Stellarvue SV80 Triplet APO

Stellarvue SV80s Triplet APO
By Phillip Jones

Introduction
The purpose of this review is to discuss the SV80s refractor from three perspectives: as a visual scope, as a CCD astrograph, and an examination of the level of build quality. This scope was ordered in October 2005 and arrived in early December of 2005.

The specs:
- 80mm aperture
- 480mm focal length (384mm with flattener/reducer)
- f/6 focal ratio (f/4.8 with flattener/reducer)
- LOMO designed lens consisting of super ED glass
- air-spaced triplet
- 2" FeatherTouch focuser
- sliding dew shield

The package I ordered includes:
- rings
- red-dot finder
- case (now comes with a hard case)

Stellarvue offers a lower priced package that excludes the rings and the FeatherTouch focuser (a different focuser accompanies the scope). At the time I placed my order, the OTA was offered in three colors: standard pearl white, Midnight Stardust Blue, and Stardust Blue. The two blue finishes add $30 to the package price.


The Stellarvue SV80s Triplet APO Refractor

What was I thinking
It was Spring of 2005 when I decided it was time to abandon the ancient art of film astrophotography and delve in the dark arts of CCD imaging. So I purchased the biggest chip that would fit on my credit card and got a ST-2000XM. When coupled with my FS128 or C9.25, the camera does great on smaller objects. But those large field-of-view DSO beauties were too large for my chip at those focal lengths. Being a CCD newbie, mosaics were beyond my skill level. I was in dire need of a well color-corrected, short focal length refractor, and I preferred a FeatherTouch focuser. The scope also had to serve as a primo visual scope for personal use, as well as public observing events. I considered a wide range of refractors from 75mm to 105mm. The allure of the SV80s was like the tractor beam on Death Star. It met all of the criteria: triplet APO, FeatherTouch focuser, a field flattener/reducer was available, small and portable, and it appeared to be well constructed.

Images I saw online captured with the SV80s were astounding. I realize that image processing skill is essential with imaging, but a superb optical setup is a major contributor to obtaining great resolution. According to experienced SV80s imagers, the TeleVue TRF-2008 field flattener/focal reducer (.8x) was the designated optic for achieving flat images.

I called Vic at Stellarvue and placed my order. I spent the extra $30 and asked for the Midnight Stardust Blue. Having seen this finish on a buddy's SV115 , I found it to be quite attractive. I should mention here that the construction of that SV115, as well as another buddy's SV152, had impressed upon me that Vic delivers a quality product.

APO Addiction
I caught the APO fever back when I first got into the hobby. I showed up at my first ever club public observing event and had my brand new SCT pointed at Saturn. I walked over to a nearby scope that was also pointed at Saturn. The white tube said Taka-something-or-other. It looked so small compared to my large SCT. Not knowing anything about optical quality or high-powered eyepieces, I expected an inferior view. What I saw was breath-taking. Why couldn't my SCT provide a similar crisp view? The owner identified the scope as a Takahashi FS102. Two years later, I acquired one. Sold it to upgrade to a FS128. I also owned a Borg 76ED briefly. My dream scope refractor is a 7-inch APO refractor.

First Impressions
The dark blue finish on the scope is aesthetically pleasing. The tube assembly of this nicely baffled refractor is well constructed. It's heavier than it looks. The alignment adapter attaching the FeatherTouch focuser to the tube is a sturdy piece of metal (see Fig. 2). The dew shield slides to a collapsible state, reducing the overall length by about 25%. It slides easily, yet firmly, and is snug enough to stay in place. A metal cap donning the SV logo threads onto the dew shield (see Fig. 1). The 2"-to-1.25" adapter is nicely machined metal. The brass knob of the FeatherTouch focuser adds to the colorful beauty of the overall assembly.


Figure 1

The scope and diagonal arrived in what looks like a suitcase (see Fig. 1). It's a nice travel style soft case with good foam inside. I'm guessing I'm one of the last SV80s owners to get the soft case. Shortly after my scope arrived, Stellarvue transitioned to a hard case. While the hard case looks nice, I'm pleased with my soft case.

The tube rings are a reflection of quality craftmanship. Nice rubber knobs secure the closure of the ring (see Fig. 2). The grips on the knobs are easy on the fingers, something I came to appreciate in 30 degree temperatures. Ring holes are pre-drilled, positioned, and threaded for use with Losmandy plates. The four holes in the DUPS are a perfect fit. The idea to have additional screws on the upper sides of the rings for attaching accessories, such as the included red-dot finder, or a finderscope, is pure genius.


Figure 2 ? FeatherTouch Focuser and rubber knobs on rings

Speaking of the included red-dot finder, we have reached the point in the review where I utter my sole complaint. This component is all plastic, wobbly even when tightened down, and does not reflect the quality that typically defines Stellarvue. But, it works. I have used it successfully each time, and despite being a tad wobbly, it retains pointing accuracy. Still, I'm certain that some night I'm going hit it accidentally while a large PanOptic is in my hand and the red-dot finder will shatter into a million pieces. If this is a concern, please note that Stellarvue offers an all metal red-dot finder as an accessory that appears to be superior quality.

Stellarvue offers their 2" dielectric diagonal at a discounted price when ordered with a refractor. I took advantage of this offer. The diagonal is nicely machined and the mirror provides excellent reflectivity (see Fig. 3). The diagonal performed well when I did my visual testing.


Figure 3 - SV80s with 2" Stellarvue Dielectric Diagonal


First Light and Binoviewing
FedEx delivered the scope on a Saturday--the Saturday of the monthly suburban public observing party for which I am host. First light was shared with several hundred people. As I was setting up for the event, and darkness and light pollution came into view, I aimed the scope at the nearly full moon and placed various eyepieces in the SV diagonal, including a 6mm TMB SuperMonocentric. Turning the focuser and micro-focuser knobs was a real treat as I felt the smoothness watching the craters come into focus. The sharpness of the image was the first thing I noticed. I was truly in awe.

The 3D effect of the craters when viewed through binoviewers has proven to be a hit at public observing events. So I placed the Denkmeier Standard Binoviewers into the SV diagonal in anticipation of lunar viewing in stereo. As expected, not enough in-focus. I replaced the SV diagonal with a 1.25" Lumicon Enhanced diagonal coupled with the Denkmeier Part S corrector (see Fig. 4). Using a pair of Antares 19mm W70 eyepieces (highly recommended for binoviewing), I reached focus and encountered a dazzling lunar exhibition. I called my fellow club members over to enjoy the same experience. "There's no fringing on the moon!" exclaimed a fellow APO addict. "It's so sharp!" declared another. The lunar view with the SV80s and Denks proved to be a hit with the public. A number of people returned multiple times for additional glimpses.


Figure 4 - SV80s with Denkmeier Standard Binoviewers and Antares W70 Eyepieces


Dark Sky Viewing
I was able to experience an evening out at our club's dark sky property in Oklahoma. Using a 35mm PanOptic, 27mm PanOptic, and 17mm Nagler, I took in wonderful widefield views of the winter night sky. First was Pleiades. I enjoyed seeing the entire star cluster set among other stars. Some of the nebulosity was visible. I moved to the Bubble Nebula and saw the fuzzy patch. In a small scope, the Bubble was uneventful. But the Double Cluster was a site to behold with the multitude of stars surrouding the cluster pair. Next was M31, which was at the zenith. When coupled with the 17mm Nagler, the beauty of the galaxy nested against a star field was captivating. Dust lanes were visible, and the satellite galaxies popped out. It was quite a while before I was able to tear myself away from this spectacular view. The next real treat was M42 with the 17mm Nagler and 27 PanOptic. It was breath-taking. I popped in a Tak 5mm LE and easily resolved the Trapezium.

Scanning rich star fields with the SV80s is such a joy. I felt the "it's in space" look because of the visual impact from viewing DSOs surrounded by stars and space. The visual effect-at least for me-is awe inspiring. I look forward to scanning the summer Milkyway with the SV80s.

A quick star test on Aldiberran showed no color while out of focus. One of my favorite eyepieces is the 13mm Wide Scan III, which has a FOV of 84 degrees. I was disappointed to find that the SV80s lacked sufficient in-focus for use with this eyepiece. I don't fault Stellarvue for this. It's simply a characteristic of short focal-length telescope. Fortunately, none of my other eyepieces encountered focus issues.

CCD Imaging
My first image was the full moon with an Astrodon h-alpha filter in the ST-2000XM (see Fig. 5). The image was captured without the field flattener to see how the image would turn out. While the moon didn't fill up the chip, I was encouraged to see no issues with field flatness where the chip was populated by lunar light.



For DSOs, I utilized the TeleVue TRF-2008 .8x field flattener/reducer. (Note: use of this reducer requires a spacer when used with the ST-2000. I placed a 5mm rubber ring between the reducer and the camera.) The Double Cluster, Pleiades, and Rosette Nebula were a perfect fit on the CCD chip (see Fig. 6, 7, and 8). Focusing manually toward a good FWHM value with the FeatherTouch is easily accomplished when using the micro-focuser. Even though I'm a CCD newbie, I was impressed with the imaging results of the moon and three DSO objects. The Rosette was captured via the Astrodon 6nm h-alpha filter from my backyard in a suburb of Dallas, TX. The Double Cluster and Moon images were also captured from my backyard. The Pleiades was imaged from the Dallas club's dark sky property in Oklahoma.


Figure 6 - Rosette Nebula in H-alpha


Figure 7 - Pleiades


Figure 8 - Double Cluster

Chromatic abberation is a large concern for me as an imager. Nailing focus in the blue spectrum is a challenge with my FS128, thus causing larger stars to have a blue fringe in some of my images. I was delighted to see no evidence of this problem with the SV80s.

Conclusion
Borrowing a phrase from my teenage hard-rockin' 80's era, this scope bodaciously rocks! I'm very pleased with the purchase, thrilled with the optical performance, and impressed with the overall quality. The scope has met the criteria as expected, and exceeded my expectations with regard to performance. It also makes a nice conversation sitting on the mantle (see Fig. 9).


Figure 9 - SV80s as a mantlepiece