Posts Made By: Gene Cross

It would be valuable to note what focal ratio telescope(s) [all?] your evaluations apply to.

Some planetary observers rate "classic" eyepiece types, such as UO orthos, Brandons, and TV Plossls, as producing superior contrast images of planets, compared to eyepieces with more optical elements, such as Radians.

Personally, I find TMB Super Monocentrics to be the "ultimate" planetary eyepiece, as long as the telescope is f/12 or slower. With f/7 or faster telescopes, TMB/SMs have unacceptable residual spherical aberration and limited field of good definition.

On Yahoo groups, the TEC group, Yuri Petrunin has a very insightful evaluation of eyepieces. The Pentax XLs rate very highly. Presumably on f/7 apos.

50 mile wide detail seen from a nominal 93,000,000 miles works out to be an angle of a mere 5e-7 radians, or about 0.1 arc second.

That's very nearly the theoretical limit of resolution.

Actually, the Rayleigh criterion for resolution for the 1.6-m aperture would be about 0.08 arc second for H-alpha light.

Amazing performance from any telescope. Truly amazing performance from a solar telescope at a groundbased observatory.

I believe the Sky 90 II has re-design of lens mount, making possible user alignment of objective lens. This has proven to be highly successful. The short FL relative to the aperture makes the objective lens sensitive to correct alignment.

The Sky 90 II was introduced at least four years ago.

The Sky 90 II is on my wish list of great scopes!

Note also that William Optics has introduced a scope with 90 mm aperture and triplet lens for a "mere" $1300, which seems like quite a bargain. It uses S-FPL53 extra low dispersion Ohara glass, the best Fluorite-like glass available. [I have the WO 80 mm f/7 ED II triplet apo, which uses the "lesser" S-FPL51 glass. It is excellent!]

We live in great times when "optical perfection" ic both achievable and affordable!

Fred,

Tom Scott definitely has made excellent telescope mirrors!

Back in the early 1980s he made some excellent mirrors for me, under the name Cross Optics.

Later he made some very large aplanatic Schmidt-Cassegrain astrographic telescope optics for Jim Riffle, of Astro Works. Learning how to make the large aspheric correcting lenses was a "killer," and almost took both Tom Scott and Jim Riffle over the "edge." But, Tom Scott eventually succeeded, and the scopes were completed. Seems like they were 24 or 25 inch aperture and something like f/6 overall.

Anyway, I am compelled to believe that anyone with a Tom Scott mirror has an excellent mirror!

Often I have viewed with the blue 24-inch [f/4?] Newtonian at RTMC. Very nice optics and beautiful image quality. The owner is to be thanked for sharing this wonderful scope!

Gene

Scott,

Were you successful in learning of the experiences of others with this product?

Like you, this looked to be quite interesting.

I believe this product first appeared at NEAF 2008.

Any info you may wish to share is welcome.

Sincerely,

Gene

Herb, you are Astromart's White Knight, keeping civil liberty alive and well, and promoting the mutual benefit of Astromart members and the astronomical community.

Many thanks-!

Gene

Excellent stray-light control in your 10-inch Mak-Cass to get excellent contrast even with Sun light blue sky producing optical noise for imaging Mars.

Technically and aesthetically excellent image-!

Ken,

How many frames did you stack?

Very impressive work with a 5-inch aperture-!

Gene

My Rep. is Pete Stark.

One good example of a very bad Congressman.

I would vote for just about anyone to replace Stark.

Still, it looks like we might have to vote incumbants out as often as we can until Repulicats finally "get-it" that the public has determined their "two-card-Monty" game has been found out.

Or maybe there will arise a potent third political party that is strong enough to whip the established "Ruling Class."

Charles, I am 100% on board with your idea.

Today is the day after the Arizona primary election. John McCain "won." I had high hopes of retiring him.

Nearly EVERY incumbant deserves to be voted out of the House and Senate. Period.