Astro ImageParacorr

Paracorr Type-2: Image of the Day!

Original Paracorr.
Original Paracorr with parrot mascot hand carved and painted by Al!

To rescue fast Dobsonian telescopes from the curse of coma, Tele Vue’s Al Nagler designed the original Paracorr (PARAbola CORRector) in 1989. By 2009 mirrors had gotten decidedly faster than they were in the late ’80s and some of our eyepieces had significantly different field stop locations (focus positions). We decided to re-optimize the Paracorr with a new Type-2 design. This new Paracorr Type-2, this time designed by Paul Dellechiaie, when inserted into an f/3 Dobsonian makes the stars appear as coma-free as a native f/12 mirror!

A popular product, Paracorr Type-2 is available in three models: 2″ Photo/Visual for drop-in use in 2″ focusers, the Starlight Integrated Paracorr System (SIPS) which is built into a Starlight Instruments Feather Touch focuser, and a 3″ photo model for integration into fast Newtonian astrographs using sensors over 30mm in diagonal. Performance improvement over the original Paracorr is most noticeable on all Newtonian/Dobsonian telescopes of f/4.5 and faster. See our blog post, Paracorr-Newtonian for Visual and Imaging to f/3! Part 2, and  Paracorr Type-2 page on our website (mobile site).

Astronomy Technology Today had Paracorr Type-2 on the cover for the Nov/Dec 2010 issue.

Here’s a quote from an imaging review of our 3″ BIG Paracorr Type-2 incorporated into a 12″ f/5 Dob — the emphasis is ours.

During my years of testing astronomy equipment, I’ve worked with some of the world’s finest telescopes designed for astrophotography. I’ve used telescopes made by Officina Stellare, PlaneWave, Takahashi, and Tele Vue, as well as top-of-the-line equipment from Celestron, Meade, Star-Watcher, Stellarvue, and others. The astrophotos with this review, however, weren’t made with any of them. Rather, they were taken with a 12-inch Meade LightBridge Dobsonian that I bought used for $500. All I did was add Tele Vue’s new Big Paracorr Type-2 coma corrector to the scope and, Voila, I had imaging performance that was on par with the best astrographs I’ve tested.

di Cicco, Dennis. “Tele Vue’s Big Paracorr Type-2”. Sky & Telescope (April 2015). pp72-76.

With its coma-freeing reputation, Tele Vue’s Paracorr coma corrector has been employed in the creation of some of the best Newtonian images posted to the Internet. Following are some AstroBin Image of the Day winners from the past year created with a Paracorr-corrected Newtonian.

Hangyeol Kang
Below we see a pink “flower” cocooned in a foggy mist in front of a star-filled background punctuated with a red sash. What a first glance seems to be a piece of modern art is actually an image of the Cocoon nebula (IC 5146). This image, by astro imager Hangyeol Kang, was the AstroBin Image of the Day for 20 October 2022. The imaging filters used were Red, Green, Blue, Luminance, and Hydrogen-α (HaLRGB). Hα was used to highlight hydrogen emissions in the background.

IC5146 (the Cocoon nebula) in Cygnus by AstroBin user Hangyeol Kang. All rights reserved. Used by permission. This was the AstroBin Image of the Day for 20 October 2022. TS-Optics 200mm/8″ ONTC f/4 Newtonian with Tele Vue 2″ Paracorr Type-2 (VIP-2010) coma corrector and ZWO ASI2600MM Pro camera. Guided with ZWO ASI174MM camera. All on a Rainbow Astro RST-300 and RST-135 mount with Super Mount CYG48RDL tripod and RDL120 Half pier. Exposures through Baader 2″ Red, Green, Blue, Luminance, and Hα 3.5nm 36mm narrowband filters as follows. Blue: 104×120″, Green: 102×120″, Hα: 218×300″, Red: 123×120″, UV / IR Cut / Luminance: 321×120″. Total exposure39h 50′. Notable software used was Pleiades Astrophoto PixInsight and Photoshop. Taken from Seoul, Gimpo, Hwacheon, and Hongchen, South Korea.

The Cocoon (IC 5146) is a compact star-forming region composed of an emission and reflection nebula with a cluster of new stars. The “flower” is hydrogen gas ionized by ultraviolet light from new stars in this stellar nursery. Powerful winds from these new stars carve out bubbles in the nebula that reveal the space beyond while dark lanes crossing through the nebula are cold gas and dust that will give birth to new stars. The surrounding bluish color is light reflecting off dust formed by supernovae explosions.

I really want to tell you that I have used Paracorr Type-2 for more than 2 years and am perfectly satisfied with it so far.

Hangyeol Kang

Hangyeol is a member of Team Dwarf Stars astrophotography club.

Robert Shepherd
Galaxies abound with dust and gas on this black velvet “painting” that was AstroBin Image of the day for 12 October 2022 and created by Robert Shepherd by imaging the night sky in Pegasus. The targets include the spiral galaxy NGC 7331, Stephan’s Quintet galaxy grouping, and an Integrated Flux Nebula using Luminance, Red, Green, and Blue (LRGB) filters.

NGC 7331 (Galaxy), Stephan’s Quintet (Galaxy grouping), and IFN (Integrated Flux Nebula) by AstroBin user Robert Shepherd. All rights reserved. Used by permission. This was the AstroBin Image of the day for 12 Oct 2022. TS-Optics 250mm/10″ ONTC f/4 Newtonian with Tele Vue 2″ Paracorr Type-2 (VIP-2010) and ZWO ASI2600MM Pro camera. All carried on 10Micron GM2000 HPS II. Other accessories included ZWO EAF focuser, EFW 7 x 36mm filter wheel, and OAG M68 guider. Imaging was done through ZWO 36mm Red, Green, Blue, and Luminance filters with the following exposures. Blue: 55×300″(4h 35′) Green: 73×300″(6h 5′) Luminance: 325×180″(16h 15′) Red: 83×300″(6h 55′) Software used was Pleiades Astrophoto PixInsight LE and Stefan Berg Nighttime Imaging ‘N’ Astronomy (NINA).

Spiral galaxy NGC 7331 is the large galaxy toward the upper right of the center. The unrelated distant galaxies above it are referred to as the NGC 7331 Group.

Stephan’s Quintet galaxy group is a tight-looking group of five galaxies at the lower left ― count the yellow nuclei in the enlargement if at first glance you see only four. Four of the galaxies are destined to merge together in the future while the brightest member is actually a foreground galaxy far removed from the others. Stephans’s Quintet was selected as one of the first targets for the James Webb Space Telescope’s “official beginning of Webb’s general science operations”.

Integrated Flux Nebula (IFN) is a recent term coined to describe the dust and gas that is far from any star in our Milky Way galaxy. These nebulae glow from the collective light of the entire galaxy. They are prominent at high galactic latitudes toward the north and south galactic poles.

The Paracorr is truly a fine piece of gear.

Robert Shepherd

Jacob Heppell
The AstroBin Image of the Day winner for 05 April 2022 was created by Jacob Heppell. He imaged the Gum 10 emission nebula with a “Hubble Palette” filter set and a Red, Green, and Blue (RGB) filter set. The nebula was processed in the Hubble Palette and the stars in the RGB set. The nebula and star images were combined for the final result.

Gum 10 (RCW 19) in SHO Hubble Palette with RGB stars by AstroBin user Jacob Heppell. All rights reserved. Used by permission. This was AstroBin Image of the Day for 05 April 2022. Sky-Watcher Quattro 250P / 10-S imaging Newtonian with Tele Vue 2″ Paracorr Type-2 (VIP-2010) coma corrector and QHYCCD QHY268M camera. Additional accessories were the QHYCFW3M filter wheel, and QHYOAG-M off-axis guider with QHY5III290M guide camera. All gear was mounted on a Sky-Watcher NEQ6-Pro mount. Antlia 3nm Narrowband and RGB Pro filters were used with the following exposures. Nebula with Hα: 67×1000″, OIII: 72×1000″, and SII: 80×1000″ Stars with Blue: 15×60″, Green: 15×60″, and Red: 15×60″ Software used was Adobe Photoshop,·Cor Berrevoets et al. Registax, Sequence Generator Pro, PHD2, and DeepSkyStacker. Image from Perth, Australia.

The Gum 10 emission nebula is rarely imaged by astrophotographers so it is a treat to see it celebrated as an AstroBin Image of the Day.

Paracorr Spot Diagrams

Paracorr Type-2 Spot Size vs Airy Radius

The above diagrams quantify how well the Paracorr-Type 2 series banishes coma for various focal ratio parabolic reflectors.  For each f-ratio shown, the curve in the diagrams indicates the RMS radius of a star image in microns from the center to the edge of the field with the 2″ Paracorr Type-2  installed. The horizontal line for each given f-ratio — the Airy Disc Radius — is the calculated radius of a distant star image. Notice that the theoretical spot size with the Paracrorr Type-2 is below the Airy Disc radius in the fastest mirrors. Except for the furthest reaches of the field in an f/3 scope, the spot size is still diffraction limited.  Just compare the spot size at the same point in the field with an uncorrected parabola — see the diagram on the right side labeled Spot Sizes for Parabola Alone.

Phil Brewer
This eye-grabbing depiction of Wolf-Rayet 134 (in Cygnus) demonstrates the ability of narrowband filters to convey a startling dimensional quality to distant objects. In the case below, the Hα and OIII filters tease out a fluorescent scene of blue “cotton candy” against a swirling sea of red. This image was unique enough to earn the AstroBin Image of the day for 29 June 2022.

Wolf-Rayet 134 by AstroBin user Phil Brewer. All rights reserved. Used by permission. This was the AstroBin Image of the day for 29 June 2022. TS-Optics 200mm/8″ ONTC f/4 Newtonian with Tele Vue 2″ Paracorr Type-2 (VIP-2010) coma corrector, and QHYCCD QHY268M camera. Guiding Camera was QHYCCD QHY5L-IIM. Imaged through Chroma Red, Green, Blue, and 3nm Hα and OIII narrowband filters as follows. Blue: 22×180″ Green: 22×180″ H-alpha: 70×600″ OIII: 63×600″ Red: 22×180″ Software used was GNU Image Manipulation Program (GIMP), Pleiades Astrophoto PixInsight, and Russell Croman Astrophotography StarXTerminator. Taken from Ida, Michigan.

Wolf-Rayet 134 (in Cygnus) is the bright center star in the blue “puff”. Wolf-Rayet stars are interesting as they are over 20 times the mass of our sun and spew material into space at the rate of several Earth masses a year! After a few million years they explode as supernovae. In this case, the outflowing material from the star is interacting with the (red) interstellar clouds of gas and dust to create the bubble around the star.

I was previously using a competitor’s product. While imaging I has serious problems with strange flat field artifacts in my images. I tried everything I could think of to fix it and literally spent years struggling with it. I finally broke down and bought the Paracorr and the problem immediately went away. It was apparently bad internal reflections or something from the competitor’s coma corrector. So you have at least one happy customer.

Phil Brewer

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