Varrow Cinder 90 refractor, tube with alt-az mount

Specifications

Description

The Cinder 90 is an achromatic doublet refractor with 90 mm of clear aperture and 630 mm of focal length, giving a focal ratio of f/7. Its objective uses two elements of crown and flint glass that bring red and blue light to a common focus. Some residual color remains, so bright planets and the Moon can show a faint violet halo along high-contrast edges, a trait typical of achromats at this focal ratio. At f/7 the instrument gives a moderately wide field at low power and still reaches useful magnification on the Moon and the planets.

The lens is multi-coated on all air surfaces and sits in a tube with internal baffles, which keeps stray light down when a bright planet sits near the edge of the field. The 1.25 in rack-and-pinion focuser holds a standard diagonal and eyepiece steadily, and the fine-focus knob makes small adjustments easier to judge when you are looking at planetary detail. A dew shield on the front of the tube helps slow dew on the objective on humid nights.

At 2.4 kg for the tube, the Cinder 90 suits a light alt-az mount or a small equatorial mount and fits in a compact case for transport. A small refractor reaches outdoor temperature faster than a reflector of similar aperture, so you can start observing soon after carrying it outside. Typical targets include double stars such as Albireo and Epsilon Lyrae, the phases of Venus, the brighter lunar craters near the terminator, and open clusters such as the Double Cluster in Perseus, which fits within one field at low power. Under dark skies you can also see the brighter galaxies and globular clusters, though their structure is subtle at this aperture.

About this configuration

This listing covers one specific configuration of the Varrow Cinder 90 refractor, defined by its bundle, finish, accessory kit, and edition year. An alt-az mount keeps setup short: level the tripod, attach the tube, align the finder, and start finding targets. Manual alt-az motion suits visual observing, though you need to nudge the tube now and then to follow objects as the sky turns. A matte white finish reduces glare from nearby lights while keeping the tube easy to see at night.

No accessory kit is included, which suits observers who already own eyepieces and want to reuse them. The 2026 edition carries the optics over unchanged and updates small parts such as dust caps and thumbscrews. Check the specifications table for the optical figures, since they stay the same across every configuration of the Cinder line.

What's in the box

• Optical tube with dew shield
• Tube rings with dovetail bar
• 1.25 in star diagonal
• 6x30 finder scope with bracket
• Front and rear dust caps
• Alt-az mount with aluminum tripod

Compatibility notes

• Accepts 1.25 in eyepieces and filters directly in the focuser.
• The dovetail bar fits most small and medium alt-az and equatorial mounts.
• A 1.25 in camera adapter can be fitted to the focuser after the diagonal is removed.