Albert Nagler is the founder of Tele Vue Optics and inventor of the Nagler eyepiece. Al Nagler also worked in the Apollo program and built simulators used to train astronauts. Al Nagler is a beloved figure in the amateur astronomy community.^[1]

Early Life

As a child^[2] in New York City, Nagler had interests in art and science. He owned a small telescope as a child and as a teen joined the "Junior Astronomy Club" sponsored by the Hayden Planetarium.^[3] Nagler later enrolled in the Bronx High School of Science with the goal of building a telescope.^[4] In the Scientific Techniques "shop" class taught by Mr. Charles Cafarella, Nagler ground an 8-inch mirror and constructed a reflecting telescope.^[5][3] Materials for grinding the mirror were obtained as a kit from "Precision Optics", a company headquartered in the Bronx, N.Y.^[3] The resulting instrument was a 350 lb, 8" aperture, f/6.5 Newtonian reflector with a wood hexagonal tube mounted on an equatorial mount fashioned from pipe fittings.^[3] Nagler exhibited this telescope at the 1958 Vermont Stellafane Convention and won third place.^[6][4] He also wrote an article for the December, 1955 edition of Mechanix Illustrated detailing the construction of the telescope.^[1][7][4] A photograph of the telescope was also included in the October, 1957 issue of Sky & Telescope Magazine.^[6]

After graduation, Nagler worked a variety of jobs in machining, chemicals, and drafting. He also took night classes for 16 years at the City College of New York and graduated with a BS in physics in 1969.^[1]

Farrand Optical & NASA

Utilizing a contact from the amateur astronomy community, Nagler obtained a job with Farrand Optical as a draftsperson.^[4] Nagler worked at Farrand until 1973 and achieved the level of senior optical systems designer.^[1]

Under contract with Grumman Aerospace Corp. and NASA, Nagler and Farrand Optical designed "Infinity Display" systems simulators for the NASA astronauts.^[8] The systems projected images to the Apollo Lunar Module training device by using six foot mirrors and giant lenses covering the triangular windows of the Lunar Module. Nagler used ball bearings as stars in a spherical map projected via camera to the module as well as an intricately sculpted moon map. The astronaut could use both eyes to see the displays projected onto the triangular Lunar Module windows.^[1] In a blog post,^[4] Nagler described this system as a "giant eyepiece that swallows spacecraft", and this system was also demonstrated in the movie Apollo 13.^[9] This experience in building wide angle projection displays was inspirational in Nagler's later development of the 82° Nagler eyepiece.^[4][9]

Keystone Camera Co. & Ambi-Tech

After receiving his physics degree in 1969, Nagler left Farrand and worked as chief optical engineer for Keystone Camera Co.^[1][4] Nagler traveled to Japan as part of his work with Keystone and made valuable contacts in the Japanese optics industry. Nagler left Keystone in 1976 and worked with a friend from Farrand, Matt Baum, to found Ambi-Tech, a company that would concentrate on building safety mechanisms for woodworking devices. Nagler worked with Ambi-Tech for twenty years. During this time, Nagler founded a part time business named Tele Vue Optics.^[1]

Tele Vue Optics

In 1977, Nagler and his wife Judi established Tele Vue Optics at Spring Valley, NY (later, Tele Vue would relocate to Pearl River, NY, Suffern, NY, and eventually Chester, NY).^[3][9] Nagler worked part time on optical designs for Tele Vue while working full time with Ambi-Tech. The Naglers were finally able to work full time at Tele Vue in 1997. Tele Vue is a family business. Nagler's son David joined Tele Vue in 1998. David's wife Sandy took over Judi Nagler's duties when she retired in 2008. David Nagler majored in communications at Syracuse University and was able to promote Tele Vue via advertising, marketing, and internet.^[1]

Al Nagler named the company Tele Vue as an abbreviation of "television viewing" and "telescope viewing". One part of the business originally focused on projection televisions. At the 1977 Consumer Electronics Show, , the projection lens system was billed as 'NASA Scientist Designs Projection TV Lens', and in 1978 science retailer Edmund Scientific sold Nagler's "5-inch super projection lens" in its catalog.^[1]

Eyepieces

By 1979, Nagler designed his first eyepiece, a wide-field telescope eyepiece termed the "Nagler". Nagler was awarded a patent for an "Ultrawide Angle Flat Field Eyepiece".^[4][10] The Nagler Eyepiece exhibits an 82° apparent field.^[4] Compared to an eyepiece such as a 50° Plössl, the view through a Nagler eyepiece is more expansive and appears to wrap more around your vision.^[11] As an observer, Nagler enjoyed low magnification "rich field" viewing of extended "deep sky" objects such as galaxies, star clusters, and nebulae, and the Nagler eyepiece was meant to produce such experiences.^[3]

Nagler was concerned about the expense of producing the new eyepiece design and reasoned that a new company would have difficulty marketing such a costly item. He decided to develop a line of 50° apparent field Plössl eyepieces to establish a foothold in the business. Nagler took a previous design, the Clave Plössl, and "improved the edge correction" in his 1980 redesign.^[4] The Tele Vue Plössl line was well received. Richard Berry in Astronomy Magazine proclaimed the Tele Vue Plössls to be the "Sharpest I've ever used".^[12] The original Plössl series had focal lengths of 40mm through 7.4mm in 1¼" eyepiece barrels.^[4] The 55mm Plössl features a 2" barrel and weighs 1.13 lbs.^[13]

After obtaining exposure and market share with the Tele Vue Plössl eyepiece line, Nagler released the first ultrawide Nagler eyepiece, the 13 mm Nagler, in 1980. This was the first eyepiece in a series named "Type 1".^[4] The introduction of the 13 mm Nagler eyepiece is considered a benchmark in amateur astronomy. It was the first eyepiece to provide an 82° wide field of view with sharp images all the way out to the edge of view.^[14] Expensive for its time, the 13 mm Nagler cost $200.^[14] The eyepiece also coincided with the introduction of the Dobsonian reflecting telescope.^[9] This telescope design made it easier to mount large telescope mirrors, and amateur astronomers became accustomed to observing dim deep sky objects such as galaxies, star clusters, and nebulae.^[15] Nagler eyepieces are well-designed for observing such large, dim, and extended objects.^[16] The Nagler series continued with Types 2, 4, 5, and 6, and each new type features innovations such as dual 2" & 1¼" inch eyepiece barrels, clickguard adjustable eyeguards (Type 4), eyepiece barrel safety undercuts, and fold-down rubber eyeguards.^[4][13] Later versions of the Tele Vue Plössls along with newer eyepiece lines were also equipped with these new features when appropriate.^[13]

Highlights of the Nagler line are the 20mm Type 2 released in 1986 and the 31 mm Type 5 released in 1999. The 20 mm (now discontinued) featured a 2" barrel and weighed 2.3 lbs. In Tele Vue ads, a miniature Al Nagler was shown leaning against the side of the 20mm Nagler.^[13] The legendary 31 mm Nagler, featuring a 2" barrel and weighing 2.2 lbs, is referred to as the "Terminagler" eyepiece.^[13][17]

In 1982, Tele Vue released a line of Widefield eyepieces featuring a 68° field, approximately midway between the 50° Plössls and 82° Naglers. The Widefield eyepieces were intended to compete with the then popular Erfle eyepiece lines. Ten years later, the series was updated and changed to the Panoptic line, and Tele Vue's magazine ads proclaimed the series to be "sharp as a tack".^[3] The 35 mm Panoptic was introduced which features a 2" barrel and weighs 1.6 lbs. The 24mm Panoptic introduced in 2002 features a 1¼" barrel and generates the same field of view as the 32mm Plössl but with a higher magnification, darker sky background, and more immersive view.^[4] The 24mm Panoptic is particularly well-suited for binocular viewing adapters or binoviewers for telescopes where two-eyed views are enabled (TeleVue once offered its own binoviewer, the Bino Vue, which has since been discontinued).^[18] The 41 mm Panoptic with a 2" barrel was introduced in the next year and weighs 2.1 lbs.^[4][13] Both the 24mm and 41mm Panoptics were designed by Paul Dellechiaie of Tele Vue, the designer of the 100° Ethos line of eyepieces.^[4]

Al Nagler's influential article "Choosing Your Telescope's Magnification" was published in the May, 1991 issue of Sky & Telescope. The article attempts to clear up some "myths" concerning telescope properties and eyepiece magnification. Nagler addressed the use of extreme low power magnifications in telescopes. He claimed that refracting telescopes were never limited by low magnification and the size of the exit pupil produced, even if this diameter exceeds that of the dark-adapted human eye. Telescopes with secondary mirrors, such as Newtonian reflectors and compound telescopes (like the popular Schmidt Cassegrain telescopes), did posses low power limit due to the visibility of the shadow of the secondary mirror hovering as as a disembodied disk in front of the field of view.^[19]

In 1998, Tele Vue released the Radian line of eyepieces. The Radians were intended to use for high magnification views of the moon and planets. The eyepieces were 60° in apparent field and parfocal, meaning that they required minimal focusing when switching between different eyepieces in the Radian line. The Radians provided a 20 mm exit pupil to facilitate observing while wearing glasses.^[4] The Radians were also available in smaller focal lengths, from 18mm down to 3mm, for high magnification viewing. The eyepieces also featured the click-stop "Instadjust" eyeshield to facilitate correct eye placement, and this feature was also included with the Nagler Type 4 eyepieces.^[20] Radians were discontinued due to the increasing cost of the element lanthanum used in some of the lenses. Aspects of the Radian series was reconfigured by Dellachiaie as the 72° Delos and 62° DeLite eyepiece lines released in 2011 and 2015 respectively. Dellachiaie also integrated innovations derived from the 100° Ethos line of eyepieces into these newer, smaller eyepiece series.^[4]

In 2006, David Nagler and Paul Dellachiaie developed a groundbreaking 100° apparent field eyepiece. David named the new eyepiece line Ethos, and the first product was a 13 mm eyepiece, the 13 mm Ethos, which was meant to acknowledge and draw comparison to the original 13 mm Nagler.^[4] The 13mm Ethos provides a 50% more apparent field than the 82° Nagler.^[21] In 2007, Al Nagler visited star parties around the country with the new Ethos eyepiece and allowed observers to try it in their telescopes.^[22] Nagler invented the concept of the "Majesty Factor" to quantify the observing experience with the new eyepiece line.^[23] In 2008, 6mm, 8mm, and 17mm Ethos eyepieces were introduced, and in 2010, 10mm and 21mm eyepieces were added to the line.^[4] The 17mm and 21mm Ethos eyepieces have a 2" eyepiece barrel, and the 21mm weights 2.25 lbs. The 13mm through 6mm eyepieces all feature the combined 2" & 1¼" eyepiece barrel introduced on the original 13mm Nagler.^[13] In 2010 and 2011, 3.7mm and 4.7mm "SX" Ethos were added respectively. At 110°, the new eyepieces were intended to mimic the view through the Apollo Lunar Module simulator that Nagler had designed in the late 1960s. SX stands for "Simulator eXperience".^[4]

Telescopes

Al Nagler first built a telescope, an 8" Newtonian reflector, in 1955 while a high school student in the Bronx.^[5] This instrument was later upgraded to a 350 lb, 12", f/5 optical system, and Nagler won a first place prize for this telescope at the Stellafane Convention in 1972.^[3]

In 1981, Nagler constructed the "Multi-Purpose Telescope", a 5", f/4 refracting telescope .^[24][25] The MPT was Tele Vue's first telescope to be offered for sale.^[1][3] The telescope featured Petzval optical design, a doublet objective lense combined with a doublet lens mounted in the back end of the telescope. This combination worked to reduce the focal length and flatten the telescope's field of view for wide-field, low magnification observing, and later telescopes offered by Tele Vue would utilize a similar design.^[3] The MPT prototype is used for eyepiece inspections at the Tele Vue factory.^[26]

In 1984, Tele Vue introduced the "Renaissance", a 4", f/5 apochromatic refracting telescope, that made available for the appearance of Comet Halley in 1986. The Renaissance featured a brass tube and 2" focuser. The brass tube was meant to hearken back to classic refracting telescopes of the nineteenth century and was also intended to be a beautiful instrument to display in the home. The telescope featured a 2" focuser with a mirror diagonal, and it excelled at wide-field observing as well as high magnification observing of the planets. Available magnifcations ranged from 10X to 286X. The Renaissance also featured the Petzval design using front and rear mounted doublet lenses (four in total) that had been introduced with the MPT. The Renaissance, including a 2" diagonal, 26mm Plössl eyepiece, and hard case sold for $895.^[3]

In 1986, Tele Vue offered a 3", f/7.4 apochromatic refractor, The Oracle, for sale. This portable, small-aperture telescope featured a 2" focuser and diagonal and excelled at wide-field observing with fields of view close to 5°. The triple, apochromatic lens also enable high magnification views of the sun (appropriately filtered), moon, and planets. The Oracle sold intially for $835 and provided a high-end, small telescope observing experience. The Oracle was discontinued in 1990 due to the high costs in supplying the triplet objective lens. The Oracle also established Tele Vue among the community of bird watching enthusiasts.^[3]

Continuing in the same vein as the 3" Oracle, Tele Vue introduced a 2.8" (70 mm) f/6.8 refracting telescope in 1993. The Tele Vue Pronto used an "Extra Low Dispersion", ED doublet for an objective and included a 2" focuser. According to Nagler, the Pronto was "a fully-featured, American made telescope for naturalists, beginners and those advanced amateurs looking for the finest quality traveling companion".^[3] The ED objective wasn't fully apochromatic, some false color was visible at high magnifications.^[27] The Ranger, a stripped-down version telescope of this telescope, featured the same optics^[28] and was introduced in 1995.^[29] Ranger weighed less than the Pronto and featured 1 1/4" focuser.^[28]