This week we feature the stories of two amateur astronomers delving into night vision astronomy: one from a built-up urban location and one under rural/suburban skies.
The Lights of Chicago
In the past, amateur astronomers located in and near large cities had to content themselves with planetary, lunar, and solar observations from their backyards and balconies. That all changed with the introduction of electronic-assisted astronomy and narrow-band astrophotography. For real-time nebula and faint galaxy viewing, night vision devices (NVD) have come to the forefront. Amateur Darren Drake tells us that with night vision he is able to view such targets as the Horsehead nebula from his “horrendous Chicagoland Bortle 9 backyard.” He sent us some images and described his viewing and imaging techniques using the Tactical Night Vision Company’s PVS-14 L3 Gen3 Un-Filmed White Phosphor (mobile site) monocular with our Tele Vue accessories.
All of Darren’s images on this blog were produced through two big Dobsonian scopes: either his 18″ f/4.42 or John Pratte’s 32″ f/3.6. The astronomical targets determined the eyepiece and filter combinations used on the Dobs. “The larger emission nebulae are always done with a wide field, low power, Tele Vue 55mm Plossl with Tele Vue 67mm Converter and hydrogen-α filter. The other images, such as the Ring Nebula are with a 17mm Stratus eyepiece with no filter. All star clusters are usually with no filter as well.”
Darren’s afocal imaging through the night vision device is done with a Samsung Galaxy S21 phone in “night mode.” This mode turns off the flash and takes deeper exposures. Darren simply handholds the phone over the eyepiece and takes several images. The best are then slightly enhanced. “It’s really quite simple and has immediate results.” Darren emphasizes that “the images are close to what is seen in real-time through the NVD.”
FoneMate for Smartphone Imaging
FoneMate™ can help to get steadier shots at the eyepiece with your smartphone camera. Unlike other phone mounts, FoneMate was designed to mount solidly and on-axis to Tele Vue eyepieces via its Tele Vue compatible lock-ring connection. Use our FoneMate™ smartphone adapter (mobile site) on a compatible Tele Vue eyepiece to share astronomy, night vision, birding and nature views with friends or to do on-the-go imaging.
While your camera app displays the image on the screen, hit the shutter or video button to capture the moment. Use voice commands to avoid button-shake on slow-shutter astro imaging. (If you’ve set up your iOS/Android phone to take voice commands, just say “Hey Siri/Ok Google, take a photo”.) Using a time-lapse photo app will allow you to capture longer events like eclipses/transits (use telescope filters for solar work).
How does the view compare to using the scopes without the TNVC PVS-14 we asked? “Since the sensitivity is higher in the red, red objects and stars are dramatically more brightened than white or blue objects. This is clearly seen when constellations become completely unrecognizable due to the red stars jumping out of nowhere to dominate star fields. This is also why hydrogen-α targets are so amazingly enhanced since they are red.” Darren’s impression is that the TNVC PVS-14 on the eyepiece empowers the scope to act as if it has a 2.5x larger mirror. That’s like being able to see a star 6x dimmer!
Night Vision Spectral Sensitivity
According to an unclassified report, Night Vision Devices and Characteristics, by H. Lee Task, Ph.D., written for the Armstrong Laboratory at Wright-Patterson AFB, in Ohio:
The second generation image intensifier tubes (typically referred to as ‘gen II’) are sensitive to light from about 400 nm to about 900 nm whereas the more sensitive third generation tubes are sensitive from about 600 nm to a little over 900 nm. This compares to a human visual spectral sensitivity that ranges from about 400 nm to 700 nm. The ‘gen III’ tubes are about 4 to 5 times more sensitive to night sky illumination than the ‘gen II’ tubes ….
Night Vision in Rural Virginia
Corey Dallmeyer (aka: Telescope Boss on social media) is working with night vision under Bortle 4 rural/suburban skies in Virginia. His Gen 3 PVS-14 night vision monocular uses an L3 brand of filmless white phosphor tube. He employs it on an Orion SkyQuest XX16G GoTo Dobsonian using a combination of Tele Vue night vision eyepiece adapter, Tele Vue 55 Plössl with 67mm converter, Tele Vue 35mm Panoptic, or several other eyepieces. Filters include Hydrogen-α or 685 nm IR filter for nebulas. He also has the filter adapter that allows for contrasty views of the night sky just using the PVS-14 hand-held.
His Instagram, YouTube and telescopeboss.com website are PVS-14 resources for amateur astronomers with equipment reviews, dark sky sites, imaging tips, night vision advice, DIY projects, and more. The Everything I Use for Night Vision Astronomy article on the site is an excellent resource for those starting out in night vision astronomy.
Corey’s imaging “recipe” is as follows: on globulars or galaxies use no filter or 685 nm IR filter; on extended or planetary nebulae use a Hydrogen-α filter.
Following is his short 1-minute crazy nebula with night vision video made with the 16″ Dob, 35mm Pan, Hydrogen-α, and handheld Samsung Galaxy A71 smartphone. It contains a gallery of nebula images made with night vision.
This second video, good focus, clean night vision phone pics!!, also from Corey’s YouTube channel uses the same hardware but substitutes (mostly) the 55mm Plössl with 67mm Converter.
TNVC / Tele Vue Night Vision System
One of the latest articles on telescopeboss.com is H Alpha Filters For Night Vision Astronomy: 6 Filters Compared. It’s a comparison of Eagle Nebula images made with Hydrogen-α filters connected to a camera lens and Gen 3 night vision device using a Huawei P30 Pro smartphone. Exposures were 30-sec at ISO 400. The review included six filters. A sampling of three is shown here in a gallery. In the gallery, Hydrogen-α filter bandwidth narrows going left to right (12nm, 6.5nm, and 3nm). While the 12nm may seem the “best”, those viewing from heavily light-polluted skies will do better with the narrower band filters.
AN/PVS-14 — What’s in a Name?
Back in World War II, the US military invented a system of naming electronic and communications gear. After the war, this system was formalized as MIL-STD-196 (aka: “Military Standard 196”).
Under MIL-STD-196, equipment names start with “AN” (originally for “Army/Navy”) followed by a slash. Next are three letters that have a specific meaning depending on what position they occupy. For instance, a leading “P” always means “Portable”, a “V” in the second position always means “Visual”, and a final “S” means “Search” using “Detecting or Range and Bearing”. Therefore, any hardware designated AN/PVS is a type of portable military gear for visual searching.
The final requirement under MIL-STD-196 is a model number to uniquely identify the product. In our example, “14” indicates a particular form factor of night vision monocular with a Generation 3 image intensifier. Likewise, the similarly named AN/PVS-7 accomplishes the same goal as the AN/PVS-14 but differs in that the “7” indicates Generation 3 night vision goggles instead of a monocular.
The export of U.S. Night Vision Devices are restricted by the U.S. State Department’s International Traffic in Arms Regulation (ITAR). However, manufacturers outside the U.S. have adopted the “PVS-14″ name for their comparable products.
The MIL-STD-196 has evolved over time. For instance, a “B” as the second letter no longer stands for “Pigeon.” While pigeons are not “electronic” they were considered “communications” gear. The US Army retired its last homing pigeon in 1957.
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