Orion 8" f/4.9 Reflector

I am a refractor lover. Here on the Cloudy Nights forums, people like me are generally called "slobbering refractor freaks" (SRFs). I've had refractors from 60mm on up to 5" in aperture over the years, the best of which has been my trusty little Orion 80mm ED refractor (which I also reviewed here on Cloudy Nights). But like all telescope owners, I eventually caught a bad case of aperture fever. The largest scope I've ever owned was an equatorial (EQ)-mounted Meade 10" reflector. I sold it in 2003 because I wanted something more portable, allowing me to set up and observe almost immediately. I ended up with an Orion 4" refractor, which was soon sold to fund the purchase of my beloved ED80. For over a year, the little ED80 had been my primary scope. Many other refractors came and went, but the ED80 remained. However, memories of that big Meade 10" kept coming back to me. I decided to go ahead and buy another moderately sized telescope that would complement my ED80.

In this review, I'll give my thoughts on the new scope, and I'll also give a few comparisons of it to my ED80 throughout.

As I mentioned, I've had refractors as large as 5" in aperture. I considered buying a 6" refractor (once you become an SRF, it's hard to be anything else) to cure my aperture fever, but I really wanted something with more than 6" of aperture. Besides, my SkyView Pro EQ mount probably would have been insufficient for such a large scope. I didn't want to spend a pile of extra money on a larger mount, so I realized that what I ended up buying either had to be a good match for my SkyView Pro, or it had to be a Dobsonian-mounted reflector. I've grown accustomed (or spoiled would be a better word) to using EQ-mounted telescopes with tracking capabilities, so that ruled out buying a Dob. I thought briefly about Schmidt-Cassegrains, but I've never really been a CAT kind of guy. Plus, I wanted something that would give me a reasonably wide field of view (FOV).

Considering all the factors led me to the conclusion that my new scope had to be a Newtonian reflector. At the risk of betraying my fellow SRFs, I have to admit that I like Newts. I've had two of them in the past: the aforementioned Meade 10" and a Tasco 4.5". (Yeah, who didn't have a 4.5" Tasco reflector at some point? I was just a teenager, I didn't know any better.)

I'm a big fan of Orion telescopes, so I was familiar with their product line. (Please note that I am in no way affiliated with Orion other than being a happy customer.) Their SkyView Pro 8" reflector had been in the back of my mind for a while; that particular scope seemed to make the most sense to me. It had sufficient aperture, and the scope seemed to be a nice match for the SkyView Pro mount since Orion has been selling it as a package for quite some time. I also knew that Orion sells this scope as an optical tube assembly (OTA) with no other accessories. Since I already had the mount, a spare 9x50 finder, and probably too many eyepieces, I decided to go ahead and order the 8" f/4.9 OTA and a set of tube rings.

The Orion 8" arrived safely and packed in the usual Orion fashion: very well-protected. The telescope is huge compared to my humble little ED80 and it has the same nice gunmetal gray metallic finish. The OTA's dust cover is a hard plastic cap that snaps in place and fits snugly over the end of the tube. The mirror cell holds the 8" parabolic primary mirror securely and it features three large thumbscrews for collimation adjustment. There are also three smaller screws that will "lock" the mirror in place after collimation is complete. The cell also appears to give the mirror adequate ventilation so that it will cool down faster.

A small dot is at the center of the primary, allowing easy collimation. The 4-vane spider holding the secondary is solid and easy to adjust. The 2" rack and pinion focuser includes a 1.25" adapter. The focuser is typical Synta. It has lots of the infamous "Syntaglue" that supposedly keeps everything lubed but usually ends up making the mechanism very stiff. Turning the plastic focus knobs revealed a lot of slop in the focuser. I could actually see the drawtube moving up and down in addition to moving back and forth. A large thumbscrew on the focuser is used to adjust the tension, and three small Allen screws allow squaring of the focuser. The OTA arrived with a free copy of The Sky Student Edition planetarium software and a simple collimation cap. The tube rings that I ordered with the scope are nice and solid. Each ring has a large thumbscrew, which makes it easy to open and close the rings and adjust ring tension.

Having been an SRF for so long, it took me a few tries to get reacquainted with collimation. The included collimation cap is a great little tool to adjust collimation, but I eventually bought Orion's sight tube/Cheshire eyepiece. Once I felt confident with my collimating abilities, I found collimation to be fairly easy. The secondary has a single Philips screw for lateral adjustment and three Allen screws for tilt adjustment. I adjusted the secondary, and then I adjusted the primary so that the center mark was in the middle of the Cheshire's crosshairs. Later star tests revealed that the primary needed further adjustment, so I simply tweaked the primary's three thumbscrews until the secondary's shadow was in the center of a defocused star image.

I've never liked the plastic knobs that so many telescopes have on their focusers. After the 8" scope's arrival, I replaced the plastic focus knobs with a set of Orion's radial aluminum focus knobs that I had. The teeth along the edge of the plastic knobs felt a little uncomfortable; the rubber edges of the aluminum knobs feel much better. Plus, the aluminum knobs look much better than that boring, plain black plastic!

I also adjusted the focuser itself to remove most of the slop. During first light I realized how much of a problem the focuser was. The image shift at high magnifications was awful. To eliminate as much of this slop as I could, I used a small Allen screw to adjust the tension on the two small Allen screws atop the focuser. Using small adjustments and setting the screws' tension to about the same level, I was able to eliminate a great deal of the image shift. Images still shift at high magnifications, but not nearly as bad as before I made the adjustment.

Another thing I've never liked very much are setscrews that mar eyepiece barrels. The 8" scope's 2" eyepiece holder has two setscrews, and the 1.25" adapter has a single setscrew. I replaced the 2" holder and the 1.25" adapter with excellent compression ring units from Mercury Systems Support. I ended up putting the original 2" holder back on the focuser because the compression ring unit had a lower profile, making it impossible for my eyepieces to reach focus. But the 1.25" adapter with compression rings is a great addition. It holds my eyepieces much more securely and without marking up their barrels.

In the near future, I'm going to remove the Synta focuser and replace it with a high-end Crayford. I think this is almost a necessity for this telescope. I may also possibly replace the 4-vane spider with a curved spider, but I haven't decided for sure.

I have been very pleased with the optics on the 8". Star tests reveal nice, round images of defocused stars. However, the mirror seems to have a bit of spherical aberration and surface roughness (in my completely non-expert analysis). A star image outside focus shows nice, round, concentric rings. But inside focus reveals a much less distinct bull's eye pattern. The concentric rings are very difficult to see and the overall image isn't as smooth and well-defined as it is outside focus. However, looking at celestial objects in focus is what's most important, and I've been happy with what I've been seeing.

This telescope doesn't show stars as well as my ED80. In my ED80, stars are textbook perfect with Airy discs and diffraction rings. The 8" shows stars not quite as "pinpointy." I would say that a combination of less-than-perfect seeing, the 4-vane spider causing diffraction spikes, the mirror with its slight aberrations, and maybe even the slightest bit of miscollimation all contribute to this. But don't get me wrong, stars are still quite sharp, particularly dimmer stars, and I'm very satisfied with what I see.
At f/4.9, this scope made me a little curious and concerned about coma. However, my eyepieces consist of several Naglers and a Panoptic, so my worries were unfounded. Stars are nice and sharp with very little, if any, distortion near the edge of the FOV. I really wish I had some Plossls or other types of eyepieces that I could use to check for coma.

In my light-polluted skies, good views of galaxies are still pretty much out of reach of this scope. The Andromeda Galaxy is much brighter than it is in my ED80, but it's still just a big, oblong, fuzzy blob. M110 and M32 are easy to grasp. M33 can be detected, but no detail is visible. So far, M81 and M82 are my favorite galaxies to view. Again, no real detail can be seen, but both galaxies' shapes are evident. And I enjoy seeing both galaxies in the same FOV. The Whirlpool Galaxy and its companion NGC 5195 are both visible, but only as 2 very faint smudges of light. I'm anxious to get this scope under some really dark skies sometime!

This telescope does a good job with other deep space objects (DSOs). The Orion Nebula is the most impressive DSO I've seen so far. Nebulosity is visible everywhere! The nebula has a green hue to it, as opposed to the mostly gray hue shown in my ED80. I can usually see five stars in the Trapezium, and on one night of excellent seeing I was able to see six. Adding an OIII filter brings out a little more nebulosity, but I don't really see a huge difference in using and not using the OIII on M42. The Crab Nebula is easy to see in this scope, but no filaments or other details can be seen. Open clusters are excellent targets for this scope. In fact, I've decided to name this scope "Cluster Buster" because of this. The Double Cluster is outstanding. Stars just fill the entire FOV, and it's pretty easy to see the different colors of stars. In the ED80, the Double Cluster is very pretty, but obviously doesn't show quite as many stars. M35 is another excellent open cluster target for the 8". This cluster's faint stars also fill the FOV. Another good set of objects to view are planetary nebulae. The first time I viewed the open cluster M46, I couldn't detect NGC 2438, the planetary nebula seemingly embedded within the cluster. But when I added my OIII filter, the little planetary made itself easily visible. In my ED80, I couldn't detect NGC 2438 with or without the OIII. The Owl Nebula is another easy target with the 8" and an OIII filter. I can't see it at all without the filter, but it stands right out once the filter is in place. I'm anxious to see the more famous planetary nebulae, such as M57 and M27.

The new 8" does a respectable job on multiple stars, but I find that my ED80 is much better suited for this due to its nearly perfect optics. Castor, Mizar, and other famous binaries are easy targets in the 8". Even bright Rigel's companion star is visible when the seeing is good and it isn't lost in Rigel's diffraction spikes. But I can usually see Rigel's companion even in bad seeing with the ED80. Beta Monocerotis is my favorite multiple star. This triple star is stunning in my ED80; the 8" does a pretty good job with it, but the stars aren't quite as sharp and well-defined as they are in the ED80.

The biggest surprise for me was the views of planets through the 8". My ED80 is an excellent planetary scope and I honestly wasn't expecting the 8" to excel at planets. I was wrong! The ED80 shows planets with more sharpness and contrast, but the 8" makes up for that in brightness and resolution. Once the planets are high in the sky and the scope has cooled sufficiently, it's capable of giving very impressive planetary views. Saturn shows at least one dark cloud band near the equator. Shading near the pole is also evident. The 8" also reveals Saturn's rings to have a little darker hue than the globe itself. I can detect very subtle shading on the rings. The Cassini Division is no problem to see; it's nice and sharp all the way around. The C-ring is also fairly easy to see. I honestly haven't paid too much attention to Saturn's moons, but I can routinely see at least five of them. I haven't seen Jupiter very high in the sky through this scope yet, but even at an altitude of about 25 degrees, many details can be seen on the planet. Several dark cloud bands are very obvious, especially the two equatorial bands. Shading is visible on the lighter bands. I can also make out festoons and other small features. I'm sure the Great Red Spot (GRS) is easy to see, but I haven't seen it yet simply because I've viewed Jupiter only once through this scope. I can spot the GRS easily through my ED80, so I think the 8" won't be a problem for spotting it. All four Galilean satellites are obvious, of course. I'm looking forward to seeing the GRS and some satellite shadow transits when Jupiter gets higher earlier in the evenings. I'm also anxiously awaiting the 2005 Mars opposition!

This telescope is still highly portable, even though it's an EQ-mounted 8" reflector. True, it takes me an additional trip outside to get it set up compared to my ED80, but that usually adds on only another 30 seconds or so of setup time. In the first trip out to my driveway, I carry the mount with its three 7.5 lb counterweights attached. Next, I carry the OTA out and attach it to the mount. Finally, I carry the tripod's spreader tray, my eyepiece case, and any other things I may need (stool, binoculars, star chart, etc.).

One slight inconvenience with the 8" on an EQ mount is the strange eyepiece positions possible when the scope is pointed in certain directions. When the scope is pointed to the east, I almost have to climb over the scope to access the eyepiece. When the scope is pointed to the west, I have to crouch under the thing to reach the eyepiece. But this can be solved by using rotating rings or adding an extra tube ring so the OTA can be rotated to place the eyepiece in a comfortable position.

One more minor inconvenience with this scope is the balance. It will balance perfectly along the mount's declination and right ascension axes, but the focuser will disrupt the balance when the scope is in certain positions. For example, the scope will seem to be top heavy when pointed a certain way and the focuser end will begin to drop. However, this hasn't been a big enough deal for me to worry about. I just hold the scope in the position I want as I tighten the mount's declination and right ascension locks.

One more issue I need to address here is the SkyView Pro mount. I feel that this excellent mount is at or near its weight limit with the 8" scope. With vibration suppression pads, a rap to the tripod will give an image the shakes for about two or three seconds. That's not too bad, but I'm used to my ED80 dampening in less than a second on the same mount. But the SkyView Pro mount does a very good job with the 8". The motors on the axes don't strain to slew the scope and tracking is perfect.

If somebody would like to do some astrophotography through this scope, the SkyView Pro would not be the best mount for the job. Something much larger and more stable would be necessary.

As I mentioned, I've been very pleased with this 8" f/4.9 reflector. I feel that between this scope and my ED80, I have two fine telescopes with their own strengths and weaknesses. In any area in which one scope falls a little short, the other will do a better job. But the 8" reflector could easily be an only telescope. It can provide a lifetime of excellent observing. I highly recommend Orion's 8" f/4.9 reflector to anybody looking for a first telescope or an additional telescope. Yes, I recommend this even to my fellow SRFs!