Equipment review
Stellarvue’s SV105–3SV is a 4.13-inch
f/7 apochromatic refractor.
Astronomy tests
Stellarvue’s 4-inch
APO refractor
The new SV105–3SV imaging scope boasts high-quality construction,
superb optics, and an oversized focuser. by Jon Talbot
S
tellarvue, based in Auburn, California, was founded in 1997 by
astronomy devotee Vic Maris.
Since then, the company has
earned a reputation for building
high-quality refracting telescopes with
apertures ranging from 2.8 to 6.3 inches (70
to 160 millimeters).
During the past several years, apochromatic refractors (those featuring the best
color correction) have become more common. Some incorporate innovative designs
to meet the needs of the amateur astronomy market. One such telescope is the
Stellarvue SV105–3SV. I had the opportunity to test this telescope recently after having used the original SV105 a few years ago.
The main difference between the current
SV105–3SV and the original instrument is
that Stellarvue designed its newest scope
with astroimagers in mind.
First impressions
The telescope arrived carefully packed in a
foam-lined carrying case (optional) with
the company logo on the side. The scope’s
finish is a sturdy powder-coated white, and
the high quality was evident. The words
“built like a tank” came to mind.
The retracting dew shield carries an
engraved Stellarvue logo, which was a nice
touch. The telescope also has a machined
and threaded dust cap. Mounted on the
scope was the company’s own 3" rotating
focuser, which is big enough to allow the
use of CCD cameras with large chips. The
focuser has coarse- and fine-adjustment
knobs and a setscrew on the side that functions as a tensioner to lock the focuser in
place once rotated into position.
The focuser accepts a standard 2" eyepiece adapter, but what I also found intriguing was that the drawtube includes an
adapter threaded to accept accessories such
as field flatteners. Being able to thread
accessories directly to the focuser drawtube
can reduce overall flex and tilt, especially
when you attach a heavy camera.
Product specifications
Stellarvue SV105–3SV
Type: Apochromatic refractor
Aperture: 4.13 inches (105 millimeters)
Focal length: 735mm
Focal ratio: f/7
Focuser: 3" Stellarvue dual-speed,
threaded for other accessories
Weight: 11 pounds (5 kilograms)
Length: With focuser: 24.5 inches (62.2
centimeters); without focuser: 23
inches (58.4cm)
Includes: Retracting dew shield
Price: $2,295
star-test. I wanted to see how well the visual
image held up at high magnification.
Stars in focus appeared tack-sharp, and
the diffraction pattern looked nearly identical inside or outside of focus.
Using eyepieces ranging from 6mm to
3mm (122.5x to
245x), I spent
some time
observing
Saturn. The planet was quite sharp, with
the Cassini Division and shading in the
atmosphere standing out like sore thumbs.
Imaging impressions
After several days of cloudy weather, I
finally had the chance to attach a CCD
camera to see how the scope performed. I
decided to use Santa Barbara Instrument
Group’s STL-11000 CCD camera to test the
scope with a full-frame 35mm-format CCD
chip. The camera provided a field of view of
approximately 2.5° by 2° at a resolution of
2.5 arcseconds per pixel.
I used Stellarvue’s 2.5" field flattener,
which provides a 50mm-wide corrected
field of view, and I was happy to see it
threaded directly into the adapter on the
focuser’s drawtube. This provided an
extremely rigid connection, which was
important when holding the 6-pound (2.7
kilograms) STL-11000. According to the
manufacturer, the spacing required with
this flattener is 114.6mm, and I ended up
quite close to this number.
Because I live in a fairly light-polluted
location, and because it was early summer,
I decided to image a few globular clusters.
My first target was magnitude 5.7 M5 in the
constellation Serpens. I stacked 18 exposures using standard RGB filters. The
SV105–3SV with Stellarvue’s 2.5" field
All equipment photos: Astronomy: James Forbes
© 2011 Kalmbach Publishing Co. This material may not be reproduced in any form
www.Astronomy.com
• January
without
permission
from the publisher.
70 Astronomy
2012
flattener produced sharp stars in two corners of the CCD chip. I saw evidence of a
bit of camera tilt in the form of slightly
elongated stars in the other two corners of
the image. Several unnamed galaxies near
magnitude 15 also showed up in the image.
Next, I imaged the Hercules Cluster
(M13). This LRGB image contained twelve
5-minute sub-exposures through each filter.
Again, tack-sharp stars appeared in two of
the corners and slightly elongated ones in
the other two. My guess is that the CCD
camera’s weight was such that the focuser
sagged just a tiny bit. However, the elongated stars were hardly noticeable. Overall,
this scope provides excellent images.
The Stellarvue SV105–3SV refractor is a
superb visual telescope that provides stunning and sharp views. The scope is wellbuilt and it also incorporates the right
design choices for the astroimager. When
used with Stellarvue’s field flattener, it
delivers well-corrected images using largeformat CCD cameras.
The first night out with the
scope, I used a 2" diagonal and
various eyepieces to do a
The front lens of the SV105–3SV is an
apochromatic triplet. Stellarvue used Ohara
FPL-53 fluorite glass for the center element.
Stellarvue
11820 Kemper Rd.
Auburn, California 95603
[t] 530.823.7796
[w] www.stellarvue.com
Overall impression
“Visual” impressions
The focuser for the SV105–
3SV is a 3" model developed by
Stellarvue. It has two focusing
speeds and internal threads to
accept other accessories.
Contact information
The Hercules Cluster (M13) was one of the author’s targets with the SV105–3SV. Superb colors and
tack-sharp stars stand out all the way to the image’s edge. Also note that the author captured spiral
galaxy NGC 6207 — the small blue object about two cluster diameters to M13’s upper right. Jon Talbot
Jon Talbot, a meteorologist by trade, is an avid
astroimager who resides in southern Mississippi
and flies into hurricanes for kicks.
www.Astronomy.com
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