Sky-Watcher Virtuoso GTi 150 Tabletop GoTo Dobsonian

Tabletop GoTo Dobsonian

It is a compact and easy-to-use table top telescope, ideal for all kinds of observations. The total assembled weight is 19.15 lb.

150mm f/5 Paraboloidal Optics

The 150mm paraboloidal primary mirror has a 750mm focal length, giving f/5, with a 47mm secondary mirror. The telescope shows details in Saturn's rings, Jupiter's bands, the Martian polar ice caps and the phases of Venus and the Moon, and its faintest stellar magnitude is 13.3.

Telescopes need at least 10 to 30 minutes to cool to outside air temperature, longer with a big temperature difference.

SynScan GoTo Over Wi-Fi and Freedom Find

Install the free SynScan or SynScan Pro app on a phone, tablet or laptop, switch the mount on and connect to its "SynScan_xxxx" Wi-Fi network (no password by default) within 15 minutes, after which the Wi-Fi turns off to save power. The SynScan app suits entry-level users and SynScan Pro experienced users. A SynScan hand controller can also be plugged into the hand control port.

Auxiliary encoders on both axes let the mount keep track of its position when you unlock the clutches and move it by hand, so you can point it manually at any time without losing alignment; re-lock the clutches to resume GoTo and tracking.

• Clutches: half engage them to point the telescope by hand while stopping it from moving freely, or fully loosen them to move it quickly.
• Pointing accuracy: Freedom Find can be disabled with the SynScan app or hand controller; do so for the best pointing accuracy if you will not move the mount by hand after alignment.

Collapsible Tube: 27" to 16"

The tube extends to 27" and retracts to 16". The tube weighs 8.25 lb, the assembled base 10.9 lb and the total 19.15 lb.

Eyepieces: 25mm SUPER (30x) and 10mm SUPER (75x), 1.25-inch, from the 750mm focal length.

• Focuser: 1.25" single-speed helical (Sky-Watcher USA). Remove the black plastic end-cap before inserting an eyepiece, and refocus after changing eyepieces.
• Red dot finder: a zero-magnification pointing tool powered by a 3-volt lithium battery. Remove the insulation sheet, turn it on with the brightness control, center a distant object in the 25mm eyepiece, and with both eyes open use the adjustment knobs until the red dot overlaps it.

Mounting and Balancing the Tube

Set the base on a sturdy, level surface. Loosen the altitude clutch wheel, rotate the saddle until the dovetail groove is horizontal and tighten the clutch.

Loosen the dovetail locking knob until nothing obstructs the groove, slide the tube's dovetail bar in and tighten the knob, holding the tube until it is firmly attached. Then, holding the tube, fully loosen the altitude clutch to check the balance, and slide the bar back or forth until the tube balances in altitude.

Power

The mount runs on:

• Batteries: 8 AA batteries in its battery compartment.
• External power: DC 7.5 V to 14 V, at least 750 mA, through a center-positive barrel plug (2.0 mm I.D., 5.5 mm O.D.). Do not use an unregulated AC-to-DC adapter; use a 12V switching supply of at least 750mA. If the voltage is too high, the motor controller stops the motors.

Observing Tips

Choose a site away from city lights, upwind from air pollution and as high as possible; the darkest sky is usually at the zenith. Do not observe immediately after sunset while the Earth is still cooling.

Expose your eyes to nothing but red light for 30 minutes before observing, keep both eyes open, and use averted vision on faint objects.

Collimation and Care

Newtonians need occasional collimation. Center a star and move the focuser so it is slightly out of focus: in good seeing, rings symmetrical about the Airy disc mean the optics are aligned. The manual uses a collimation cap, a plastic cap with a small central hole that fits the focuser in place of an eyepiece.

The manual's two stages:

• Secondary: point the telescope at a lit wall and adjust the three small screws around the central bolt until all three primary mirror clips are visible through the collimation cap.
• Primary: use the three adjusting screws at the back until the secondary's reflection is centered, then tighten the three locking screws. A friend can turn the screws while you watch.

Replace the dust cap whenever the telescope is not in use. Do not clean the mirror unless you are familiar with optical surfaces; clean the finder and eyepieces with special lens paper only.

Solar Safety

Never look at the Sun through the telescope or the finder without a proper solar filter.