Explore Scientific ED80 Review Hands-On

Written by Zane Landers 2 years ago, for TelescopesToBuy.

Introduction

The Explore Scientific ED80 Essentials Triplet is a poor choice for most astrophotography work compared to competing telescopes, and the scope’s triplet optical design has little correlation with high quality.

The Explore Scientific ED80 Essentials Triplet is a compact ED triplet refractor sold at a similar price tag to many 80 mm ED doublets, and unsurprisingly concessions have been made to make this possible. The ED80 Essentials Triplet offers roughly equal quality views and images to most 80 mm doublets at its price range but is heavier and less compact, with a variety of issues that make it less than ideal for the price. The more expensive FCD100 glass upgrade improves the optics but has a lot of competition and suffers from similar mechanical drawbacks to the Essentials version. Either is unsuitable for use with a reducer-flattener or large full-frame camera sensors, both of which are major disadvantages compared to most competing imaging telescopes. The Explore Scientific triplet refractors make great scopes for visual observation and were seemingly designed for such, with imaging capabilities as more of an afterthought.

Optics

The Explore Scientific ED80 Essentials Triplet is a 3.2” apochromatic refractor telescope with a focal length of 480 mm and an f/6 focal ratio. While triplet refractors are typically known for superior chromatic aberration control compared to doublets, the ED80 Essentials Triplet will produce blue halos around bright celestial objects visually and will show noticeable chromatic aberration comparable to a typical ED doublet refractor in images. This is a consequence of the cheap FCD-1 glass used in the telescope, which is roughly equivalent to the cheaper FPL-51 glass used in the most inexpensive ED doublets and sure to be a disappointment if you expect the triplet design to mean improvement over a similarly priced doublet. The FCD-100 glass used in the more expensive ED80 offered by Explore Scientific does clean up the image, but not without significant expense.

At f/6, a field flattener is certainly necessary with the ED80 Essentials Triplet to eliminate field curvature in your images. Unfortunately, Explore Scientific does not offer their own dedicated, optically optimized reducer-flattener anymore, and you will not be happy with the images produced by a 0.8× reducer-flattener from another manufacturer; the only choice for an optimized flattener at all is Explore Scientific’s in-house unit. The size of the illuminated image circle of the ED80 is not specified by Explore Scientific but is around 21 mm, which will vignette with full-frame sensors.

Another major issue with the ED80 Essentials Triplet is that the screws used to hold and adjust the objective lens in its cell poke into the light path. This introduces odd spikes and crosses on bright stars in your astrophotos. Backing off the screws can reduce the problem but will leave the lens loose in its cell and may introduce collimation issues. The only real fix is to stop down the telescope’s aperture by a few millimeters, which consequently reduces your speed for photography and your light-gathering or resolving power for visual.

Mechanics

The ED80 Essentials Triplet is equipped with a 2” dual-speed Crayford focuser with a brass compression ring, which can be rotated to adjust your framing for images. While this focuser is generally effective, it has been known to slip under heavy loads, while the single thumb screw that enables rotation can easily slip or cause the focuser assembly to become tilted. The FCD100 version has a 2.5” Crayford focuser with a hexagonal drawtube which is stiffer but suffers from the same issues with its rotation axis relying on a lone screw. You also get thread-on extension tubes to reach focus with certain cameras or eyepieces, which may require additional focus travel.

The ED80 Essentials Triplet features an unusually wide and stubby dew shield that retracts for transport. The dew shield does a poor job of preventing condensation or blocking stray light due to its narrower design and also gets in the way of mounting tube rings to the telescope, which is why the ED80 uses a simple ring and “foot” style dovetail like small, cheap 60–72 mm ED doublets. This design can sag and also prevents the installation of a second dovetail atop the tube to attach a guide scope to.

Mounting Options

In addition to the tube itself and a Vixen-style dovetail bar, you also get a finder/guide scope mounting shoe capable of fitting almost any style bracket, along with a 2” dielectric star diagonal and 1.25” adapter for visual use. Weighing 7.5 lbs without the addition of any camera, guide scope, or accessories such as a flattener or the provided star diagonal, the ED80 Essentials Triplet requires an EQ5-class mount like the Sky-Watcher HEQ5 Pro or Celestron Advanced VX for astrophotography use. For visual use, Explore Scientific’s own Twilight I or a similar heavy-duty alt-azimuth mount is ideal.

What You Can See

While an 80 mm refractor is hardly a capable instrument for deep-sky visual astronomy—especially at the high price tag of the ED80 Essentials Triplet—this scope can still provide enjoyable views with the right eyepieces. The short focal length makes it ideal for wide-field, low-power viewing of nebulae or star clusters, and the 2” diagonal enables you to achieve the widest possible field of view with 2” oculars. You can split double stars at high magnification even from the city and view nebulae like the Veil or North America Nebula with a UHC filter under dark skies. Globular star clusters, planetary nebulae, and galaxies will appear as dim, detail-less smudges on these small sensors, however.

Within the Solar System, the ED80 is sufficiently powerful to reveal phases of Mercury and Venus, detailed lunar features such as craters and ridges, Mars’s ice caps and dark markings, Jupiter’s cloud belts and Great Red Spot, and Saturn’s rings and Cassini Division. A larger telescope is necessary to resolve Uranus and Neptune clearly or observe their moons.

Drawbacks

The small illuminated image circle, combined with optical issues and vignetting induced by any attempt to use a third-party reducer-flattener, confines the field of view severely for deep-sky imaging and limits you to smaller sensors like APS-C DSLRs. The scope is also prone to mechanical flexure due to its higher weight and the poorly designed focus rotator and dovetail foot. Visual observers seeking an economical option are better served by a larger catadioptric or Dobsonian telescope, and imagers should consider a better-quality triplet or a well-made doublet or Petzval 80 mm refractor instead.

Conclusion

The Explore Scientific ED80 Essentials Triplet is hardly the bargain it may appear to be. Astrophotographers and visual observers alike would best be served by a different telescope with fewer mechanical and optical concessions.