The TMB 105 4” f/6.2 optical tube is a truly international telescope. It is designed by Thomas M. Back in the United States. Its optics are manufactured and multicoated by a Zeiss subcontractor in Russia. The lens cells are manufactured in Germany on computer-controlled milling machines and lathes for absolute precision, extremely tight tolerances, and unit-to-unit consistency. Once the individual optical and tube components have passed their initial testing in Europe, they are shipped to TMB in Ohio for assembly, optical tweaking, and final optical and mechanical testing by the designer himself. Only those optical tubes that pass Tom Back’s personal rigid final inspection standards are covered by the TMB U. S. warranty. TMB telescopes imported into the U. S. through channels other than through TMB itself – and/or through Astronomics, the sole U. S. distributor – are not subject to the designer's inspection and testing and consequently are not covered by the TMB U. S. warranty.
The TMB 105’s super ED apochromatic air-spaced triplet lens provides virtually color-free images across the entire visual spectrum – and beyond, into the infrared, for astrophotography. The Sky & Telescope review commented, “The optical quality of the Russian lens did not disappoint. In side-by-side comparisons with a TMB 100-mm f/8 triplet refractor, the faster f/6.2 instrument showed just the palest rim of color when I viewed stellar diffraction disks inside and outside of focus. The longer f/8 TMB, also with Russian-made optics, was utterly color free right through focus.
”With the f/6.2 scope, the star test revealed an almost complete lack of axial aberrations, with just a trace level of spherical aberration or sphero-chromatism softening the diffraction pattern outside of focus and preventing absolutely identical diffraction patterns inside and outside of focus.
”At 220x (obtained with a TeleVue 3-mm Radian eyepiece) Jupiter and Saturn appeared extremely sharp and contrasty, snapping into focus with an assuredness not seen in lesser telescopes. The lunar limb and crater rims were totally color-free, as was brilliant Venus. The Double-Double was resolved as four dots of light, like tiny drops of white paint set in a black sky, surrounded by the dim ripple of a single diffraction ring. At low power with the 35-mm Panoptic eyepiece, stars were pinpoints across the entire field, except at the very edges, where they began to fuzz out.
“In short, these are optics to please the most discriminating ‘optophile,’ providing, in my opinion, views as sharp as you’ll see in any apo refractor.”
Premium multicoatings on all surfaces assure 99.75% transmission per surface, with a total transmission through the triplet objective in the unusually high 96+% range. The Sky & Telescope review called the optics “immaculately multicoated.”
For other reviews, we suggest you follow this link to the non-commercial “Cloudy Nights” review of the TMB 105. The review is extensive, unsparing, and has a number of useful photos.
There are few fast focal ratio apo refractors that reach such rarified levels of hand-crafted optical and mechanical excellence. The TMB 105 is one of them. It follows in the tradition of the Astro-Physics Traveler as an ultra-portable apochromat (it will break down to a length of only 17” and fit into a 20” case, after all). Unlike the Traveler, however, you can have a TMB 105 without having to get on a multi-year waiting list to get one.
