New Scope : The Stellarvue SVX130T
The Company has currently have completed a number of 130 apo triplet objectives at better than .99 Strehl.
Air-spaced lenses that are 5" and larger are often mounted in aluminum cells. These cells expand and contract many times more than the glass. The larger the lens is, the more important it is to have it mounted in a cell with a similar coefficient of expansion (CTE). LZOS in Russia has always provided their 130 mm and larger lenses in a steel cell for this reason. Many other 127 - 130 mm refractors use simple aluminum cells which expand and contract around the glass many times more than our cells, distorting the image. Using a material that closely approximates the expansion and contraction rate of the glass is heavier and much more expensive, but it maintains the performance of the lens despite dropping temperatures.