TMB 152 Triplet Apochromat
The TMB 152 is an impressive astrophotography instrument. The fully CNC machined tube and mechanical components are very well made, but it's a heavy scope at well over 45 lbs. with rings and mounting plates. The 4" (100mm) rack and pinion focuser has about 95mm of clear aperture, so it's suitable for medium format work, but it requires an accessory field flattener for photography that reduces the clear aperture down to about 88-90mm or so. The camera mount appears to be Japanese-made, and using the same Borg adapters I already had, it can mount 35mm cameras as well. At its native speed of f/7.9, it offers an FOV similar to a 600mm lens in 35mm format, but with the advantage of producing huge 6x7 slides and negatives. This scope is expensive and heavy, and not nearly as portable as a 35mm format setup with a similar image scale (like the much-loved Epsilon 160), but it has top of the line optics, no false color, and superb resolution for its size.
The scope is supplied with mounting rings, and these can be easily mated to Losmandy doveplates by the use of their mounting block adapters for Astro Physics scope rings. TMB scopes also have sliding dew shields, which are helpful in reducing the overall length of the scopes to fit into a case for transport. I looked at several different cases in which to store and transport this large scope, and ultimately settled on a stock size from Thermodyne, because their case is a tough polymer instead of veneered construction, and I thought it would stand up better to my adventures than a wood-composite case. The case includes wheels on one end and a handle on the other, so it's relatively easy to move it around. It's still a delicate and somewhat heavy lift up into my pickup bed. So far, this case has worked out very well.
In the photo below, the TMB 152 is shown ready for deep sky astrophotography, with the Pentax 67 camera mounted to the field flattener, and the FC60 guidescope mounting on the top doveplate. Plugged into the focuser of the FC60 is the excellent, but expensive, SBIG STV autoguider/imager. The photo was taken in the San Mateo Mountains, Cibola National Forest, New Mexico in 2003.
The photos that follow show the Thermodyne case open, and both the wheeled and handled ends. The shots were taken just after I hosed the case and all my other gear down following an adventure that covered everything in dust. That's one of the best things about having watertight cases - you can just hose everything off when you get home.
TMB 152 Triplet Apochromat Specifications:
Aperture: 152mm (about 6")
Focal Ratio: f/7.9
Focal Length: 1200mm
Field of View: Approximately 2.7 x 3.5 degrees on 120 film