The FRA300 Pro is the smallest 60mm F/5, 300mm focal length Petzval APO astrograph with the fastest native focal ratio in the FRA series. As with all astrographs that have the field flattener built into it, the stars are sharp across the image plane. At the center of its field of view, the RMS radius can reach 2um. FRA stands for Flat-Field Refractive Astrograph, a new series of instruments from Sharpstar/Askar.
The Petzval design means no additional optics such as focal reducers are necessary and allows for maximum flexibility when incorporating additional accessories (e.g., filters). This is an ideal instrument for wide-field imaging of the deep-sky over a 44mm image circle.
What is an Astrograph?
The biggest advantage of an astrograph are the flat fields with pinpoint stars across the image plane and the FRA300 performs wonderfully with smaller sensors of less than 1”, cameras with full-frame sensors may detect slight aberrations at the edge of the image plane.
The fast F/5 focal ratio can reduce exposure times, allowing for more efficient imaging sessions. In addition, the entire OTA is compact, making it a good, portable choice for remote locations.
The objective lens adopts a quintuplet air-spaced design, including one piece of ED glass with multiple coatings to reduce stray light and internal reflections.
This fast APO refractor approaches performance usually seen in much more expensive telescopes and when coupled with a smaller camera sensor, this is an amazing astrograph in the under $1000 price category.
The FRA300 Pro is assembled with high-quality CNC-machined components , wrapped with smooth spray coating and light oxidation process. The tube ring design is lightweight and capable.
The focuser is a solid 2.5" rack-and-pinion. It's designed with dual-speed hand knobs, twin knobs for coarse adjustment and a fine adjustment knob to accurately focus. It is also equipped with a universal M48X0.75 thread adapter. There are also two separate M54X0.75 and M48X0.75 adapters in the standard kit for easy access to a variety of imaging equipment and accessories. The OTA end is equipped with a 360° rotator, which is convenient for users to rotate at any angle when shooting.
FRA300 Pro also comes standard with a multi-function handle and a 300mm vixen-style dovetail plate, which can be directly connected to various mounts and accessories, the multi-functional handle can also be connected to the universal vixen-style finder base. The 300mm dovetail plate allows the astrograph to easily attach onto most mounts.
specifications
Aperture
60mm (2.25")
Back Focus
71 mm
Camera/Eyepiece Connection
Male M42x0.75
Camera/Eyepiece Connection
Male M48x0.75
Camera/Eyepiece Connection
Male M54x0.75
Corrected Image Circle
44 mm
Dew Shield Size
92 mm
Focal Length
300mm
Focal Ratio
f/5
Optical Design
Petzval
Tube Diameter
82 mm
Tube Length
303mm
Tube Weight
5 lb
included items
Askar FRA300 Pro
300mm dovetail plate
Tube ring
Multi-function handle bar/saddle
M54, M48, and M42 camera adapters
Manual
Product Reviews
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