Reviews

A small refractor fan shares the goods on this AT Apo...

Eyepiece AFOV and Barlow magnification factors can effectively vary from manufacturer specified values.

The carbon fiber newcomer takes on the classic Tak FS-152 fluorite

Choosing and Using Large Binoculars

The 32mm 1.25” plossl is one of a handful of available eyepieces that offers the maximum possible TFOV in the 1.25” format. However, reviews of the various 32mm 1.25” options are hard to find. With that in mind I gathered a sample of five different 32mm 1.25” eyepieces currently in production and added the 35mm 1.25” Orion Ultrascopic to the sample.

Taking the Fight to Chromatic Aberration with Filters: #8 Light Yellow vs. Baader Fringe Killer vs. #12 Yellow vs. Baader 495 Longpass yellow filter

Though big Dobs and high-quality catadioptrics are often the telescopes of choice IF they have the time to reach and keep thermal equilibrium, something else is needed to make the most of less-than-ideal conditions while maintaining significant capability. That, at least to me, means a 4-inch APO refractor. Great optics, a short cool-down time, and reasonably light weight are the needed virtues.

The eyepiece market provides numerous options with a 20mm focal length ranging from inexpensive 20mm plossls to expensive “premium” options offered by Pentax and Televue. Eyepieces with a 20mm FL are very versatile giving exit pupils ranging from 4.4mm to 2.0mm with scopes having focal ratios from F/4.5 to F/10...

A touch of Pulkovo, Lick, and Yerkes... On a budget.

The long and short of the little guys...

Yes, that Keck (with apologies to Tolkien, Vance, Monty Python, etc.).

Vintage telescopes are highly prized on the AstroMart web site. Watchful buyers are quick to snatch up brand name instruments like Tinsley and Cave. Another icon among collectible telescopes is Unitron. These bygone refractors harken back to the era before apochromatic lenses when tubes were long and mounts were rigid.