Askar FRA300 pro F/5 APO Refractor User Manual
- June 9, 2024
- Askar
Table of Contents
FRA300 pro F/5 APO Refractor
User Manual
WARNING!!
DO NOT LOOK AT SUN THROUGH TELESCOPE. IT WILL CAUSE IRREVERSIBLE DAMAGE TO
YOUR EYE.
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
backfocus, 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.
Aperture size： 60mm
Focal length： 300mm
Focal ratio： F5
Objective lens： quintuplet fully air-spaced Petzval APO (including one
ED glass)
Image circle： 44mm full-frame
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
Net weight：2.26kg
Gross weight：3.12kg
Rear-end thread：
M42×0.75 male thread
M48×0.75 male thread（built-in 2″ filter thread adapter）
M54×0.75 male thread
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