Stellarvue Doublet Apo SVX127D

Outstanding optical quality! Bench test interferometry from Stellarvue showed a Strehl of 0.99. I ran a WinRoddier software analysis of the scope with a high-speed video camera under live-sky. The scope was not force-cooled to ambient temp yet and was tested in less than ideal atmospheric conditions.

Despite the conditions I got 0.98 Strehl in the Green (visual) wavelengths. So the 0.99 Strehl factory Zygo test in a controlled lab bench environment appears to be legitimate for sure on this scope.

I got a polychromatic Strehl (full color all throughout the Red, Green, and Blue wavelengths) of 0.97. This indicates very tight control of any Chromatic Aberration or Spherical Abberation all through the visible light spectrum.

I checked Rigel, Betelgeuse and Sirius visually for any defocused or at-focus ghost color fringing and could not detect any on these very bright stars.

This is the first doublet I've tested of several brands and models of doublets that I've ever seen that result from.

I put the optical tube through a variety of other tests:
In and Out-focused diffraction rings from near-focus out to 18-20 waves of defocus were essentially perfect and on a par with other premium brands of refractors I've tested previously that were triplets, not doublets!

The Feathertouch 3" focuser was mechanically and aesthetically perfect with virually zero lateral drawtube shift or focuser collimation drift when checked with lasers and a magnified test pattern to see errors easier.

When checked with a Takahashi Collimator Scope, the lens set test pattern views showed perfect collimation all the way front to back to the focuser drawtube and focal point.

I've owned and tested several other brands of premium triplet apo refractors. This is the first time I've seen a doublet lens set that could compare to those high-end triplets, but this one really does.

And with this tube being about 4 lbs lighter than similar 5 inch scopes that have heavier triplet lens cells, the easier portability is especially appreciated out in the field on remote setups or with lighter mounts.

Another unique feature that is very seldom seen is the fact that Vic is willing to back up the scope's claimed performance with an interferometry bench test printout provided to each scope's owner. That is a pretty uncommon thing to see in the industry.

The premium companies will do that for you, but typically you'll pay several hundred bucks extra to get that information. It is included automatically with these Stellarvue "X" models without you having to make a special request and pay extra money for it.

Eventually I'll post more complete optical test data with graphs and pics to my website once I have more time to compile it all (compubuild.com/astro). But this SVX127D refractor really stands out to me as "best-in-class" of any doublet I've ever seen including some older premium models of Flourite-lens doublets that were considered the best of their time.

What truly stands out about this scope though is how well it compares to premium TRIPLET apo's. That's something I didn't expect and makes this model something really special.

Thanks,
Wade

Wow! Holy Cow this scope is amazing! I am purely a visual observation guy. I hit up binary stars, star clusters and galaxies the first night and was blown away that a 5 inch doublet scope could deliver such nice contrast and crisp clear views. I had the SXV102T, but caught aperture fever so I decided to go this route and I am not disappointed. I also decided to go with the Stellarvue focuser to save a little money. The focuser is great and smooth. The mechanics are solid. So like I said... stop thinking about it and just get this scope:-)

I received my Stellarvue SVX127D on December 23 and had "First Light" under rather dismal skies. Since then I had two additional observing sessions (5 Feb and 8 Feb) under cold, crisp skies with above average seeing. I have the SVX127D mounted on my Losmandy G-11...a rather perfectly matched combination. Eyepieces used were TV's: 22mm Panoptic (46x); 10mm Radian (101x); 6mm Ethos (169x); and 3.5mm Nagler (290x).

The Moon was available for viewing early on and to say I was blown away by the crispness and contrast of the lunar features is an understatement! And this is from someone who is used to observing with some top quality long FL Unitron's! Even at 290x using the 3.5mm TV Nagler, features displayed very sharp with very little softening.

Beyond the Moon, my plan was to check out some doubles to test the optics, as well as lots of open star clusters in Canis Major, Monoceros, Gemini, Cancer, Perseus, and Cassiopeia. Standouts were M35, M47, and the double cluster....with a nice field of stars embedded in a perfectly black background. I also viewed M44 using a Brandon 48mm EP at 21x. Quite the view!! I checked out a dozen or so double stars during the evening, but Iota Cas and Zeta Cancri (Tegmine) standout. Iota Cas has always been my favorite triple with its whitish primary and golden and bluish companions. The stars displayed pinpoint. With respect to Tegmine, the AB pair are <1.0 arcsec separated and at 290x the dark split was obvious.

This is my second Stellarvue, my first being an SV110ED. The quality and engineering of both is truly exceptional! Looking forward to many satisfying hours behind the eyepiece.

Finally some clears skies to try this out! The quality of work put into building this scope really shows. It is beautiful!. Mine is fitted with the SFFX1 field flattener and the first images showed perfect optics and alignment with pinpoint stars across the entire field using an APS-C mono camera. I used it visually on Jupiter, Saturn, the Moon, and a couple globular clusters. The views were outstanding at the magnifications I used ranging from 50-200x. My only concern is how far the Stellarvue focuser needed to be racked out to achieve focus. Nearly 3/4 full travel out with the camera and a little over 1/2 with the diagonal and eyepieces. With the length of this scope, it requires some extra caution in setup to make sure there is no crash with the tripod. My first impression is this is a fantastic scope! Great job Stellarvue Team!!!