Re: What makes them think this apo will be cheaper?

On Dec 23, 7:42 pm, Rich <rander3...@xxxxxxxxx> wrote:
Than the 2 or 3 element products out there?  The alignment problems
would exceed those of the TeleVue products.

http://www.wipo.int/pctdb/en/wo.jsp?IA=RU2007000305&WO=2008002188&DIS....

I've previously looked at creating apochromatic telescope objectives
using methods that I believe are similar to those shown in this
patent. However, I've always found that either variation of coma with
wavelength is almost impossible to control or the tolerances get
crazy. However, maybe these problems have been solved.

A much easier way to understand apochromatization without large
elements of exotic glass is to perform the correction at an image of
the objective. In this case it is possible to perform the
apochromatism using small glass elements which can be a significant
cost saving. The downside is an increase in the number of glass
sufaces and length.

Correcting aberations at the image of "offending" elements can be a
powerful tool.
.