Takahashi

Takahashi FC-100DZ

The connoisseur's 100mm fluorite doublet: a longer f/8 focal ratio that pushes colour correction and high-power sharpness to the very limit of what a 4-inch refractor can do.

91/ 100

Polaris Score

#1 of 7 premium 100mm apo

See the breakdown ↓

Aperture

100mm

Focal Length

800mm

Focal Ratio

f/8

Mount Type

None (OTA only)

Optical Design

Fluorite Doublet APO

Weight

2.8 kg

From$3,090

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Price tracked by PolarisObserved 52 timesTracking since Jul 2026

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Where to buy

Agena AstroProductsPartnerBest price$3,090→Astronomics$3,490→

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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 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

Rich field — fainter members fill out the cluster

Open view →

Within reach

Ring Nebula

Small disk visible, hints of central star and structure

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

✓The fluorite doublet at f/8 corrects colour so completely that even the brightest objects show no false colour at high power

✓The longer focal ratio is optimized for demanding visual work on the planets, Moon and doubles

✓At about 2.9kg it stays portable, riding on a modest alt-az mount for grab-and-go sessions

✓Takahashi's build quality and star test are the reference the whole industry is measured against

Trade-offs

!As a doublet a trace of residual colour shows on the very brightest objects versus a triplet

!f/8 is longer and slower than the imaging-focused apos

!It is an OTA only and needs a mount, diagonal and eyepieces

!Takahashi accessories are also premium-priced

02In plain English

What These Numbers Mean

Aperture

100 mm

Four inches of fluorite glass at the highest level of correction Takahashi offers in this size. It is enough for high-power lunar and planetary study, tight double stars, and satisfying views of the brighter deep-sky objects.

Focal length

800 mm

Longer than the FC-100DF, which is deliberate: the extra length improves colour correction further and suits high-magnification planetary work. It reaches 160x with a 5 mm eyepiece.

Focal ratio

f/8

Slow enough that residual colour error is effectively invisible, even on Venus and the lunar limb where doublets usually betray themselves. The cost is a narrower field and slower imaging than the f/7.4 version.

Optical design

Fluorite doublet apochromat

The DZ is the planetary-leaning member of the FC-100 family, trading a little field width for the cleanest correction. Two elements keep it light and quick to reach outdoor temperature.

Weight

2.9 kg tube

About 6.4 lb, so a good alt-azimuth head on a sturdy tripod is all it needs. That portability is a large part of why these telescopes get used so often.

Mount

OTA only

No mount included. Visually a quality manual alt-azimuth is ideal; for imaging at 800 mm you will want a tracking equatorial and the matching flattener.

02The Polaris Score

How it scores, and why.

91/ 100

Takahashi FC-100DZ

#1 of 7 premium 100mm apo

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