William Optics

William Optics ZenithStar 73 APO Doublet

No longer sold

A 73mm f/5.9 ED doublet that hits the popular grab-and-shoot wide-field imaging class, pairing William Optics build quality with a friendly price and a light, portable tube.

86/ 100

Polaris Score

#2 of 8 compact imaging refractor

See the breakdown ↓

Aperture

73mm

Focal Length

430mm

Focal Ratio

f/5.9

Mount Type

None (OTA only)

Optical Design

ED Doublet Refractor

Weight

3 kg

Try in simulator →

No longer sold

Discontinued by the manufacturer (per Agena Astro). We keep the page for reference — see current alternatives below.

See alternatives ↓

What it's built forOpen these in the simulator →

This telescope was built for sweeping wide.

A short, fast refractor with a generous true field — the whole sword of Orion in one view, star fields that spill past the field stop. It rewards low power and dark skies far more than chasing magnification.

Widest true fieldsTack-sharp to the edge

The view people remember

The Orion Nebula, wings unfolded.

The four stars of the Trapezium sit inside folded sheets of glowing gas — the closest stellar nursery to us, bright enough to show real structure even from the suburbs.

See Orion Nebula through this telescope →

Where else it shines

Easy first target

The Pleiades

Many cluster members resolved with color contrast between bright stars

Open view →

Needs patience

Ring Nebula

Faint stellar-looking blob — confirm with averted vision

Open view →

Rewards a dark sky

Andromeda Galaxy

Faint elongated smudge — averted vision helps

Open view →

Also excellent on

Saturn

Small bright disk — featureless point at low magnification

Open view →

✦

Tight planetary detail belongs to a longer scope. This one trades reach for a breathtaking field.

01What it's good at

What it's best at — and the trade-offs.

Best at

✓The FPL-53 ED doublet controls color well for its price, keeping stars clean across the field with a flattener

✓430mm at f/5.9 frames large nebulae and the Milky Way, an ideal wide-field imaging focal length

✓At about 3kg it rides on small trackers and mounts, keeping the whole rig portable

✓William Optics fit and finish make it feel more premium than its price

Trade-offs

!A matched flattener is a separate purchase for the flattest stars when imaging

!As a doublet it shows slightly more residual color than a triplet

!73mm and 430mm keep small targets small in the frame

!It is an OTA only and needs a mount, diagonal or camera to work

02In plain English

What These Numbers Mean

Aperture

73 mm

Just under three inches, gathering about 43 percent more light than a 61 mm. That is a meaningful reduction in the integration time needed for the same image quality.

Focal length

430 mm

Wide field with slightly more scale than the smaller ZenithStars. Large nebulae fit an APS-C frame while the brighter galaxies keep enough size to be worth processing.

Focal ratio

f/5.9

Fast enough for practical exposure times and short enough that guiding demands stay light. A forgiving combination for anyone still learning the imaging workflow.

Optical design

ED doublet apochromat

Two elements with ED glass control colour well at this speed, keeping stars tight without the weight or cost of a triplet. Add the matching flattener for clean corners.

Weight

3 kg tube

About 6.6 lb, which a small equatorial or a well-loaded star tracker handles. It stays a one-case travel telescope.

Mount

OTA only

No mount included. A tracker or entry-level equatorial with basic guiding suits it, keeping the total cost of a complete setup low.

02The Polaris Score

How it scores, and why.

86/ 100

William Optics ZenithStar 73 APO Doublet

#2 of 8 compact imaging refractor

Performance

Ease of use

Portability

Upgrade potential

Polaris weighs optical capability, how easy the scope is to live with, how portable it is, and how far it takes you before you outgrow it — not list price or brand.

03Who it's for