"Telescope Talk: The TMB 130 Signature Series Refractor"
Refracting telescopes using expensive glass in multiple lens elements, to correct for false color inherent in traditional refractors, are called apochromats. The TMB 130 SS uses an air-spaced ED (extra-low dispersion) 3 lens "triplet" objective. Combined with multiple lens coatings and sharp-edged internal tube baffles, this design is optimized for the best possible image contrast. Add the straight-through, unobstructed light path, and you help enhance distinctions between light and dark shades, making image details "pop" in human eyes. Telescope fans will argue forever about the merits of expensive refractors versus much larger objective mirrors in reflectors and compund scopes. I'll tell you there is plenty of room to use and enjoy all types of scopes - but you'll also hear me gush about this scope's performance.
External impressions: This scope is really handsome, plus it fills that classic image - it's what many people expect a telescope to look like. Looking at it from a few steps away, I think of those sketched images from 19th century astronomy books, in which a polished optical tube reaches high into an old wooden dome. The long white enameled tube is a real eye-catcher at public viewings and other astronomy events (image: right). The smooth machining, and precise fit and finish are obvious to anyone taking even a passing look. It comes in a high quailty, well-padded alluminum case, and feels very substantial as you lift it from the cradle. Extending the self-stowing sliding dew shield really changes the scope's appearance (note the difference in the two images, left and below right). This scope weighs only about 20 pounds / 9 kg, making it really easy to set up and take down using the included mounting rings. I'm happy to see this sort of old-fashioned precision construction in a modern instrument every time I upack this scope.
Observing impressions: The weather in south Texas since I purchased the scope in Spring 2007 has been terrible, with nearly constant clouds and rain, so I've only had about seven decent observing sessions this year. The scope has been in action about half the time in the light-poluted suburban skies around 5th magnitiude, and at dark sites well into the west Texas open spaces. Despite being based on this limited number of observing runs, I'm still overwhelmed with this scope's performance. The triplet lens system is very well colored corrected, with no violet or yellow halos around bright objects such as the Moon, Jupiter, Saturn, or bright stars. However, pushing the magnification really hard on Venus, our brightest planet, will generate a small fringe of false color. In the one chance I've had to push up magnification under stable seeing, star images test very tight and sharp, with the expected Airy disk rings. As I'd hoped for - and expected - in a true apo with a medium objective size, images have a fine sharpness all the way to the edge of the field. I'm working at much higher powers with this scope than its bargain apo little brother, the Orion 80 ED, but have yet to see the image break down appreciably above 200x.
Saturn has been the biggest planetary target thus far, and the 130 shows a full, belted disk with good color saturation among the tans and golds of the planet's "stripes." It splits out the A, B, C main belts with a full Cassini Division, under stable seeing of course. Apart from easy-to-spot Titan, it easily to resolves Tethys, Dione, and Rhea under medium magnification. As expected, this scope is a killer on the Moon, with smaller craterlets, valley/rille floors, and anything along the terminator looking tack sharp. On deeper space objects such as globular clusters, the contrast offers three dimensional depth, resolving the "grains" within the core. Here we're just below 30 degrees north latitude, so "super cluster" Omega Centauri just clears the horizon during the spring months. On it's first dark sky trip, the 130's "in-your-face" view of this massive object just floored us all!
The TMB 130 SS offers an opportunity to own apochromatic performance in a medium-sized scope. Definately worth putting on your list of afforable bigger refractors. -- JW