The TMB 100 optical tube is a truly international telescope. It is designed by Thomas M. Back in the United States. The optics are manufactured and multicoated by a Zeiss subcontractor in Russia. The initial optical testing is done in Germany. The lens cells, tubes, and focusers are manufactured in Germany on computer-controlled milling machines and lathes for absolute precision, extremely tight tolerances, and component-to-component consistency. Once the Russian and german 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 100’s super ED apochromatic air-spaced triplet lens provides color-free images across the entire visual spectrum – and beyond, into the infrared, for astrophotography. Premium multicoatings on all surfaces assure 99.75% transmission per surface, with a total transmission through the triplet objective in the unusually 96+% range.
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 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 adapter is also provided. A 3" diameter x 4" long extension tube that mounts between the drawtube and 3” to 2” adapter provides the correct amount of back focus spacing for visual use with an eyepiece and diagonal. Removing the extension tube shortens the spacing to allow any binocular viewer to reach focus without a Barlow lens. This feature, unique among premium quality refractors, allows the widest low-power fields possible with a binocular viewer, for truly panoramic and almost three-dimensional deep space images. Because of the removable extension tube, the total back focus from focuser to image plane is an exceptionally long 220m. The shortest possible tube length is 520 mm with the extension tube removed, while the standard tube length during visual observing is 845 mm. The focuser itself has 70mmm of travel available, so that any focal length eyepiece can be accommodated.
The focuser has large anodized focuser knobs with rubber O-ring gripping surfaces for a firm grip and frostbite-free handling in cold weather. The focuser has thermally compensated mechanics so that the motion is as smooth racking in as it is racking out no matter what the temperature.
The CNC (computer numerical controlled) machined tubes are machined and lathed with extremely tight tolerances to hold the focuser and lens cell in precise alignment The tubes have internal light baffles spaced by aluminum rods for precise positioning to avoid vignetting during medium format photography and when using wide field 2” eyepieces. The tube diameter is 130 mm. There is a retractable 156mm diameter dewcap/lens shade with a thumbscrew lock that slides smoothly over the tube without scratching. The tube and dewcap are painted, the machined metal parts are hard anodized, and the tube rings are satin-finished aluminum castings. The tube rings have flat bosses on opposite sides to allow an equatorial mount’s dovetail plate to be attached to one side of the rings, while a mounting plate for accessories is installed on the opposite side. Both mounting bosses have three 1/4”-20 threaded holes with a spacing of 2.
