The refractor is what most people think of when you say “telescope” – a long tube with a lens at the top and an eyepiece at the bottom. A refractor has the advantage of being an unobstructed optical system. Unlike other designs, there is no small mirror at the front of a refractor to block incoming light and scatter it into the image, so a refractor’s contrast is better than other telescope types. Refractors also require less maintenance, particularly collimation (keeping the scope’s optics aligned for the best images). They are more tolerant of temperature changes when the telescope is taken outside, so they deliver good images without having to wait for the optics to cool down, as with a reflector. Given favorable seeing conditions, a modestly-sized refractor can show you lunar and planetary features with better contrast range and more detail than any other telescope type. This is especially true on nights of less-than-perfect seeing, when the details visible in a larger scope are often blurred by turbulence in our atmosphere. A smaller refractor looks through less of our unstable atmosphere. Its images are consequently less affected by this turbulence. A good 80mm refractor, for example, can reveal more lunar detail than you can sketch in a lifetime of observing.
Since the Moon and planets are all brightly lit by the Sun, a large light-gathering capacity is not as important as high magnification within the solar system. The relatively small aperture of a refractor is therefore often an advantage for this kind of observing, as is the high magnification capability of its long focal length, as there is less glare from brightly lit planetary surfaces to wash out faint detail.
For purely visual lunar, planetary, binary and star cluster observing, an altazimuth refractor with slow motion controls may be perfectly adequate. If a family shares the telescope, however, an equatorial mount with slow motion controls or a motor drive will keep objects centered in the field of view so all can share the same view. If you plan on doing a lot of daytime terrestrial observing, the altazimuth refractor is a good scope with which to do it.
The drawbacks of a refractor? Except for very expensive apochromatic designs, all refractors suffer from chromatic aberration (or “spurious color”). This is an optical defect that produces a faint, and generally unobjectionable, pale violet halo around bright stars, the limb of the Moon, and the planets. There are eyepiece filters available to reduce this aberration if it becomes a problem. While they are light in weight and economical in smaller sizes, refractors become bulkier and considerably more expensive than reflectors or compound scopes as apertures hit 4” (102mm) and above. But these drawbacks aside, and if sheer light grasp is not essential – for hunting very faint galaxies, for example, where a larger reflector would have the light-gathering edge – the clarity, contrast, and sheer image quality of a good refractor is well worth your consideration.
Here are a few refractors in different price ranges that make good first telescopes: Celestron FS70E 2.7” equatorial, Konus K90 3.5” equatorial, Meade M70AT 2.7” computerized go-to altazimuth. There are another dozen or so choices in our refractor catalog.
REFRACTOR REPORT CARD
(used in excellent seeing conditions and with no light pollution; adapted from Astronomy Magazine):
| E = excellent | VG = very good | G = good |
F = fair
| P = poor | Refractors under 3” aperture: | 0
| | Portability: | E | | Ease of setup: | E | | Ease of
use: | F | | Performance on the Moon: | G | | Performance on comets: | P | | Performance on
double stars: | P |
| Performance on galaxies and nebulas: | P | | Performance on
planets: | F |
|
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The refractor is what most people think of when you say “telescope” – a long tube with a lens at the top and an eyepiece at the bottom. A refractor has the advantage of being an unobstructed optical system. Unlike other designs, there is no small mirror at the front of a refractor to block incoming light and scatter it into the image, so a refractor’s contrast is better than other telescope types. Refractors also require less maintenance, particularly collimation (keeping the scope’s optics aligned for the best images). They are more tolerant of temperature changes when the telescope is taken outside, so they deliver good images without having to wait for the optics to cool down, as with a reflector. 
