I’m at the 2009 Pacific Astronomy and Telescope Show (PATS) that runs Saturday and Sunday.

Early Friday, I ducked into several sessions of the Riverside Astroimaging Workshop (RAW). Organizers of RAW this year found speakers to present sessions on “affordable” and “advanced” imaging. Don Goldman from Astrodon Filters gave more seasoned astrophotographers a 2-hour talk on narrowband imaging. Don contributes fabulous deep-sky images to Astronomy, and his talk had lots of details astroimagers could try.

The sessions I saw were hands-on. Participants brought laptop computers, and they followed along as the speakers unveiled new processing techniques. About 50 people attended this daylong workshop.

Later, as I was walking to the then-empty convention hall where PATS would occur, I saw Al Nagler, founder of Tele Vue Optics.

Nagler has been a fixture in the telescope scene since the early 1980s when he introduced the first Nagler eyepiece, the 13mm, that revolutionized observing. People who know Nagler call him “Uncle Al.”

We chatted for more than an hour, and Al showed me lots of pictures he’d taken during the past 2 weeks. He’d been to several star parties and also had stopped by Lowell Observatory in Flagstaff, Arizona. On Saturday morning, he presented the first talk at PATS, “Choosing Eyepieces.”

Al shared with me details of a new product Tele Vue is developing — a ParaCorr, which stands for “parabolic corrector. The ParaCorr corrects an optical defect called coma. This defect causes stars far from the center of the eyepiece’s field of view to appear to have tails (like comets — hence the name). Coma is present in all Newtonian reflectors, but it’s especially noticeable in those that have a fast focal ratio.

Some telescope manufacturers install mirrors with ultra-short focal lengths (below f/4) in their telescopes so they can shorten the scopes. This benefits observers who don’t want to climb a ladder all night to observe faint objects. For example, consider a 20-inch telescope with a focal ratio of f/3.3. The eyepiece of such a scope would be only 5.5 feet off the ground when the scope is pointed at the zenith (the overhead point).

Such a short focal ratio introduces lots of coma. That’s where Tele Vue’s new product comes in, Nagler told me. The ParaCorr model will deal with coma in scopes with focal ratios in the low-2s. That’s incredible. And it’s just one of the cool new things I’ve learned since I arrived at this year’s PATS.

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