Askar 40mm f/5.5 Triplet Apo Lens / Guidescope # FMA180
- ASKAR FMA180 40mm aperture apochromatic telescope/camera lens features multiple optical configurations
- Uses three-element objective lens with two ED elements for superb color correction and image quality
- Configures as a finder/telescope/guide scope with a focal length of 220mm and focal ratio of f/5.5
- Includes three-element focal reducer and spacers to configure as a six-element f/4.5 apo telescope with focal length of 180mm for wide-field astronomical imaging
- Includes tube mounting rings, Vixen-style dovetail, and Swiss-Arca mounting plate for a wide range of mounting configurations
The ASKAR FMA180 is a premium multi-functional optical instrument that features a 40mm ED triplet objective to deliver superb image quality. It works at f/5.5 as a finder/small telescope/guide scope. It can also be easily configured as a six-element f/4.5 apochromatic refractor/camera lens, making it an ideal instrument for serious wide-field astronomical or terrestrial imaging.
The heart of the FMA180 is an air-spaced 40mm apochromatic f/5.5 triplet with two ED elements to minimize chromatic aberration. With a focal length of 220mm, the objective lens is optimized and tested for demanding astronomical applications. The objective is carefully matched to the included three-element focal reducer that transforms the overall focal ratio to f/4.5 and a focal length of 180mm, yielding flat fields and razor-sharp images with a full-frame DSLR or dedicated astronomy camera.
With the included focuser ring and extension tubes, the FMA180 is easily configured for visual or photographic use. When configured for imaging with or without the focal reducer, the telescope side of the extension tube terminates in a standard M42x0.75 male T-thread for mating to a camera T-ring adapter (not included). The back focus is a standard 55mm, or it can be changed to 99mm by removing an extension tube to allow more freedom to attach other camera accessories.
For straight-through observing with an eyepiece or for use as a guide scope, there’s a standard 1.25” adapter that threads onto to extension tube. The scope can also be configured to work with a 1.25” star diagonal (not included) for visual observing. The FMA180 can be used visually with the focal reducer but may have some color fringing that isn't present at f/5.5.
When configured as a finder or guide scope, the optical tube mounts in dual rings attached to a standard narrow Vixen-style dovetail. The dovetail riser can be removed to expose a Swiss-Arca mounting plate to attach the scope to a suitable tripod head for visual or photographic use. The plate can also attach to a narrow Vixen equatorial adapter (not included). The rings can be completely removed from the scope when it’s used with a DSLR for handheld shooting or when the camera itself is mounted to a tripod.
The overall tube length is 145mm in photographic mode and 160mm in visual mode without a star diagonal. The FMA180 weighs just 395g (0.87 lbs).
- Aperture: 40mm
- Focal Length: 220mm
- Focus Ratio: f/5.5
- Objective Type:
- Triplet Dual ED Air-spaced APO (Objective lens)
- Sextuplet Refractor for full-frame astrophotography (with reducer)
- Overall length:
- 145mm (photographic mode with focal reducer)
- 160mm (observation mode without star diagonal)
- Helical focuser travel: 30mm
- Weight: 395g
- Back-end Adapter:
- M42x0.75 (photographic mode)
- 1.25" Adapter (visual observation mode)
- FMA180 Body
- Pair of tube rings
- Finder scope bracket
- Two extension tubes
- 1.25" Adapter
- Allen Wrench
- Country of Manufacture: China