Sky-Watcher 254N EQ5 PRO: The Cure for Aperture Fever!
When you move up to a 254mm (10”) aperture, it can be like rediscovering your favorite astronomical objects all over again. They appear bigger, brighter, and better. In addition, there are all those new favorites waiting to be discovered now that you have the aperture.
The Sky-Watcher 254mm Newtonian reflector offers tremendous light gathering capability combined with portability. The SW 254N is capable of discerning remarkably fine detail in solar-system and deep-space objects. Its large 254mm aperture will allow you to capture faint galaxies, nebulae, and star clusters they way you want to see them. The 10” SW 254N will hit the sweet spot for many amateur astronomers searching for large aperture, modest cost, and GO TO capability.
Viewing with Sky-Watcher 254N EQ5P
The additional detail to be seen with the 254mm aperture SW 254N is truly impressive. Its larger light gathering capability pays big dividends in brightness and increased resolution, especially with respect to faint magnitude objects beyond the visual limit of an 8” (203mm) telescope. For instance, the 254mm (10”) aperture is within the threshold for observing coveted astronomical gems like the elusive planetary nebula the Crab (M1), a supernova remnant with several subtle, gaseous filamentary structures. M97, an interesting planetary nebula in Ursa Major is definitely more available to a 10” than an 8”. In Orion, M43, a small emission nebula located near its famous neighbor M42 can be see best in a 10”. The 254mm aperture will keep observers in the hunt discovering faint comets at magnitudes near the instrument’s visual limitations – magnitudes where smaller telescopes are simply blind.
Objects seen well in an 8” telescope will look even better in the SW 254N, such as diffuse emission nebulae in the summer sky like the Lagoon (M8), Trifid (M20), and Swan (M17); the stunning globular star clusters M13 and M92 in Constellation Hercules; the awesome winter sky’s Great Orion Nebula (M42) in Constellation Orion, and the beautiful Rosette Nebula in Constellation Monoceros which takes on the appearance of a blooming, to name a very few, will appear more spectacular, brilliant, and wider in extension in a SW 254mm (10”). The Moon almost takes on a feeling of viewing in 3D. Subtle discontinuities, ripples, and festoons in Jupiter’s bands present themselves in bold relief against surrounding Jovian landscape. Saturn’s inner crepe-ring is clearly discernable. Martian polar-regions and surface mottling is presented with clarity impossible to experience with a smaller aperture telescope. Many an amateur astronomer will find the SW 254N EQ5 PRO delivers all the sophisticated performance ever needed for a lifetime of enjoyable astronomical pursuits.
Understanding Reflecting Optical Systems:
Any instrument that uses a primary mirror to gather light is a form of reflector. Numerous reflector designs exist, but this discussion will be limited to the more popular classic Newtonian, and mirror-lens (catadioptric) designs. While resolving power is a function of aperture alone, there are differences, however subtle, attributable to these designs which merit at least a brief discussion.
The classical Newtonian optical design utilizes a parabolic shaped primary mirror, and an ellipse shaped diagonal mirror suspended by a holder & vane assembly in the front of the optical tube. The diagonal mirror projects the image through a perforation in the optical tube to the observing position at the focuser-assembly. The tube length of a classic reflector is longer than that of an SCT because the SCT folds the focal length back on itself. Unlike the upright terrestrial image orientation provided by refractors and mirror-lens reflectors, the classic Newtonian presents images upside-down. However, this is perfectly acceptable for astronomical use where directional orientation is relative. The powerful advantage of the Newtonian design is lower cost. Compared to a refractor or mirror-lens design of equal aperture, a Newtonian provides higher resolution per dollar invested.
Optical Subtleties and Aberrations:
All well-made reflector designs do a great job of gathering light and providing resolving power. From an observer’s perspective, Newtonians, especially those with fast focal ratios, exhibit subtle, comet-like star images from about 1/3 of the field outward from the center. This is normal. This condition is called “coma”. This condition is minimized in mirror-lens designs and absent in refractors. The vanes suspending the diagonal in Newtonians can produce diffraction spikes on very bright stars. Many Newtonian observers revel in this attribute. In contrast, refractors and mirror-lens designs are devoid of this effect as no vanes or suspension rods are employed.
Much like the function of corrective eyewear, the Maksutov and Schmidt corrector lenses used in mirror-lens Cassegrain designs compensate for spherical aberration inherent in the primary mirror. They serve no light-gathering or detail resolving function. These relatively thin correcting lenses rarely introduce false color, or “chromatic aberration”. Therefore, unlike refractive instruments, it is generally accepted that Newtonian and mirror-lens reflecting telescopes produce no false color.
As you compare and contrast these various attributes, keep in mind, for most amateur astronomers, resolving power trumps subtle differences attributable to design variations discussed above. Portability and cost usually weight in with aperture as the paramount considerations in choosing a primary telescope.
World-Class SW Newtonian Optical Quality:
Sky-Watcher’s primary mirrors are fabricated to the highest standards of optical smoothness and correction, ensuring diffraction-limited premium optical performance that is second to none worldwide.
On each parabolic shaped primary mirror, and elliptical diagonal mirror aluminum is vacuum deposited to the front glass surface and then over coated with hard quartz (SiO4). Additional layers of Titanium Dioxide (TiO2) and (SiO4) are then applied.
Optical focus is achieved by means of a mechanically ultra-smooth, backlash-free, precision 2” Crayford rack & pinion focuser-assembly.
The optical tube material is rolled steel, powder-coated reflective gloss black with gold fleck accent. The tube interior is flat blackened to help prevent internal light reflections from reducing contrast at the focal plane. The front and back cells are cast-aluminum painted black.
Telescope Tube Attachment Hardware:
The optical tube comes with attachment hardware that allows it to be securely fastened to the SW EQ5P mount. These quick-release tube rings are cast-aluminum, painted white.
The SW EQ5PRO Computerized Mount is Standard-Equipment:
To facilitate precise equatorial alignment of the SW EQ5 PRO mount, a polar alignment scope is installed as standard equipment in the R.A. axis. A transparent etched glass screen illustrates the region about the north celestial pole. The screen shows the position of Constellation Cassiopeia, Ursa Major (Big Dipper), and the defining position of Polaris, the North Star. It also shows Constellation Octans whose star Sigma Octantis visually defines the south celestial pole. The Sky-Watcher EQ5 PRO equatorial mount is a premium-grade observing platform utilizing quality mechanical and electronic component materials throughout.
Equatorial Body. The elegantly appointed equatorial body is cast from virgin aluminum and powder coated in classic scientific instrument white. The professional fit and finish of the SW EQ5 PRO mount is abundantly obvious from the very first minute the mount is uncrated. The large polar and declination castings provide large, stable thrust bearing surfaces with tight tolerances. Setting-circles are provided in both RA and Dec. axes. All gears, motors, and electronics are internalized within the equatorial body or separate motor-controller chasse box. The counterweight shaft is made from solid stainless steel. The provided three 11 lb. counterweights are cast iron, powder coated white. (Note: All SW EQ5 PRO Series telescope models come with optical tube mounting rings and/ or dovetail attachment brackets of cast aluminum)
Motors, Gears & Bearings. Sky-Watcher EQ5 PRO computer models utilize high-torque DC stepper motors with 1.8? angle steps yielding resolution of 0.28764 arc-seconds. The advanced Allegro IC driver is a DMOS dual full-bridge micro-stepping PWM motor driver with power savings feature. A 12vDC car plug adapter is provided to connect to a user supplied power supply (Power requirement: 12V DC-power 2000mA mini w/2.1mm tip positive plug). Bronze-metal worm-gear control systems enable precise, incremental mechanical movement with minimal gear backlash in RA and DEC. Gear size in R.A. and DEC. is a robust 72mm (2.83”) with 144 teeth. Sealed ball-bearings are used on load bearing surfaces in RA and DEC. Mount tracks celestial objects in R.A. axis when equatorially aligned.
Mechanical Surface Controls. Thumb locks are provided in RA and Dec. to allow swift manual orientation of the optical tube assembly. Micrometric elevation and azimuth controls are provided to help achieve precise polar alignment. For manually operated SW telescope models, deluxe spring-steel cable control knobs are provided in R.A. and Dec. to enable precise manual tracking of sky objects.
Rock-Solid Tripod, and Payload. Every SW EQ5 PRO mount includes a metal tripod commensurate in rigidity and load bearing capacity to the EQ5 PRO mount itself. Tripod legs are made of industrial strength tubular steel of 1.75” diameter, except for the SW 254N EQ5 PRO and the SW 11” SCT EQ5 PRO which are supplied with 2” diameter legs. The tripod head is rigid cast aluminum. A spreader-bar with tension lock is integral to the tripod to help insure optimum rigidity. The mount and tripod support a hefty payload of up to 25 lb.
Computer Operation. Sky-Watcher GO TO telescope models include the revolutionary SynScan Computer Controller. The SynScan’s remote hand-controller plugs into SW motor-control panel. The easy-to-read, 2-line, 16-character backlit LCD display will operate to approximately minus 10-degrees F?. Astronomical object location has never been easier or more fun. The telescope responds instantly to keypad commands at the touch of a fingertip. Serial PC connector/ Hand-controller phone-jack plug computer interface cable included. Utility and Setup functions are available to perform customized SynScan operations.
Motor Speeds, Tracking Modes, and Alignment Types:
The operating versatility of SynScan provides guiding speeds of .25x, .5x, .75x, and 1x. Slewing speeds include 1.25x, 1.5x, 1.75x, 2x, 8x, 16x, 32x, 64x, 400x, 500x, 600x, 800x, or 3.4? per second. SW tracking modes offer Lunar, Solar and Sidereal rates. Sky alignment choices are One-star, Two-star, and Three-star. Mount is compatible with operations in both the Northern and Southern hemispheres.
Astrophotography:
Sky imagers will appreciate the auto-guider port for guiding using a PC via the RS-232 port (if the software supports ASCOM). SW firm-wear includes a programming algorithm for periodic error correction (such error is common to all worm-gears). In addition, programming is provided for RA and Dec worm-gear backlash compensation to keep slewing and tracking response prompt and uniform. SW can also be controlled remotely by PC using popular planetarium software via a RS232 connection on the hand-controller. There is even a GPS upgrade option to facilitate entering precise time, date, and location. PAC: Pointing Accuracy Enhancement provides extra precise pointing accuracy for photographic applications.
Database: The SynScan computer includes a celestial database of over 30,000 objects, including all the crowd pleasers like planets, the Moon, Messier objects, and interesting double stars. In addition, the library includes objects for advanced studies cataloged within the CNGC, IC, Caldwell, and other lists, plus 25 user-defined celestial favorites.
Advantages of the Sky-Watcher EQ5 PRO Equatorial Telescope Mounting System:
The equatorial mount is the most versatile telescope platform ever designed. Without question it is the most popular and most utilized mounting system favored by amateur astronomers today worldwide. There are several important reasons for its popularity:
Versatility. In the process of becoming serious amateur astronomers, observers at some point often desire to vary their viewing routine. More often than not, this involves changing the optical configuration used for observing between reflective, refractive, or compound systems. It is a well established fact that no one optical design serves every situation perfectly. The SW EQ5 PRO mount, for instance, will hold a large SW 6” refractor offering pristine, textbook-like images of subtle planetary surface phenomena. It will also carry a SW 10” Newtonian reflector with huge light gathering capability for observing faint, gaseous filamentary structure in galaxies and nebulae. The versatile SW EQ5 PRO mount will also house a SW 11” Schmidt-Cassegrain optical tube assembly. In contrast, fork-mounts typically work with one telescope optical configuration only. There is no flexibility for changing optical tubes based on observing needs or preferences.
Portability. Equatorial mounts, like the Sky-Watcher EQ5 PRO, also offer great convenience to observers seeking portable equipment that disassembles into manageable components that can be easily lifted and carried. This is especially helpful with larger aperture optical systems. In contrast, one piece optical tube/ mount configurations can be surprisingly heavy to lift and awkward to transport by one individual.
Stability and Balance. The equatorial mount is renowned for stability, and ease-of-use in achieving mechanical balance of the optical tube and mount. The SW EQ5 PRO is mechanically rigid, and mechanical motions are smooth and inherently vibration-free. An industrial strength tubular steel tripod is standard equipment.
Computer Operation. The SW EQ5 PRO Series offers manual or computerized operation. The revolutionary SW SynScan computer works seamlessly with the SW EQ5 PRO mount to facilitate effortless, automatic tracking and object location of over 30,000-objects.
Astrophotography. The equatorial mount is also the preferred platform for astrophotography. Why? An equatorial alignment facilitates astronomical tracking in just one axis, which is the best physical orientation for imaging the sky. Computerized altazimuth mounts track the sky in two axes, but this introduces undesirable field rotation. Field de-rotators have not proven to be particularly practical. Serious amateurs who own fork-mounted altazimuth telescopes, for instance, buy equatorial wedge adaptor plates to place between the tripod and mount. They then switch the telescope’s tracking mode to equatorial. If you are seriously contemplating astrophotography, an equatorial mount is your best bet for insuring quality results.
