Never Seen One Of These Before

[cohiba]

Hey Guys check this out it looks awfully complicated
http://www.zerochromat.com/
I guess at over $15,000 it wants to be:eyepop:

[iceman]

Very interesting design! First time i've seen one like that.

[bkm2304]

Think that's weird? Have a look at these! I thought it was a Monty Python spoof page at first! The 12.5 inch Newtonian noted for its "simplicity" beggars belief!
http://myweb.tiscali.co.uk/hanwellobservatory/30_inch.htm

[Wavytone]

Aaah yes, amateur Boffinry at its British best.

It's basically a Dialyte, folded. The Dialyte (dating from the era of uncoated optics) was based on the idea of using a whopping positive singlet first element, as big as one could afford, followed by a second negative element well down the optical path of much smaller aperture (and lower cost) to correct the aberrations of that first element. The Dialyte design was a big compromise when it comes to off-axis astigmatism, field curvature, chromatism and lateral colour. Basically its a very big telephoto camera lens, with only 2 elements.

These guys have folded it and modernised it - coated optics suggests a four element second group should be no problem, and modern glass types suggest a significantly better result should be possible than the early Dialytes I have data for.

The snag is, if you're going to shell out for a multi-element sub-aperture second group you may as well shell out for a really decent ED doublet or better, triplet and folde the path of that; it will wind up about the same size, costing much the same, and outperforming it in all aspects. Finding some fool silly enough to make a 30" triplet shouldn't be too hard, in England, methinks...