| The 19mm Astro-Tech Flat Field is a very good medium power eyepiece for lunar observing, resolving globular clusters (and open clusters with short focal length refractors), scanning the star clouds of the Milky Way, etc. It has a very flat field that keeps your image sharply in focus from one edge of its wide 65° field to the other. This flat field makes it a great match to the new breed of flat field/coma-free catadioptric telescopes.
The flat field of the 19mm Astro-Tech lets you scan the lunar surface with a long focal length catadioptric scope or refractor, for example, and see sharply defined craters and rilles filling the entire field, rather than having the image soften and blur disconcertingly towards the edges as you often find is the case with the curved field of conventional eyepiece designs.
When used with short focal length refractors, the Astro-Tech’s flat field shows you views of open clusters in which all the stars in the cluster are in focus, not just those in the center of the field. The moons of the gas giant planets show as sharply focused dots when they are at their maximum extension on either side of their sharply focused parent planet, not as the out-of-focus smudges often seen in lesser eyepieces.
Its 19mm focal length gives an f/4.5 Dobsonian owner a wide and bright 4.22mm exit pupil for rich field scanning of the Milky Way star clouds in Sagittarius, with sharply defined stars all across its wide 65° apparent field (a 1.08° actual field with a 10" f/4.5 Dob, more than two lunar diameters across). And the 19mm Astro-Tech is an excellent choice to complement the 40mm eyepiece provided with some go-to Schmidt-Cassegrains.
This 19mm Astro-Tech Flat Field has a reasonable 12mm eye relief that may mildly vignette the field for eyeglass wearers. Those who must wear eyeglasses while observing due to severe astigmatism might want to forgo the pleasure of using this flat field gem, but those willing to put up with minor vignetting will enjoy the view, as will all non-eyeglass wearers.
Best of all the 19mm Astro-Tech Flat field eyepiece is priced well below similar design eyepieces from other suppliers, and with double the warranty.
| 
Printer friendly version
Email page link to a friend
Do you have a question about this product?
