William Optics

William Optics RedCat 71 APO

No longer sold

The bigger sibling to the cult-favorite RedCat 51: a 71mm f/4.9 Petzval astrograph that delivers a flat, fast, full-frame field in a jewel-like package built for grab-and-shoot wide-field imaging.

88/ 100

Polaris Score

#1 of 7 wide-field imaging refractor

See the breakdown ↓

Aperture

71mm

Focal Length

348mm

Focal Ratio

f/4.9

Mount Type

None (OTA only)

Optical Design

Petzval Astrograph

Weight

2.5 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 the camera.

A fast f/4.9 astrograph designed to throw a wide, flat, well-corrected field onto a sensor. It is an optical tube first — give it a tracking mount and a camera and it rewards long exposures, not eyepieces.

f/4.9 — built to imageNeeds a tracking mount

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

Rewards a dark sky

Andromeda Galaxy

Long-exposure capture revealing galaxy core and outer structure

Open view →

Needs patience

Ring Nebula

Planetary nebula captured with characteristic ring or shell visible

Open view →

Easy first target

The Pleiades

Field rich with stars — long exposure pulls in fainter members

Open view →

Also excellent on

Saturn

Processed planetary capture with rings or bands clearly visible

Open view →

✦

There is no eyepiece experience here. Its reward shows up on a sensor, after the exposure — not in the moment.

01What it's good at

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

Best at

✓The four-element Petzval design bakes the flattener into the tube, so stars stay round to the corners of a full-frame sensor with nothing to add

✓348mm at f/4.9 frames large nebulae and the Milky Way beautifully while collecting light fast for short, clean exposures

✓A weight of about 2.5kg lets it ride comfortably on lightweight star trackers, so the whole rig stays truly portable

✓William Optics build quality is exceptional: a rotator, Bahtinov mask cover and locking helical focuser come as part of the package

Trade-offs

!It is a dedicated astrograph, so visual use is possible but beside the point

!348mm is short, so small targets stay small in the frame

!As an OTA it needs a tracking mount, camera and often a guide scope to produce results

!The premium build commands a premium price for the aperture

02In plain English

What These Numbers Mean

Aperture

71 mm

Just under three inches, gathering about 94 percent more light than the RedCat 51. That halves the integration time for the same result while keeping the same wide-field character.

Focal length

348 mm

Wide but with more scale than the RedCat 51. Large nebulae still fit an APS-C frame while smaller targets such as the Rosette or the Heart hold usable detail.

Focal ratio

f/4.9

Fast, so exposures stay short and total integration times stay reasonable even under suburban skies with a dual-band filter. Guiding demands remain light at this focal length.

Optical design

Petzval astrograph

The field flattening is built into the optical design, so full-frame corners stay clean with nothing added to the imaging train. No spacing to calculate is one less source of elongated corner stars.

Weight

2.5 kg tube

About 5.5 lb, still within star tracker limits with a light camera and easy for any small equatorial. It remains a travel-first telescope.

Mount

OTA only

No mount included. At 348 mm a tracker or entry equatorial with basic guiding is enough to get round stars, which keeps the entry cost modest.

02The Polaris Score

How it scores, and why.

88/ 100

William Optics RedCat 71 APO

#1 of 7 wide-field 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