Introducing the Askar SQA70 70mm f/4.8 Petzval Astrograph, where precision optics meet cutting-edge design to redefine astrophotography. Engineered for celestial enthusiasts and professionals alike, this revolutionary lens combines the classical Petzval design with modern optical advancements, delivering unparalleled clarity and breathtaking detail in capturing the wonders of the night sky. SQA70 Features Petzval Lens Structure: Self-flattened design, no need to calculate specific back focus between 37mm and 68mm connection distance, users can directly use it for shooting after the OTA is in focus Excellent Star Performance: The central star point has an RMS radius of less than 1.84 µm, and the star point at the corner is less than 2.4µm. It also has excellent full-field illumination and MTF data. Stable Lens Structure Design: 70mm aperture, 336mm focal length, the native focal ratio is F4.8. Quintuplet air-spaced lens design, including 2 pieces of ED glass. The optical system of the SQA70 has been fully optimized, utilizing a special glass combination design paired with ED glass to achieve optimal results. Integrated Tube Ring: Integrated pair of tube ring sets, with a hollow design in the middle to reduce overall weight. Enlarged hand screws allow users to open and close the tube ring without additional tools. There are 4 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 multi-functional finder base, which can be used to install astronomical accessories. Dual-Speed Focuser: The dual-speed rack-and-pinion 2.5-inch focuser is compatible with most motorized focusers on the market. The focusing travel is 32 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. 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. Retractable Dew Shield: The dew shield is a retractable design that can be pulled out when used. Protects the lens from the impact of external and internal light and protects the lens itself. 360° Rotator: The rear of the focuser is equipped with a 3600 high-precision rotator with a precision scale to allow the user to adjust and save the angle of rotation. It is also equipped with an edge-shaped locking screw for easy locking. High-Quality Machining: The entire SQA70 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 exclusive nameplates, demonstrating high-end quality. Rear-End Adapters: The end of the SQA70 is equipped with a variety of adapters, all of which are toothed and ribbed, making it easy to rotate manually without slipping. The adapters are available in sizes M54, M48, and M42 and can be used to attach various accessories, such as cooled cameras. Diversified Photography Scene Applications: In addition to connecting to the astronomical camera for astrophotography, the SQA70 can also be connected to a mirrorless camera or DSLR camera for shooting. Specifications Aperture 70mm Focal Length 336mm Focal Ratio f/4.8 Objective Type Quintuplet Petzval APO（Including two pieces of ED glass） Image Circle 44mm Rear-End Adapter M42/M48 (with M48×0.75 filter thread) / M54 adapters Rear-End Connection Distance Supports 37-68mm range (Recommended connection length is 55mm) Total Length 332mm (dew shield contracted); 372mm (dew shield extended) OTA weight 2680 g Total weight (including handle & dovetail plate) 3500 g Optical Path The SQA70 is a quintuplet air-spaced lens design, including 2 pieces of ED glass. MTF Chart In the two sets of curves corresponding to low and high frequencies, even at the edge of the full frame the sagittal lines and sagittal lines distance of the SQA70 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 SQA70. Relative Illumination: The SQA70 guarantees a high illumination of about 90% even at the edge of the full frame, minimizing vignettings. Spot Diagram The imaging quality of the optical system can be evaluated by analyzing the distribution of the spots on the spot diagram. The SQA70 has a central star point with an RMS radius of less than 2.5 µm, and the star point at the corner is less than 4 µm, showing fine star point. Longitudinal Chromatic Aberration Curve: It is a representation of the deviation of different wavelengths of light at the focal point. The different curves in the diagram correspond to different wavelengths of light. Longitudinal chromatic aberration (LCA) occurs when different wavelengths (colors) of light fail to converge at the same focal point along the optical axis of a lens or telescope. Resulting in inconsistent colors in the image, usually manifested as blurred edges or color separation. The longitudinal chromatic curves of SQA70 lenses show very small spacing and even coincide, and the curve curvature is very low, indicating that the chromatic aberration control ability of the SQA70 lens is very good.
