ED Refractor Telescopes for Visual Use and Imaging
ED refractors use one or more elements made from extra-low-dispersion glass to reduce chromatic aberration compared with a basic achromatic refractor. This can produce crisp, high-contrast views of the Moon, planets, star clusters and landscapes. The degree of colour correction depends on the complete optical design; the ED label alone does not mean that all visible colour fringing is eliminated.
This category includes compact travel instruments and larger ED refractors for visual observing and astrophotography, including complete packages and optical tube assemblies with varying accessories. Compare aperture, focal length, focal ratio, focuser and supplied items before choosing. Browse our telescopes for more options.
Choosing an ED Refractor for Your Observing
ED telescopes are refractors that use one or more elements made from extra-low-dispersion glass. This helps bring different wavelengths of light to a closer focus and reduces chromatic aberration. Bright objects may therefore show fewer coloured fringes than in a comparable basic achromat. The degree of correction depends on the objective design, glass types, focal ratio and optical quality, so an ED label does not guarantee a completely colour-free image.
Aperture and focal length
Aperture affects light gathering and resolution: a larger objective can reveal finer detail and fainter objects, but it also makes the optical tube heavier and calls for a more capable mount. Focal length works with the eyepiece to determine magnification. Short focal lengths are useful for wide star fields and compact travel setups; longer focal lengths make higher magnifications on the Moon and planets easier to reach. Consider how much portability, aperture and observing scale matter to you.
Visual observing and daytime use
For the Moon, planets, double stars and bright deep-sky objects, look at colour correction, sharpness and a focuser that can make fine adjustments. A 2-inch focuser can accept wide-field eyepieces when the eyepiece and diagonal are compatible with the telescope. For terrestrial viewing, an Amici prism is useful when you need an upright, correctly oriented image. A conventional star diagonal or mirror gives a different image orientation. Check the product description to see whether a diagonal, eyepiece or finder is actually included.
ED refractors for astrophotography
Many compact ED tubes can be used for astrophotography with a suitable camera. Check the focuser's load rating, camera connection, available back focus and the stability of the mount. A field flattener may be needed to keep stars sharp toward the edges of a larger sensor; whether a reducer or specific adapter is also needed depends on the telescope, camera and desired field of view. The focal ratio helps compare imaging speed and field scale, but it does not replace checking optical and mechanical compatibility.
Complete telescope or optical tube assembly?
Supplied accessories vary between products. Some telescopes include items such as an eyepiece, diagonal, finder or carrying case. Others are listed as an OTA (optical tube assembly) and do not include a mount and may also omit eyepieces, diagonal and finder. Several Evostar EDX models in this category list tube rings, a dovetail bar and a case while excluding common observing accessories. Read each product's contents before ordering and account for any mount, tripod, eyepieces and diagonal you still need.
To compare the full range, browse our telescopes. Choose according to your intended use, and match the mount and accessories to the specific tube rather than relying on the ED designation alone.
Quick buying guide
- For travel and wide star fields, prioritise a short focal length and compact tube, with a stable tripod or mount.
- For the Moon and planets, consider aperture, focal length, precise focusing and a steady setup.
- For astrophotography, check the focuser, camera connection, back focus, mount and any required field corrector together.
- Before ordering, compare aperture, focal length, weight and the actual included items with your planned use.
Even a well-corrected ED refractor needs a stable mount and careful focusing to perform at its best. Allow the telescope to adjust to large temperature changes and choose accessories that fit the exact model.