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, tubes, and focusers 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.”
A large 3" focuser allows for 6x7 medium format astrophotography without vignetting. The focuser rotates 360 degrees with zero image shift to allow a photo to be composed after the camera is focused. The Sky & Telescope review noted that the “rack-and-pinion motion was smooth, without any image shift or backlash.”
The focuser terminates in a removable 3” drawtube to 2” diagonal adapter with a clamping ring to protect the finish of your eyepieces and diagonals from scratches. A 2” to 1.25” clamping ring 2” to 1.25” adapter is also provided. A 3" diameter x 4" long extension tube that mounts between the drawtube and the 3” to 2” adapter provides the correct amount of back focus spacing for visual use with an eyepiece and diagonal. The Sky & Telescope review pointed out about the extension tube that, “unique among refractors, the TMB focuser is designed to accommodate a binocular viewer. Because of their lon
