Choosing
A telescope listing mixes three kinds of figures: the two that define the instrument, a few that tell you what fits it, and many that describe nothing. Knowing which is which takes five minutes and saves most bad purchases.
The diameter of the lens or mirror decides what a telescope can show. A listing that hides it, like CLAVOLO’s travel telescope, quotes a magnification range with nothing behind it.
Divide the telescope’s focal length by the eyepiece’s. Celticbird’s 80/600 publishes 600 mm and 20 mm and 9 mm eyepieces for 30x and 66x, and every figure checks. EcooPro’s 70/360 publishes 360 mm and 25 and 10 mm eyepieces, then claims 51x to 128x: the real figures are 14x and 36x.
About twice the aperture in millimeters on a perfect night. National Geographic’s 76/700 EQ states 233x and a recommended maximum of 152x in the same sentence, which is honest. Its 114/900 AZ reaches 675x only with a 4 mm eyepiece in a 3x Barlow.
A 1.25-inch fitting takes every eyepiece sold today; a 0.965-inch fitting takes almost nothing. See eyepiece barrel diameters.
“HD”, “professional”, “high power” and “Galileo” describe nothing. Look for a number behind each adjective.
Aperture, focal length, mount: three lines are enough to sort, and they are often buried.
A magnification in large type describes no capability of the instrument.
The stated supplied accessories decide what can be done on the first night.
| What the listing leads with | What it is worth | What to look for |
|---|---|---|
| A magnification | Nothing | The aperture |
| Many accessories | Little | What they are |
| An adjective | Nothing | The focal length |
| A price | A marker | The mount |
This guide maintains nothing, but a well-read listing avoids an instrument abandoned after two nights. The kit that lasts is the kit chosen on its specifications, not on an argument.
This site publishes stated specifications and assesses no seller.
80 mm (3.15 in) at 600 mm (23.6 in), f/6.7 · 20 and 9 mm for 30x and 66x · 13% Moon filter · tripod 17.7 to 52 in
Celticbird's 80/600 AZ refractor: fully multi-coated optics at f/6.7, 20 mm and 9 mm eyepieces for 30x and 66x, a 13% Moon filter, a 5x24 finder, a phone adapter, a backpack and a tripod from 17.7 to 52 inches.
Best for: A first 80 mm whose numbers can be checked, used by a child from a low tripod and an adult from a high one
≈ $100
76 mm (2.99 in) mirror · 700 mm (27.6 in) focal length · f/9.2 · equatorial mount · 152x recommended maximum
National Geographic's N 76/700 EQ: a 76 mm Newtonian at 700 mm focal length on an equatorial mount, advertised to 233x with a recommended maximum of 152x stated in the same description.
Best for: A first equatorial telescope light enough to move fully assembled
114 mm (4.49 in) mirror · 900 mm (35.4 in) focal length · f/7.9 · alt-azimuth mount
A 114/900 Newtonian reflector on a simple alt-azimuth mount and aluminum tripod, supplied with 25, 9 and 4 mm eyepieces, a 6x30 finder, a 1.5x erecting lens and a 3x Barlow.
Best for: A family telescope for planets and bright deep-sky objects, where nobody wants to learn polar alignment
70 mm (2.76 in) · 360 mm (14.2 in) · f/5.1 · K25 and K10 for 14x and 36x · magnification figures that disagree · backpack
EcooPro's 70/360 refractor: fully multi-coated optics, K25 and K10 Kellner eyepieces, an erect-image diagonal, a 5x24 finder, an aluminum tripod and a backpack, sold with three different magnification claims.
Best for: Wide low-power views and daytime use, by a buyer who does the magnification arithmetic
≈ $60
Aperture and focal length not published · H20, H12.5 and SR4 eyepieces · 18x to 135x claimed · 1.5x erecting eyepiece · tabletop tripod
CLAVOLO's small refractor for children: three eyepieces (H20, H12.5, SR4), a 1.5x erecting eyepiece, a finder, a Moon mirror, Moon and star maps and a tabletop tripod, with a stated range of 18x to 135x.
Best for: A child's first telescope bought on price, with the two figures that matter asked of the seller first
≈ $33
Aperture: the diameter of the main lens or mirror. It decides how much light is gathered and how fine a detail can be resolved.
Divide the telescope's focal length by each eyepiece's. If the listing's figure needs a Barlow or an erecting lens to reach, it is arithmetic, not performance.
Ask the seller before buying. A telescope that hides its aperture usually has a small one.
For observing: A first 80 mm whose numbers can be checked, used by a child from a low tripod and an adult from a high one
Where it is strong: Focal length, ratio and magnifications all published, and they agree
Where it is weak: f/6.7 achromat shows some false color on bright objects
For observing: A first equatorial telescope light enough to move fully assembled
Where it is strong: f/9.2: easy on eyepieces and collimation
Where it is weak: 76 mm is a small aperture
For observing: A family telescope for planets and bright deep-sky objects, where nobody wants to learn polar alignment
Where it is strong: 114 mm of aperture at f/7.9: enough light for bright clusters and nebulae, and an easy ratio for eyepieces
Where it is weak: The 675x top figure is arithmetic: a 114 mm mirror tops out near 230x
For observing: Wide low-power views and daytime use, by a buyer who does the magnification arithmetic
Where it is strong: Aperture and focal length both published
Where it is weak: Stated 51x to 128x (and 15x to 150x in the title) does not match 360 mm
For observing: A child's first telescope bought on price, with the two figures that matter asked of the seller first
Where it is strong: Three eyepieces and an erecting eyepiece for daytime use
Where it is weak: No aperture or focal length published
$33 – $100
8 models
$103 – $227
9 models
$238 – $500
8 models
Model against model, where the comparison is already published.
The models above are taken from the catalog of this site. Specifications are the ones the maker publishes and the ones on the Amazon page; prices are the Keepa reading for the date shown, and both change. Ranking uses declared specifications, the weight of stated strengths against stated limits, and price. Nothing here has been pointed at the sky by us, and the page makes no such claim.
Last checked on
Any figure written into the body of this page was true on the day it was written. The amount shown next to each instrument is requested from the retailer as the page loads, and it is that amount, not the text, that stands.
