Sky-Watcher

Sky-Watcher Esprit 100EDX

A three-element ED apo built for the camera: flat, color-free, pinpoint stars across a full frame, a serious astrophotography refractor, not a grab-and-go.

93/ 100

Polaris Score

#1 of 4 astrophotography refractors

See the breakdown ↓

Aperture

100mm

Focal Length

550mm

Focal Ratio

f/5.5

Mount Type

None (OTA only)

Optical Design

ED Triplet Apo Refractor

Weight

6.4 kg

From$2,095

Lowest in 90 days

Price tracked by PolarisObserved 7 timesTracking since Aug 2026

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Where to buy

Agena AstroProductsPartnerBest price$2,095→Starizona$2,095→

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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 Double Cluster, side by side.

Two glittering knots of stars sharing one low-power field — a wide, effortless showpiece that rewards the biggest true field you can throw at it.

See Double Cluster through this telescope →

Where else it shines

Within reach

Orion Nebula

Stronger structure — embedded stars plus dark lanes within the core

Open view →

Easy first target

The Pleiades

Rich field — fainter members fill out the cluster

Open view →

Rewards a dark sky

Andromeda Galaxy

Definite galaxy shape — core stands out against the sky

Open view →

Also excellent on

Saturn

Recognizable disk with subtle markings under steady seeing

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

✓A true triplet ED objective: no visible chromatic aberration, tight stars corner to corner.

✓Ships with a dedicated field flattener matched to the optics, so stars stay round to the edge of a large sensor.

✓At 550mm f/5.5 it frames big nebulae and galaxy groups while staying fast enough for short subexposures.

✓Rotatable 3-inch focuser, tube rings, dovetail and a foam case included, a complete imaging OTA.

Trade-offs

!No mount included; it needs a capable EQ mount, which is a significant added cost.

!A camera, flattener spacing and guiding are required to realize the optics.

!100mm of aperture is modest for visual use next to a Dobsonian.

!Premium price for a refractor of this size.

02In plain English

What These Numbers Mean

Aperture

100 mm

Four inches of premium apochromatic glass. Enough light grasp for demanding deep-sky imaging and enough optical quality that it also gives reference-grade planetary and lunar views for its size.

Focal length

550 mm

Wide field with real aperture behind it. Large nebulae fit an APS-C frame while galaxies keep usable scale, which is a rare balance and part of why the Esprit line is popular with imagers.

Focal ratio

f/5.5

Fast for a triplet of this quality, so exposures build quickly and guiding tolerances stay comfortable. Combined with the supplied flattener, corner stars stay round across a full-frame sensor.

Optical design

ED triplet apochromat with dedicated flattener

Three-element correction plus a matched field flattener designed for this exact tube, which removes the guesswork of pairing a generic flattener. Colour correction is strong enough that bright stars stay clean in long exposures.

Weight

6.4 kg tube

About 14 lb before rings, camera and guiding. A mid-size equatorial handles it, but this is past the point where a star tracker is enough.

Mount

OTA only

No mount included. For a loaded imaging rig at 550 mm, plan on a tracking equatorial rated around 15 kg with autoguiding to do the optics justice.

02The Polaris Score

How it scores, and why.

93/ 100

Sky-Watcher Esprit 100EDX

#1 of 4 astrophotography refractors

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