Tessaro Ironwood 180 f/5 Newtonian reflector, tube with equatorial mount

Specifications

Description

The Ironwood 180 is a Newtonian reflector with a 180 mm parabolic primary mirror and a focal length of 900 mm, giving a stated focal ratio of f/5. That ratio keeps the tube compact while still delivering a wide field at low power. At 180 mm, the telescope gathers about twice the light of a 127 mm instrument, which makes faint galaxies and nebulae easier to see from suburban skies. The primary is figured to a smooth parabola, so star images stay sharp toward the center of the field at moderate powers.

The primary mirror carries an aluminum coating overcoated with silicon dioxide to resist tarnish. The secondary is held by a four-vane spider, and the tube has a cooling port at the rear cell that lets the mirror reach outdoor temperature sooner after you carry it out. Because a reflector's optics are open to the air at the front of the tube, you may need to collimate the mirrors before some sessions. The supplied collimation cap and laser collimator make that adjustment quicker, and a few minutes of checking each time the telescope is moved keeps star images round.

The 2 in dual-speed rack-and-pinion focuser accepts a star diagonal and heavier eyepieces, with a 10:1 fine-focus reduction for planetary work. An 8x50 right-angle finderscope mounts on the tube. At about 11.5 kg for the tube, the Ironwood 180 needs a mount rated for that payload, and a Dobsonian base or a sturdy equatorial mount with a higher payload capacity is the usual choice.

Typical targets include the Orion Nebula, the Whirlpool Galaxy in Canes Venatici, and the globular cluster M13 in Hercules, which begins to resolve into individual stars at this aperture. Under dark skies, you can see the cloud bands and the shadow of the rings on Saturn, and the Cassini Division appears when the seeing is steady. Lunar craters near the terminator show fine relief at medium power.

About this configuration

The Tessaro Ironwood 180 f/5 Newtonian reflector is offered in several configurations, and the notes below describe what this particular combination adds or changes. The equatorial mount follows the sky along one axis once you align its polar axis with the celestial pole. With the equatorial mount, slow-motion controls let you keep a planet centered at high magnification with one hand. Carbon fiber saves some weight compared with a metal tube, which eases the load on the mount and on your arms.

The astrophotography kit adds a T-ring adapter for a camera body and a Bahtinov mask for precise focusing on a star. The 2023 edition uses the same optical design as later years, with small differences in fittings and labels. The optical figures in the specifications table apply to this configuration and to every other version of the Tessaro Ironwood 180 f/5 Newtonian reflector.

What's in the box

• Optical tube with primary mirror cell
• Four-vane secondary spider with secondary mirror
• 2 in dual-speed rack-and-pinion focuser
• 8x50 right-angle finderscope with bracket
• Collimation cap and laser collimator
• Dust covers for tube ends and focuser
• Equatorial mount with steel tripod
• Counterweight and counterweight shaft
• T-ring and T-adapter
• Bahtinov focusing mask

Compatibility notes

• Accepts 2 in eyepieces directly and 1.25 in eyepieces through a standard 1.25 in adapter sold separately.
• Tube rings are sold separately and accept a Vixen-style dovetail bar.
• Pair with a Dobsonian base or an equatorial mount rated for at least 11.5 kg of payload.