Optec NextGEN Ultra Wide Field 0.7X Reducer
The Optec Ultra WideField 0.7XL is designed specfically to speed up the focal ratios of highly-corrected telescope systems. This design assumes that the image formed by the telescope is flat and aberration-free. If so, the resulting image will also be highly corrected and nearly parfocal with the original image. The speed of an f/8 APO would be increased to f/5.6 with this system, and the optics would still be nearly diffraction-limited. While optimized for an f/8, the Optec Ultra WideField 0.7XL reducer will work for any focal ratio in the range of f/5.6 to f/20. The field is highly corrected up to 18mm in diameter and would work well even with larger fields with only slight degradation near the corners.
Like other reducers in the Optec NextGEN series, all surfaces have a broadband multilayer coating optimized for the 450 - 650nm passband. Filter mounted in front as with the IFW are compatible. In fast systems, it is always better optically to mount the filters in front of any reducer to keep the incoming rays closer to being normal (collimated) to the filter surface.
The Optec Ultra WideField 0.7XL reducer was redesigned and improved in late 2006. It now has a much longer back focus distance and uses the same mounting plate adapters as the 0.33X and 0.50X models. This allows the use of this reducer with SBIG cameras having the CFW-8/10 filter wheels mounted.
The optical design of the Optec NextGEN 0.7XL was done with Zemax and optimized for four field points using wavelengths of 450, 550 and 650 nm. The goal was for the smallest blur diameters for the four field points. The system was modeled using an idealized telesope of f/8 and with perfect optics. The resulting lens curvatures of this designed were made without adjusting the radii to the optical lab's tool list. Custom tools were made for all surfaces.
Optect Product Number: 17409