The ASKAR FRA400 “Flatfield Refractive Astrograph” incorporates a five-element design to deliver flat fields and sharp, color-free images from edge-to-edge. With a 72mm objective, two ED elements, and Petzval optical layout, this f/5.6 scope has a focal length of 400mm and it’s ideal for capturing stunning wide-field images of the deep sky over a 44mm full-frame image circle. It works great for visual observing also (star diagonal not included).

This premium astrograph includes a large 3” rack-and-pinion dual-speed focuser that’s fully rotatable through 360 degrees. The focuser tube terminates with an M68x1 thread for direct camera attachment, and it comes with an M68-M48 adapter for smaller camera. It also includes a 2” adapter ring and 1.25”-2” adapter for use with diagonals, eyepieces, or smaller cameras.

The attractive optical tube of the FRA400 is complemented with a highly functional set of aluminum rings, Vixen-style dovetail, and a carrying handle. The rings include separate mounting holes for additional accessories. The entire tube is just 317mm long and weighs 2.6kg.

While the fast f/5.6 focal ratio is ideal for deep-sky imaging, ASKAR also makes an optional FRA72RD focal reducer (not included) for the FRA400 scope to bring the focal ratio to f/3.9 while still supporting full-frame imaging.

For the price, this fast apochromatic telescope offers excellent value and can approach the performance of telescopes that cost three or four times as much. This is especially true when matched with astronomy cameras with smaller 1" and 4/3" sensors. Cameras with larger APS-C and full-frame sensors may reveal slight aberrations at the edge of the field, especially when using the focal reducer.

Specifications:

• Aperture: 72mm / 2.83in
• Focal Length: 400mm
• Focus Ratio: f/5.6
• Objective Type: Quintuplet Dual ED Air-Spaced APO
• Overall length: 317mm
• OTA Weight (without rings/dovetail/handle): 2.65kg (5lb-14oz)
• OTA Weight (with rings/dovetail/handle): 3.25kg (7lb-2oz)
• Back-end Adapter: M68x1 Male Thread, 2" Adapter/1.25" Adapter
• Back focus: 140mm
• Accessories:
  • Pair of Tube Rings
  • Handle
  • Dovetail Plate (length 150mm)
  • M68-M48 adapter, 2” adapter, 1.25”-2” adapter
  • Inspection List
  • Manual

Schematics

Astrophotos

(Click for high resolution version)

F/5.6 is a relatively fast focal ratio for astrophotographic use, but Askar further provide an ultra focal reducer to satisfy the special needs of experienced imagers, greatly reducing the practical focal ratio to f/3.9. This inventive combination supports full-frame imaging and can dramatically shorten the exposure time, which is a pioneering design in the astrophotography field.
 
The inborn mission of Askar FRA400 is to simplify and enhance customers’ observing and imaging practice, bringing them infinite surprise when safariing the boundless universe.