Askar SQA106 f/4.8 Quintuplet APO

Super fine 106mm aperture quintuplet air-spaced SD glass Petzval Astrograph

Excellent Star Performance 

Quintuplet air-spaced lens design, including 2 pieces of SD glass. The SQA106 supports a 55mm image circle. The central star point has an RMS radius of less than 1.7 um, and the star point at 55 mm is less than 2.2 μm, showing a super-fine star point. It also has excellent full-field illumi- nation and MTF data. The relative illumination can be higher than 90% at 44 mm image circle.

Petzval Structure

Integrated self-flattened design, no need for additional flatteners, and no need for additional calculation of the back focus. Between 48mm and 78mm connection dis- tance, users can directly use it for shooting after the OTA is in focus.

Retractable Dew Shield

The dew shield is a retractable design that can be pulled out. It protects the lens from the impact of external and internal light and protects the lens itself. 

INTEGRATED TUBE RING

• Enlarged hand screws allow users to open and close the tube ring without additional tools.
• Integrated pair of tube ring sets, with a hollow design in the middle to reduce overall weight.
• There are 6 M4 and M6 threaded holes on both sides of the tube ring, which are convenient for installing the base or dovetail plate and connecting different accessories. You can even set up another set of OTA for shooting.
•  The handle on the top of the tube ring is slotted with a multifunctional finder base, which can be used to install astronomical accessories.
  

Finder Bases

On both sides of the focuser, there are two finder bases, which not only eliminate the need for disassembling when changing the position of the finder scope but also provide additional mounting positions for other astronomical accessories.

Dovetail Plate

The standard Losmandy-style 300mm dovetail plate is easy to dismantle and install. 

Large, Rigid Dual-Speed Focuser

Dual-speed rack-and-pinion large 2.8-inch rigid focuser, which can be compatible with most motorized focusers on the market. The focusing travel is 30 mm, and the focuser tube is engraved with high-precision scales. The entire focuser barrel is CNC machined with an anti-reflective internal design and matting paint, providing extra measures to eliminate stray light.

Rear-End Adapters

The end of the SQA106 is equipped with various adapters, all of which are toothed and ribbed, making it easy to rotate manually without slip- ping. The adapters are available in sizes M68, M54, and M48 and can be used to attach various accessories, such as full-frame cameras.

360° Enlarged Rotator 

The rear of the focuser is equipped with a 360° high-precision rotator with a precision scale to allow the user to adjust and save the angle of ro- tation. It is also equipped with an enlarged lock- ing screw for easy locking even under high loads.

High-Quality Machining

The entire SQA106 tube is crafted using high-quality CNC machining with anodized and surface spray paint treatments. The top of the handle and the focuser are all designed with ex- clusive nameplates, demonstrating high-end
quality.

MTF Chart

The modulation transfer function (MTF) is a quantitative description of the clarity of the image (including resolution and contrast) of an optical lens. The vertical axis is the MTF value, and the horizontal axis is the distance from the center of the frame to the edge. In the two sets of curves corresponding to low and high frequencies, even at the edge of 55mm image circle. the sagittal lines and sagittal lines distance of the SQA106 lens remain very small, and at the low frequency of 10LP/mm, it is higher than 0.9 overall, showing the high resolution and sharpness of the SQA106.

Spot Diagram

The imaging quality of the optical system can be evaluated by analyzing
the distribution of the spots on the spot diagram.

The SQA106 has a central star point with an RMS radius of less than 1.65 μm, and the star point at the corner is less than 2.2μm, showing fine star point.