MegrezII ED Triplet initial impressions

I received and installed my triplet which is a drop in relacement of
course for the original Megrez II doublet. Initial indications are the
triplet has good wavefront quality--always the most important
thing--and that the color correction is indeed ED class.

Color correction is obviously much better than the MII doublet was,
looks like a solid ED-class performer. Not zero color like the much
more expensive zero-color fluorite triplets, but at half the price,
something of a bargain.

Most importantly, the star test is very good indeed, very round
fresnel rings with ruddy-fringed rings inside of focus, essentially
perfect correction of spherical abberation. In focus, the airy disk
is hard and round, with a single dim red diffraction ring, on
moderate brightness stars. I do not see how you could ask for a
better result at this price.

Cosmetic quality of the glass is very clean indeed. It does not look
like the cell is collimatable like the doublet, then again mine
doesn't need it like the doublet did.

On A-B nighttime star tests, I estimate the color error about 2x the
color of the TV76, primarily a little excess red.

I once compared the Orion ED80 to the TV76 and the former had a
little more red excess than the latter, lets say 1.5x. A Tak FS78
beat them both, again in the red, but not by much, just to give you
an idea of the level of performance we are talking about here. All
these scopes have many times less color than an achromat.

Vignetting is not an issue, either at the foam ring baffles, which
can be scooted against friction if necessary, nor at the focuser body
or extender tube.

Next comparo: I estimate the TV Ranger (Pronto) has a good 4x the
color of the MII/EDT.

The color halo around stars is quite obvious on the Ranger, with a
actinic mixture of red and blue. Switching back to the MII/EDT is a
dramatic improvement, the airy disk changes from yellow to off white,
and the halo goes from a bright violet 3+ diffraction rings to 1 dim
red.

The MII/EDT color error reminds me of the original TV Genesis I once
owned, and also the TV Oracle, the under-appreciated and short lived
75mm F7.4 triplet. The colorful rings of the Ranger are due purely to
the color defocus, as it has a superb star test otherwise.

My tally so far from most color to least, in the small scope
sweepstakes:

Achromat
Ranger/Pronto/Megrez doublet

TV Oracle
MegrezII EDTriplet
Orion ED80 APO
TV76

FS78 fluorite doublet

80 TMB F6 fluorite triplet
80 TMB F7.5

It looks like this is William's answer to the Orion ED80.