Paracorr-Newtonian for Visual and Imaging to f/3! Part 2

 
At top is a cropped image of the Pinwheel Galaxy (M101) by AstroBin user Luca Marinelli. All rights reserved. Imaged through Teleskop Service ONTC 10″ f/4 Newtonian with Tele Vue Paracorr Type 2 coma corrector and ZWO ASI1600MM Pro mono camera. At right is the Tele Vue Paracorr logo. At bottom are the placement and back focus diagram for the 3″ BIG Paracorr.

In the last blog, we covered the history of the Newtonian reflector, its inherent aberrations, and how Tele Vue’s Paracorr enlarged the “sweet spot” of fast scopes to cover the entire field. We also compared the Paracorr – Newtonian combination against more “exotic” telescope designs for imaging. If you missed it, you can read Part 1 before continuing.

Which Paracorr to Use?
Over the years there have been two optical versions of the Paracorr.  The original Paracorr came in various mechanical designs which developed as we developed new eyepieces. For this BLOG, we’ll focus on the currently available three versions of the Type-2 Paracorr: 2″ Photo/Visual, SIPS, and 3″ Photo models. Performance improvement over the original Paracorr is most noticeable on all Newtonian/Dobsonian telescopes of f/4.5 and faster.

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Paracorr-Newtonian for Visual and Imaging to f/3! Part 1

At left is the original Paracorr with the Parrot Mascot. “Strawberry Fields” was a set of stickers on Al Nagler’s backyard shed (built by Al, David, and grandpa Max!) that were used to illustrate how the Paracorr eliminates coma in the corners. Within “Strawberry Fields” are superimposed various versions of the Paracorr.
Paracorr and the Evolution of Newtonian / Dobsonian Telescopes
Chromatic aberration in a simple glass lens. In this exaggerated image, each color (wavelength) of light focuses a different distance behind the lens. (public domain image)
Invented from lenses used to make eyeglasses, refractors were the first telescopes when introduced in the 1600s. However, the early refractor builders could not avoid building scopes that displayed color fringes (chromatic aberration) around bright objects. It was Sir Isaac Newton (1642–1727) who figured out that white light is composed of different wavelengths that we see as colors. Each wavelength will refract (bend) by a different amount as it passed through the refractor’s objective glass. The longest wavelengths (red) refract less while the shorter wavelengths (blue) refract more. As a result, the red component of the image focuses behind the blue component. Pinpoint images and higher magnification were out of the question with these primitive scopes. Even after the cause of chromatic aberration was revealed, refractor builders didn’t have the glass types and manufacturing skills to counter it for another century. Sir Newton, however, had an idea to build a second type of telescope that avoided refraction: a reflector.
 

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NP101: Imaging the Skies Over Colorado & New Product!

Horsehead and Flame Nebulae in Hα by SmugMug user Steven Schlagel. All rights reserved. Used by permission. Imaging details: the Tele Vue-NP101 APO (Nagler-Petzval) refractor (101mm, f/5.4) with a Nikon 810Da camera and narrowband Hydrogen-alpha filter were used to create this image. Exposure time was 3-hours total.

The above portrait of the Horsehead and Flame nebulae is stunning.  Created in Hydrogen-alpha light, this monochrome image is filled with wispy tendrils, puffy molecular clouds, dark lanes, and glowing gas. It really brings out the interplay of shockwaves and ionizing radiation at work in this region of the much larger Orion Molecular Cloud Complex. 

You can compare this image with the color one below of the same region. The red hues are dramatic, but we lose a sense of the “sculpting” that is taking place in the gas and dust. 

Horsehead and Flame Nebulae by SmugMug user Steven Schlagel. All rights reserved. Used by permission. Imaging details: the Tele Vue-NP101 APO (Nagler-Petzval) refractor (101mm, f/5.4) with a Nikon D810a DSLR camera for 6-hours.

The Horsehead (Barnard 33) and Flame Nebulae (NGC 2024) are separated by the bright blue supergiant star Alnitak (center-left in the above image), the easternmost star in the “Belt”  of constellation Orion. Like a giant neon sign, the “Flame”, below Alnitak in the image, is “lit up” by ultraviolet light from the star. The flame-like appearance is enhanced by dark “branches” of light-absorbing gas in the nebula. As for the Horsehead, its appearance is due to the three-star system Sigma Orionis “above” the “horse” (bright star along a line through the horse’s neck and head). It causes hydrogen gas to glow behind a dark concentration of dust that has the distinctive appearance of a horse’s head. 

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Tele Vue-NP101is: Imaging the Skies Over Southwest Florida

Rosette Nebula and NGC 2244 Cluster (Narrowband) by SmugMug user Linwood Ferguson. All rights reserved. Used by permission. Imaging details: the Tele Vue-NP101is APO (Nagler-Petzval) refractor (101mm, f/5.4), riding on an iOptron CEM70G mount, imaged with a ZWO ASI6200MM Pro camera, with ZWO Filter Wheel and Chroma 5nm narrowband filters. All subframes were 300s using these filters: Hα x 47, SII x 37, OIII x 31. (The OIII had a pretty strong gradient from the moon). Stacked and processed using PixInsight in roughly the Hubble Pallet with green shifted into blue and gold (star color shifted off magenta a bit). Finished off in Photoshop Lightroom Classic 10.0 (Windows).

The lead-off image of this post is certainly an eye-grabber! It is one of the most unique interpretations of the Rosette Nebula (NGC-2237 or Caldwell 49)  in Hubble Palette filters we’ve seen. Most striking, the usual Hubble Palette aquamarine color surrounding the central cluster is cobalt blue! The typical outer ring of yellows and burnt ochre now has a deep-orange hue. This color manipulation was done while maintaining the filamentary wisps and dark protostar Bok Globules in the nebula, along with a jet-black sky background.  The resulting dimensional quality of this image draws the viewer from the ruddy edges of the nebula into the blue-colored center and then out the “back” aperture of the structure.

In the middle of the Covid pandemic, stuck at home, I decided to resurrect an interest in astronomy, and in particular astrophotography.

This image is from a great collection of Tele Vue NP101is images posted by Linwood Ferguson on SmugMug. At the top of this SmugMug page is stated the motivation for his astro imaging: “In the middle of the Covid pandemic, stuck at home, I decided to resurrect an interest in astronomy, and in particular astrophotography”. In this blog, we present a gallery of Linwood’s NP101is images.

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Tele Vue-85: Imaging Under New York City Light Dome!

Deep sky images and annotated map courtesy of Mauri Rosenthal. All rights reserved. Used by permission.

Mauri Rosenthal’s Tele Vue 2.5x Powermate solar images appeared in our Here Comes the Sun! blog last December. Imaging from just 10-miles (16-km) from New York City, it was reasonable to expect that his flickr and Instagram walls featured images of the Sun, Moon, and Planets. To our surprise, we also saw some images of deep-sky objects (DSOs), taken with a Tele Vue-85, from the same light-polluted location. We were intrigued at how he was able to get such reasonable results from his poorly situated location and asked if he’d relate his experiences in this blog.

It turns out we’d found the right guy for the job. Mauri wasn’t a “typical” amateur astronomer/imager: he actually teaches Urban Astrophotography in New York City, under the auspices of the Amateur Astronomers Association of New York. His instructor’s biography, on a  recent class registration page, describes Mauri’s motivation as follows: 

Surprised by the image quality achievable with small telescopes from his yard in Westchester County, Mauri has been developing deep expertise in Ultraportable Urban Astrophotography and is on a mission to use new technology to extend the access of city-dwellers to the wonders of the night sky.

In this guest blog post, we asked Mauri about his overall experience and how Tele Vue Optics contributes to the enjoyment of his hobby.

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Imaging the Skies with the Tele Vue-NP127is

We’re quite impressed with Frank Wielgus’ exquisite collection of wide-field, deep-sky images on SmugMug. Photographed with a Tele Vue-NP127is APO refractor, the attention to image capture and software craftsmanship is evident in his collection of galaxies and nebulae. His images have often been selected as winners in the Amateur Astronomers Association of Pittsburgh’s Kevin J. Brunelle Photography Contest.

In his guest blog Frank shows and tells us the story of his astrophotography.

Sh2-155 — Cave Nebula (crop) by SmugMug user Frank Wielgus. All rights reserved. Used by permission. Emission, reflection, and dark nebulosity delightfully combine with young stars in this area of Cepheus around the Cave Nebula. The ‘Cave’ is the dark area below the red nebulosity at the lower left of the image. Tele Vue-NP127is (127mm, f/5.2, Nagler-Petzval) APO Refractor with Atik 383L Camera on CGEM mount. Exposures were multiple 400 sec. through L, R, G, B filters. Maxim DL and Photoshop CS5 were used. Imaged from Cherry Springs, PA Dark Sky Park.

I started astrophotography in the early ’90s using film. It was a Pentax camera with screw mount lenses, piggybacked on an SCT using slide film. Boy, I’m glad those days are gone! I have recently started using those lenses again on a wide field DSLR set up. I then moved to imaging through the SCT. At some point, I wanted to up my game in quality, and for me, that meant a refractor.

M8 – Lagoon Nebula by SmugMug user Frank Wielgus. All rights reserved. Used by permission. Tele Vue-NP127is (127mm, f/5.2, Nagler-Petzval) APO Refractor with Atik 383L Camera on CGEM mount. Exposures were 300 sec. each through L (binned 1×1), R (binned 2×2), G (binned 2×2)  & B (binned 2×2) filters. Maxim DL and Photoshop CS5 were used. Imaged from Cherry Springs, PA, Dark Sky Park.

Ever since I first acquired Tele Vue Plössls in the early ’90s, I have always admired Tele Vue products. Quality, design, and locality of service were important considerations for me. For these reasons, the NP127is was a dreamed-for acquisition for a number of years. So when the opportunity arose and with the prompting of a good friend, I acquired one. I remember being blown away by the quality. Now stars look like stars and the sharpness with flat field are incredible things to see. Barring any unusual circumstances, this scope and I are in it together for the long haul.

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Tele Vue-76: Imaging New Mexico Skies!

Brian Paczkowski has been employed by NASA/Jet Propulsion Laboratory in Pasadena, California since 1983. Some of his work includes the Galileo Mission to Jupiter and the Cassini Mission to Saturn.  He is currently the Europa Clipper Science Manager.

Every clear night he images with his Tele Vue-76 installed at a remote observatory located at Dark Sky New Mexico (DSNM). He dedicates his Instagram wall of astroimages, “to my love of astrophotography.” 

Bode’s Galaxy (M81), Cigar Galaxy (M82) by Instagram user Brian Paczkowski . All rights reserved. Used by permission. Tele Vue-76 telescope with Tele Vue TRF-2008 0.8x Reducer/Flattener and QSI 683 CCD camera riding on 10Micron GM2000 HPS II mount. Exposure through Astrodon Lum+Ha+RGB filters at -20C (22 hours of LRGB data and 15 hours of Hydrogen-Alpha). Processed in PixInsight and Photoshop. Images acquired in December 2020.

Located in the northern regions of Ursa Major and 12-million light-years from Earth, the two prominent galaxies in Brian’s image are Bode’s Galaxy (M81) and The Cigar Galaxy (M82). They are joined by NGC 3077 (an elliptical galaxy slightly further away) in the upper-left corner.  All three are gravitationally interacting members of the M81 Group of Galaxies. This wide-field image shows foreground dust in our own galaxy covering the starscape.

In the close-up crop below, the intervening dust is not emphasized in processing. The yellowish core of M81 indicates an older population of stars while the red “spots” are from glowing hydrogen gas excited by ultraviolet light from newly formed young giant stars.

Bode’s Galaxy (M81), Cigar Galaxy (M82) (crop) by Instagram user Brian Paczkowski . All rights reserved. Used by permission. Tele Vue-76 telescope with Tele Vue TRF-2008 0.8x Reducer/Flattener and QSI 683 CCD camera riding on 10Micron GM2000 HPS II mount. Exposure through Astrodon Lum+Ha+RGB filters at -20C (22 hours of LRGB data and 15 hours of Hydrogen-Alpha). Processed in PixInsight and Photoshop. Images acquired in December 2020.

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The “Best” of 2020

Tele Vue Optics, Inc. started the year 2020 optimistically.

For Tele Vue, January 2020 began optimistically: our Apollo 11mm Commemorative eyepiece had started shipping in mid-December and we innocently opined on this blog that the year would be best remembered for “20/20 vision” puns. Our usual round of winter telescope shows and star parties began with David Nagler jetting off for the late-January European Astrofest in London and Al Nagler debuting a 67mm converter for our 55mm Plössl eyepiece at the Winter Star Party in February. David Nagler visited the studio at OPT Telescopes in Carlsbad, CA to discuss The Future of Visual Astronomy for an early-February Space Junk Podcast. In March we were looking forward to the “2020 Messier Marathon” and the arrival of Spring in the latter half of the month. Instead, COVID-19 precautions shut us down from March 20th — the first full day of spring — to May 26th. Thankfully, we all returned to work healthy, but the new concept of “social distancing” put an end to any chance of in-person appearances for the rest of the year.

With the strange year of 2020 behind us, we now choose to look back at the positive. In 2020 we managed to publish 34-postings covering a variety of topics. In this week’s blog we’ll examine our most popular stories for the year based on reader raw page views.

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Mars: Keep on Viewing & Imaging!

Mars at opposition, 13th October 2020 (center image) by flickr user Roger Hutchinson. All rights reserved. Used by permission. Hubble’s Closest View of Mars — August 27, 2003 (left image), credit: NASA, J. Bell (Cornell U.) and M. Wolff (SSI). BAA Mars Mapper image (right image) is © The British Astronomical Association 2020. Roger’s image is rotated 180° from the original to match BAA Mars Mapper orientation for locating features. Mars is centered at about 160° west latitude in his image with Olympus Mons super volcano (on top of the Tharsis bulge volcanic plateau) at lower-left. This is one of the best Olympus Mons / Tharsis renditions we’ve seen this Opposition: compare it with the scaled-down and rotated Hubble image on left. Roger’s image was made with a Celestron Edge HD11 with Tele Vue 2.5x Powermate and ASI174MM camera.

Even though we’re past the point of closest approach and opposition, Mars continues to loom large in the sky and is higher each night at the same time. In the northern hemisphere, the nights are coming sooner and lasting longer. Until mid-November, Mars will appear bigger than at any opposition until 2033!

You can use the excellent Mars Mapper 2020-2021  web app (mobile version) on the British Astronomical Association website to identify features on the planet when you observe or image it.

If you’d like to try your hand at imaging the planet, study the next sections carefully as they contain image processing tips from top Martian imagers on the Internet.

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NP127is Imaging the Skies Over Sydney!

We were struck by the neon-like colors produced by Murray Parkinson’s imaging through our Tele Vue-NP127is APO Refractor using different combinations of Hydrogen-alpha (Hα), doubly ionized oxygen (OIII), and ionized sulfur (SII) filters. His Porpoise Nebula image below looks like it is leaping out of the page! Others agree: he provided the cover and inside cover spread images for Nightfall October 2017 (a journal of astronomy in South Africa). He tells us “I love my two Tele Vue refractors. Only wish you made a 12-inch refractor … .” This week’s guest blog post is a gallery of his work from suburban Sydney, Australia.

“When I became interested in astrophotography, I quickly learned that the quality of the optics was crucial to achieving high-quality results. Only the very finest telescope designs can deliver round, pinpoint stars across the entire frame. I chose the Tele Vue-NP127is partly because of the reputation of Al Nagler and partly because of trust in products made in the USA. I also had a lot of trust in the salesperson who looked after me at BINTEL in Sydney. He always gave excellent advice on what to buy.

“Without a doubt, the versatility of the Tele Vue-NP127is stands out in my mind. The telescope delivers true astrograph performance when imaging at multiple focal lengths. It also delivers brilliant views when used visually and is light enough to transport to a dark sky location on a car camping trip. I still love visual observing and appreciate a telescope that can deliver on all accounts.

The Porpoise Nebula in Canis Major
2019_03_03_EZ_Canis_Major_HaOIII by flickr user Murray Parkinson. All rights reserved. Used by permission. Imaged with Tele Vue-NP127is APO Refractor at f/5.2 with QSI 683wsg camera on EQ8 mount. Exposures through filters with 2 x 2 binning as follows: Astrodon 3-nm Hα for 10-hours total and Astrodon 3-nm OIII for 18-hours total.  Acquisition and processing software used: Nebulosity 4, PHD2, PixInsight, Lightroom and Photoshop. Imaged from suburban Sydney.

“This faint Oxygen III nebula is catalogued as Sharpless 308 in the constellation of Canis Major and is commonly called the Gourd Nebula, but I am one of those people who see a Porpoise first, or I am fonder of porpoises than gourds anyway. The nebula is classified as a Wolf-Rayet bubble and originates from the star located close to the centre of the frame.

“When I was a young boy in the early 1970s, my stepfather took me to see a movie at a drive-in theater in the country. At the end of the movie, I stepped outside the car and looked up to behold the summer Milky Way overhead. This was the first time I had seen the Milky Way from a dark location and I was overwhelmed with awe. To this day, I still experience awe, swooning at the beauty of a starry night when I am lucky enough to camp somewhere truly dark.

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