Askar 111F Flat-Field Astrograph

The Askar 111F: Imaging and Visual

The combination of a 111mm aperture and a 766mm focal length provides the image scale needed to resolve details in medium-to-large galaxies and nebulae. After attaching the imaging accessories, you can shoot directly once the OTA is in focus, with no external corrector to space.

The rear interface also includes 1.25-inch and 2-inch adapters for visual use.

A 111mm f/6.9 Quadruplet APO with ED Glass

At the heart of the 111F is a quadruplet air-spaced apochromatic (APO) objective lens. It uses four lens elements (three in the front and one in the rear). One of them is ED (Extra-low Dispersion) glass, which can effectively reduce chromatic aberration.

The CNC machined and painted tube also includes an internal baffle to suppress stray light.

A 44mm Flat Field Without an External Flattener

The defining feature of the Askar 111F is its "self-flattened" design. You do not add a separate field flattener; the 111F supports a 44mm image circle, large enough to cover a full-frame (36x24mm) sensor.

• No Extra Accessories: You do not need to purchase a separate flattener, simplifying your imaging train and reducing overall cost.
• A Connection Range, Not a Fixed Distance: The effective connection range is 42mm to 73mm from the base of the M48×0.75 male thread; within it you attach your camera, focus and shoot.

3-inch Rack & Pinion Focuser with 30mm of Travel

The Askar 111F is fitted with a 3-inch rack-and-pinion dual-speed focuser supporting 1:10 fine focusing.

The focuser provides 30mm of travel. An integrated field rotator at the rear, with the inner tube marked in 360° increments, lets you frame your target without rotating the optical tube in its rings.

42-73mm Working Distance via M48 and M54 Adapters

The Askar 111F comes standard with a 4-section photographic extension tube: an M78×1 55mm extension, an M78×1 to M54×0.75 adapter with a built-in reducer mounting thread, a 13.5mm M54 extension, and an M54×0.75 to M48×0.75 filter adapter with a built-in 2-inch filter thread.

The working range depends on which thread is the final connection point:

• M48x0.75 Connection: 42mm (focuser fully extended) to 73mm (fully retracted) from the base of the male thread to the sensor.
• M54x0.75 Connection: 60mm to 91mm from the base of the male thread to the sensor.

The 0.74x Reducer: An f/5.1 System at 566mm

For imagers seeking a wider field of view and shorter exposure times, the optional Askar 111F 0.74× Reducer turns the telescope into a faster instrument. This triplet accessory reduces the focal ratio from f/6.9 to f/5.1 and shortens the focal length from 766mm to 566mm. With a full-frame sensor the field grows to about 3.6 x 2.4 degrees, enough to frame the Andromeda Galaxy (M31).

The reducer has built-in field-flattening correction and supports a 44mm full-frame image circle. Its back focus is 55mm from the base of the M48 male thread, both ends are M68×1, it has a built-in 2-inch filter thread and weighs 0.5kg. The 111F extension tube adapters connect directly to it.

Tube, Dew Shield, and Triple Finder Bases

The CNC machined and painted tube has a retractable dew shield that extends 87mm; with the 1.25-inch adapter the total length is 664mm retracted and 751mm extended.

The 111F provides three locations for a finder or guide scope:

• Two Focuser Bases: Finder bases are located on both the left and right sides of the 3-inch focuser.
• One Handle Base: A finder slot is integrated directly into the top carry handle.

This allows flexible adjustment of the finder position without disassembly and gives extra options for other accessories.

6.76 kg on a 300mm Vixen Dovetail

The Askar 111F's optical tube assembly (OTA) has a net weight of 5.74 kg. When mounted in the included tube rings with the carry handle and 300mm Vixen-style dovetail plate, the gross weight is 6.76 kg. The tube rings have CNC-machined thumb screws and a clamshell opening for tool-free installation and removal.

The 300mm standard Vixen-style dovetail plate includes standard 1/4"-20 and 3/8"-16 threaded holes, allowing the telescope to be mounted directly onto a robust photo tripod.

Adapters for 2-inch and 1.25-inch Eyepieces

Askar designs the 111F for visual observation as well as imaging. The rear interface includes 2-inch and 1.25-inch adapters for diagonals and eyepieces.

With its 766mm focal length, the 111F can provide wide, rich-field views of open clusters like the Pleiades (M45) or offer enough magnification for detailed observations of the Moon and planets. The connection distance is up to 132mm from the 1.25-inch adapter and 142mm from the 2-inch adapter with the focuser fully retracted.