In addition, a Questar's central baffle tube is not merely black plastic or painted black to reduce reflections, as with lesser scopes, but is a centerless ground stainless steel tube, anodized matte black and containing a wire helix with 19 internal knife-edge baffles to eliminate low-angle reflections that no paint alone can stop. They all have larger light-scattering secondary or diagonal mirror obstructions than a 7" Questar Classic Titanium. The same holds true with any other larger reflector or catadioptric telescope you care to name. The small secondary mirror of a Questar Seven Maksutov (only 1.87" in diameter) scatters far less light than a 14" Schmidt-Cassegrain's much larger 4.5" secondary. The larger the aperture of the scope, the greater the image-blurring effect of these microcells, as the larger scopes simply have to look through more of these turbulent cells than a smaller scope.įinally, there is the matter of contrast. In essence, when observing, you are usually looking through bubbles of disturbed air - microcells typically 4" in diameter in the layer of the atmosphere nearest the surface of the Earth. This significant difference in total system accuracy is one reason why a 7" Questar can routinely outresolve a 14" Schmidt-Cassegrain (or virtually any other larger aperture catadioptric or reflector scope) on globular clusters, binary stars, and lunar and planetary details - with the Questar invariably exceeding Dawes' limit for the best resolution available from an optical system of its aperture.Ī second reason is the turbulent Earth atmosphere all telescopes must look through. In either case, it's a far cry from the 1/8th wave total system accuracy entering the eyepiece of a Questar. However, they do not specify whether that is for individual components or the system as a whole. Most commercial telescopes claim to be "diffraction-limited" (which is generally assumed to mean 1/4th wave accuracy). That's twice the accuracy needed to meet Lord Rayleigh's Criterion, which specifies the level of optical excellence required to yield visual performance that is indistinguishable from perfect optics. Simply this: a fanatical devotion to hand-crafted accuracy.Įach optical element in a Questar typically tests out at a truly outstanding 1/50th wave accuracy (shaped to within four ten-millionths of an inch of perfection!) This produces guaranteed total system performance at the Cassegrain focus of 1/8th wave or better. What is it about a Questar that lets it outperform larger scopes on a day in/day out basis? The Crêpe Ring and Encke's Division in the rings of Saturn are routine with a Seven Classic in good seeing, as are myriad whorls and festoons in Jupiter's belts and hundreds of sub-kilometer craters on the lunar surface. While the 14" scope was brighter on the fainter objects, the superior contrast and resolution of the Questar Seven was easily visible. I have compared my own Questar Seven to a 14" Schmidt-Cassegrain on deep space objects such as the Sombrero galaxy, the Saturn Nebula, and Omega Centauri. You'll see detail and clarity in the skies that you have never seen through any lesser scope, or even through many larger scopes. Look through a Questar Seven Classic Titanium optical tube with a zero thermal expansion quartz mirror, and you're looking through an absolutely superb example of the telescope maker's art. Astro-Tech AT60ED and AT72EDII Black Friday Sale.Explore Scientific Nebraska Star Party Sale.Various Closeouts Meade, Kendrick, Bob's Knobs, JMI and others.Astronomics Used, Demo, Closeout, Spring Cleaning Page.Rechargeable Batteries And Power Supplies.Personal Planetariums / Electronic Sky Guides.Focal Reducer and Field Flattener Combos.Equatorial & Altazimuth Accessories & Adapters.
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