71F Flat-Field

The Askar 71F is an OTA with an aperture of 71mm, a focal length of 490mm, and a native focal ratio of F6.9. The Askar 71F adopts a quadruplet air-spaced APO lens design, including one piece of ED glass， which can effectively reduce chromatic aberration. The Askar 71F supports 44mm full-frame imaging with great performance of the surrounding star points. The Askar 71F is a self-flattened design that allows users to avoid calculating the back focus and buying additional flattener, after attaching the imaging accessories, users can directly use it for shooting after the OTA is in focus. This further reduces the cost and improves the pleasure of shooting.  With practicality and versatility in mind, the Askar 71F's weight and size are effectively controlled, making it easy to carry and use. The Askar 71F OTA weighs only 2.5kg and the gross weight is 3kg (including the tube rings and dovetail plate). The Askar 71F is versatile in its use, allowing for both visual observation and astrophotography. For users' convenience, we've also included three observation accessories standard for the 71F: an 8mm eyepiece, a 20mm eyepiece, and a 1.25-inch 45° erecting prism. The 8mm eyepiece has a magnification of 60x and the 20mm eyepiece has a magnification of 25x. The Askar 71F can be used with different eyepieces depending on the target, and both eyepieces are ideal for viewing birds and landscapes. Both eyepieces have a 1.25-inch barrel and a rubberized top for a soft and comfortable user experience. The 1.25-inch 45° erecting prism provides correct left-to-right and down-to-up image views, making users easy for you to observing without the hassle of seeing images reversed up, down, left, and right.  The Askar 71F also comes standard with a photographic extension tube, which includes M48*0.75&M54*0.75 adapters, it also contains a built-in 2-inch filter thread for easy shooting connections. No matter whether connecting a traditional DSLR camera or a professional astronomical camera, it is very convenient to use. When users go out, they can directly connect the shooting accessories to record the beautiful view at any time.  The mechanical design of the Askar 71F itself adheres to Askar's consistent philosophy of taking into account the user's habits and minimizing the user's invisible costs. The dew shield of the Askar 71F is a retractable design, further shortening the overall length and increasing portability. The entire lens tube of Askar 71F is crafted using high-quality CNC machining. All the inner of the Askar 71F's dew shield is covered with matting paint to effectively reduce stray light reflections. The overall blue and white color scheme makes the telescope look more refined. On the handle bar of Askar 71F, it designs a finder base slot. Besides, there are two finder bases on both sides of the focuser, which not only eliminates the need for disassembling when changing the position of the finder scope but also provides additional mounting positions for other astronomical accessories. In terms of the focuser, the Askar 71F is equipped with a dual-speed R&P 2.4-inch rigid focuser, which has a 1:10 fine adjustment and a 360° scale field rotator at the rear end for precise angle adjustment. The Askar 71F's dovetail plate is a 230mm standard Vixen dovetail plate, which slotted 1/4 screw holes as well as 3/8 screw holes for direct tripod attachment. As an affordable and high-quality versatile self-flattened OTA, we look forward to the Askar 71F accompanying you to discover more beautiful!  Specifications Parameters Aperture size 71mm Focal length 490mm Focal ratio f/6.9 Objective lens Quadruplet air-spaced APO(including one ED glass) Image circle 44mm Maximum accessory connection (with the focuser fully retreated) Imaging mode:    82.5mm (from the base of M48×0.75 male thread）    100.5mm（from the base of M54×0.75 male thread) Observing mode:    111mm（from the end of 1.25" eyepiece holder）    121mm（from the end of 2" eyepiece holder） Minimum accessory connection (with the focuser fully extended) Imaging mode:    32.5mm (from the base of M48×0.75 male thread）    50.5mm（from the base of M54×0.75 male thread) Observing mode:    61mm（from the end of 1.25" eyepiece holder）    71mm（from the end of 2" eyepiece holder） Total length 372.5mm(including 1.25" adapter as dew shield contracted）    430.9mm(including 1.25" adapter as dew shield fully stretched）    415mm(including the photographic adapter as dew shield contracted）    473.4mm(including the photographic adapter as dew shield fully stretched） Focuser travel length 50mm Net weight 2.5kg Gross weight(Including tube ring&dovetail plate） 3.0kg Rear-end thread type: M64×0.75-M54×0.75    M54×0.75-M54×0.75    M54×0.75-M48×0.75 (with M48×0.75 filter thread) Standard package items A 71F OTA， a pair of tube rings, a handle, a Vixen 230mm dovetail plate, a set of photographic adapters, a 1.25" 45° erecting prism, an 8mm eyepiece, a 20mm eyepiece Product Size Diagram  71F Connection Diagram The Locking Screw Position Diagram EAF (optional) Installation  Optical Path Diagram  Spot Diagram Images Nerci Flückiger  | Wolf's Cave - Barnard 175 | Askar 71F Flat-Field + ZWO ASI2600MC Pro Ákos Takács | NGC6888 Crescent Nebula | ASKAR 71 Flat-field + ZWO ASI533MC Pro Keon-Ho Lee  | NGC7000  |  ASKAR 71 Flat-field + Nikon Cooled Z6 Sandwall  | M42  |  ASKAR 71 Flat-field + ASI2600MC Donn Miller | M51 The Whirlpool Galaxy | ASKAR 71 Flat-field + Player one Uranus C pro IMX585