Celestron International

Celestron has been a well respected maker of Schmidt - Cassegrain telescopes for many years. They were the first commercial supplier to make this telescope widely available, and have been building dual fork mounted telescopes in a wide range of sizes ever since.

	In 1971 a 5" f/1.65 Schmidt camera was introduced by Celestron as an astrographic accessory for piggyback mounting on other telescopes. This spurred the subsequent 1972 release of the orange C5. This was an f/10 optical tube mounted on the C8 base, with forks suited to the smaller tube diameter. Because of the excellent stability of the small optical tube on a comparatively large base, as well as the wider field of view provided by this optical system, many preferred this unit over the C8 for deep sky photography. After 1983 this model was dropped from the Celestron line.
Orange C5
	At the end of 1992 the C5 was reintroduced with a single fork mount in the tradition of the Celestron "C90 Astro" and Optical Techniques "Quantum" telescopes. The venerable 5" diameter f/10 optical system was still supplied with an AC spur gear drive. The now white optical tube sported a 1 1/4" star diagonal, eyepiece, a smallish 5x24 finder and a wedge which could be mounted on a tabletop or on a heavy tripod. Then in 1993 the C5+ was announced, which replaced the AC drive with a sophisticated, quartz controlled, DC system driven by a single 9 volt battery. The package included the same accessories as the C5, with the addition of a handbox for guiding in RA and declination with the optional dec motor.
Celestron C5+ (new style)

	In 1970 Celestron began an amateur astronomer's revolution with the introduction of an 8" SCT called the Celestron 8. The optical tube provided a focal length of f/10, which allows plenty of magnification with moderately sized eyepieces. These early units had standard aluminum coatings on the mirror and no coatings on the corrector, unless they are marked "Special Coatings." These included the magnesium-fluoride coatings for lower light dispersion. A 1 1/4" star diagonal, eyepiece and a 6x30 finder were included with the optical tube, which is placed on a fork mount driven by a two motor spur gear system. Manual slow motion controls are provided on both the Right Ascension and declination axes. The lightweight, but stable tripod and wedge were not included in the basic telescope cost. Because of its flexibility and relative portability, the orange C8, as it was later called, started the long love affair between amateur astronomers and the 20cm SCT.
Orange C8
	The year 1984 marked the introduction of the tremendously popular Super Polaris mount. This was an updated version of the Polaris mount previously offered on Celestron's reflectors and larger refractors. This outstanding new mount, imported from Japan, allowed for an optional built-in polar axis finder as the name suggests, as well as optional motor drives, including an electronic dual axis drive. When the 8" SCT optical tube was released on this mount it was given the name SPC-8, maintaining the 1 1/4" star diagonal and 6x30 finder. The early models had large rings to mount the tube to the equatorial head. In later models the optical tube was mounted on a bar that fit a sliding connection on the equatorial head as shown in the picture. Both mounting arrangements allowed movement of the tube for balance with various accessories. A computer was later developed as an option that could guide the user to 450 pre-selected objects once the date, time, latitude and longitude were input.
SPC-8 with RA Drive
Early Model Super C8+	Later Model Super C8+
The first of the upgrades to the basic C8 was the Super C8 offered in 1984. The drive base of this model was changed from the basic round shape of previous models to one with a square front to allow for a worm gear drive. This drive incorporated in this model was a very accurate Byers 359 tooth worm gear system with a single synchronous AC motor. In addition, a very nice 8x50 helical focusing finder was added that could be converted from straight through viewing to right angle viewing. The wedge and tripod were generally included in the price of the basic telescope package with this model. Later the same year the Super C8+ was released. This model include the features of the Super C8, but now was supplied with a new 8x50 finder having a mirror diagonal and a battery illuminated polar reticle. Although the focusing of this finder was not as elegant as that on the Super C8, it still allowed focusing by turning the objective cell. In additon, a 1 1/4" mirror diagonal replaced the previous star diagonal and a second eyepiece was added. Improvements were also made to the wedge for easier polar alignment. Celestron's "Starbight" multi-coatings began to be offered as an option on this telescope.
Note: The conversion from the famous orange tube to the newer black assemblies began during production of the above models. Therefore do not assume that because a model is advertised as having an orange tube, it is not a Super C8. The accessories are what resulted in the change in model name. Note the drive base, the finder, and the markings on the cover plate as shown in the pictures above.
Powerstar Panel	Powerstar PEC Panel
With good polar alignment, the drive on the "Super" series was accurate enough for piggyback photography using photographic lenses with a focal length of up to 100mm without guiding. Nevertheless, you still needed an AC power source or a drive controller to enjoy the good tracking. In 1986 the "Powerstar" series was introduced to deal with this shortcoming. The first model of this series was the Powerstar C8. A 12 volt DC drive was added to the Super C8. The telescope's main motor was accompanied by an internal quartz controller, a dew shade and a dual axis drive corrector hand box. Power could be supplied by 6 AA batteries, an automobile cigarette lighter or by AC current. The handbox offered quite a few features, such as control of optional declination and focus motors, a built-in map light, a North/South hemisphere switch to reverse the RA drive and 2x or 4x guiding speeds. "Starbright" multi-coatings, a wedge with micro adjustments for altitude and azimuth adjustments and a variable height tripod completed the package. Powerstar II was released in 1987 with a deluxe carrying case as standard equipment. The next year, 1988, the model name changed to Powerstar III when a tele-extender and T-adapter were added as part of the standard package. Finally, in 1989 the name was updated again to Powerstar 4 and the tele-extender was replaced with a piggyback camera mount.
Then late in 1990 an entirely new telescope package was released as the Powerstar 8 PEC. This incorporated the impressive 9 volt battery powered electronics of the Ultima line including Periodic Error Correction. For more information on the Celestron PEC feature see the section on the Ultima 8 below. The even more rugged Ultima tripod was now supplied with the system. However, there are always tradeoffs for improvements. The new release did away with many of the nice standard accessories of the previous models. The telescope was now delivered with a standard 6x30 finder, star diagonal, one eyepiece, carrying case and hand control. Declination and focus motors remained as options. The only real feature that distinguishes the above telescopes from the previous models is the drive base cover, and the photos above reveal the differences.
	In 1987 Compustar system took the DC drive system to the next logical step with a totally computerized go-to telescope. Although the Compustar models were made in 8", 11" and 14" sizes, the only one less than $5000 when new was the Compustar 8 (also sometimes referred to as CCC8). Although somewhat cumbersome with its large declination cover and display panel, this unit allowed automatic go-to for over 8,000 objects. The f/10 optical tube with "Starbright" coatings was supplied with an 8x50 polar axis finder, a 2" star diagonal and 50mm 2" Plossl, heavy duty wedge and tripod and carrying case. Starting in 1993 the Compustar was shipped with an 1 1/4" star diagonal and eyepiece with the 2" accessories as options.
Compustar
	In 1989 Celestron resurrected the basic C8 as a low cost introductory model. This model was called the Classic 8 and was reincarnated with a single spur AC gear drive. The tracking of the drive was nevertheless quite good. The base changed from the old round casting to the more familiar square front. The telescope's standard accessories included an equatorial wedge (but no tripod), 1 1/4" star diagonal and eyepiece and 6x30 finder. "Starbright" multicoated optics were optional.
Classic 8
	1989 saw the introduction of the Ultima line. The Ultima 8 telescope is arguably one of the most stable commercially built SCTs for the amateur. Apporpriately it is also one of the heaviest. This line maintained the same basic "Starbright" multi-coated optics of previous models in redesigned castings for the optical tube. This is coupled to a redesigned, heavier fork mount with carrying handles and a large 2 5/8" diameter polar shaft. The initial drive system was unique, but with some deficiencies. The telescope was driven by an AC motor, run by a high efficiency quartz locked inverter. This, in turn, was powered by internal, rechargeable, lead acid batteries. Although this resulted in a fairly long lasting power supply and did not involve replacing batteries, some of the advantages of the DC drive used on the Powerstars were lost. Standard accessories included a heavy duty wedge and tripod, 1 1/4" star diagonal and eyepiece and an 8x50 polar finder. A heavy duty, high impact molded plastic carrying case provided good protection for the telescope. The very next year, the rechargable battery was replaced with a 9 volt alkaline battery and the drive was replaced by true DC motors and a microprocessor. The processor allowed four digitally controlled drive rates, including solar, lunar, siderial and King. It also allowed use in both hemispheres just by flipping a switch as well as the addition of Periodic Error Correction (PEC). This electronic wizardry was a great benefit to astrophotographers, allowing them to track almost any object and to "train" the drive to automatically counteract the errors that are inherent in any gear system. While even the basic system without PEC was extremely accurate, enough to allow unguided piggyback photography with as much as a 500mm lens, using the new feature further reduced guiding effort for photography. A minor irritation to some was that the PEC training was lost each time you turned off the telescope. There was, of course, a tradeoff between losing precious dark time and assuring that each PEC training session addressed the situations peculiar to that setup. The hand control box, optional on the initial units, was now made standard.
Ultima 8
	In 1994 the basic 8" SCT from Celestron was revamped and reintroduced as the C8+. This model used the same optical tube as the new Ultima line, but mounted it on lighter, more simply designed forks. These, in turn were driven by a new 9 volt DC spur gear system. A drive corrector and handbox were supplied as standard accessories along with a 6x30 finder, 1 1/4" diagonal and eyepiece and wedge. The tripod was optional. This was a good basic instrument with quality optics. It looks can be differentiated from the Classic C8 only by the front panel which is the same as on the C5+. It was also available with the Advanced Astro Master computer as a factory installed component. This computer, with the accompanying encoders gave the telescope digital setting circles. The computer, like others was preprogrammed with over 10,000 sky objects. After setting up the computer by synchronizing it with two known stars, the user can select an object from the database and manually move the telescope until the computer indicated the object was in view. This provides an effective and less expensive way to have the telescope "find" objects for you.
C8+ Front Panel
In 1993 Celestron's popular SPC telescopes received an updated equatorial mount from Japan. Functionally this was the same telescope as the SP-C8 but it was now called the GP-C8. It came the Starbright coated optical tube on the polaris equatorial mount, a 6x30 finder, 1 1/4" diagonal and eyepiece.
	In 1995 Celestron released a long-expected replacement of its popular computerized telescope. The chief problems with the Compustar were its bulk and weight, in addition to being expensive. Celestron addressed all these issues admirably with new Ultima 2000, and made the best of new computer tracking technologies as well. Like the competing LX200, the Ultima 2000 shipped without a wedge as part of the standard package. Its computer electronics track objects in the sky after alignment of the telescope on two stars. Due to its built-in high resolution encoders, once the initial alignment is made, the telescope can be turned under power or manually while still maintaining its position memory. The electronics include Periodic Error Correction as implemented in the previous Ultima models. Two motors are used to drive the telescope in each axis, one for slow speeds, and another for high speeds. As a result, the telescope can track normally and be guided at 2x or 6x, or can be moved across the sky at speeds up to 10 degrees per second, and it accomplishes this quietly. The telescope can be powered by a set of 8 AA batteries mounted in the base, or by an external 12 volt power source. Internal wiring paths for the encoders, etc, mean that the control panel on the base seems quite sparse, but it provides inputs for all the necessary options for a fully operational system. Plugs are provided for external power, electronic focusing, the hand control and an "AUX" port for connecting a computer, an auto-guider or other items. The weight of the optical tube and fork is only 31 pounds. Add another 18 pounds for the sturdy tripod and you have a featherweight compared to the old Compustar. A small handbox replaces the old control panel. With a few buttons and a two line display, it gives access to all of the aligning, setup, identification, positioning and touring features.
Ultima 2000
	In 1996 the 9 volt DC spur gear driven C8+ was placed on a new tripod and the name was changed to Celestar 8. The new tripod combined the former wedge and tripod into a "wedgepod" where removable legs attached directly to fixed sockets on the bottom of the wedge. This result was a usable, but fixed height design, less weight and lower production costs. The Celestar 8, like the C8+ was available with or without a factory installed computer as an option. The hand control was now only included as an option, as with the declination motor.
Celestar 8
	In 1997 Celestron brought the Celestar name to an astrophotography standard with the Celestar Deluxe. Contrary to what might be implied by the name, this is really an entirely different telescope than the basic Celestar. It is of the same class as the old Powerstar PEC series. The Celestar optical tube has been placed on heavier forks, which are carried by an Ultima-like drive base with an accurate worm gear drive. It includes the 9 volt DC drive and PEC electronics of the Ultima series. A declination motor was added as standard, along with car and AC adapters and the hand control. The finder was increased to a more useful 9x50 and the wedge and heavy duty tripod were restored. The improved stability and the hand control with full correction capability allowed long exposure astrophotography. This model was available with and without the factory installed computer as an option.
Celestar 8 Deluxe

	In 1996 Celestron produced a completely new optical tube with the introduction of the Ultima 9 1/4. This retained the weight and stability of the Ultima 8, but gave 34% more light collection. The f/10 optical tube also introduced a unique micrometer focuser with a digital readout. This allowed repeatable focusing for those doing CCD work or astrophotography. This optical tube is rumored to have particularly high quality control, and although it falls short of the light grasp of a 10" system, the views are said to be consistently superior to the run of the mill SCTs. To support the significantly greater weight of this tube, a larger, heavy duty wedge was provided. The package was completed with a 6x30 finder, 1 1/4" diagonal and eyepiece.
Ultima 9 1/4
At the same time this new OTA was made available on a GEM as the CG 9 1/4. This coupled an outstanding set of optics with a fine Losmandy head similar to the G8. This is a ball bearing equatorial head with highly accurate dual axis 2 3/4" stainless worm gears. The drive is a 12 volt DC dual-axis system that is switchable for North and South hemispheres. Four tracking rates and three guiding or slewing rates as well as Periodic Error Correction are provided, with control through a handbox. The optical tube is mounted on the head with a well machined dovetail bar which allows balancing of the tube and accessories over the declination axis, and the whole is mounted on an unfortunately light aluminum tripod. A polar alignment scope is optional.
In 1980 The C11 was added to Celestron's line to provide a replacement mid-size model, since production of the C10 had ceased some years before. This was also in an f/10 optical system that included a 1 1/4" star diagonal, eyepiece and counterweight bar. It included the 8x50 right angle polar axis finder, wedge and tripod. This model was generally available through 1984 in the orange color, and was converted with the rest of the line to the present black tube after that.
In the latter part of 1989, a few months after the Ultima 8 was announced, the Ultima 11 was released. The well respected optical tube with "Starbright" multi-coatings was coupled the to the same base, wedge and tripod as the 8" model. Although the combination was not as sturdy as the smaller unit, it was certainly adequate by all previous standards. This new model included as standard such amenities as vibration suppression pads for the tripod legs, a 2" mirror star diagonal with 1 1/4" adapter, two eyepieces and a counterbalance bar. Of course the 8x50 polar finder and a high impact case were also included.
	In 1992 Celestron partnered with Losmandy to bring out an exciting new telescope. The CG-11 paired the C11 optical tube with "Starbright" multi-coatings, 1 1/4" star diagonal and eyepiece and 8x50 polar finder with a high quality German Equitorial Mount similar to the Losmandy G11. The new mount was called a "semi-pier" mount. It consisted of a 6" diameter pier welded to 3" diameter leg struts. The one piece legs attach to the top by means of solid clamps and this results in an extremely stable base. On top of this is a ball bearing equatorial head with highly accurate dual axis 5 1/2" stainless worm gears. The 12 volt DC dual-axis drive that is reversible for North and South hemispheres. The control panel contains four tracking rates and three each of guiding and slewing rates as well as Periodic Error Correction, adjusted by an attached handbox. A plug was also provided for a CCD for automatic guiding. The polar alignment scope on the mount contained both north and south hemisphere star patterns for accurate alignment. The optical tube is mounted on the head with a well machined dovetail bar which allows balancing of the tube and accessories over the declination axis. The package was made complete with carrying cases for both the optical tube and the equatorial head. In my mind this was Celestron's finest astrophotography system for the amateur.
CG-11
	Production of the C14 has continued through most of Celestron's history in various forms as its flagship model. The C14 of the 1970s is an f/11 optical system on a heavy dual motor fork mount similar to the smaller C8 and C11 units described above. However its visual back uses 2" accessories as standard rather than 1 1/4". Standard accessories included an 8x50 finder, two counterweight bars, 2" diagonal, and 1 1/4" eyepieces. The C14 has gone through similar adjustments in color and improvements in coatings as the rest of the line, but otherwise has remained the same throughout its life.
C-14
CG-14 has been the latest and the best of the larger instruments. In this model the C14 optical tube is mounted on the same mount described for the CG-11 above. The telescope is still supplied with a 7x50 finder, two counterweight bars, 2" diagonal and 1 1/4" eyepiece. Additional counterweights to balance the large tube result in a total weight of 135 pounds.