is classified by three primary optical designs (refractor, reflector, or catadioptric), by sub-designs of these types, or by the task they perform.
Refractor
Warranty:
1 year
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  • Dual-speed Crayford focuser
  • Dust cover
  • Carrying case
  • Pressure Tuning system
  • 1.25” star diagonal with integral 12mm blocking filter
  • Clamshell mounting ring
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LS60THa 60mm f/8.33 refractor, 12mm blocking filter, Pressure Tuning

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LS60THa 60mm f/8.33 refractor, 12mm blocking filter, Pressure Tuning
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Our Product #: L60T12P
Manufacturer Product #: LS60THa/B1200CPT
Price: $1,896.00  FREE ground shipping - Click for more info
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This Lunt 60mm solar telescope with Pressure Tuning and a 12mm blocking filter for both visual observing and high resolution Hydrogen-alpha imaging of explosive solar flares and prominences as well as sunspot and surface features on our nearest star . . .





. . . our 34th year