Askar FRA600 108mm f/5.6 Quintuplet Petzval Flat-Field Astrograph

Like its smaller sibling, the 72mm FRA400, the FRA600 “Flatfield Refractive Astrograph” incorporates a five-element design to deliver flat fields and sharp, color-free images from edge-to-edge. With a 108mm objective, two ED elements, and Petzval optical layout, this f/5.6 scope has a focal length of 600mm and it’s ideal for capturing stunning wide-field images of the deep sky over a huge 66mm full-frame image circle.

This premium astrograph includes a large 4.2” rack-and-pinion dual-speed (1:10) focuser that’s fully rotatable through 360 degrees. The focuser tube terminates with an M90x1 thread, and it comes with an M90x1 to M54x0.75 adapter and M54x0.75 to M48x0.75 conical extension tube for direct camera attachment. It also includes a 2” adapter ring and 1.25”-2” adapter for use with diagonals, eyepieces, or smaller cameras. The scope works great for visual observing (star diagonal not included).

The attractive optical tube of the FRA600 is complemented with a highly functional set of aluminum rings, "D" Losmandy-style dovetail, and a carrying handle. The width of the "D" rail is 73.2mm. Please make sure that your saddle can clamp down to this size (for example, some ADM saddles will not go under 75mm and will not clamp on to this scope).

The rings include separate mounting holes for additional accessories. The entire tube has a diameter of 120mm and has a length of just 493mm with the dew shield retracted. It weighs 6.5kg. This astrograph has a back focus of 160mm which leaves ample room for accessories.

While the fast f/5.6 focal ratio is ideal for deep-sky imaging, ASKAR also makes an optional focal reducer (not included) for the FRA600 scope to bring the focal ratio to f/3.9 and focal length to 420mm 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.

The telescope is shipped in a foam-fitted hardcase (22.6" x 12.5" x 11").

The ASKAR FRA600 offers excellent value in a premium larger-aperture astrograph for serious astronomical imaging!

Specifications:

• Aperture: 108mm / 4.25"
• Focal length: 600mm
• Focal ratio: f/5.6
• Objective type: Quintuplet flat-field Apo (including 2 ED elements)
• Image circle: 66mm
• Back focus: 160mm (from the end of rotator M90x1 thread)
• Overall length: 493mm
• Dew shield OD: 148mm / 5.82"
• Tube weight: 6.5 kg / 14.3 lbs
• Back-end adapter: M108x1 male thread (no rotator), M90x1 male thread, 2" adapter, 1.25" adapter
• Conical adapter: M90x1 to M54x0.75, M54x0.75 to M48x0.75
• Accessories: a pair of tube rings, handle, dovetail plate, conical tube adapter (with M54x0.75 and M48x0.75 male threads, checklist, and manual), and hard case
• 0.7x f/3.9 reducer sold separately