Coma Correction

Now you can eliminate Coma when you use your Tele Vue Eyepieces with a Newtonian Telescope

What is Coma?

Coma makes stars look like blurry comets whose tails point out radially from the centre of the field. The faster your scope's speed, that is the shorter the focal length, the worse the effect. All parabolic mirrors used in Newtonian reflecting telescopes are limited in field sharpness due to coma. Even a perfectly made 13" f/4.5 parabola has only about 0.1 degree diffraction limited field.

TeleVue Paracorr is a universal corrector that tightens and intensifies star images on all f-ratios from f/3.5 to f/8 without adding any false colour or spherical aberration! You no longer have to constantly shift a Dobsonian to keep objects centered for sharp viewing. Using a Tele Vue eyepiece, put M-13 at the edge of the field and enjoy resolving its beauty as it drifts across your view.

Paracorr is recommended for use with all Tele Vue eyepieces that you may use with a Newtonian telescope, because our Plossls, Radians, Panoptics, and Naglers achieve higher levels of aberration correction than competitive models. However, Paracorr is also compatible with other eyepiece.

Paracorr Eats Coma

The Paracorr can be used with both 2" and 1¼" eyepieces, as well as with your 35mm camera body. For visual use, slip Paracorr into your focuser like a Barlow lens, and your eyepiece into Paracorr. 1 1/4" eyepieces will make use of Paracorr's special low profile 1 1/4" reducing adapter. Paracorr is threaded for 2" filters.

Tele Vue Visual Paracorr (PVL-2008) is for primarily visual use and comes with the 2" - 1¼" Adapter (ACF-2125) However, it can be used for CCD nosepieces having 2" or 1¼" diameters, like eyepieces. You must adjust distance from last lens surface to CCD surface to 55mm +4mm for best performance.
Front View of the Visual Paracorr	Back View of the Visual Paracorr showing the marks on the Tunable Top (see below for more information)
Tele Vue Visual Paracorr with Tunable Top PVL-2008 Price £295.00

OPTIMIZING YOUR TELE VUE NAGLER TYPE 4 AND TYPE 5 EYEPIECES WHEN USING PARACORR'S TUNABLE TOP

All Newtonian/Dobsonian telescopes can benefit from using a Tele Vue Paracorr (Parabola Corrector) to eliminate coma in the image. One aspect to optimising this correction is the distance of the eyepieces focus point (field stop location) to the last surface of the Paracorr lens (within a small +/- tolerance of course). Typical eyepieces used with fast Newtonians can have field stop locations differing by as much as half an inch. To accommodate for the differences, we developed the "Tunable Top."

The "Tunable Top" permits optimised aberration control for all Tele Vue eyepieces and many others, by simply loosening a screw and rotating the Tunable Top. The eyepiece barrel height raises and lowers, allowing you to maintain the proper field stop to Paracorr lens distance. For your reference, here is a recommendation guide for choosing the best setup for various Tele Vue eyepieces to get optimum correction: Recommended Eyepiece Position Chart - Setting Marks

Recommended Eyepiece Position Chart - Setting Marks
Mark 1	Mark 3	Mark 4	Mark 5	Mark 5
2" Eyepieces	2" Eyepieces	1¼" Eyepieces	2" Eyepieces	1¼" Eyepieces
20mm Nagler T2	26mm Nagler T5	All Radians	31mm Nagler T5	16mm Nagler T2**
20mm Nagler T5	17mm Nagler T4	All Plössls through 32mm	22mm Nagler T4	12mm Nagler T2**
13mm Nagler* (original)		All 1¼ only Naglers (original, T5 & T6)	17 & 21mm Ethos	12mm Nagler T4**
41mm Panoptic		24mm Panoptic		9mm Nagler** (original)
10 &13mm Ethos		6mm & 8mm Ethos**		10 & 13mm Ethos***
35mm Panoptic		19mm Panoptic
27mm Panoptic		15mm Panoptic
22mm Panoptic*		All Tele Vue Zooms
* Use only in 2" mode as listed for best correction ** Use only in 1¼" mode as listed for best correction *** For best correction use with the Tele Vue Hi-Hat 2" to 1¼" adapter.

CAUTION: Do NOT use Barlow lenses with the Tunable Top Paracorr; the Barlow may contact the Paracorr lens.

Tele Vue Paracorr to SBIG STL-series
Introducing a Paracorr designed for the SBIG STL-series astro camera. The Paracorr to STL-series (model PSB-1100) photographic Paracorr has wide threads that attach directly to the body of the STL-series cameras, placing the CCD chip at the optimum distance. For best correction, large internal lenses minimize vignetting while achieving the flat and sharp fields Paracorr is famous for with fast Newtonians. 2" barrel for standard 2" focusers.
	Tele Vue Paracorr to STL-series (model PSB-1100) Price £249.00
Universal Paracorr
For Newtonian owners that image with a variety of DSLR and CCD cameras, the Paracorr of choice is the imaging-only Universal Paracorr (PLU-1106). Universal Paracorr accepts the complete range of Tele Vue's 2.4" Imaging System (IS) camera adapter and spacer rings. The Universal's large lens coupled with IS adapters provides Newtonian imagers with maximum illumination in the image plane.. The extensive collection of IS adapters includes: standard T-Ring and Canon Wide T-Ring for DSLR; 2" nosepieces adapter for CCDs and direct connect adapters for select SBIG and Apogee CCDs. T-Ring adapters for DSLR need no additional spacers to achieve the standard 55mm ±4mm distance from Universal Paracorr flange to camera chip. CCD users need only to subtract the chip depth (from the camera face to chip) from 55mm to determine the correct IS spacer(s) (±4mm) to use. Universal Paracorr will accept all future IS adapters and spacers. Like all Paracorr's, the Universal fits into 2" focusers and adds 15% to telescope focal length.
	Tele Vue Universal Paracorr (model PLU-1106) Price £249.00