Sky and Telescope - December 2016 - 61
Mama Scope I've spent innumerable happy hours observing the night sky with my Orion 4.5-inch StarBlast, so I was pleased to see that the optical tube of the LightBridge Mini 114 appears to be precisely identical, except for the paint job. Indeed, Mama has exactly the same strengths and weaknesses as the StarBlast. It's outstanding at low power; the stock 26-mm MA eyepiece gives a vast 3°° true field of view at 17×, enough to encompass the entire Veil Nebula or the Andromeda Galaxy with its two main companions. The view is also impeccable with the 9-mm MA at 50×, an excellent magnification for deep-sky observing with this aperture, and ample to show pretty views of Jupiter's main bands and Saturn's rings. Things get more problematic when you attempt serious planetary observing by adding a 2× Barlow lens or using an eyepiece with very short focal length. The focuser is fine for a 9-mm eyepiece, but it's hard to make the tiny adjustments needed to achieve good focus at 100× or higher. I also had some problems with the mount, which I'll describe later. Baby's Huygenian eyepieces at left look very much like Mama's and Papa's modified achromats, but the modified achromats have much better optical quality. Papa Scope As much as I love Mama's 114-mm f/4.0 optics due to my long experience with the StarBlast, I have to admit that the 130-mm f/5.0 mirror of the LightBridge Mini 130 is clearly superior. You give up a little at the low-power end, achieving "only" a 2° field of view using the 26-mm MA eyepiece for 25×. On the other hand, the low-power view is much sharper near the edge than Mama's because inexpensive eyepieces work far better at f/5 than at f/4. A 24-mm eyepiece with a 68° apparent field of view increases Papa's true field of view to its theoretical maximum of 2.5° - a worthy investment even though it's likely to cost almost as much as the telescope itself. Whatever Papa loses at the low-power end, it more than makes up for at high power. The combination of extra aperture and magnification means that Papa resolves globular star clusters far better using its 9-mm eyepiece at 72× than Mama does at 50×. And when you add a 2× Barlow to achieve 144×, you're in the planetary major leagues. This is enough to show the Cassini Division in Saturn's rings easily when the atmosphere allows, and to show considerable detail on Jupiter and on Mars near opposition. Focusing is a little hard at 144×, but no more so than at 100× using Mama - and the gorgeous views are worth a little hassle. Mount Issues The LightBridge Mini series is striking for its unusually small and lightweight mount. For instance, Mama weighs three pounds less than the StarBlast, which is very noticeable when you're carrying the scope in one hand. Unfortunately, the mount is a little underbuilt; it takes about one second for vibrations to damp out when To improve the azimuth motion, remove the lock washer that holds the turntable to the base. Above: Inspect the Teflon pads on the base. Smooth off any rough spots and countersink any staple that protrudes above the pad. Inset: Cut the two "washers" shown here from the sides of a plastic milk jug, sandwich a USS ½-inch washer between them, and stack them on the spindle. (The steel washer has a 9/16-inch inner diameter and 1 3/8-inch outer diameter.) When re-assembling the mount, tighten the lock washer and then back it off about ¼ turn to make sure that the turntable rotates smoothly. Sk yandTelescope.com December 2016 61
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