An Overview of FirstScope’s Optical Tube
The Celestron FirstScope is a 76mm (3”) f/3.95 Newtonian reflector with a focal length of 300mm and a spherical primary mirror. If you have done some basic research about telescopes, you probably know that a spherical mirror won’t focus light correctly like a parabolic one does, and that is indeed the case with the Celestron FirstScope. It can not deliver sharp images at anything over about 40x, and even at lower magnifications, stars are a bit bloated and fine details on almost any object are smeared.
At f/3.95, precise collimation is critical with a Newtonian. Unfortunately for Celestron FirstScope users, the primary mirror sits on a plastic plate that doesn’t allow for any kind of collimation. You have an approximately 50% chance of the scope coming in with decent enough collimation to render a remotely acceptable image. If your Celestron FirstScope arrives out of collimation and you’re feeling adventurous, you can enlarge the mirror cell mounting holes to tilt the mirror slightly, or, failing that, pry the mirror out of its cell and attempt to shim and re-install it. Alternatively, you can simply return the scope to Celestron or exchange it for a new unit.
The focuser on the FirstScope is actually more or less the same thing you see supplied on most cheap small Newtonians, even four times its price – a plastic 1.25” rack and pinion.
The Celestron FirstScope has no finder – you’re supposed to simply sight along the tube. With the mere 15x supplied by the included low-power 20mm eyepiece, this is easy enough but may take some practice.
The Celestron FirstScope’s tube is wrapped in vinyl adorned with the names of famous opticians, astronomers, and physicists throughout history—a nice touch. This was originally done when the FirstScope was brought out for the International Year of Astronomy in 2009 to celebrate the 400th anniversary of Galileo’s first discoveries with the telescope, and Celestron has kept it in the decade since.
The Accessories with Celestron FirstScope 76
The FirstScope comes with two eyepieces: a 20mm Huygens giving 15x and a 4mm Ramsden (“SR”) giving 75x.
The 20mm Huygens… works. Barely. The apparent field of view is extremely narrow (30 degrees), and the view is fuzzier than it already would be with a good eyepiece in the Celestron FirstScope. The Huygens design also adds some chromatic aberration (something one should never see in a Newtonian). A real Kellner or Plossl delivers much sharper views, but buying one would cost a significant proportion of the overall cost of the telescope.
The included 4mm Ramsden is useless, being the same hated eyepiece supplied with Celestron’s Powerseeker line. It provides too much power for the scope (75x), the eye lens is tiny, it has zero eye relief, it doesn’t perform well with a fast focal ratio telescope like the Celestron FirstScope, and the field is slightly narrower than the 20mm Huygens. It also has an annoying tendency to get stuck in the focuser, the solution to which is to turn the scope upside down, loosen the screws, and shake it – preferably while above a garbage can, where it belongs.
You can buy an “accessory kit” for the FirstScope. All the kit contains is some more garbage Huygenian eyepieces, a useless 5×24 finderscope, and a cheap Moon filter, which you plain don’t need and don’t work well anyway.
Celestron offers a “Cometron” variant of the FirstScope which is exactly the same, except with passable Kellner eyepieces and the same godawful 5×24 finderscope attached. If that’s all you can afford, I would recommend it over the base FirstScope, but really, I would strongly caution you about both.
Tabletop dobsonian mount
The FirstScope 76 Newtonian reflector telescope comes with a simple tabletop Dobsonian mount to which it is semi-permanently attached. Altitude tension can be adjusted with a hand knob while azimuth can be adjusted by tightening or loosening the nut in the middle with a wrench or pliers. As to the smoothness of the mount’s motions, they’re pretty good, but it’s more or less irrelevant for a scope that is probably not able to handle more than 40x.
Should I buy a Used Celestron FirstScope 76?
If you can get a FirstScope for less than the already-low new price, why not?
Aftermarket Accessory Recommendations
Rather than purchasing additional accessories for the Celestron FirstScope 76mm newtonian reflector telescope, we would recommend saving your money for a better telescope entirely, which will include better accessories anyway.
What can you see with the Celestron FirstScope?
The Celestron FirstScope 76 is, surprisingly, more limited by a user’s ability to aim it than its optics. Anything besides the Moon, planets, or any other naked-eye visible target is going to be a bit of a challenge to find.
Within the solar system, don’t get your expectations too high. Mercury is a mushy blob. Venus shows its phases, and the Moon looks pretty good (especially if you’ve never looked through a telescope before). Mars is a featureless red blob even when it’s in opposition-not even the ice cap is visible. Jupiter’s moons are visible, and the cloud bands can just barely be spotted. Saturn’s rings and a couple moons can also be seen. Good luck finding Uranus or Neptune, let alone distinguishing them from stars.
Galaxies are, of course, quite underwhelming in the Celestron FirstScope. Under less-than-dark skies, only Andromeda and M33 are big enough to easily identify and show little in the way of detail. If you can escape city light pollution, you’ll be rewarded with a dust lane in Andromeda and faint hints of M33’s spiral arms. With luck, you may be able to spot M81, M82, M51, and some of the brighter members of the Virgo Cluster or the Leo Triplet, but they’re quite tiny at 15x and won’t show any detail.
Globular clusters are visible in the Celestron FirstScope and can be clearly distinguished from stars even at the mere 15x provided by the 20mm Huygens, but of course, no 3” telescope is capable of resolving stars in them, and certainly not one with the poor optics of the FirstScope.
Forget observing planetary nebulae-they’re too small to identify at 20x and trying to increase the power will, of course, only lead to blurry views.
Bright, large nebulae such as Orion and the Lagoon are visible through the FirstScope but require dark skies for optimal views.
Open star clusters—a particular challenge to locate without any finder whatsoever—are probably the most beautiful sights to behold in the Celestron FirstScope because they’re bright, lack fine detail to worry about being blurred, and are usually pretty large. The Double Cluster and the Pleiades, in particular, look excellent and are relatively easy to get the FirstScope pointed at.