Super Houghton Astrograph

The Super Houghton
Astrograph

11.4" full aperture correctors during fabrication

The Super Houghton is a full-aperture corrector, with auxiliary near-focal corrector, Newtonian type astrograph unlike any other. It's fast and covers a large angular field with high definition. Aperture ratios from 4.5 down to 2.78 have been designed that yield flat, diffraction limited image circles of unusual size. For example, an 11" aperture astrograph at f/4.1 can cover a 2.36" flat, image circle absolutely diffraction limited; that is to say, the spots are at or within the Airy disk, and the Airy disk is 5.6 microns in diameter. In this case the stellar field covered is 3 degrees, and this with a 45% obstruction. Useful image circles up to 3" in diameter are practical. The f/4.1 prototype under construction is designed for a completely unvignetted field of 2.2 degrees with an image circle of 1.72" and a central obstruction of 41%. Additional advantages include relative insensitivity to misalignment of optics and thermal change. In other words, the system is loose in terms of dimensional tolerancing, due largely to the zero-power two-element Houghton corrector.

For an astrograph speed and high definition is everything. Many of the new astrographs that use the Cassegrain design as their base have an inherent speed problem, they are slow systems by their very nature (the secondary mirror always lengthens the focal length of the primary) and attempts to speed them up result in ultra-fast primary mirrors and very large central obstructions. It's axiomatic that very strongly curved optics and extreme aspherization results in difficult to adjust (and keep adjusted) optics and very difficult to fabricate (unrealistic design tolerances) optics. The results are never as good as less curved and less aspherized optics. The Newtonian design is an inherently fast system and the Super Houghton especially well corrected, the combination is unbeatable.

An 11" aperture, f/2.78 system can cover 3 degrees (maximum 8 micron spots) with a 1.60" image circle and a central obstruction of 50%.

The optical system is manufactured entirely by me, in the United States of America, and is tested and finished in double pass as a complete system, not anonymously manufactured as individual parts and then assembled.

These astrographs are completely custom designed and fabricated to specific customer needs. They come with carbon fiber tubes and systems can be made up to 14" clear aperture. No standard designs will be manufactured. Prices are individually quoted based upon design and manufacturing work required, however, as an example, the 11" f/4.1 Super Houghton is in the range of $15,000. Price will be refined upon production of prototype.

Serious inquiries are invited.