Telescope Reviews: Takahashi 22 x 60

That the Tak 22 x 60 field is fully illuminated out to an unusual portion of the field is not surprising, when it is considered that the basic body-prism-eyepiece was built for a 7 x 50 with a much steeper light cone, something between f/3.5 and f/4.

I rapidly skimmed through 1991 to 1996 Tenmon Guides, but could not find any Tak ads featuring those, nor Japanese retailer ads with them included. I recall such ads in issues of TG , and probably in Sky& Telescope. Are they from the 1980's? Or from after 1996? My TGs from those periods are in a different location, away from here.

I have never used one. When I saw the adverts, I thought it was a strange combination, in particular since I had spent time fixing Swift and USMC Tasco with cracked glue around the prisms, liberal use by Katsuma of grease-retained shims under the prism plates , to bring the collimation error to within the range of adjustment provided by the somewhat loose eccentric rings around the objectives, heavy rubber, among unsavory aspects of what is a virtual copy, but with lower mechanical quality and integrity, of the WW II USN Bausch and Lomb Rochester Mk. 28 7 x 50.

A post in this forum stated, or speculated, that the objectives of the 22 x 60 Tak are a Canon product. What is the collimation method? Single or double eccentrics around both objectives? Double eccentric around only one objective, as in the Nikon 20 x 120 II and III? Prism plate tilting(which would likely require removing the coverplates, it seems from the photos)?

One wonders if the objectives were respaced (only ?, or radii and/or spacings changed) to work with the prisms, if they originated as part of a prismless refractor? If one has used fluorite, it seems that the prism effects must have been at least considered in the hybridization.

Another successful hybrid with add-on objective tubes screwed into a 7 x 50 body is the WW II USN 9 x 63, which has high axial image quality ( but not flourite or ED or Apo). The making of a hybrid similar to the Tak seems straightforward: untapered cylindrical tubes , ED or flourite objectives, narrow light cones. The major question is the compensation for the presence of prisms, hopefully by a simple respacing of the objective. The use of the phantom roof mode II Amici mirror airprism avoids those problems,should prism presence be significant with narrow cones and relatively( to most telescopes) low magifications, and gives comfortable zenith views.

With all of the attention drawn to those Taks recently, it seems that this is not a good time to look for one. Better to do some other type of observing until things cool off.