September 16, 2008

In Today's One Minute Astronomer...

Wide-Field Eyepieces

For expansive views of star fields, nebulae, and other deep-sky objects, you'll want a couple of good wide-field eyepieces for your telescope: one for low-power and one for medium power. There are many on the market, but here is a comparison of some superior offerings for a range of budgets.

The Basics

• Antares Speer-Waler. These wide-field eyepieces have the same 82-degree apparent field of view as the far more expensive Televue Naglers. But you get what you pay for. Quality is modest, and some report these eyepieces work better with f/10 Schmidt-Cassegrains than f/6 Dobsonian reflectors. Fixed focal length from 5 mm to 17 mm. Less than $190.

• Baader Hyperion. Fairly new on the market and well received. These wide-field eyepieces have the same 68-degree apparent field of view as Televue Panoptics. These are large eyepieces. Fixed focal length from 3.5 mm to 24 mm. Less than $120. Well worth a try.

• Meade Ultra-Wide. Similar to the Nagler with an 82-degree AFOV. Good value. Focal length 4.7 mm to 30 mm. Price $200-$450.

A Deeper Look

• Televue Naglers. The gold standard for medium to short focal length eyepieces. Tack-sharp images to the edge of the field. If you have the means, get at least one. Best choice is whatever eyepiece that gives you a roughly 2 mm exit pupil (the focal length of your eyepiece divided by the f# of your telescope). Available with focal length of 2.5 mm to 31 mm. Price $290-$640. Naglers hold their value over time, and they're worth every penny. Especially for medium focal lengths.

• Televue Panoptics. These are Televue's low-power wide-angle eyepieces. Amazing contrast with a 68-degree AFOV. Great for faster focal ratio reflectors. Good eye relief. Look through the 27 mm or 24 mm focal lengths and you'll feel like you're looking out the window of a space ship. Available in 19 mm to 41 mm focal length. Price $245-$510.

• Pentax XW. These eyepieces give the folks at Televue a run for their money. Very long eye relief… great if you need to wear glasses with your scope. AFOV of 70 degrees. Focal length 3.5 mm to 40 mm. Price $340 to $549.

• Televue Ethos. Brand new. These are like Naglers, only better, with an incredible 100-degree AFOV. I've not yet tried one but the reviews are excellent. Focal length 8 mm or 13 mm. Price… don't ask (O.K., they're $600 each).

A Bit of History

If you want to learn more about eyepiece science and selection, check out the instructive tutorials at Televue.

Personal View

In a perfect world, a 41 mm Panoptic, a 13 mm Ethos, and a 5 mm Nagler with a short-focal ratio apochromatic refractor and bone-dry clear dark desert skies. For a visual observer… Nirvana.

--- Highly Recommended ---

A great scope for kids and casual stargazers, this easy-to-use Dobsonian has no complicated control knobs or adjustments. See bands on Jupiter, craters and mountains on the moon, as well as hundreds of star clusters, galaxies, and nebulae. Includes two eyepieces and Starry Night software. Sky and Telescope calls it ".... a new standard for the beginner's telescope". Learn More.

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