Askar FRA300 Pro F-5 APO Refractor User Manual
- June 12, 2024
- Askar
Table of Contents
Askar FRA300 Pro F-5 APO Refractor
Product Information
The Askar FRA300 Pro is a short focal ratio astrograph designed for astronomical amateurs. It is the smallest 60mm F/5 Petzval astrograph in the FRA series, with a focal length of 300mm. The objective lens of the FRA300 Pro features a quintuplet fully air-spaced structure, including one piece of ED glass. It also has a fully-multi-coating to effectively remove stray light. The rear group lens adopts two far-separated refractive lenses, improving star quality and aberration correction performance. The native Petzval design eliminates the need for backfocus calculation.
Mechanically, the FRA300 Pro is assembled with high-quality CNC-machined components and has a smooth spray coating and light oxidation process for a beautiful and practical finish. The tube ring design is lightweight and stylish. The package includes a multi-function handle and a 300mm vixen-style dovetail plate, allowing for direct connection to various mounts and accessories. The handle can also be connected to the universal vixen-style finder base. The 300mm dovetail plate helps maintain balance on the mount.
Product Usage Instructions
To use the FRA300 Pro, follow these steps:
- Attach the tube ring to the main tube of the astrograph.
- Connect the multi-function handle to the handle attachment point.
- If needed, attach the vixen-style dovetail plate to the bottom of the astrograph for mounting on a compatible mount.
- Choose the appropriate adapter (M540.75 or M420.75) based on your camera or accessory requirements.
- Attach the chosen adapter to the focuser adapter.
- If necessary, attach the M76x1 adapter for specific camera setups.
- Securely attach your camera or accessory to the chosen adapter.
- Use the locking screw to secure the camera or accessory in place.
- If desired, attach a lens hood or filter using the built-in filter thread adapter.
- Ensure the astrograph is balanced on the mount using the 300mm vixen-style dovetail plate.
- Refer to the user manual for further information and specific usage guidelines.
Note: The FRA300 Pro also supports electric focusing bracket installation, which can be done using the bottom locking screw. Please refer to the instruction manual for detailed instructions on electric focusing bracket installation.
Instructions for use
Since their inception, Askar FRA series short focal ratio astrograph have been very well received by astronomical amateurs. This year, we launched the FRA300 Pro–the smallest 60mm F/5 Petzval astrograph with the fastest native focal ratio in the FRA series so far, its focal length is 300mm.
The star is sharp and delicate. At the center of its field of view, the RMS radius can reach 2um. Even a serious user can also be satisfied when it comes to the shape of stars .It performs excellence with full-frame and supports 44mm imaging ,which is a rare astrograph for amateur astronomers .Compared with F/6 or F/7， F/5 can effectively reduce the exposure time, helping you get the same exposure in less time. In addition, the entire OTA is compact, making it the portable choice for field photographers.
FRA300 Pro ‘s objective lens adopts a quintuplet fully air-spaced structure,
including one piece of ED glass, it also adopts a fully-multi-coating to
effectively remove stray light.
In particular, the rear group lens adopts the two pieces of far-separated
refractive lenses, which improves both the star quality and the aberration
correction performance , and it has a very good control of full-frame
peripheral light reduction.
Thanks to the native Petzval design, the user does not need to calculate the back focus, as long as the focus is within a certain range is the optimal position.
Mechanically，FRA300 Pro is assembled with high-quality
CNC-machined components , wrapped with smooth spray coating and light
oxidation process, both beautiful and practical. The tube ring design is
equally lightweight and stylish .Despite the increased cost, we want
enthusiasts to use the FRA300 Pro that performs well in every way and was
considered thoroughly in every aspect.
The focuser is 2.5″rack-and-pinion, which is solid and beautiful. It was designed with dual-speed hand knobs, twin knobs for coarse adjustment and a fine adjustment knob to accurate the focus, equipped with a universal M48X0.75 thread adapter. There are also two separate M54X0.75 and M42X0.75 adapters in the standard kit for easy access to a variety of imaging equipment and accessories. The 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 maintain balance on the mount.
FRA300Pro, as the first Pro version launched by Askar, goes further on the good reputation of the original FRA series, with amazing shooting performance, convenient carrying and using experience.
Specifications
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Aperture size: 60mm
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Focal length: 300mm
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Focal ratio” F5
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Objective lens: quintuplet fully air-spaced Petzval APO (including one ED glass)
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Image circle: 44mm full-frame
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Maximum accessory connection (with the focuser fully retreated)：
Imaging mode:
71mm (from the base of M42×0.75 male thread)
67mm (from the base of M48×0.75 male thread)
71mm (from the base of M54×0.75 male thread) -
Total length: 303mm
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Net weight: 2.26kg
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Gross weight: 3.12kg
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Rear-end thread：
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M42×0.75 male thread
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M48×0.75 male thread (built-in 2″ filter thread adapter） M54×0.75 male thread
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Standard package items: a tube ring, a handle, a 300mm Vixen-style dovetail plate, a M540.75 adapter, a M420.75 adapter, a warranty, a manual
Product Size Diagram
Connection Diagram of Camera
M42, M48, M54 Adapters Diagram
Product Parts Diagram
The Locking Screw Position Diagram
Items in FRA300 pro Packaging A tube ring ,a handle, a 300mm Vixen-style dovetail plate, a M540.75 adapter, a M420.75 adapter, a warranty, a manual
Instruction manual
Read User Manual Online (PDF format)
Read User Manual Online (PDF format) >>