S&T Test Report by Dennis di Cicco

ImageIntensified
Observing

TNVC-Tele Vue NightVision System
U.S. Price from: $3,260 ($4,255 as testedwith white phosphor image tube andaccessories for smartphone photography)
tnvc.com / televue.com

What We Like
Excellent versatility for
astronomy
Connects to a wide range ofTele Vue eyepieces
Ease of capturing images witha smartphone

What We Don’t Like
Legal restrictions forownership and use

58

JU N E 2 018 • SK Y & TELESCOPE

The heart of the TNVC Night Vision System is a standard-issue
PVS-14 monocular. It’s seen here attached to a Tele Vue 18.2-mm
DeLite eyepiece on the Sky-Watcher Dobsonian reflector reviewed in
the April issue. The 4½-inch-long monocular weighs only 12 ounces,making it smaller and lighter than many modern eyepieces.

THE UNDERLYING TECHNOLOGY for

modern image intensifiers has beenaround for a couple of decades. It hasgiven us a variety of self-contained,
palm-size devices capable of amplifying light more than 30,000 times, andthis gives us the reasonable expectationthat an image intensifier could makeordinary backyard telescopes perform
like monster light buckets. As such, it’sfair to ask why the current generationof image intensifiers hasn’t played agreater role in amateur astronomy. If
there’s a simple answer to that question,
I don’t know it. But I do know that this
could change, thanks to a recent collaboration between the Tactical Night
Vision Company (TNVC) and Tele

Vue Optics. The resulting night-visionsystem (picked as one of our 2018 Hot
Products in last January’s issue) proved
to be the most impressive visual lightamplifying setup I’ve ever used.
For the record, I’ve dabbled withimage intensifiers going back to the daysof war-surplus equipment offered byEdmund Scientific in the 1960s. But themost useful device I’ve tried for astronomy was an “electronic eyepiece” called
the I³ Piece and sold by Collins Electro
Optics in the 1990s. It was based ona generation-three image intensifier(essentially the same basic technology in use today). I reviewed the I³
Piece in this magazine’s February 1999
issue, and I ended up buying one but

A LL PHOTOS BY THE AU THOR

The versatility of this new lightamplifying observing system
just might make it a gamechanger in the world of amateur
astronomy.

only occasionally did visual observing
with it. I found it more useful for video
recording things like asteroid occultations and, when adapted to wide-angle
camera lenses, meteor showers.
I was less than an hour into my firstevening testing the TNVC night-visionsystem when it became clear to me
that its adaptabilityg could run circles
around the I³ Piece.

The TNVC Night Vision
SystemAt the heart of the TNVC system is anunmodified, standard-issue, militarygrade PVS-14 Night Vision monocular.
Several versions are available fromTNVC, and I tested the TNV/PVS-14
L3 Gen3 Un-Filmed White Phosphor
model. That’s a mouthful for sure, butbasically this unit uses technology thathas between 15% and 20% greater lighttransmission and a phosphor viewing
screen with a nearly neutral color compared to other generation-three image
intensifiers. For readers interested in
the technical details of, and differences
between, various night-vision devices, I
strongly recommend checking out theexcellent material on the TNVC website(tnvc.com), especially the sections ontechnology, astronomy, FAQs, and thebuyer’s guide. The website also has
detailed sets of technical specifications
for the various monoculars.
Nighttime terrestrial viewing with
the PVS-14 monocular is a jaw-dropping

But there’s anotherexperience. The unit
aspect of the mondelivers a circular fieldocular than makes theof view covering about
magnitude comparison
40° at 1× magnificadifficult, and this goestion. Just the lightfor observing by nakedfrom my suburban
eye or with a telescope.
night sky is enough to
Visual observers use
render my backyard
various techniques
as if it were daytime
to eke out the faintwhen viewed throughest stars, with averted
the monocular. Evenvision being the bestmore impressive wasp From the author’s suburban homewest of Boston, pointing the PVS-14
known method. But
the terrestrial viewing
monocular at the night sky revealedwith the monocularunder the inky black
more stars than are plotted in Sky &the faintest stars on
skies in the mountains Telescope’s Pocket Sky Atlas. The
the phosphor screenof southern New Mexmonocular alone shows a 1× field ofare seen with direct
ico. With only starview approximately 40° in diameter. It
is seen here roughly centered on thevision, even if theylight illuminating theGreat Square asterism of Pegasus.
did teeter at the edge
ground, the monocuof visibility because
lar showed surprisingof atmospheric seeing and the image
detail, albeit not with the same clarity
intensifier’s scintillation — a peppering
as I had under my light-polluted skiesof point-like flashes that appear ranback home in Massachusetts.
domly, especially when the monocular’sTurning the monocular to the night
gain is turned all the way up.
sky was equally impressive, with stars
Perhaps a good way to illustrate thearound 8th magnitude visible. Oddly,magnitude increase due to the monthis result was about the same inocular is through a pair of observations
Massachusetts and New Mexico, evenmade from my backyard on a night
though the naked-eye limit was veryof below-average transparency. At thedifferent for these two locations. Detertime I struggled to see naked-eye stars
mining the exact magnitude limit withand without the TNVC monocular waschallenging, in part because the monocular’s enhanced red sensitivity gives
a bigger apparent boost to red stars,
which shine with light less sensitive tothe unaided eye.

ttt In addition to the PVS-14 monocular, thesystem has available an adapter (center) thatconnects the monocular to any Dioptrx-compatible Tele Vue eyepiece and another adapter (left)that fits over the monocular eyepiece to connect
it to Tele Vue’s FoneMate smartphone camera
holder (right).
tt Much of the TNVC Night Vision System’s versatility comesfrom its ability to use different Tele Vue eyepieces, thus offering theobserver an easy way to vary the magnification. The author did
most of his testing using eyepieces with magnifications ranging
between 54× and 308× on the 18-inch Sky-Watcher telescope.
t The PVS-14 monocular is waterproof and powered by a single
AA battery. The Duracell alkaline battery pictured here will run themonocular for about 50 hours at room temperature. The small
knob above the battery compartment is the monocular’s gain control, which the author usually had set to maximum for his tests.

p Adding to the adaptabilityof the system is a simple
setup for capturing images
seen in the night-visionmonocular with a smartphone. Using a method
explained in the text, the author made all the accompanying astronomical images
with his Apple iPhone 6s
pictured here.

sk yandtelescope.com • JU N E 2 018

59

S&T Test Reportin the Little Dipper fainter than Polarisand the two at the end of the dipper’s
bowl, but the monocular easily showed
more stars in the area than are plottedin Sky & Telescope’s Pocket Star Atlas.
That’s a gain in the ballpark of threeplus magnitudes. And it’s also about thesame gain I experienced when viewing
the open star cluster M67 in Cancer
with and without the monocular a few
minutes later using the Sky-Watcher
18-inch Stargate Dobsonian reviewed in
the April issue, page 58.
Speaking of telescopic observations,this is where the TNVC Night Visionsystem really eclipsed my experienceswith the I³ Piece. The main reason ismagnification. The I³ Piece has the fixedmagnification equivalent of roughly a25-mm eyepiece. The TNVC system, on
the other hand, connects directly to any
Dioptrx-compatible Tele Vue eyepieceand thus allows you to vary the magnification by simply switching eyepieces.
And many of the objects seen to advantage with an image intensifier, such as
small globular and open star clusters,
planetary nebulae, and faint stars, arebest viewed at higher magnifications
than afforded by a 25-mm eyepiece.
Indeed, I spent a great deal of timeobserving with the TNVC unit attached
to a 7-mm eyepiece, which yielded morethan 300× with the 18-inch scope.
While the performance of the TNVC
system was outstanding for the objects
mentioned above, it was far less effective on diffuse objects such as nebulaeand galaxies, with the exception ofsome hydrogen-emission nebulae thatI’ll mention later in this review. Theissue here is one of contrast. While theTNVC amplifies the brightness of these
diffuse objects, it equally amplifies
the brightness of the background sky
and as such does little to improve thecontrast. In a truly dark sky, boosting
the brightness of a telescopic view helps
with the visibility of some faint nebulaeand galaxies, but the effect is not nearly
as profound as when viewing compact
objects like planetary nebulae and anything involving resolvable stars.
As much as I savor the “natural”
view through a telescope eyepiece, the60

JU N E 2 018 • SK Y & TELESCOPE

NGC 2392

NGC 40NGC 7662

p Planetary nebulae were excellent targets
for the 18-inch telescope and TNVC Night
Vision System. This is just a small sampleof the many such objects the author
viewed with the setup.

increased magnitude reach available
with the TNVC system became almost
addictive at times. This was especiallytrue when I was hunting small starclusters. The increased number of stars
visible was one reason, but the ease ofseeing even the faintest stars with direct
vision was equally appealing.

Smartphone Imaging
My past experiences trying to capture
still images with the I³ Piece involved
custom adapters and, at best, were only
marginally successful. Not so with theTNVC system. An optional adapter
couples Tele Vue’s FoneMate directly tothe monocular eyepiece, and because
the phosphor screen is relatively bright,
it’s easily captured with a smartphonesnapshot. But single exposures are rarely

p These images don’t do justice to theimpressiveness of seeing large emission
nebulae through the monocular equippedwith a hydrogen-alpha filter. Stars are heavily
suppressed because the filter blocks 99%of visible light. And as explained in the text,
emission nebulae are only seen in the central
part of the field because the filter goes offband at large viewing angles. Cygnus with
its famous North America Nebula (top) is
reproduced in color to show the approximate
hue of the monocular’s white-phosphor
viewing screen. The shot of Orion (above)clearly shows Barnard’s Loop, but the largenebulosity surrounding the celestial Hunter’shead isn’t apparent because of the filter’sband shift away from the center of the field.

impressive, since they are degraded bynoise and the image intensifier’s scintillation mentioned earlier, which the eye/brain automatically averages out duringvisual use.
I don’t know the features of every
smartphone camera, but there’s a very
cool one available with my Apple iPhone
6s. When the camera’s self-timer isactivated, the result is not a single
exposure, but rather a burst of 10 shots
made in less than a second. For normal
photography I’d select one good shotfrom the burst — when everyone had
his or her eyes open, for example — andsomewhat short of the visual impression you get when looking through theTNVC monocular.
M15

M52

M67

M71

p Globular and open star clusters arealso excellent targets for the imageintensifier system, which showed stars
at least two and sometimes three-plus
magnitudes fainter than one sees by justlooking through an eyepiece without themonocular attached to it.

delete the rest. But when shooting with
the TNVC system I kept all 10 frames
and later exported them for stacking
with astronomical image-processing
software. The results were remarkable,
and the photos an order of magnitude
better than those obtained with just asingle exposure, even if they still fell

An Unexpected Treat
One of the most interesting experiences
I had with the TNVC system is clearlybiased by my long standing interest in
the glowing clouds of hydrogen scattered throughout the Milky Way. It
began one night at last year’s Stellap After Tele Vue’s Al Nagler treated the author
fane convention in Vermont when Teleto views of faint hydrogen-emission nebulae
Vue’s founder, Al Nagler, handed mewith a filter-equipped monocular (described in
his TNVC monocular. “Here,” he said,the text), the author made this plastic piece on a“check out the Milky Way.” As I swept
lathe to fit a 3-nm hydrogen-alpha filter over theupward from Sagittarius to Cygnus I
objective of the monocular he tested. The setup
was used for the pictures of Cygnus and Orionwas dumbfounded to see amazingly
faint hydrogen-emission nebulae almost on the facing page.
magically appear as they crossed thecenter of the field. I’d looked for them
TNVC monocular, it’s a federal crimein the past with the I³ Piece fitted toto send or take one out of the countrywide-angle camera lenses, but only thewithout a proper export license issued
brightest ones were faintly visible. Al’sby the U.S. Department of State. I
trick had been to attach a narrowband
knew this from previous experienceshydrogen-alpha filter to the front ofwith night-vision equipment. But I was
his monocular (and ascaught off-guard byI later learned througha restriction spelledexperimentation, theout in the paperwork I
fast f/1.2 speed of thesigned in order to bormonocular’s objective
row the TNVC device— the camera lenses Ifor this review — it’s aexperimented with inviolation of ITAR rules
the past were f/2.8 andto allow any non-U.S.
slower). Because narcitizen to look throughrowband interference
the device even here atfilters are only effective
home. You can read theover a limited angle
details in the FAQ secp As explained in the text, thenight-vision system was not asof view, the hydrogention on tnvc.com.
effective for viewing many galaxies
nebulae were only seen
It seemed a little
as it was for planetary nebulae andin the center of the fieldawkwardasking people
star clusters. This view of the An(approximately 20° ofif
theywereindeed U.S.
dromeda Galaxy through the monthe monocular’s fullocular was not substantially better
citizens before offeringthan what was visible without it.
40° field), but watchingthem a look throughthem swim in and out of
the monocular, but evenvisibility as they swept through the field
for the sake of a product review I’m not
was part of this truly novel experience.
willing bend federal laws! Fortunately,
all were citizens, and I could enjoy theirgasps of amazement when they first
There’s Always a Caveat
took a peek through it.
As exciting as the TNVC Night Vision
System is, ownership of one comes with■ As a partner in the MDW all-sky
a catch, and in this case it’s legal. Thishydrogen-alpha survey projectlevel of night-vision equipment falls(mdwskysurvey.org), DENNIS DI CICCO
under the International Traffic in Arms
Regulations (ITAR) regulatory regime.
was particularly excited to see glowing
While U.S. citizens are free to own theclouds of gas with this handheld device.
sk yandtelescope.com • JU N E 2 01861