You may know that Tele Vue’s Paracorr Type-2 accessory is the color-free cure for coma (star elongation) in fast Newtonians. But did you know that Paracorr™ users can enjoy their coma corrected Dob/Newts with two eyes using Bino Vue?
Last December, we received a letter from David Shear, of San Pedro, CA expressing an interest in using the Tele Vue Bino Vue binocular viewer with our Paracorr Newtonian coma corrector. David Shear explained to us why he choose our Bino Vue over others on the market.
I tried several brands of binoviewers before buying the Tele Vue, and like you promised, I found the Tele Vue to be the best, as the optical quality is significantly better than the other brands that I tried. As you explained it, while other brands offer convenience features like low power correctors and power switch optics, your developmental testing showed that these features require trade-offs in optical quality, which you were not willing to accept. I’m glad you chose to preserve the optical quality with your design.
We thought Bino Vue with Paracorr (Bino-corr?) was an interesting setup and wrote up some notes on how these two optical components can be configured to work together. Here’s what David told us about his viewing experience with this combo on his 15″ f/4.5 Newtonian:
After extensive use of a Paracorr 2 with my 15″ f/4.5 Newtonian reflector, I became accustomed to a sharp field and pinpoint stars edge to edge when using a single eyepiece like an Ethos or Nagler. I was also spoiled by using the Bino Vue with your TV-NP101 4″ refractor, as that setup provides a perfectly sharp image edge to edge. As a result, when I started using the Tele Vue Bino Vue with my f/4.5 reflector, the inherent coma visible towards the edge of the field was somewhat bothersome, even at f/4.5. I was therefore quite pleased when I learned that I could use the Bino Vue in conjunction with the Paracorr 2, achieving near-perfect coma correction to the edge of the field. This was most significant for me when observing the Moon (the edge of the field is now sharp instead of slightly blurry), Jupiter (the image of Jupiter itself is not improved but the Galilean satellites towards the edge of the field are now perfect round discs on nights of excellent seeing), and star clusters (stars are pinpoint edge to edge). Thank you again for designing and manufacturing your products to such a high standard.
Bino Vue comes in two models. For refractors and Newtonians, we sell the Bino Vue with 2x Amplifier-Corrector (BVP-2002). Amplifier-Corrector is more than just a “Barlow” for bringing the focus out into the Bino Vue: its design maintains optimal optical performance by fully compensating for the introduction of spherical aberration, color, and astigmatism, due to prisms. A “Flat Coupler” — called that because it doesn’t add path length — attaches the 2x Amplifier to the Body. This makes the Bino Vue close to parfocal on the Paracorr.
Bino Vue is fully parfocal when the 2x Amplifier-Corrector is used with the included Extension Coupler “nose piece”.
Bino Vue is also available as a Bino Vue “body only” model (BVB-2003) for scopes such as SCTs which have the necessary focus in-travel to work without the Amplifier-Corrector. In that case, the product is supplied with just the Extension Coupler “nose piece”.
Our highly versatile 2″ Paracorr Type-2 (VIP-2010) comes with a “Tunable-Top” for visual use. It can handle 2″ eyepieces and includes a 2″-1¼” adapter. The Tunable-Top feature moves the eyepiece up and down to maintain the proper eyepiece field-stop to Paracorr lens distance to optimize coma correction. For f/3 Dob/Newts, the Paracorr Type-2 makes star images at the edge of the field of view 25 times smaller than without any correction.
You can separate Paracorr’s optical assembly from the Tunable-Top and use it with Tele Vue imaging system components to permit imaging with DSLR and CCD cameras.
APS size formats 27mm-diameter or smaller are recommended to minimize field vignetting. Ideal for mirrors as fast as f/3, this is an essential accessory for wide-field imaging through fast Newtonians.
This is how to use Paracorr with Bino Vue. First make sure the Bino Vue 2x Amplifier / Corrector is used ONLY with the Flat Coupler (NOT the “nose piece”). This limits the insertion length to only 2-inches, which prevents any contact with the upper lens in a Paracorr. Use setting “A”, the lowest setting on the Tunable Top, for best coma correction. Make sure of course, to remove the lens cap on the 2x Amplifier-Corrector and do NOT add a filter. (The Paracorr accepts 2″ filters if desired).
Do not use any other amplifier or Barlow lens since excessive length may contact the Paracorr lens. For the Paracorr Type-2, make sure to only use the 2″ to 1¼” adapter that came with it. (Shorter adapters could allow the 2x Amplifier-Corrector to contact the Paracorr lens). It is important to set the “Tunable Top” to the “A” setting to achieve the best coma correction.
NOTE 1: The above Bino Vue technique works for all older Paracorr models with Tunable Tops. Just set the Tunable Top to the lowest setting.
NOTE 2: Do not use the Bino Vue with a SIPS version of Paracorr to avoid any possible installation that could allow the 2x Amplifier-Corrector to contact the SIPS top lens.
So that is it. Hope you enjoy using Bino Vue with the coma corrected field of the Paracorr.
- Bino Vue at Tele Vue website (mobile version)
- Bino Vue reviews from S&T and Astronomy
- Paracorr at Tele Vue website (mobile version)
- Panoptic 24mm eyepiece (mobile version)
- Read Paracorr’s role in the New Dobsonian Revolution (PDF) article from Astronomy Magazine
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