An optical chain is as good as its weakest link. With the development of 82 degree Nagler eyepieces, Tele Vue offers the largest, flattest and best corrected visual fields in the industry. Combine the Nagler revolution, Dobsonian revolution and Paracorr for the ideal mating for spectacular wide and sharp "spacewalk" observing.

Life before Paracorr

Coma makes stars look like blurry comets whose tails point out radially from the center of the field. The faster your scope's speed, 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.

Previous attempts to correct for coma have been limited in usefulness. Some correctors were designed mainly for astrophotography. Dedicated coma correcting eyepieces were another approach. However, these were limited to 50 degree apparent fields and would orphan your existing eyepiece collection.

Life with Paracorr

Paracorr is a universal corrector that tightens and intensifies star images [see performance graphs here] on all f-ratios from f/3.5 to f/8 without adding any false color 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 easy to use. It slips into your focuser, just like a Barlow. To minimize focuser in-travel, due to additional length, a mild 15% Barlow effect was designed into Paracorr to effectively push the focus out. Paracorr is recommended for use with all Tele Vue eyepieces because our Plössls, Radians, Panoptics, Naglers and Ethos achieve higher levels of aberration correction than competitive models. However, Paracorr is also compatible with other eyepiece makes.

Try Paracorr on your "DobNewt." We think you'll agree that the revolution is complete.

Paracorr Eats Coma

The visual Paracorr can be used with both 2" and 1.25" eyepieces. The imaging models work with DSLR and CCD cameras (see Astrophotograpy). For visual use, slip Paracorr into your focuser like a Barlow lens, and your eyepiece into Paracorr. 1.25" eyepieces will make use of Paracorr's special low profile 1.25" reducing adapter. Paracorr is threaded for 2" filters.

Optimizing the Coma Correction by Using Paracorr's Tunable Top

As you've read, all Newtonian/Dobsonian telescopes can benefit from using a Tele Vue Paracorr (Parabola Corrector) to eliminate coma in the image. One aspect to optimizing 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 optimized 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.

Astrophotography

Mount your DSLR or CCD camera to imaging Paracorrs (see models below), and the quality of full frame photos will be spectacular since star image sizes on film can be less than .001" over the full frame for an f/4.5 mirror. Edge-of-field sharpness is further enhanced since Paracorr also acts as a field-flattener. See our Strawberry Field fast Newtonian images.

Important Note -- Paracorr is designed to work properly only with parabolic mirrors in Newtonian or Dobsonian telescopes.

You must adjust distance from last lens surface to CCD surface to 55mm +/-4mm for best performance.

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.

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.