Spectrum Telescope

Spectrum Full Aperture Glass Solar Filter for 149 mm - 156 mm OD Telescopes

Name: Spectrum Full Aperture Glass Solar Filter for 149 mm - 156 mm OD Telescopes
Brand: Spectrum Telescope
Price: 136.95 USD
Availability: InStock

A coated glass filter in a sturdy machined cell, the durable, drop-tolerant alternative to film. Warmer orange Sun, harder to damage, and sized to slide over larger scopes.

88/ 100

Polaris Score

#2 of the white-light solar filters we recommend

From$136.95

Where to buy

High Point ScientificBest price$136.95→

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What changes

You can’t look at all.
Now you can see the surface.

Drag to compare. Without the filter the Sun is a blinding, featureless glare no eye can face. Cut it to a hundred-thousandth and the photosphere appears, limb darkening, and a group of sunspots.

No filter

solar filter

◄►

01What you see

What the Sun actually shows.

A white-light filter shows the photosphere, the Sun’s visible surface. No exotic gear, no darkness required: these are daytime sights any small scope can reach, safely.

The main event

Sunspots

Cooler magnetic storms, often larger than Earth. They drift across the disk over days and cluster near solar maximum, the reason most people buy a solar filter.

Fine detail

Granulation

The Sun’s surface is a boiling mosaic of convection cells. On a steady day, a good filter and small scope resolve the mottled “orange-peel” texture between the spots.

Near the limb

Faculae

Bright magnetic patches, easiest to spot near the darkened edge of the disk. They often mark where new sunspot groups are about to appear.

Rare events

Planetary transits

Mercury and (very rarely) Venus cross the disk as a crisp black dot. A safe solar filter is the only way to watch one, the next Mercury transit is worth planning for.

When they come

Partial eclipses

The Moon takes a bite from the Sun. A full-aperture filter lets you follow every phase of a partial, or the partial stages either side of totality, without ever risking your eyes.

02Read this first

Safety is the whole product.

A solar filter is the one accessory where a mistake blinds you, instantly, painlessly and permanently. Four rules matter more than anything else on this page.

✕Full aperture, over the front

A safe solar filter mounts over the front of the telescope, stopping the light before it is ever focused. Never use a small filter that screws into the eyepiece, focused heat shatters them.

✕Never look without it fitted

Not even for a second, not to “line it up.” Unfocused sunlight through a scope causes an instant retinal burn with no pain to warn you. Fit the filter before the scope ever points near the Sun.

✕Inspect before every use

Hold the film or glass up to a bright lamp. Any pinhole, scratch, tear or crease means it is done, into the bin, not onto the scope. Store it flat and capped.

✕Cap the finderscope

A finder is a small unfiltered telescope. Cap it or remove it, or it will scorch the mount, your hand, or your eye the moment you look through it out of habit.

03Where it fits

It goes over the front, not the eyepiece.

This is the one filter that lives at the very front of the light path. It cuts the sunlight to a safe fraction before the telescope ever focuses it, which is exactly what makes it safe.

01

The Sun

Far too bright

Never look directly

→

02

This filter

Over the front aperture

Blocks ~99.999%

→

03

Telescope

Now safe to point

~1/100,000 gets through

→

04

Eyepiece

Frames the disk

Low–medium power

→

05

Your eye

Sees the photosphere

Sunspots, granulation

04Which kind

How solar filters compare.

All four let you observe the Sun safely, but they show different things, and cost wildly different amounts. Most people should start with white-light.

White-light film

Baader / Thousand Oaks

Bandpass

Full visible

Best for

Sunspots, transits

The affordable standard. A sharp, neutral-to-pale-orange view of the photosphere. What almost everyone should buy first.

This one

Full-aperture glass

Coated optical glass

Bandpass

Full visible

Best for

Sunspots, eclipses

Sturdier and usually warmer-orange than film, in a rigid cell. Pricier, can be a touch softer, but hard to damage.

Herschel wedge

Refractors only

Bandpass

Full visible

Best for

High-contrast white light

Diverts the heat out the side instead of blocking it at the front. Superb contrast, but only ever on refractors, never reflectors or SCTs.

H-alpha

Dedicated instrument

Bandpass

≈ 0.5–0.7 Å

Best for

Prominences, flares

A different view entirely, the chromosphere, with flares and prominences arcing off the limb. Costs many times more than white-light.

05The numbers

What These Numbers Mean

5 numbers in plain English · full specifications

Filter mediumDurable

Coated glass

Glass tolerates handling, wind and years of storage far better than film, which punctures easily. For a filter that will be taken to public events or used every clear day, durability is worth more than the last few percent of sharpness.

What you seeWhite light

Warm orange Sun

Coated glass renders the Sun a warm orange rather than neutral white. Sunspots and faculae are clear; the finest granulation is marginally better on neutral film, which is the usual trade for glass.

FitMeasure first

149 to 156 mm tube outer diameter

The range describes the outside diameter of the telescope tube or dew shield it slides over, not the aperture. Measure before ordering, and check the fit is snug enough that a gust cannot lift it off.

MountingCritical

Full aperture, front of tube

Sunlight is blocked before it enters the telescope, so nothing inside heats up and no concentrated light reaches the eyepiece. Eyepiece-end solar filters sit at the focus and are unsafe.

Before every sessionSafety

Inspect and secure

Check the coating for scratches or thin spots and confirm the filter is seated firmly. Cover or remove the finder scope as well, since an uncapped finder is a genuine hazard and a common oversight.

Optical

TypeWhite-light, full aperture glass

MaterialCoated optical solar glass

DensityND 5.0 (visual)

Transmission≈ 0.001%

View colourWarm orange

BlocksUV, IR, 99.999% visible

Fit & build

Cell OD range149–156 mm

Also availableMany OD sizes 41–400 mm

MountMachined cell with set screws

UseVisual & imaging

ReusableYes, rigid, wipe-clean

NeverOn the eyepiece end

06Pairs with

Compatible gear.

3 matches for this filter

Match by aperture

Fit is by outer diameter (OD)

Measure the OD

Across the front of the tube or dew shield

Pick the range

Each filter lists an OD window it fits

Snug, not loose

Set screws or a foam grip hold it firmly

Best telescopes

For daytime solar

Small refractor

Sharp, high-contrast disk, the classic solar scope

80–150 mm aperture

More than enough resolution for the Sun

Any cappable scope

If it has a lens cap, it can take a front filter

Handy extras

Make it easier

Solar finder

Point at the Sun without looking up the tube

Continuum filter

Sharpens sunspot detail on white-light views

Steady alt-az mount

Daytime tracking is easy and quick to set up

07Learn more

Guides for solar observing.

2 guides that cover this ground

Guide · 5 min

How to observe the Sun safely (and what you’ll see)

The rules that keep your eyes safe, how to fit a front filter, and a tour of what a small scope reveals on the daytime Sun.

Read the guide →

Guide · 6 min

White-light vs H-alpha: two very different Suns

One shows sunspots on the surface, the other shows flares leaping off the limb. Which view each filter gives, and what each one costs.

Read the guide →

Spectrum Full Aperture Glass Solar Filter for 149 mm - 156 mm OD Telescopes

You can’t look at all.Now you can see the surface.

What the Sun actually shows.

Safety is the whole product.

It goes over the front, not the eyepiece.

How solar filters compare.

What These Numbers Mean

Compatible gear.

Guides for solar observing.

You can’t look at all.
Now you can see the surface.