Askar 40mm f/5.5 Triplet Apo Lens / Guidescope # FMA180

Article number: FMA180
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ASKAR FMA180 is a Triplet air-spaced APO refractor, which includes two pieces of ED (extra-low dispersion) glass,
providing excellent correction of chromatic aberration. The high-quality optics producing a flatter image with striking clarity,
and it is tested to ensure that high standards for astrophotography and observation.

When your guide scope becomes your imaging scope (and visa versa)

Photo Courtesy of Avi Wolf

Inline image

To be used for very wide field imaging. With the attached ZWO ASI533 a 3.6 x 3.6 degree field can be imaged.


    ASKAR FMA180 reducer is Triplet air-spaced designed for use with refractor optical tube, providing superior contrast and sharpness image, specifically optimized for astrophotography, which is its strong point, you don't have to worry about chromatic aberration that can appear in the field of view. Using the f/4.5 reducer makes it capable of capturing clear astrophotos in considerably less time.


    With special F4.5 full frame reducer, the 40mm aperture, 220mm (f/4.5) focal length ASKAR FMA180 become a professional APO refractor with 180mm focal length , both scenery observation and astrophotography, the bright color and good permeability will present the image with high quality and brilliant brightness.

For traditional astrophotography, it is difficult to achieve a focal length of less than 200MM with commercially available telescopes. The only choice in this range is the ordinary camera lens. However, the camera lens is not optimized for astrophotography, so the result is not satisfactory. 

FMA180 make it new, if you wanted to capture extended deep-sky objects, it will get superior optical performance in image like telephoto prime lens.
In addition to photography and observation, FMA180 is also suitable for a high-performance finder-guider of your choice. The overall tube length is 145mm, the small size of FMA180 tips the scales at a mere 395g.
Therefore, the assembled product includes a pair of tube rings and a finderscope bracket, which can be easily attached to the finder base on the market. In addition, the finder bracket can be divided into two parts, among which the dovetail plate can be used alone, and it can be connected to the tripod with standard camera thread and other head. This ARCA-SWISS standard dovetail can be connected to the corresponding plate slot more conveniently, and it can also attach to the VIXEN narrow equatorial adapter. Hence you can get rich connectivity for both photographic purposes and observation.

Its small size could be directly attached to camera like a normal lens, easy to carry away the view time.

Below are FMA180 usage patterns for reference:

Photographic Mode:
1) Main tube + focuser + reducer + reducer connection adapter: 180mm F4.5 sextuplet APO flat field correction astrograph lens (recommended photographic mode, product assembled)
2) Main tube + focuser + extension tube 1 + extension tube 2: 220mm F5.5 triplet APO lens
Observation Mode:

1) Main tube + focuser + extension tube 1 + 1.25" adapter: It can be combined with 1.25" star diagonal and eyepiece for standard observation mode or finderscope mode.
2) Main tube + focuser + extension tube 1 + extension tube 2: It can be combined with 1.25" eyepiece for visual observation mode or finderscope mode.

Spot diagram
Optical path diagram
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