$spider veins create diffraction spikes$

$spider veins create diffraction spikes$

SPIDER VEINS CREATE DIFFRACTION SPIKES FREE

You can attach a small fan to the rear plate to circulate air and accelerate acclimation. A sealed optical system like this extends cool-down time, however, so take that into account when you’re setting up. The backing plate protects against dust infiltration, reducing the need to have the optics periodically recoated. The tube comes with white end rings as well as a backing plate that covers and seals the primary mirror’s cell. The optics sit in an attractive steel tube that sports metal-flake glossy black paint. The tube’s interior is flat black, but to help improve image contrast even further, the manufacturer glued a small square of ultra-flat black material to the inside wall directly opposite the focuser. Baffles prevent extraneous light from infiltrating the optical path.

$spider veins create diffraction spikes$

Inside, the tube has five baffles to help maximize image contrast.

SPIDER VEINS CREATE DIFFRACTION SPIKES FREE

Therefore, photographs taken through this scope will be free of diffraction spikes around bright stars. That results in roughly a 30 percent central obstruction, about the same as a Schmidt-Cassegrain telescope.īecause the secondary attaches directly to the front meniscus, there are no spider veins like in traditional Newtonians. To accommodate photography, the secondary mirror has a stated minor axis of 2.5 inches (64mm) to illuminate the entire field of the sensors used in many popular digital single-lens reflex (DSLR) cameras and CCD imagers. The meniscus measures 7.48 inches (190mm), the determining aperture. In this case, the primary is 8 inches (203 millimeters) across. The primary mirrors in all Maksutov telescopes need to be larger than the stated aperture to work correctly. As I discovered, the results speak for themselves. The meniscus lens is also fully multicoated with the company’s proprietary Metallic High Transmission Coatings to maximize image contrast. Sky-Watcher USA uses an enhanced aluminizing for both the primary and secondary mirrors, resulting in 94 percent reflectivity. Manufacturers prefer this type because it holds its precise curvature better as the temperature changes through the night. Both are made of low-expansion borosilicate glass. To that end, Sky-Watcher USA offers its Maksutov-Newtonian 190mm, a 7½-inch f/5.3 Mak-Newt that proved to be an outstanding yet affordable example of the breed.Īt the heart of the 190mm is a spherical primary mirror teamed with a deeply curved front meniscus lens. The Mak-Newt’s unattainability has started to erode over the past few years, with prices coming down and availability going up. The compound optical design eliminates two fundamental drawbacks of the mirror-only Newtonian reflector: astigmatism (where light rays focus at different points) and coma (where stars at the edge of the field of view have comet-like tails). Maksutov-Cassegrains, in which light passes through a central hole in the primary out to an eyepiece, have become popular among today’s amateurs thanks to improved mass-production methods (and thus lower costs).īut Maksutov-Newtonians, on which the eyepiece is at the tube’s front like a traditional Newtonian reflector, have always been custom-made telescopes carrying hefty price tags. Each uses a front corrector plate, or meniscus, and a rear-mounted primary mirror to collect light and bring it to a focus. Maksutovs come in two basic varieties: Maksutov-Cassegrains and Maksutov-Newtonians. But that changed in recent years with the introduction of several lower-priced models. Amateur astronomers considered them exotic. Until fairly recently, Maksutov telescopes were not commonly seen at star parties.

$spider veins create diffraction spikes$

Spider veins create diffraction spikes