Sharpstar 121 SDQ

The Sharpstar 121 SDQ is an apochromatic Petzval quintuplet refractor with a focal ratio of f/5.6. The telescope features a five-element in two groups design that includes one Japanese FPL-53ED lens and a full-surface multi-layer coating. The air-spaced triplet objective includes the ED glass element and the rear doublet acts as corrector and field flattener.

Sharpstar 121SDQThe five-element, fully multi-coated optical design makes the Sharpstar 121SDQ an excellent imaging instrument. The fully-corrected image circle of 60mm makes the 121SDQ a good match for full-frame DSLR, CCD or CMOS cameras, even with a medium sized sensor and a focal length of 678mm makes this a fast astrograph for the advanced astrophotographer.

Using a fixed two-element corrector in the optical tube means the user does not have to set the camera at a specified position relative to the flattener, which is unlike the case with external field flatteners and focal reducers. This allows the freedom to use a wide range of accessories such as filter wheels or off-axis guiders in front of the sensor without concern about the correct distance between flattener and sensor. The Sharpstar 121SDQ provides 145mm of working distance.

The large 4″ brass rack-and-pinion focuser is fully rotatable by 360° to perfectly frame the subject and it has a precise dual-speed 10:1 focusing mechanism for precise focus control. The focuser supports a 7.5kg payload and the drawtube has an opening for standard 2″ diagonals and accessories with 110mm of focuser travel. The robustness of the focuser makes it suitable for heavy-duty accessories such as a filter wheel and OAG.

The aluminum tube is internally blackened to reduce reflections and absorb stray light. The telescope includes a Vixen/Synta-style finder mounting base, tube rings, a 180mm long Losmandy/D style mounting rail, a carrying handle, a metal objective dust cover, and a protective hard case.

The Sharpstar 121 SDQ specifications include:

– Aperture: 121mm

– Focal Length: 678mm

– Limiting Star Magnitude: 12.1

– F Ratio: f/5.6

– Resolution: 0.97 arc seconds

– Objective Type: Quintuplet Air-Spaced Apochromatic

– Back Focus: 145mm (from thread of focuser end

– Net Weight: 7.98kg (8.92kg including tube-ring, dovetail plate, handle)

– Length: 698mm with the Dewshield Extended and 598mm with the dewshield retracted

– Tube Outside Diameter: 130mm

– Dewshield Outside Diameter: 160mm

You can learn more here.

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