Celestron 80MM "Wide View" Spotting Scope

There are some times when I have just wanted something to give me a quick low-power look at things when it seems too much of a bother to lug around my ten inch. This especially bothered me after a visit to my parent's house in the Arkansas Ozarks, when a little table-top scope would have been ideal for a peek at the wildlife or the fat moon high in a clear starry sky. It was with this nagging feeling that I stood at the Eagle Optics table at the 7th Annual Nebraska Star Party admiring a rather inviting black-tubed wonder; the Celestron 80mm f/5 "Wide Field" Spotting scope on a small table- top tripod. A few quick glances in the eyepiece of the scope made me blurt out, "I want that!". I plopped down my credit card and walked away with my new toy.

Description and Features

In general characteristics, this is a "short tube" type of simple 80 mm aperture f/5 scope very similar to the Orion Short Tube or the Galileo 80mm versions. In fact, the build and overall layout between these differing telescopes is virtually identical, with only minor cosmetic variations such as paint or parts layout. The objective is a simple 2-element achromat with a 400 mm focal length. The OTA is about 15.5 inches long, with a maximum width of about 4 inches at the dewcap end. The removable dewcap alone extends about 3.25 inches in front of the objective, providing reasonably good dew protection. The scope weighs in at a modest 4.7 lbs with the mounting rings and finder installed, but for best stability, some sort of tripod should be used. The overall finish is gloss black, except for the rack-and-pinion focuser, which is a crinkle cast finish. The focuser is smooth, with about 2.5 inches of travel (but no draw tube), and has a set screw for locking the focuser position. The back end of the focuser has a built-in threaded "T" adapter, allowing the T-ring from a camera to go directly on the back of the telescope, transforming it into a 400mm telephoto lens. The tube assembly came with two nice quick-opening mounting rings which were bolted onto a photo-tripod adapter for tripod mounting. The front ring also has a threaded camera mount for piggy-back photography. The interior of the scope is fairly well baffled and painted flat black.

The unit I purchased came with a 45 degree Amici prism diagonal, providing upright and correct left-to-to right orientation for terrestrial viewing. It also had an additional "extender" T-adapter which also allowed straight-through eyepiece viewing when a diagonal is not in place. A 6x30 Celestron finder and easily-removable bracket were provided, and were of reasonably good quality. Two eyepieces were also provided: 20mm and 10mm Plossls (20x and 40x), which both had slightly loose upper barrel assemblies. However, both eyepieces were fairly good peformers, with the 20mm providing a 2.6 degree field at 20x.
For terrestrial and some quick astronomical viewing, I purchased a small "table-top" tripod for about $20, which has altitude and azimuth slow motions. The slightly unbalanced weight of the scope when tilted upward at angles beyond 45 degrees was too much for the little tripod's altitude locking screw to hold well, sometimes making the scope abruptly pivot straight up. It was necessary to counterweight the lower front end of the scope to keep this from happening. However, my regular camera tripod had no trouble holding the scope at any angle, although it was difficult to do much other than rough pointing. To solve that problem, I built a wooden bracket with a simple "T"-nut-based altitude bearing to attach to the scope's back mounting ring. I then attached the bracket to the azimuth portion of the somewhat "gutted" tripod mount from my old Sears Discoverer 2.4 inch refractor. This provided much easier pointing and smoother movement about both axes, as well as a sturdy fully adjustable tripod. With this experience behind me, I would recommend to others that inexpensive camera tripods should not be used with this scope, and that a dedicated mount be built or purchased for it.

Performance

Overall, I was quite pleased with the 80mm Wide Field Spotting Scope. It isn't an APO or even an ED, but it does give good basic low to moderate power performance in a fairly small package and at a very reasonable price. My first test of it came on the picnic table next to our cabin at Merritt Resort, where I watched skiers and boaters out on the lake. I tried my 30mm Ultrascopic eyepiece in it, and like the 20mm, it showed little or no color fringing ("secondary color"). The scope gave me a nice wide field with sharp contrasting images and little in the way of scattered light in the field. At 40x, I did begin to note slight bluish or violet secondary color on bright objects or edges, but it wasn't very objectionable. I noted a couple with their dog walking on the distant beach of the "Powder Horn" section of Merritt Reservoir over 1 mile from my cabin, so I put in my Televue 2.5x Powermate and my 6.4mm Meade SuperPlossl (156x), to get a close up. At that power, I could now see a weak violet haze-like fringing of secondary color in the view, but this was pushing the telescope well past the powers it was designed to use. This level of secondary color is typical of most short focal length 2-element achromats, so it wasn't exactly unexpected. Still, I had no trouble seeing all the fine details at that range, including counting the number of holes in the metal detector the man was holding! Images were sharp across the field, but looking at distant telephone wires showed slight pin-cushion distortion at the edges, which is common with many eyepieces when used at short f/ratios. The focuser travel was enough to allow me to focus on objects as close as 15 feet, so the 80mm Wide Field might make a fairly good birding scope.

When night fell, I put the scope to some real deep-sky use under the pristine skies of the Nebraska Star Party (unaided-eye mag. 7.6). With the 30mm eyepiece, I got about a 3.7 degree true field on the sky, which was marvelous for scanning the brilliant Milky Way so commonly seen at the Nebraska Star Party. M24 nearly spanned the field and glittered with stars and dark nebulosity, while M6 and M7 were nicely resolved. I did note that the 45 degree prism did impart a weak diffraction spike through bright stars, as well as adding a little to the amount of scattered light in the field. Those of you who plan on doing a lot of Astronomical observing with this scope should probably replace the 45 degree diagonal with a quality mirror star diagonal to improve the performance as well as to save your neck from strain when viewing things high in the sky (more on this later).

I put in my Lumicon UHC filter and was dazzeled by M8 and M20, both well contained in the same field of view. In fact, M8 looked as large as it was shown on some long exposure photographs. Much of the Milky Way's dark nebulae came out strikingly well in the scope. Moving northward, I managed to get both sides of the Veil Nebula in the 3.5 degrees of field using the UHC filter on the little 80mm Wide Field scope. The North America Nebula showed its full form nicely in the scope, with the Pelican showing up faintly next door. At slightly higher power (63x, no filter), I had little trouble seeing the "Apple Core" form of M27, and the tiny smoke ring of M57. Bright stars did show hints of color fringing, but it was generally fairly slight. However, higher power use (over 60x) on stars too faint to show much color still revealed a small halo of weak haze of aberrated light around them which might make resolving tight rich clusters of fainter stars more difficult. Still, M11 showed many faint component stars at 156x in a dim granular haze. Again, not using the 45 degree diagonal helped reduce the scattered light to some degree. The view of the Double Cluster was spectacular at 17x and 29x, with an outer halo of very faint stars around the brighter core stars being visible to me for the first time.

The wide field provided by my 30mm Ultrascopic also allowed me a great view of the Perseus OB Association, as well as the Hyades later on that night. M31 was very nice in the scope, with the dim diffuse arms showing up as they curved around the ends of the galaxy. Even the bulky 14mm Meade Ultrawide gave me a stunning view of the galaxy. The Pleiades were simply wonderful in the 80mm, with pinpoint star images set in a dark field with the faint glow of the nebulosity near Merope fairly easy to see.

When I got back home, I did some more extensive testing of the 80mm Celestron Wide Field Spotting scope using my entire eyepiece collection on a variety of objects. During daylight hours, I checked the amount of scattered light and residual color the scope had both with the 45 degree diagonal and my Televue 90 degree mirror star diagonal. Below 40x, both diagonals produced clear crisp views with little in the way of color excess. However, at 40x, I could just start to see some very slight color fringing. Higher power showed a weak but noticable bluish haze with the 45 degree diagonal, but the Televue mirror diagonal gave a somewhat better view with less scattered light and better color correction. For powers over 20x, a mirror star diagonal (or straight through viewing) is probably necessary for the best performance. The 80mm Wide Field Scope has a lens cap with a 50mm stop in its center, allowing the user to stop the scope down to 50mm. This greatly improved the color correction at moderate to high powers, although the view was slightly dimmer.

When darkness fell, a friend of mine and I did extensive comparisons of the 80mm Widefield to my ten inch f/5.6 Newtonian stopped down to 80mm. We both concluded that the 45 degree prism diagonal supplied with the Wide Field Scope was unacceptable for anything except very low power. At 63x, stars did not show clear diffraction patterns using the 45 degree diagonal, with some slight doubling of the star images. However, using the Televue 90 degree mirror diagonal, the stars showed clear Airy disks at 63x and 156x, with slightly asymmetric ring structure around the disks. This may indicate a slight wedging of the objective. In addition, star testing revealed a small amount of spherical aberration in the main objective. At this point, we stopped using the 45 degree diagonal and went with the 90 degree mirror one.

When used on Vega, the Celestron 80mm Wide Field showed a faint violet halo of color excess at 63x and 156x. Alberio-A showed a faint reddish hue between the diffraction rings, while Alberio-B showed a more bluish halo. Again, this level of color excess was expected in a 2-element f/5 Achromat. Epsilon Lyrae was resolved at 63x and fairly well split at 156x. However, each of the stars was surrounded by a faint diffuse halo of light about a minute of arc in diameter. In any case, the view in my stopped down (80mm) ten inch Newtonian at the same high powers was definitely better than the 80mm Wide Field, with higher contrast and little or no scattered light.

On the moon, again, the 80mm showed slight color fringing at the edges of the limb at 40x and above. My 6.4mm Meade Super Plossl had real trouble with the f/5 light cone, yielding a slightly hazy color-fringed image. I got better results with a barlow and a longer focal length eyepiece, so those of you planning to use these 80mm short tube refractors at anything except the lower powers should plan on using a Barlow. A 2.5x Televue Powermate is recommended, as regular barlows may have some difficulty getting focused due to the lack of focuser travel. Even with my 2.5x Powermate and a variety of eyepieces, my friend of mine and I agreed that much beyond 60x, the 80mm Wide Field Spotting Scope's performance showed a noticable falloff. However, when the 50mm lenscap stop was used on the 80mm scope, the image improved noticably with little residual color. This made casual views of the moon at powers up to 100x fairly pleasing.

The acid test came when Jupiter and Saturn finally got high enough for a good look. Seeing wasn't outstanding, but Saturn did show the rings at 40x, as well as its moons Titan and Rhea. However, the views at 100x and higher were not quite as pleasing. The rings and the ball of the planet remained clearly visible, but the overall view seemed to lack some of the contrast I was seeing with my ten inch stopped down to 80mm. Again, stopping the 80mm scope down to 50mm did help with the color excess, but little detail improvement was noted. Even at 156x, I could not clearly discern the Cassini Division. A quick look in the ten inch stopped to 80mm did show the division at 141x, so again, the 80mm Wide Field Scope wasn't quite up to the challenge of planetary observing. Jupiter was a somewhat more stringent test, and beyond 60x, it was surrounded by a faint violet glow, although I could still see the two main equatorial belts fairly well. 156x showed the two main belts fairly easily, as well as the polar darkenings. However, again, the view in the ten inch Newtonian stopped to 80mm was superior to that of the 80mm Wide Field Spotting Scope's, as four belts were easily visible in the Newtonian with much higher contrast less scattered light. Curious about this apparent lack of adequate higher power performance, I took the scope downstairs and set up an artificial star in my basement. After releasing the objective lens locking ring and moving the front element slightly, I put the locking ring back on and noticed that now, the artificial star's diffraction pattern was more symmetric. Going back outside and pointing the scope at Jupiter and Saturn showed that there had been a definite improvement in the view. Saturn's rings now showed Cassini's division at 100x and 156x, as well as the main equatorial band. 100x and 67x also revealed the tiny faint pinpoint of Saturn's moon Dione in addition to Titan and Rhea. Jupiter also showed more detail with two additional narrow belts being glimsed, along with additional detail in the main equatorial ones. Both planets were still surrounded by faint color halos, but at least now, they were showing some detail. However, the view was still noticably inferior to my ten inch stopped to 80mm. The short focal length of the Wide Field scope along with the gearing of the rack-and-pinion focuser made precise focusing at high power somewhat tricky as well. Clearly, the Celestron 80mm Wide Field scope is not a great instrument for detailed planetary viewing, although it will work at least to some degree for casual use.

In summary, the Celestron 80mm Wide Field Spotting Scope is a pretty versatile and cost-effective low-power instrument for those who want a fast way to satisfy their need to get out and observe wide field vistas on a moment's notice. It performs best at powers under 60x, although somewhat higher magnfication use is possible. For best results, it should be used on a decent mount which allows free smooth movement and good stable support.

David lives in southeastern Nebraska and has been observing the sun in H-alpha for nearly 15 years. He currently owns 4 telescopes and has compiled the stunning article "Observing The Sun in H-Alpha" at the website of the Prairie Astronomy Club