This 2” Astro-Tech 38mm Titan is a really big low power eyepiece with a super wide angle wide 70° field . . . at a surprisingly economical price. It provides dramatic “picture window onto space” images with virtually any telescope that uses a 2” star diagonal or focuser.
For example, with an 8” f/10 catadioptric it will give you a wide 1.33° actual field (well over two and a half times the diameter of the full Moon) at 52.6x. With f/6 and f/8 Dobsonians and short focal length refractors, the 38mm Titan is a superb low power eyepiece.
With an f/4.5 Dobsonian, however, it has an 8.44mm exit pupil, significantly larger than the maximum diameter to which most eyes can dilate. You will lose a significant portion of the light-gathering capability of your f/4.5 Dob with the 38mm Titan, as about 30% of that 8.44mm eyepiece exit pupil will fall on your eye’s iris, rather than usefully entering your eye. With an 8” f/6 Dob, however, the 38mm Titan provides 32x, a very bright 6.33mm exit pupil, and a wide 2.19° field of view that’s well over four times wider than the full Moon. It takes an object nearly nine minutes to cross that very wide field, giving multiple observers plenty of time to take a look before you have to manually re-aim your scope. The 38mm Titan is a great eyepiece for family observing and star parties with an 8” f/6 or 6” f/8 Dobsonian.
Please note the 24.8 ounce weight of this eyepiece if you have a Dobsonian scope. It may pose a balance problem with some Dobsonians when switching to the 38mm from a much lighter 1.25" eyepiece. Use of the 38mm Titan may require some temporary rebalancing of your scope to avoid balance problems.
With a small refractor like the 80mm f/6.8 Astro-Tech AT-80ED, the 38mm Titan provides a huge 4.84° field at 14.5x. That makes the scope its own best finderscope and ideal for very wide field views of galaxy clusters, the larger nebulas, open clusters, the star clouds in Sagittarius, and more.
The Titan’s long 20mm eye relief provides unvignetted viewing for eyeglass wearers. But whether you wear eyeglasses or not, you will find you have to move your head from side to side while observing to see the entire Cinemascope-type field. The 38mm Astro-Tech Titan gives you a huge field of view at only a fraction the cost of a more exotic super wide angle eyepiece.
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