Brent/Bob, Is it possible that because the mask is, essentially, touching the mirror there is not the diffraction inherent with the spider and secondary obstruction? I mean, yes, there is a larger obstruction but isn't that obstruction basically diffraction free because of it's proximity to the mirrors surface? I would think that would be the only reason to place it upon the mirror as opposed to above the secondary mirror/spider where an aperture stop or apodizing mask normally would be placed. David Bennett On Wednesday, February 26, 2003, at 10:02 PM, Brent Watson wrote:
Bob,
This is an interesting idea, but I don't see that it would make the view any netter. The mask still acts like the spider, and in fact is worse because it is wider. It MAY get rid of the temperature effects mentioned in the article. I would be scheptical about it working, and would have to conduct several careful tests to see if it made an improvement.
Brent