0
Tele Vue 85 Refractor
Jan 01 2006 02:54 AM |
Joe1
in 80mm - 90mm Refractors
Discuss this article in our forums
Tele Vue 85
Joe Silverman
I purchased a Tele Vue 85 f7 refractor to complement my 12.5" f5 T-Scope truss Dob, and 6" f12 Intes Mak Deluxe. I did not need to purchase a mount since I can use the Great Polaris mount that came with my Intes Mak.
When I head out to a dark site, I take my Dob and the refractor. While waiting for the Dob to cool down, I use my Tele Vue 85. I will also leave my Dob to discover the Milky Way with my refractor. I start exploring the river of stars at Sagittarius and head up to Cygnus, then Cepheus. Often I attach an OIII filter to observe the Veil, the North America Nebula, and the Pelican Nebula. The Tele Vue 85 lets me see the big picture. My Dob the detail. With my Nagler 26mm, the FOV of the Tele Vue 85 is 3.34 degrees - seven times more observing area then my 12.5" Dob that has a 1.27 degree FOV.
Sometimes, the following day, after a night of observing, the panoramic views through my Tele Vue 85 left the strongest memories. Exploring the Milky Way produced memorable views with the Tele Vue 85 because the stars were bright and pinpoint. The stars sparkled inside the dark void of the universe. Only a refractor that is well-collimated, has optics that are figured to high tolerances, and is well baffled could produce such stunning views.
Before walking my dog, I check the sky. If it is clear, the stars are not twinkling, and I am not too tired, I quickly set up my refractor. It takes about 5 minutes. After the walk, I start observing. If I intend to observe for a long time, I will also take out my Mak and wait 1.5 hours for it to cool down and then use it instead of my refractor. Sometimes the Mak never cools down. The Tele Vue 85 takes 15 minutes to cool down.
I usually confirm the seeing conditions with a star test. If the central disk is not stable after the scope has cooled down, I would head back into the house and wait or I would observe for a short while and quit. From my home I only observe the planets and the moon ? too much light pollution to observe DSOs.
I purchased a helical focuser for my 1.25" eyepieces. I rarely needed to use it because the images just snapped into focus using the Tele Vue 85 focuser.
Over time, comparing views through my Mak and refractor from my home, I have concluded that if the seeing is less than 3.5/5 then there is no difference in the views of the planets and the moon. In moments of very good seeing, the Mak would show a tad more detail. Very good seeing does not happen very often in my area. On occasion, I observed that the Tele Vue produced a smidgeon of color on the limb of the moon. It is, after all, an APO doublet. But, it was never a problem since I use a polarized filter when observing the moon. At a dark site, the Mak will easily outperform the refractor when observing nebulas and globular clusters under just about any conditions. Aperture does count.
When I head out to a dark site about, I always take my Tele Vue 85 along with my Dob to observe the Milky Way. At home, I use it to observe the planets and the moon. It is hard to beat the quick setup and cool down times.
Of all the refractors why the Tele Vue 85? I wanted premium refractor that is portable, easy to set up, produces panoramic views, and has a focal ratio of at least f7. The Tele Vue 85 fits the bill. It weights 8.5 pounds, is 21.5 inches in length, and comes in a sturdy well-padded carrying case.
Why f7? An f7 scope produces a much smaller exit pupil than an f5 scope. I can observe at lower power. My entrance pupil is around 5.5. I sold my Panoptic 35 and replaced it with a Nagler 26mm because of my f5 Dob. On any f5 scope, the Panoptic 35 will produce a 7mm exit pupil. (exit pupil = focal length of eyepiece/ focal ratio of scope).
A person with a 5.5 mm entrance pupil can only trap 62% of the light coming out of the 7mm exit pupil. Although the FOV would be the same, the loss of light would affect the view. It would be like reducing the aperture of the telescope by 1.5/7 or 21.5%. On a small refractor, losing 20% of the aperture is significant even at low power.
My Tele Vue 85 is the scope that I use the most. I use my Dob 15 to 20 nights a year. My Tele Vue 85 gets used, on average, about twice a week.
I can highly recommend the Tele Vue 85 for exploring the Milky Way in dark sites and for lunar and planetary observing in light polluted areas.
Joe Silverman
I purchased a Tele Vue 85 f7 refractor to complement my 12.5" f5 T-Scope truss Dob, and 6" f12 Intes Mak Deluxe. I did not need to purchase a mount since I can use the Great Polaris mount that came with my Intes Mak.
When I head out to a dark site, I take my Dob and the refractor. While waiting for the Dob to cool down, I use my Tele Vue 85. I will also leave my Dob to discover the Milky Way with my refractor. I start exploring the river of stars at Sagittarius and head up to Cygnus, then Cepheus. Often I attach an OIII filter to observe the Veil, the North America Nebula, and the Pelican Nebula. The Tele Vue 85 lets me see the big picture. My Dob the detail. With my Nagler 26mm, the FOV of the Tele Vue 85 is 3.34 degrees - seven times more observing area then my 12.5" Dob that has a 1.27 degree FOV.
Sometimes, the following day, after a night of observing, the panoramic views through my Tele Vue 85 left the strongest memories. Exploring the Milky Way produced memorable views with the Tele Vue 85 because the stars were bright and pinpoint. The stars sparkled inside the dark void of the universe. Only a refractor that is well-collimated, has optics that are figured to high tolerances, and is well baffled could produce such stunning views.
Before walking my dog, I check the sky. If it is clear, the stars are not twinkling, and I am not too tired, I quickly set up my refractor. It takes about 5 minutes. After the walk, I start observing. If I intend to observe for a long time, I will also take out my Mak and wait 1.5 hours for it to cool down and then use it instead of my refractor. Sometimes the Mak never cools down. The Tele Vue 85 takes 15 minutes to cool down.
I usually confirm the seeing conditions with a star test. If the central disk is not stable after the scope has cooled down, I would head back into the house and wait or I would observe for a short while and quit. From my home I only observe the planets and the moon ? too much light pollution to observe DSOs.
I purchased a helical focuser for my 1.25" eyepieces. I rarely needed to use it because the images just snapped into focus using the Tele Vue 85 focuser.
Over time, comparing views through my Mak and refractor from my home, I have concluded that if the seeing is less than 3.5/5 then there is no difference in the views of the planets and the moon. In moments of very good seeing, the Mak would show a tad more detail. Very good seeing does not happen very often in my area. On occasion, I observed that the Tele Vue produced a smidgeon of color on the limb of the moon. It is, after all, an APO doublet. But, it was never a problem since I use a polarized filter when observing the moon. At a dark site, the Mak will easily outperform the refractor when observing nebulas and globular clusters under just about any conditions. Aperture does count.
When I head out to a dark site about, I always take my Tele Vue 85 along with my Dob to observe the Milky Way. At home, I use it to observe the planets and the moon. It is hard to beat the quick setup and cool down times.
Of all the refractors why the Tele Vue 85? I wanted premium refractor that is portable, easy to set up, produces panoramic views, and has a focal ratio of at least f7. The Tele Vue 85 fits the bill. It weights 8.5 pounds, is 21.5 inches in length, and comes in a sturdy well-padded carrying case.
Why f7? An f7 scope produces a much smaller exit pupil than an f5 scope. I can observe at lower power. My entrance pupil is around 5.5. I sold my Panoptic 35 and replaced it with a Nagler 26mm because of my f5 Dob. On any f5 scope, the Panoptic 35 will produce a 7mm exit pupil. (exit pupil = focal length of eyepiece/ focal ratio of scope).
A person with a 5.5 mm entrance pupil can only trap 62% of the light coming out of the 7mm exit pupil. Although the FOV would be the same, the loss of light would affect the view. It would be like reducing the aperture of the telescope by 1.5/7 or 21.5%. On a small refractor, losing 20% of the aperture is significant even at low power.
My Tele Vue 85 is the scope that I use the most. I use my Dob 15 to 20 nights a year. My Tele Vue 85 gets used, on average, about twice a week.
I can highly recommend the Tele Vue 85 for exploring the Milky Way in dark sites and for lunar and planetary observing in light polluted areas.
- Scott Beith, txarrua and PlanetMacro like this
0 Comments