Sky-Watcher S11540 Overview

      With the largest aperture in the series, the Sky-Watcher 180mm f/15 Maksutov-Cassegrain Telescope is a powerful astronomical tool that remains manageable and portable. The Maksutov design exchanges the conventional front corrector plate of a Schmidt with a convex meniscus lens, resulting in a smaller secondary mirror that limits obstruction and increases contrast, while eliminating the need for periodic collimation. This modified optical path results in a slower focal ratio and narrower field of view versus a similar Schmidt, but the optical benefits, when coupled with the larger aperture and fully multi-coated optics, make this an ideal scope for making detailed solar, lunar, and planetary observations, while being able to resolve deep-sky objects like stars, clusters, galaxies, and nebulae.

   The scope is outfitted with a large 2" visual back. To get users started, Sky-Watcher includes a 28mm long eye relief eyepiece that produces 96x magnification and a 90° star diagonal for viewing with the optical tube assembly (OTA) pointed at or near the celestial zenith. The OTA is offered here without a mount or tripod for users who have a reliable support system or want to use it as part of a dual-OTA setup for star parties or observation/imaging rigs. It is outfitted with a Vixen-style dovetail plate for use with compatible mounts. This OTA's compact form factor belies its observation power and resolution and is ideally suited as a grab-and-go option for quick observation sessions or heading out to remote locations.

               Optical Performance

                      180mm aperture

       f/15 focal ratio

       2700mm focal length

       Front convex meniscus lens corrects spherical and chromatic aberrations as well as comas (off-axis aberrations) across the entire field of view

       Smaller secondary mirror versus Schmidt-Cassegrains reduces obstructions and increases contrast

       Fully multi-coated optics maximize light transmission to improve brightness, color rendition, sharpness, and contrast

       Resolution: 0.64 arcsec

       Internal primary mirror focus

       2"-diameter visual back accepts larger eyepieces and accessories

              Mounting

                      Requires mount and tripod for proper use

       Vixen-style dovetail plate

       Weight: 19 pounds including OTA, dovetail plate, finder, diagonal, and eyepiece

              Included Accessories

                      Eyepiece:      

             2" barrel diameter

       Accepts most 2" astronomical filters

       28mm eyepiece yields 96x power

       Comfortable long eye relief

      Diagonal:

             2" snout and eyepiece holder

       90° angle places head in a comfortable viewing position

       Star configuration corrects image horizontally for terrestrial use

      Finderscope:

             Relatively low 8x magnification provides a wide field of view for easier alignment and faster star-hopping navigation

       50mm aperture helps resolve dimmer objects that dot finders cannot