My personal review of the Celestron FirstScope, a tiny 3-inch f/4 Dobsonian mounted reflector telescope
This is one of the first tabletop telescopes
Introduction
The tiny telescope is so cute, just keeping it on the shelf may be enough for a conversation starter. The 3 inch f/4 spherical mirror of lesser optical quality won't win any awards and in fact you will need to process the Hell out if any astrophotos taken with it to get acceptable images. The included plastic eyepieces are best thrown in the garbage asap and replaced with new glass lens aspheric oculars from Svbony that work outstanding with this scope.
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The rack & pinion has excellent tension and
outstanding smooth mechanical action, perfect
for EPs and cameras. Plus, the rack tension is
adjustable with two screws. However, when
the rack and pinion achieves focus with the EP,
the tube extends too far down and causes a very
large secondary mirror obstruction that severely
degrades the image. |
Worth & Value
What good is the scope, you may ask... The scope, in spite of optical shortcomings, is a real gem. It costs about $60
Dob Mount
The minuscule scope comes with the smoothest and easiest to use Dobsonian mount. Even the spirit of the great John Dobson would be pleased with its ease of its use. Objects are found by manual GOTO; a process of sight and point, then slosh around the scope in the general vicinity until the object is found in a low power eyepiece.
It works! Simple Analog
Actually, this is the only working telescope that I have now, amidst a plethora of larger and more costly telescopes, with some rigs priced around 20 grand! Those set idle, too complicated to use, too heavy to set up or take down, or with high tech failures. There is something to say about the reliability of a simple analog telescope with hands-on ability.
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Small aperture telescopes seem to do better
with big city light pollution because they
collect less of it. Only one planet is seen in
this light polluted central urban sky. |
Known for Cuteness
Speaking of hands-on, this scope is known as the
cat's pajamas for the cuteness factor alone. It comes bare bones, no finder scope, and no calibration screws for the primary mirror, but it's not really a problem - sight down the tube to find Heavenly objects, and the secondary mirror has 3 screws for collimation.
Lightweight Tabletop Telescope
The minuscule telescope can be handled with one hand, as its combined weight is only 4.3 pounds! Set it on a table. It sets up in 3 seconds. My other telescopes are too big and heavy to set up and take down.
Focuser & Lightweight
The focuser works flawless and can hold each of the entire line of lightweight 1.25-inch eyepieces and computer USB astro cams for astro imaging - or simply hold an iphone or android above the eyepiece to capture the Moon. The goal here is to find lightweight accessories so as not to upset fixed tube balance. For example, there is a lightweight accessory plastic finderscope that weighs only a fractional ounce that screws onto the tube.
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No matter how the "too small" diagonal
mirror is positioned, the larger primary
mirror will not fit into full view. Plus, the
diagonal is is not properly elliptical
shaped so when it tilts at 45 degrees, the
mirror looks irregular and is ill fitting.
When new, the diagonal mirror came
with fine scratches and a marred surface. |
Optical Quality
It's not a perfect world and small cuteness comes with a price. The optics leave something to be desired. The primary mirror is F/4 but spherical. The secondary elliptical flat mirror is too small and geometrically misshapen, therefore does not show the entire primary mirror for calibration. Due to this, only certain aspheric eyepieces will give performance.
Secondary Mirror
Further inspection last night when I started to collimate it revealed a disappointing secondary mirror far too small (it won't show the entire primary mirror, about 30% is missing) and it has the wrong ellipse shape! - when tilted 45-degrees, it's not a circle! In dealing with these anomalies, it's a wonder we can get any image at all.
The Telescope that Could
But maybe, just maybe, this is the
little telescope that could. The story of the Little Engine that Could
In the tale, a long train must be pulled over a high mountain after its engine breaks down. Larger engines, treated anthropomorphically, are asked to pull the train; for various reasons they refuse. The request is sent to a small engine, who agrees to try. The engine succeeds in pulling the train over the mountain while repeating its motto: "I-think-I-can". The story of the little engine has been told and retold many times. The underlying theme is the same — a stranded train is unable to find an engine willing to take it on over difficult terrain to its destination. Only the little blue engine is willing to try and, while repeating the mantra "I think I can, I think I can", overcomes a seemingly impossible task.
https://en.wikipedia.org/wiki/The_Little_Engine_That_Could
Stock Eyepieces
These eyepieces came with the telescope and are made of plastic lens and plastic upper barrels. The cheap plastic lenses melted on a hot summer day. While other quality eyepieces are engraved, these have a cheap paper sticker on the top. Throw these away asap. If you look through these, the view will be disappointing, fuzzy, and dim without focus.
Image Processing
Given the spherical optics and subsize misshapen secondary, you will need to try and make up for any defects somewhere. This is where image processing comes into play. By transferring the digital image to a computer, the system OS will usually have a photo app that can offer image sharpening, noise reduction, color adjustment, gamma correction, with rotation and cropping. Also feel free to make corrections to the image with more than one level or iteration of processing, as needed.
Endearing Telescope
As both an amateur and professional astronomer for a half century, I have many uses for the Celestron FirstScope, doing experiments, testing lenses and optical configurations, use as a fast grab & go telescope that needs practically no setup time, plus running wild experiments and doing super fun projects. I've collected many telescopes and this one is a favorite.
Celestron FirstScope - Indexhttps://otisastro.blogspot.com/2020/08/celestron-firstscope-index.html
