Updated 30 November 1998
Added a link to an article dealing with upgrading Tasco (or other "department store") telescopes.
This page contains review comments on pieces of astronomical equipment that I (Joe Roberts) have personally owned (or used extensively). The goal is to post information that prospective buyers might want to know (stuff that the advertisers might not tell you).
Please note that I am not a "professional" writer... the reviews that appear below are my own opinions about particular pieces of equipment. Also please note that I am not an optician. I do not have the knowledge or equipment to perform highly precise optical performance measurements, however, I have enough "real world" experience with amateur telescopes to "know" good optical performance when I "see" it.
NOTE: "OTA" means "Optical Tube Assembly"
I do not intend to provide an overall description of the CG-11 as other reviews (as in Sky and Telescope) have already covered this basic information. I intend to report what I like and don't like about this scope (there's allot more I like about the CG-11 than I don't like). I've had the unit for 4.5 years now, and I am quite familiar with its good and bad points.
I purchased my CG-11 from Orion Telescope Center in August of 1992. I received the unit 6 days after ordering it. It came UPS in about 7 or 8 boxes. There was some shipping damage to the case that the optical tube came in (however the OTA itself was not damaged).
When I purchased my scope, the cost was $3099.00, plus $98.00 for shipping. The CG-11 has changed since I ordered my unit. When I ordered my unit, the polar alignment scope was a standard feature (now it's a $159 option). Also, my scope came standard with a 30mm Ultima eyepiece; CG-11's now come with a lesser 26mm Plossl eyepiece. In addition, the finder scope has been changed to a lesser model. When I ordered my scope, the legs for the tripod were of a fixed non adjustable length; I believe the newer models have adjustable legs. The new models come with a different declination shaft and counterweight setup then the unit I have (mine came with two 11 pound weights... the newer models come with one big weight I believe). And, of course, the newer models are considerably more expensive. When I ordered my unit from Orion, the salesperson said "I don't think we will be able to keep this unit at $3099 much longer."
One thing I noticed right away upon setting up the CG-11 for the first time is that the supplied counterweights are just barely adequate to balance the scope. Addition of almost any accessories required more weights. I did order an additional weight. Unfortunately, the price of an additional weight was a VERY overpriced $71.00! I had really no choice but to pay the price. Other weights would certainly work, but since the CG-11 is such a nice looking unit I wanted a matching weight. The CG- 11 mounting (which of course is made by Losmandy) is of very fine craftsmanship and very nicely finished. As other reviewers have commented, the workmanship and finish of the mounting is "a work of art". My only comment is that the paint used on the legs (of the unit I have) is vulnerable to damage. Other reviewers of this unit have reported this issue; supposedly Losmandy has since made some adjustments to the painting process on the legs.
The CG-11 mounting operates in a very smooth fashion. I only have two "complaints". One, the knob which adjusts the mounting for the observers latitude has about 90 degrees of "play" in it... that is, you have to turn it about 90 degrees before it starts to actually move the mounting. This is not a big deal, though, since it is a "set and forget" type adjustment. The bigger complaint I have (and other reviewers have also stated this) is that the locks for the RA and DEC axis do not lock the position of the scope too well unless you REALLY clamp down on them. This is not normally a problem for visual observing (the scope balances well and will usually stay where you point it even with the locks unclamped). The action of tightly clamping down on the RA or DEC clamps can cause the position of the scope to change, which can be a nuisance. For astrophotography, locking of the axis is quite important; I wish the scope would lock position more securely with less torque on the clamps. The inability to adequately lock the scope position for me is compounded. I have optical encoders mounted on the scope, and the insertion of the necessary encoder hardware makes the tube clamping situation much worse. Even when I put tremendous torque on the RA and DEC clamps, the telescope is still rather easy to move. I feel that this is an area which needs improvement. As I said, for visual observing this issue is not really that big of a concern. For astrophotography (which this mounting is otherwise excellent for) I would like to see the RA and DEC clamps provide much more locking capability.
The CG-11 can accept a polar alignment scope (my unit came standard with it). I find this feature to be indispensable for lining up on the north pole (which is essential for astrophotography). One minor complaint: the polar alignment scope has a small amount of "play" when mounted in the polar shaft. This "play" of course means some error in polar alignment. I must admit however that the play does not seem to cause too much error, since when I use the polar alignment scope to line up on the pole, I can track planets at 467x for 10 minutes or so with no significant drift. One other thing (again other reviewers have mentioned this): the red LED accessory which is used to illuminate the polar alignment scope laser etchings is too dim. I find that shining a small flashlight into the LED hole works much better.
One thing I don't like about Schmidt-Cassegrain scopes is that the focusing mechanism works by moving the primary mirror back and forth. Since consumer items can only be made to certain tolerances (without being extreme in cost) the mechanism necessarily has some "play", which translates to an annoying image shift when adjusting the focus knob. This image shift is noticeable at 70x, but is not a problem. At high power (say 300x or so) the shift is obvious and somewhat annoying for visual observation. For CCD work I suspect it would be intolerable. I outfitted my scope with a JMI focuser (the NGF-S), which is great for fine focusing (rough focusing must still be done with the conventional knob). This image shift problem is not unique to the CG-11, all SCT's suffer (to some degree) from it.
I find the drive of the CG-11 to be excellent. While it is not one of the types that can slew the scope to automatically find objects, the accuracy and smoothness of the drive makes it a pleasure to use. For example, I have taken 4 minute exposures of the totally eclipsed Moon with the drive set to "Lunar" rate. When I received the processed photos, the Moon was extremely sharp, and stars in the picture were streaks about 3/16 inch long! Similarly, I find that guiding corrections are not necessary for shots I take with a piggyback 500mm telephoto lens (assuming good polar alignment!). I am totally satisfied with this aspect of the CG-11.
One accessory that comes with the CG-11 is a total piece of garbage: the AC-DC converter for running the telescope electronics and drive. The unit I had failed a few hours after first using it. I opened the unit and found it to be very poorly made; among the worst I have ever seen (check my Resume for credentials in evaluating such units). With a telescope of this caliber, I would expect Celestron to not go to the lowest quality offshore supplier available for the power supply. I did not even call for a replacement (I would not want a "new" unit of the same quality). I went to Radio Shack and purchased a 12V 1 amp power supply which is infinitely superior to the one Celestron supplies. I would normally recommend that anyone who has a CG-11 throw out the power supply... however, Celestron probably obtains these supplies from various vendors so maybe some improvements have been made.
In conjunction with the previous paragraph, I would like to comment on the power supply used for this telescope. If one plans to observe with this (or any SCT) telescope for anything more than an hour or so on a damp night, an electrical heater to prevent dew formation on the corrector plate is a virtual necessity. I have an Orion Flexishield dew cap which works pretty well for 2 or 3 hour observing sessions on most nights. However, any "all night" observing session or any summer evening session which lasts more than an hour or so really does require the heater in my experience. You can use a hair dryer to periodically dry off the corrector plate, but this causes bad seeing and has to be repeated fairly often once dew starts to form. I personally use a deep cycle ("boat") battery. Portable DC supplies in the 1 amp range do not have the necessary current to operate a heater and the drive. So, unless you carry around a DC power supply with 3 or 4 amps capability (like one used to power a mobile CB radio inside a house), you will not be able to power a heater. A battery, while much heavier, offers enough power to run any heater and accessories for the entire night, without the need to run AC extension cords from your house. At star parties out in the middle of nowhere (like Stellafane in Vermont), AC power is not likely to be available anyway. In my opinion a good, powerful battery is a necessity for serious work.
In my opinion the finder scope that came with my CG-11 is excellent. It is an 8x50 unit, with illuminated reticle, which can be operated in right angle or straight through mode (I use it straight through). The finder is mounted on a removable bracket which keeps alignment very well when removed and re-installed on the OTA. The star images are very clear and bright, and the apparent and true fields of the finder are very pleasing to me. I don't know which finder is supplied with newer CG-11's. I do not plan to upgrade mine as I am totally satisfied with it. I did make a dew cap extender for it since it will otherwise dew over on all night observing sessions.
The case that the OTA is shipped in is marginal at best. Mine was damaged in shipping; I called Orion and they arranged for Celestron to send a new one (which I did receive intact). However, the case for the OTA will hold only the OTA. The finder scope and other accessories cannot stay on the OTA when it is in the case. I made a new, larger case out of plywood (it's much sturdier than the supplied case). My new case allows me to leave the finder scope on the OTA in addition to the JMI focuser and 2 inch diagonal. This saves considerable time when setting up and breaking down the unit. The case that Celestron provides is obviously not made by them; they look nearly identical to some trunks I have seen for sale at K-Mart and Caldor. The case is fine for storing the OTA when not in use, but I personally would NEVER use it as a shipping container!
Speaking of cases, the CG-11 equatorial head also comes in a case. This case is made to a much higher level of quality that that of the OTA case. It resembles the quality of road cases used by musicians. One obvious issue: the equatorial head DOES NOT FIT properly into the case. The case was obviously not designed for the equatorial head... Celestron (or Losmandy) went out and found a case that "fit" the equatorial head the best. Unfortunately, the equatorial head will only fit in the case a certain way, and even then has to be "forced" in somewhat (one of the stepper motors interferes with the thick foam lining of the case). The equatorial head is in no danger of being damaged by the force necessary to get it into the case, but it is somewhat of an inconvenience.
No other pieces of the CG-11 come with storage/carrying cases. Items that would benefit from having a case are the 3 legs, the pier which attaches the legs to the equatorial head, and possibly the declination shaft/counterweights. If you only plan to move the CG-11 from your house to a backyard, cases are not needed. However, if you attend star parties at remote locations, cases to protect the finish of the pieces during transport would be a definite plus. I plan to make cases for the remaining CG-11 parts.
The OTA used on the CG-11 is the same as is used in Celestron's fork mounted models. As such, it has some bolt holes in the rear cell that are not used in the CG-11 configuration. Instead of filling these holes with some "dummy" hardware, Celestron simply supplies the OTA with scotch tape covering these holes (this is how mine arrived anyway). I wouldn't expect Celestron to produce a different rear cell just for the CG-11 (such that no unused holes were in it), but I would have preferred to see the holes filled with dummy bolts rather than covered with tape. At least they put tape on to keep dust out of the tube!
Optically, the CG-11 should be pretty much the same as any other Celestron 11 inch scope (since the OTA is the same). I find that the C-11 is a good "all-around" performer. As most experienced observers are aware, SCT's are not the best instrument for serious planetary observing (due to contrast degradation from the large central obstruction). I have heard that there have been considerable variations in optical quality of Celestron telescopes over the years. I have also heard that C-11 OTA's generally have consistently good performance (as compared to C-14's which can be quite good to marginal). Overall, I am quite satisfied with the optical performance of my CG-11.
Speaking of planet observing, experienced observers know that the quality of the image is closely related to optical quality of the telescope AND the seeing conditions at the time the observations are being made. I have found that on steady nights when the scope has been outside for 3 or 4 hours (i.e. totally cooled down to ambient) the planetary views through the C-11 are really quite good. I remember viewing Saturn while attending Stellafane in 1994. The seeing was excellent, I had Saturn at 280x (using a 10mm Celestron Plossl eyepiece) with a yellow filter in the path. The image was very steady and clear, and five moons were visible, two in close proximity to the planet. Two observers that asked for a look were genuinely impressed with the quality of the view... and they were owners of 6 and 7 inch Astrophysics refractors! While in general I'm sure the Astrophysics units would be the clear winner for planetary work, the C-11 can yield excellent planetary views when used with quality eyepieces and filters on nights of excellent seeing.
While the amount that can be seen through any telescope depends on a number of factors (sky conditions, observing experience, telescope quality, etc.),I find that most any object in Wil Tirion's Sky Atlas 2000 is visually observable in the CG-11 with the exception of planetary nebulas). Planetary nebulae, often being very small, present more of an identification challenge as opposed to a visibility problem. Most any galaxy I attempt to find with the CG-11 is visually observable in the CG-11,and I have often stumbled upon galaxies which are not shown in Sky Atlas 2000. I have seen stars as faint as magnitude 14.8 in the CG-11; however, I knew where to look for them beforehand (based on a finder chart in Sky and Telescope). The 14.8 magnitude stars were "difficult but visible" at 311x (9mm Nagler eyepiece) in the CG-11. I also find that most globular clusters are at least partially resolved in the CG-11 (using high power). Some are spectacular (M13, M3, M22, M5, etc.). I have seen M31's brightest globular cluster with "no difficulty" in the CG-11. On the other hand, I have tried to spot the central star of M57 numerous times without success. At magnitude 15.4, it is just too faint for the CG-11 at any site I have observed from so far.
I have seen various load capacities published for the G-11 mount that the CG-11 comes with. In the heaviest configuration, I have loaded up my scope with the JMI focuser, 2 inch prism diagonal, 2 inch eyepiece, light pollution filter, Orion Flexishield dew cap, corrector plate heater, and a Tasco 2.4 inch telescope with a hefty 1970's vintage Canon SLR (piggyback mounted). I find that the G-11 mount handles this load pretty well, however all three 11 pound counterweights need to be at the far end of the declination shaft in order to balance the scope. I would estimate the load on the mount at about 40-45 pounds. Celestron offers a scope called the CG-14, which is basically the same as the CG-11 except with a 14 inch OTA. The 14 inch OTA weighs 50 pounds. I would expect that a 14 inch OTA with accessories would be stretching the limits of the G-11 mount. Just looking at the CG-14 gives one the impression that the OTA is a bit big for the mount (in my opinion). Overall, The G-11 mount is excellent for astrophotography and general observing.
To sum up, I am generally quite happy with the optical and mechanical performance of the CG-11. As with any product, there is room for improvements and refinements in the design. The CG- 11 is an excellent platform for anyone wishing to do astrophotography. It is also a large enough scope to allow a huge number of objects to be visually observed. The G-11 mount by its nature allows a number of configurations and would be an excellent choice for those who have more than one OTA. The CG-11 is reasonably portable. The CG-ll is a pleasure to use due to the extremely smooth performance of the mount and drive. The CG- 11 is not an inexpensive telescope; however I feel the CG-11 is worth the money I paid for it.
The Meade 4500 is a 4.5 inch F8 Newtonian reflector telescope with an equatorial mounting. The unit retails for $399; I picked mine up new at the bargain price of $249 (it was one of the last few in a mall store that was closing after the holidays). Based on what I've seen in the mail order ads, you can expect to pay about $300 for the Meade 4500. My "main" scope is a Celestron CG-11; the Meade makes a nice second scope, and is much smaller and easier to move around than the 11". It's nice if you just want to take a "quick look" around (as is often the case on worknights when you can't stay out for hours).
The Meade 4500 is generally well made considering its price class. The tube is a rolled piece of aluminum, and there is a seam along one side of the tube. The focuser is plastic, but it is the 1.25" size, allowing use of good quality eyepieces. The Meade 4500 comes standard with an MA25mm eyepiece, providing a magnification of 36x (MA stands for "Modified Achromatic"). The focuser is the rack and pinion type and has a total useful travel of about 3 inches. There is a set screw in the eyepiece holder for securing the eyepiece. The finder scope is a fixed focus 6x30 unit. The objective of the finder is set very far forward in its cell, necessitating the need for a dew cap to prevent dewing. The finder scope bracket that comes with the scope is plastic, and has six set screws for adjusting the position of the finder (I replaced the "stock" finder scope bracket with a metal one I had from my "junk box"). The main optical tube comes with a dust cover, however it fits very loosely on the front of the tube. The tube is secured in the cradle by two "half rings" which are tightened by use of two knobs. To remove the tube from the cradle, the knobs must be completely unscrewed from the rings. The optical tube may be rotated in the cradle by loosening the two knobs and turning the tube. The primary mirror is secured in its cell by three clips; the mirror is fully adjustable from the rear of the scope. The secondary mirror is also fully adjustable and is held on a 3-stalk mounting.
The mounting of the Meade 4500 is also decent for the price class. There are slow motion controls in each axis, and the mount is capable of accepting an optional motor drive. The gears on the declination and Right Ascension shafts are about 2.5 inches in diameter. Setting circles are also standard on this mounting; the declination is marked in increments of 2.5 degrees. Right ascension is marked in increments of 10 minutes. There are locks in both the right ascension and declination axis. Slow Motion knobs are provided for both axis; the knobs are located at the end of flexible shafts which are about 12 inches long. The mounting is capable of moving (of course) in right ascension and declination; the altitude and azimuth may also be adjusted (useful for doing polar alignment). The mounting is mostly cast metal construction (the gears appear to be the only machined items). The tripod is aluminum construction with some cast items and plastic lock knobs. The tripod height is adjustable from a minimum height of about 30 inches to a maximum of about 50 inches.
I have used my Meade 4500 for about 2 years, enough time to become rather familiar with its good and bad points. Like any telescope, there are a few things that could be improved. A list of things I have found annoying or lacking follows:
The slow motion controls do have some "play" in them, meaning that when one changes the direction of rotation of the control, there is some "slop" before the tube begins to follow. Some of this "play" can be eliminated by making some adjustments to the position of the worm gears (this is not mentioned in the manual, I just did it myself). I do not list this "play" in the mounting as a "bad point", because the amount of play is acceptable for a mounting in this price class. At low magnification its not a problem at all; at powers around 120x or higher it can be a bit of an annoyance, but easy to get used to.
So, the Meade 4500 does have some finicky points; none are show stoppers (with the possible exception of the inability to bring a camera to prime focus).
Additional comments: The eyepiece that Meade supplies with 4500 is a 25mm MA design. This is an entry level eyepiece; not in the league of Televue, for example, but certainly a good basic performer. The apparent field of view is around 40 degrees. The field edges are a bit fuzzy on the MA25mm; this is likely due to misplacement of the field stop, and is not generally an optical quality problem. The MA eyepieces are from a series put out by Meade (but in all likelihood these eyepieces are made in Japan to Meade's specs). The eyepieces are "Multicoated", however I doubt that all optical surfaces are multicoated (the optical surface closest to the observer's eye certainly is). The MA series of eyepieces uses 3 optical elements. I also own a MA40mm EWF and a MA6mm eyepiece from this series (both 1981 vintage however). The 40mmEWF (extra wide field) is an excellent eyepiece; I used it extensively when a 6" reflector was my prime scope. The MA6mm is of acceptable quality, but notably inferior to a high end Meade 6.7mm eyepiece I also own. Meade has made a good choice in providing a 25mm eyepiece with the 4500; it yields 36x magnification, a perfect power for beginner astronomers. Planetary discs are a bit small at 36x, but the rings of Saturn are still able to be seen. The next logical choice for a second eyepiece would be something with a focal length of around 9 or 10mm, providing a magnification suitable for detailed views of the planets.
The tripod legs of the Meade 4500 can be adjusted to accommodate uneven ground, and the range of height adjustment is more than adequate for me (I am 6' 1"). If a young (or short) person were to use this scope, the eyepiece may still be too high for objects located near the zenith (even with the tripod legs at minimum height). This should not be a major problem for most users however.
Plan on making a dew shield for the finder scope if you expect to be out observing on nights of even moderate humidity. The objective of the finder is very far forward in the tube and is very susceptible to dewing prematurely. I made a dew cap for the finder out of a toilet paper tube that works quite well. I have never had a problem with the primary (or secondary) mirror dewing over.
As with any reflecting telescope, collimation of the optics is quite important if quality stellar images are to be had. My scope was wildly out of collimation "out of the box"; I did a rough alignment indoors. Fine tuning was completed outdoors. It can be a fitful task, especially if you do not have a helper. Any adjustments on the primary or secondary tend to throw the star out of the field of view, requiring it to be recentered often. I can just barely reach around to the rear of the cell to make adjustments while looking through the scope at the same time. Frankly, collimating the scope can be a pain, but no more so than with many other scopes. The images through the Meade 4500 are quite nice when the scope is properly collimated.
What can you expect visually through the Meade 4500? Your results will of course depend upon the sky conditions where you observe. As always, the darker the better. The Meade 4500 will easily show all of the Messier objects, although many of them (especially the galaxies) will still be dim, featureless "smudges". The brighter globular clusters (like M13, M5, M22, M4, etc.) are beginning to resolve, some nicely. Many open clusters appear quite beautiful in the Meade 4500. The persistent observer could easily expect to find hundreds of other deep sky objects and double stars (under dark skies that is). Considerable structure can be seen in the Orion Nebula. The Moon of course is spectacular through this scope. Reasonable detail can be seen on Jupiter, Saturn and Mars (Mars only when at opposition) if the seeing conditions are good and if the collimation of the scope is good. I have seen surface markings and a polar cap on Mars (using a color filter when Mars was at opposition) at 134x. Stellar images are also good when the scope is properly collimated. NOTE: I have made many observations using the Meade 4500; to get a "feel" for more on what it can and cannot do, check out my Observation Log (look for entries made with the Meade 4500 of course!)
How about Astrophotography with the Meade 4500? The Meade 4500 is in my opinion a "beginner" telescope, and although it does have an equatorial mounting, it is not a scope designed with serious astrophotography in mind. As mentioned earlier, prime focus astrophotography using the Meade 4500 will require some modifications to the scope because of the inability to bring a camera to focus with the "as supplied" optical tube assembly. The Meade 4500 could be used (with good chance for success) for some forms of astrophotography however. Its equatorial mounting is not adequate to do high power "through the scope" photography, but a piggyback camera could likely be used with good results if the scope is properly polar aligned (and equipped with the optional motor drive). Lenses of up to about 250mm focal length could likely be used if exposures are held to 10 minutes or less. In addition, "afocal" photography of the Moon can be done with good results (I have done this). Photography of the planets through this scope, while not impossible, would be an extremely challenging undertaking. For other than afocal astrophotography, the motor drive (which I do not own) would be mandatory. In summary, the Meade 4500 is not really intended to be a telescope for serious astrophotography, however some basic forms of astrophotography (mentioned above) are within its capabilities. You can check out a picture of the Moon I took with the Meade 4500: 8 day old Moon taken through a Meade 4.5 inch reflector with "camera up to eyepiece and snap" (afocal) method. Kodak Royal Gold 400 film, 10 October 1997. [18k]
In Summary: The Meade 4500 is a "real" telescope, it is not in the "toy" class. It provides a decent aperature and an equatorial mounting with slow motion controls, allowing for relatively easy tracking of celestial objects. Meade has made an excellent choice of eyepiece for this telescope. You can expect decent views through the Meade 4500, but also expect to learn how to collimate a scope. The Meade 4500 is nicely portable (I can carry it with one hand for short distances). The Meade 4500 is a good "all around" telescope for visual use; it can also be used for basic forms of astrophotography. The Meade 4500 will not show you as much as a 6" Dobsonian reflector, but if you cannot afford a 6" Dob the Meade 4500 would be a nice second choice (you won't see as much with it, but you'll have the convenience of an equatorial mounting). There are a few "quirks" with the Meade 4500 (listed above), but then again, most any scope has some. Overall I like the Meade 4500 and would recommend it as a nice "first" telescope.
NOTE: Although I have never personally owned one, Orion offers a 4.5" F8 reflector (called "SkyView 4.5" Equatorial Reflector") which is quite similar (but not identical) to the Meade 4500, and retails for the same price. The Orion telescope does not have a seamed optical tube (better in my opinion), and it comes with two decent eyepieces. It also has (in my opinion) right ascension and declination locks which are of a better design than those on the Meade unit. The mounting and tripod appear to be otherwise almost identical to the Meade (they are probably made at the same factory). I have seen the Orion 4.5" reflector at a star party, and it looks to be a strong competitor with the Meade 4500. If you're considering the Meade scope, compare it with the Orion unit. I suspect the Orion unit would be a nice performer also.
LATE UPDATE: (added 6 October 1998) A reader of AAN wrote in to inform me that the Meade catalog now states that a barlow lens must be used with the telescope for prime focus photography (Meade must have become aware that the unit would not come to focus in prime focus mode without a barlow). Use of a barlow will certainly work, but there are some things to be aware of. The Meade 4500 scope without a barlow is basically a 900mm F8 system. Assuming a 2x barlow is used, it will become an 1800mm F16 system as far as prime focus photography is concerned. What does this mean? (1) the image on the film will be larger by a factor of 4 in area and (2) the image will require an exposure four times longer than without the barlow. In short, it represents a more challenging shot. With the larger image scale, the scope will be more susceptible to vibration, and this will be compounded by the need to take longer time exposures. Nevertheless, a beginner should have little trouble taking decent photos of the full moon using this setup (you will be limited to fast films in the ISO 1000 speed range however). Quarter phase lunar photography will be trickier due to the longer exposures required. Note that the 1800mm effective focal length of the system will very nicely frame the Moon on a 35mm film format; on 4x6 prints, the moon will be slightly more than 3" diameter.
The Celestron 500mm F5.6 Maksutov Telephoto/Spotter is a physically well made unit. There appears to be little if any plastic on this unit. The only complaint I had is that the block of material that provides the 1/4-20 tripod mounting threads was not securely fastened to the tube. It is held in place by two screws, which I attempted to tighten. Not satisfied with the security of this plate, I ended up using epoxy (and the two screws) to secure the plate once and for all.
Optically, the Celestron Mak 500 lens is not too good for astrophotography work. I was disappointed in the first shots I took with this lens (mostly of Milky Way and deep sky objects). The star images in the center of the field are very good (photographically), but the quality rapidly deteriorates away from the center of the photograph. Star images appear as "streaks" aimed away from the center of the photo (similar to the "jump to light speed" effect on the movie Star Wars). I purchased a used 500mm Vivitar telephoto lens (1971 vintage) a short time after the Celestron unit. The Vivitar lens is F6.3, but I believe it is actually equal or faster in speed than the F5.6 Celestron unit. The Celestron unit is 90mm diameter, but it has a large central obstruction due to the secondary "spot". The Vivitar unit has an 80mm clear aperture (no obstruction). The star images on photographs taken with the Vivitar lens are outstanding, far superior to those produced by the Celestron unit. In short, I do not recommend the Celestron Maksutov 500mm unit for astrophotography.
I have used the Celestron unit for conventional photography and found that it produces very good images. For example, I took several close up shots of the top of the Washington Monument and the White House; the results were very good to excellent. The Celestron Mak 500mm lens has a fixed F stop of 5.6, so if you plan to use this lens be certain your camera has a wide range of settings above about 1/250 second (if you plan to handhold the unit).
I have used the Celestron Mak 500 unit as a "telescope". It accepts a star diagonal easily. I used the scope for very casual looking around the sky. The performance is about what could be expected for a small, fast scope. It's not easy to get a high enough magnification for planet viewing, but the scope performs fairly well on bright deep sky objects. Overall, though, I would not recommend the unit for astronomical observing (there are a number of units better suited to casual astronomical observing).
I have various filters, a list follows:
Both Orion filters are the type that thread on to the back of a Schmidt Cassegrain scope. The Lumicon filter is the type that threads into a 1 1/4 inch eyepiece. My comments on each filter appear below:
The Orion DeepMap 600 is basically a fold out star atlas, or as they call it, a 'roadmap" for Amateur Astronomers. Even though I have a number of star atlases and books, I decided to purchase the DeepMap 600 since I travel often and it looked like a nice thing to have along on such trips. And, even if it wasn't good, it's only $13.95, so it there is no great risk. As it turns out, the DeepMap 600 is very nice and is worth the $16 (after shipping) cost.
The Orion DeepMap 600 is a "one sheet" star atlas, printed on a fairly heavy plastic stock. Orion claims that the plastic is very durable, and I agree (I could probably have ripped it had I really tried, but in normal use ripping accidentally is not likely). The DeepMap 600 comes supplied in a plastic "ziplock" pouch, and is folded into 14 rectangles. Upon unfolding the map, one must be careful not to "kink" the plastic, or stress can result at the folds resulting in damage to the ink. One side of the map is dominated by a large star chart which covers the sky from +70 degrees declination to -60 degrees declination. The 0 hour right ascension "ticks" are on opposite edges of the map. The right ascension scale has been slightly compressed (Orion mentions this) in order to keep the dimensions of the map more reasonable. I found the compression noticeable but not a problem. Grid lines are shown at 1 hour (RA) and 10 degree (DEC) increments. The Ecliptic is also shown. The sky is depicted with a dark blue background, stars are white (as are constellation lines). The Milky Way is shown in a lighter shade of blue. The deep sky objects are depicted in the "traditional" colors and symbols for the most part. The open clusters are depicted with a symbol that looks like a small "sun". The map covers stars to magnitude 5, and there are a considerable number of deep sky objects plotted. The scale is manageable, but the "galaxy region" is rather busy (there is no "enlarged resolution" section for this region). The other side of the DeepMap 600 has a north polar star chart of about 1 foot diameter. It also has a large list of deep sky objects, plus lists of double and variable stars. The list of deep sky objects contains information for 510 objects. Info includes NGC or Messier number, object type, coordinates, constellation in which the object lies, size, magnitude, and a brief description of the object. Messier objects are listed in bold font; in addition, objects which have a "common name" (such as the Helix Nebula or Sombrero Galaxy for example) are also listed in bold font. There is also a list which contains 79 double/multiple stars and the basic data for them, including name, coordinates, separation, magnitudes and description (position angle is not included). A list of variable stars is also included, containing info on 21 stars (info includes name, type, coordinates, period, magnitude range and description). In addition to the lists, there are "boxes" containing info on various topics. A box titled "Celestial Objects" contains descriptions of the various types of deep sky objects (including double and variable stars). Another box contains the Greek alphabet and constellation names and abbreviations. There is also a box called "How to use DeepMap 600". Finally, on the "atlas" side of the map, there is a box containing observing tips. I have noticed that DeepMap 600 "plots" more objects than it has listed in the tables (galaxies were the "extra" objects I found on the map).
Although the DeepMap 600 is printed on heavy plastic stock, Orion cautions against folding up and storing the map in a wet condition (a condition that is probably "the norm" for many observers). Orion recommends that the map be allowed to dry completely prior to folding up. I have not tested the behavior of the DeepMap 600 in extreme cold; some plastics become brittle in cold temperatures (I'll report on this aspect of the DeepMap 600 after I have some "field use" in the cold with it). The only other thing I can see being a problem... the DeepMap 600 is very likely to blow away in the wind if something is not used to hold it down. And, like conventional roadmaps, I suspect that fatigue at the folding joints (especially where corners meet) will result in the ultimate demise of the map (although I expect it would last quite a while if folding and unfolding is done carefully).
The DeepMap 600 is not a "replacement" for an atlas like Tirion's Sky Atlas 2000. However it does fill requirements for basic observing sessions, and is very handy for those who travel often (like myself) or for those "unexpected" observing sessions (like when you are driving late at night in a dark sky area and it happens to be very clear and dark). I plan to keep DeepMap 600 in my vehicle (where I often carry binoculars also). I remember driving home from work late one night on a dark stretch of highway and the sky was very clear and beautiful... I had binoculars and stopped to look around. Had I had DeepMap 600 then, I'd have been able to search out and locate deep southern clusters I can't see from my house (because of an obstructed horizon). DeepMap 600 fits this need perfectly.
In summary, Orion's DeepMap 600 is a very handy "extra" to have, especially if you travel and like to keep baggage to a minimum. DeepMap 600 plots a substantial number of the best objects in the sky, and contains data for the great majority of them. Many "pocket guides" exist which contain the same basic info, but DeepMap 600 is nice because all of the data is contained on the two sides of the map. It is a comprehensive "atlas" that both beginners and advanced astronomers could find useful. I would not hesitate to recommend DeepMap 600, and for whatever reason if you end up not using it, it's a small amount of money to have spent.
Orion has a website at www.telescope.com.
Use your browser's "back" button, or use links below if you arrived here via some other path:
This page is part of the site Amateur Astronomer's Notebook.
E-mail to Joe
Roberts
Images and HTML text © Copyright 1997, 1998, 2000 by Joe Roberts. Please request permission to use photos for purposes other than "personal use".
![8 day old Moon taken through a Meade 4.5 inch reflector with "camera up to eyepiece and snap" (afocal) method. Kodak Royal Gold 400 film, 10 October 1997. [18k]](images/moonmead.jpg){kind=link}