Askar SQA85 85mm f/4.8 Quintuplet APO

Askar SQA85: A Portable 85mm f/4.8 Astrograph

The Askar SQA85 combines an f/4.8 focal ratio with a self-flattened Petzval design. It needs no additional back focus calculation: between 40mm and 70mm connection distance, you shoot once the OTA is in focus.

This astrograph is best suited for imagers using cameras with sensors up to full-frame format, targeting large nebulae, galaxy clusters, and expansive star fields. At 408mm a full-frame sensor covers about 5.0 x 3.4 degrees, enough for the Andromeda Galaxy (M31) or the North American Nebula (NGC 7000) in one frame.

Quintuplet Petzval APO: A 5-Element Flat-Field Design

At the heart of the SQA85 is an air-spaced 5-element Petzval system with a self-flattened structure, so there is no separate flattener. It has great star performance, with excellent full-field illumination and MTF data.

The objective includes two pieces of SD glass, low-dispersion glass that reduces chromatic aberration, the color fringing that can appear around bright stars.

85mm Aperture and 408mm Focal Length at f/4.8

The SQA85's core optical parameters are balanced for wide-field deep-sky imaging. The 85mm aperture keeps size and weight manageable for portable setups.

The 408mm focal length provides a wide perspective on the sky, ideal for capturing large-scale celestial phenomena. At f/4.8 the same exposure takes about 64% of the time needed at f/6 and 47% at f/7.

A 44mm Corrected Field for Full-Frame Sensors

The Askar SQA85 supports full-frame imaging with a 44mm image circle, covering full-frame (36mm x 24mm) DSLR, mirrorless and astronomy camera sensors. The Veil Nebula complex fits in one full-frame field.

Because the field correction is built in, no additional optical accessories are needed.

55mm Spacing with M48, M54, and M68 Adapters

The SQA85 offers a flexible back focus range between 40mm and 70mm, with a recommended distance of 55mm for optimal performance. Many cameras and T-rings are built around 55mm, and the 40mm to 70mm range leaves room for filter drawers and off-axis guiders.

The SQA85 ships with three toothed and ribbed adapters that change easily without slipping:

• M68 Adapter: The largest connection.
• M54 Adapter: A common intermediate thread size used by many astronomy accessories.
• M48 Adapter: M48×0.75, fitted to the OTA as delivered.

A 2.8-inch Rack and Pinion Focuser with 32mm of Travel

The SQA85 has a dual-speed 2.8-inch rigid rack-and-pinion focuser that is compatible with most motorized focusers on the market.

The focuser provides 32mm of travel, and the focuser tube is engraved with high-precision scales. A rotator with a thumb screw lets you frame your target. The manual marks screw positions for an electric focusing bracket and shows the EAF installation steps.

Pairing Cameras and Accessories with the SQA85

Choose the rear adapter (M48, M54 or M68) for your equipment. The M48×0.75 adapter is fitted as delivered. Aim for 55mm to the sensor; anything from 40mm to 70mm is supported.

A DSLR on an M48 T-ring is typically built to 55mm (mirrorless bodies usually need extra spacing). For a dedicated astronomy camera with a shorter built-in back focus (e.g., 17.5mm), you would add 37.5mm of M48 extension tubes between the SQA85's adapter and the camera. Two finder bases sit on both sides of the focuser, which removes the need for disassembly when moving the finder.

Tube Rings, Dew Shield, and 290mm Dovetail

The tube ring is an integrated pair with a hollow middle to reduce weight, and 6 M4 and M6 threaded holes on both sides for bases, dovetail plates or accessories. The handle on top has a multifunctional finder base slot.

The retractable dew shield takes the total length from 403mm (contracted) to 439mm (stretched). On the bottom is a standard Vixen-style 290mm dovetail plate.

A 3.64kg OTA with a 403mm Transport Length

Portability is a major strength of the Askar SQA85. The bare optical tube assembly weighs only 3.64kg (8.0 lbs), and the gross weight with tube rings and dovetail plate is 4.62kg (10.2 lbs).

The telescope is also physically compact. With the dew shield fully retracted, the total length is just 403mm (15.9 inches). An Oxford cloth case is included.

Getting Started with the Askar SQA85

Setting up the SQA85 for its first night of imaging is a simple process. Follow these steps to get started:

1. Mount the Telescope: Secure the 290mm Vixen dovetail plate into the saddle of your polar-aligned equatorial mount.
2. Attach Imaging Train: Connect your camera, filter wheel, and any other accessories to the rear of the telescope using the appropriate M48, M54, or M68 adapter. Aim for 55mm from the adapter to the sensor (40 to 70mm supported).
3. Balance the System: With all equipment attached, slide the telescope forward or backward in the mount's saddle to balance the declination axis. Then, adjust the counterweights for balance on the right ascension axis.
4. Attach Guiding/Finding Scopes: Mount your guide scope or finder on one of the two finder bases on the focuser or on the handle's finder base slot.
5. Achieve Focus: Point the telescope at a bright star. Use the coarse focus knob to get the star close to focus, then use the fine focus knob to make the star as small and sharp as possible. A Bahtinov mask is highly recommended for achieving critical focus.
6. Frame and Image: Slew to your desired target, use the rotator to frame it, and begin your imaging sequence.