In our pursuit of the finest optical quality possible, the HyperStar lenses have gone through several generational changes. Below are details on the improvements made in each generation, and a guide to identifying the different models. Since the Meade models are relatively new, there has only been one generation of each. The sections below describe the various models of HyperStars for Celestrons.
The HyperStar lens for the 8" Celestron SCT has gone through three generations. The models differ in both mechanical and optical design. The second- and third- generation models feature collimation adjustments and independent camera rotation, allowing the camera to be oriented in any position without affecting collimation. Most impressively, the newest model allows for large-format CCD chips up to 27mm diagonal to be used, covering a field over 3 degrees wide!
The HyperStar lens for the 11" Celestron SCT was the first HyperStar lens. Read more details below in the section on the History of HyperStar. The HyperStar C11 has undergone five mechanical changes and three optical design changes. The HyperStar C11 was the first model to incorporate collimation adjustments. The latest iterations both have independent camera rotation. The newest model, the HyperStar 3, has coverage for sensors up to 27mm and is compatible with DSLRs.
The HyperStar lens for the 14" Celestron SCT has undergone two revisions. The first model was designed for use with the larger SBIG ST-series CCD cameras, and it illuminated a larger field than the smaller HyperStar lenses. After the design of the HyperStar M14 for the Meade 14" SCT, the HyperStar C14 was revised to be compatible with digital SLR cameras as well. The newest HyperStar C14 is the same optically as the second generation, but has a different housing. Note that the new version has a smooth tapered wall, while the older design has a stepped wall. Both models include collimation adjustments and independent camera rotation.
In 1997, Celestron introduced the Fastar 8 telescope. This Schmidt-Cassegrain telescope incorporated an easily-removable secondary mirror assembly and a Fastar corrector lens which could be used in place of the secondary mirror. This allowed a CCD camera to be mounted at the front of the telescope, converting the optical system to an incredibly fast f/1.95 focal ratio. This provided both more speed for shorter exposures, and a wider field of view. The latter was especially important for the small CCD chips available at the time. Celestron later introduced Fastar compatibility on other 8" SCTs. A 14" Fastar lens, which converted Celestron's largest SCT to an f/2.1 system, was developed as well.
When Celestron released their NexStar 11 GPS, that telescope included the Fastar-compatible removable secondary mirror assembly. However, the Fastar lens for the 11" telescope was never put into full production. This provided the impetus for the first HyperStar lens from Starizona. We could see the immense benefits of the Fastar system, especially for beginning imagers, but also for advanced astrophotographers. So we took it upon ourselves to develop a fast corrector lens for the Fastar-compatible telescopes, starting with the 11". When the NexStar 11 GPS was released in 2001, CCD imaging for amateur astronomers was taking off. Larger and less expensive CCDs were becoming available. This meant the performance of optical systems over larger fields of view was becoming more critical.
The first HyperStar lens, released in 2002 for the Celestron 11" SCT, improved on the original Fastar design in both optical performance and speed. The HyperStar lens converted the 11" SCT to an f/1.8 system, 31 times faster than the telescope's inherent f/10 focal ratio!
The next HyperStar lens was for the Celestron 14" SCT. The larger aperture of the C14 made possible a HyperStar that could cover the larger CCD chips available at the time. The f/1.9 HyperStar was nearly 25% faster than the original Fastar 14 and it allowed for the use of larger-format CCD cameras.
The HyperStar C8 soon followed, completing the collection for Fastar-compatible Celestron SCTs. But there was plenty of demand for a HyperStar system for Meade telescopes. We were surprised to discover that certain models of Meade SCTs were actually "HyperStar-compatible", meaning they had easily removable secondary mirror assemblies. Soon Meade owners could join the high-speed imaging revolution with HyperStar lenses for the 10" and 14" Meade SCTs.
The Meade 14" HyperStar also made the next major step in the evolution of the HyperStar lenses. By the time of its development, digital SLR cameras had become popular for deep-sky astrophotography. The HyperStar M14 was designed to allow the use of DSLRs and larger-format CCD cameras (see Rosette Nebula image below). Deep-sky imaging was easier than ever! A DSLR compatible HyperStar C14 followed, replacing the original model.
All current HyperStar models are collimatible. This was discovered to be a critical issue when using the original Fastar 14. Due to the way the primary mirror is mounted in a Schmidt-Cassegrain telescope--it is held only in the center on the baffle tube--there is a possibility of the mirror becoming misaligned with respect to the optical axis of the telescope. With the secondary mirror in place, this is not an issue since collimation can be corrected using the secondary mirror. (The spherical mirrors in an SCT also help make this alignment less critical.) But with a HyperStar lens in place and the secondary mirror removed, any misalignment becomes noticeable. At f/2 the optical system is very sensitive to slight errors in alignment, so making the HyperStar lenses adjustable allowed sharp star images to be obtained over very large fields. All models incorporate independent camera rotation, allowing the camera to be oriented without affecting collimation.