Atmospheric Dispersion Corrector ???

I read the article in the August S&T regarding atmospheric dispersion correction with prisms (at that time there was no mass produced version) and then the Nov. S&T comes out with the news of a retail product in the New Product Showcase section with AVA's new "Planetary Atmospheric Dispersion Corrector." I did a search of the forum but from what I can tell this hasn't been discussed here much. The article gave a pretty good description of "how and why" this works. I have only been at this about a year and a half so I thought I would put out a question to see if there is any interest in this thing by those of you who have been at this a while or if any discussion would generate. Are there differing opinions as to HOW MUCH improvement this will actually make for planetary viewing? Has anyone tried this by making their own and did it make a big difference? Is it worth the price(starting at $135 and up). I will spend most of my time with clusters and galaxies this winter but I'm really looking forward to viewing Jupiter and Saturn again when spring approaches and they come up earlier in the evening--- what do you think?

Lynn

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Yes, it does help for stars and planets.
I see significant improvement for objects
at elevations below about 50 degrees, which
is more than half the sky. I did not get
the AVA version (yet); I decided to make my
own while waiting for AVA to ship. There are
various wrinkles:
(1) you need to get the system F-ratio to
about 40 or higher, else the proism causes
astigmatism. Typically this means using the
prism behind a 3x or more Barlow lens.
(2) you will need good seeing to notice the
improvement, and seeing at low evelvations is often
poor anyway.
(3) the eye has some minor ability to correct
for atmospheric dispersion, which may make the
improvement less noticable.