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Upgrading your eyepiece is one of the best--and most affordable--ways to transform your telescope and give yourself a new window on the night sky. For stunning views without compromise, the 21mm Celestron Ultima Duo series checks off everything on your wish list: an impressive 68-degree field of view, superior quality glass elements, and sturdy construction. But one of its most exciting features is hidden beneath the rubber eyecup: integrated T-threads ready for connecting your DSLR camera.
Ultimate Versatility: From visual observing to astrophotography
If you already have a computerized telescope and a DSLR camera, the Ultima Duo is the perfect "missing link" to turn you into a astrophotographer. It couldn't be easier: simply remove the rubber eyecup to expose Ultima Duo's built-in T-adapter. Connect that to a T-ring on your DSLR and you're ready to shoot stunning images right through the eyepiece. This setup is ideal for capturing craters on the Moon, Saturn's rings, Jupiter, and other Solar System objects.
Eyepiece lines from other manufacturers allow you to connect a camera via T-threads, but require you to buy a series of expensive adapters. Ultima Duo accomodates 42mm T-threads with no additional equipment needed! This is by far the most common thread type used in astrophotography, found on all DSLR cameras and a host of astronomical CCD cameras as well. If your particular camera features C-threads instead, Celestron offers an inexpensive T-to-C Adapter for Ultima Duo.
See the difference with a 68-degree field of view
If you're new to wide field eyepieces, you'll be amazed at the difference Ultima Duo's 68-degree field provides compared to standard Plossl eyepieces that come with your telescope or in price-conscious eyepiece kits. This eyepiece will literally expand your horizons, showing you more spectacular detail and nebulosity in faint celestial objects. You'll discover that many of your favorite objects actually have structure and areas of interest that lie beyond the view of most standard eyepieces. And while you could spend hundreds more for even wider views, 68 degrees is the point where you really begin to appreciate the benefits of wide field observing.
Inside, all of Ultima Duo's optical elements are fully multi-coated to provide maximum light transmission. Plus, the edges of every lens are blackened to reduce internal reflections and produce sharp views against a deep black background.
Comfortable and easy to use
From a large Dobsonian to a compact refractor, Ultima Duo accomodates just about any telescope, since it's capable of fitting 1.25" and 2" focusers. With a full 20mm of eye relief and fold-down rubber eyecup, this eyepiece is comfortable to use with or without eyeglasses, making it ideal for observing with a group. The sleek industrial design features a low profile so you can pair up two Ultima Duos for use with binoviewers.
When you're out in the field, you can count on solid performance from these sturdy eyepieces. A rubber grip ring helps you keep your eyepieces secure when switching or adjusting them. Plus, the entire unit is fully waterproof and nitrogen purged so it's ready for dew, snow, or any other ambient moisture.
Celestron 21mm Ultima Duo Eyepiece
Dimensions & Specifications
Eyepiece Series: Celestron Ultima Duo
Eyepiece Barrel Size: 1.25"
Eyepiece Focal Length: 21mm
Eyepiece Apparent Field of View: 68º
Number of Lens Elements: 8 elements in 5 groups
Eyepiece Eye Relief: 20mm
Eyepiece Weight: 16.05oz
We stand behind all the products we sell, and your satisfaction is our top priority. If you're not satisfied with the quality of your purchase, simply send the item back to us in its original packaging within 30 days of its delivery.
Default manufacturer warranty.
Return & Exchange Policy
At our site, returns are easy! You may return new, unused, and resalable items for a refund or exchange. Simply ensure that the item is returned in its original product packaging within 30 days of delivery.
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