Galileoscope - Plastic vs Glass Lenses

A day and a half ago I made my first lunar observations with the Galileoscope. I took that opportunity to also experiment with eyepieces.

The Galileoscope's eyepiece and barlow lenses are all made of uncoated plastic. From a cost point of view the decision to make them so was a good one. A single eyepiece with coated glass lenses tends to cost substantially more than the whole Galileoscope kit.

I had noted in an earlier post that glare, or scattered light, was evident when observing Jupiter. When I observed the moon the glare was once again evident. As with Jupiter, at 25x the glare was confined to the region around the limb of the bright object (in this case, the moon).

When I used more costly eyepieces with coated glass lenses the views of the moon became very sharp, contrasty, and glare-free. Yet, the view with the Galileoscope's plastic lenses (at 25x) wasn't too terribly worse. The moon itself looked very similar, virtually identical except for the glare around the lunar limb.

At 50x using a quality eyepiece composed of coated glass lenses the moon was very sharp, contrasty, crisp, and glare-free. But the finest detail visible with the quality eyepiece became very difficult or even impossible to see with the Galileoscope's stock eyepiece and barlow. The moon appeared 'washed out' with the plastic lenses. Nevertheless, one could still see more lunar detail at 50x than at 25x with the plastic lenses.

What about the Galileoscope's glass, achromatic objective? The eyepiece experimentation revealed that the objective is capable of producing very sharp, contrasty images. I was impressed by the quality of the objective, but at magnifications greater than 25x one needs to use higher quality eyepieces to make the most of what the objective has to offer.

On the same night I made observations of Jupiter, Neptune and Uranus with the Galileoscope. The latter two looked indistinguisable from stars. Nevertheless it was a pleasure to see them with the Galileoscope.

While observing the moon and trying out different eyepieces I noticed that an occultation of a star was going to take place. I observed the occultation using the Galileoscope with a far more expensive 7mm Nagler eyepiece. Of course, the occultation could have been observed with the Galileoscope's own eyepiece with or without the barlow. It was with the stock, 25x eyepiece that I became aware that an occultation was imminent.

Size is Relative

Is the 47mm clear objective Galileoscope a small telescope or a large telescope? Is it a serious telescope or a toy? The answer depends on one's attitude.

For starters, Galileo revolutionized astronomy with the insights provided by telescopes that were inferior in capability to the Galileoscope pictured above. With a serious attitude of inquiry others can follow in Galileo's footsteps while using a telescope (the Galileoscope) that Galileo would have treasured. To Galileo, the Galileoscope would be a large, high quality telescope -- and indeed it is -- until one starts comparing it with larger and better telescopes.

Don't be fooled! The Galileoscope will not show things as well as the pictures you've seen taken through the vastly more expensive Hubble Space Telescope. After all, if a $15.00 telescope could do as well as Hubble, what would be the point of building and putting into orbit such a large and costly beast?

Many telescopes are marketed by displaying sharp, colorful, astronomical images. Sometimes the images were taken through a telescope just like the one being sold. Yet, more often than not, no one can see the same objects when looking through the same telescope as well as the camera and (often) image-enhancing software depict them in the advertisements. It takes patience and experience to learn to see all that any telescope is capable of showing. Even then, it takes knowledge and the right attitude to appreciate what one sees.

My point? Don't expect miracles from the Galileoscope nor from any other telescope. The amount of joy that any telescope can provide is directly related to the attitude and drive of the individual using it. The most pleased new telescope owners are those that harbored no unrealistic expectations. In other words, since no beginner truly knows in advance what to expect, the clearest road toward pleasure with any telescope is the road on which one has no expectations.

I can honestly say that I've enjoyed the few sessions I've had so far using my own Galileoscope. Yet, it's with some reservation that I would recommend the same telescope to a beginner. This is because I know that the beginner would be, more likely than not, disappointed with his/her initial views. Few beginners start out with an attitude that allows for a pleasurable experience when using a relatively small telescope. Nevertheless, in my opinion the Galileoscope would make a good first telescope. Just remember to supply it with a reasonably sturdy tripod that's tall enough for comfortable use.

In my opinion it would be a mistake to provide a beginner with a far more expensive first telescope. Telescopes need tender, loving care if one wants them to last and continue to perform as well many years later as they did on their first night out. The higher a telescope's quality is, the easier it is to abuse, improperly use, and damage by ignorance and negligence. It's better to learn how to care for a telescope while using a less (rather than more) expensive instrument. This is another factor that makes the Galileoscope a good first choice.

I enjoy pushing myself as well as whatever telescope I'm using to both of our limits. This is a large part of the reason why a person like myself, who has access to larger and better telescopes, can still enjoy observing with a small Galileoscope. I'm fortunate to live in a region where I have easy access to a truly dark night sky. Though that didn't happen entirely by coincidence! A dark sky greatly enlarges the list of what one can see with any telescope. City dwellers will have to be content to observe only the brighter objects visually -- objects like the moon, Venus, Jupiter, and Saturn. Of these, the moon is likely to be of greater interest. Each night the shadows on the moon are different. Each night there's something different to see.

I started out in this hobby using a telescope somewhat similar to the Galileoscope. The hobby became far more interesting after I started recorded my observations using words and sketches. Some have started out differently while still achieving a life-long interest. Unfortunately, many others have dropped out of the hobby after spending a brief time attempting to use a telescope. To succeed one needs a usable telescope along with a die-hard attitude. Of the two, attitude is of greater importance.

So, is the Galilescope a serious telescope or a mere child's toy? The answer depends on the end user and their attitude.

Galileoscope Assembly Instructions

For those who have or will be getting a Galileoscope, the assembly instructions that come with the telescope are not quite complete. I suggest the following modifications or additions to those instructions. It is assumed that the reader has the original assembly instructions in hand when trying to make sense of what I've written below.

Step 5 -- Modify to read: Secure the two ends of the focuser assembly with the two smaller rubber 0-rings that fit into the grooves at the ends of the tube.

Step 8 -- Add the following to the supplied instructions for this step: Slide the two larger o-rings over the telescope body, positioning them over the two grooved rings.

Pay due attention to the photos as well as the Exploded View diagrams when assembling your Galileoscope.

When assembling the Galilean eyepiece/barlow (this is the two-lens eyepiece) take care to place the convex side of one lens against the concave side of the other. When placing this lens pair into the eyepiece halves be careful to place it so the concave side faces the wider part of the eyepiece body.

Note in the exploded view the plastic covering that fits over the eye end of the Galilean eyepiece. That covering is removed when the Galilean eyepiece assembly is placed into the barlow tube for use as a 2x barlow.

Hints and Suggestions for Using the Galileoscope:

The telescope works reasonably well with a photo tripod that can be extended high enough for the observer to comfortably look upward through the eyepiece without having to squat or crawl under the telescope. In other words, a tall tripod is better than a tripod that is too short.

If you have no tripod, rest the telescope on a wall, fence, tree branch, etc. in order to steady the view. You might even be able to use one of the included cradles in a creative manner. Anything that offers steady support is better than nothing.

The Galileoscope is easier to use with the 25x eyepiece. Always start your observing with that eyepiece. For closer (50x) views of bright objects use the 25x eyepiece along with the 2x barlow. You'll probably want to switch back to 25x before seeking a new target for observation. If you find the telescope too difficult to manage at 50x then use the telescope only at 25x. None of Galileo's actual telescopes could magnify as much as 50x.

If you own other telescopes and have 1.25-inch O.D eyepieces, you can use those eyepieces with the Galileoscope. Keep in mind that the magnification is equal to the focal length of the objective (500mm) divided by the focal length of the eyepiece.

Expect nothing when using an astronomical telescope! Your views will not look like the photos that are so easy to find all over the Internet. Similarly, when used at night for astronomy expect to see no color. You should be happy with whatever you can see. The Galileoscope is a far better telescope than anything Galileo actually used, but there are plenty of other telescopes around that are better. Nevertheless, for its price, the Galileoscope is tough to beat!

The Galilean eyepiece is perhaps best reserved for demostration purposes -- in order to get a better feel for what Galileo had to work with. I suspect you'll find yourself using the telescope primarily with the 25x Keplerian eyepiece.

Galileoscope - First Light

The above photo shows the $15.00 (plus postage) Galileoscope atop an optional (but recommended) camera tripod. My order was received yesterday. First light was last night - 25 July 2009 UT.

The telescope arrived unassembled with incomplete instructions. More complete instructions were available online. I never did find what I would call 'complete' instructions, but the remaining details I was able to figure out for myself.

The design of the Galileoscope was well thought out. All parts fit together very nicely. The objective is a high quality, 50mm glass achromat. Once fitted inside the optical tube assembly (OTA) the effective aperture becomes 47mm. The plastic eyepiece lenses do a decent job magnifying the image. The telescope can be used at 25x with the included eyepiece, 50x when the included barlow is added, or 18x if one desires to use the telescope as a true Galilean telescope (using the barlow as an eyepiece) - resulting in a narrow field of view (FOV) and erect image. In the 25x and 50x arrangements the image is upside down - typical of many astronomical telescopes, but the FOV is larger, making the telescope more comfortable to use.

Last night I observed and sketched seven astronomical targets including four galaxies (M101, M31, M32, and M110), a globular star cluster (M13), a double star (Mizar - aka Zeta Ursae Majoris), and a planet (Jupiter). A few other objects were observed but not sketched - including M33, a galaxy that some in light polluted areas cannot see even when using much larger $1,000 telescopes! I considered sketching M33, but I was getting tired and decided to go instead for the more beautiful trio of galaxies in the M31 family.

Even at 25x the FOV is rather narrow in the Galileoscope. I had to off-center M31 in order to include M32 and M110 in the same FOV.

Most of the night's observations were made at 25x. Jupiter was sketched at 25x and again at 50x. The double star was sketched only at 50x.

Jupiter's North Equatorial Belt (NEB), South Equatorial Belt (SEB), and Equatorial Zone (EZ) were all visible upon close examination at 25x. At 50x I was able to make out a zone south of the SEB and another north of the NEB. Since none of the Galilean Satellites were in eclipse or transit, all four were easily visible at 25x.

Some structured glare was apparent around Jupiter at 25x, perhaps from the uncoated, plastic eyepiece lenses. That was the only optical defect that really stood out at 25x. It went unnoticed for all other objects observed. Similarly, at 50x, the only optical problem encountered was a smooth, even glare throughout the field of view when observing Jupiter. No glare was noticed when observing any of the less brilliant targets observed. In my opinion the glare is easy to tolerate and ignore considering the price of the telescope.

I enjoyed observing and sketching the deepsky objects! Many, if not most amateur astronomers believe that 'aperture is everything' in a telescope - particularly when one wants to observe deepsky objects. In my opinion and experience a dark sky and observer experience are often of greater significance. I *really* enjoyed observing these objects with the Galileoscope!

Far Ranging Thoughts

Last night was my best night with Jupiter this season. My third and fourth sketches of the planet for this year were completed. Excalibur was used at 218x.

For the first sketch (started at 6:45 UT) I employed a Moon-SkyGlow filter which had perhaps a subtle effect. I feel that my 'Jupiter Observing Eye' has returned now. I was able to sit down and make my most carefully rendered Jupiter sketches of this season. Callisto's shadow showed up as a small, round, pitch black spot below the trailing edge of the Great Red Spot. It looked really nice in such close proximity to Jupiter's most famous feature.

The GRS was very pale. It's leading edge was darker than it's following edge. Nevertheless, even the leading edge was very pale. Some structure within the planet's two primary belts (as well as a little zonal detail) was also recorded.

The second Jupiter sketch of the night was started at 8:50 UT. The GRS had moved to the preceding limb of the planet and was no longer visible, but the disrupted end of the South Equatorial Belt following the GRS remained visible. Callisto's shadow remained on the planet, but it now lagged a little behind the GRS.

In the second sketch the impact scar was visible near the planet's south limb. It hadn't quite reached the planet's central meridian at the time of the sketch. The scar seemed to be a little smaller than Callisto's shadow and clearly elongated in the east-west direction. It was considerably less dark than Callisto's inky, black shadow. The scar was about as dark as the matter making up Jupiter's major belts. In other words, it was far less obvious to the eye than was Callisto's shadow.

I'm hesitant to upload these latest sketches, preferring to keep them for my selfish self. Both would provide good material for future paintings -- if I ever get around to it . . .

I've recently become quite discouraged with an astronomy forum that I've been frequenting lately. Forum content has had little to offer me despite my own attempts to increase its faltering signal to noise ratio. Of course, my own lack of a full night's sleep might be adding to the feeling. Time will tell . . .

Anyway, I've been rethinking my Internet presence in general. Eventually re-working my website is a possibility. Also being considered is a limitation on my blogging -- perhaps making one entry at the beginning of each month describing one night's observing session (with sketches if applicable) from the just ending month.

I find it discouraging that there appears to be so little (relatively speaking) Internet discussion and sharing of observations relating to the recent impact on Jupiter. This is only the second time in recorded history that a Jovian impact event has been positively identified and observable with backyard telescopes.

Then there's imaging. It seems that more and more amateurs are becoming interested in setting their eyes aside and letting their cameras do the looking. With visual observing and sketching I feel that I'm in a minority special interest group within a minority hobby. I get the impression that few care to see sketches when digital cameras can show more detail and more color with less work under worse conditions. Such are a few of my thoughts in the early twenty-first century.

Impact on Jupiter!

Date: 21 July 2009
Time: 8:52 - 9:02 U.T.
Telescope: 13cm refractor
Magnification: 218x
Seeing: Fair
NELM: 6.5
Temperature: +46 F (+8 C)

The above sketch is mirror-reversed due to the use of a star diagonal. North is up. Preceeding is to the left. The dark spot to the lower left (southwest) is a new impact scar on Jupiter. The small, dark, impact scar was spotted as soon as I looked into the eyepiece and focused the telescope at 218x.

Anthony Wesley, an amateur astronomer in Australia, was the first person to discover this impact scar on the 19th of July. Thanks to the Internet, I heard about the dark spot shortly thereafter.

Considerable fine detail was visible within the two major belts, but I would have had to up the magnification a bit (and taken more time) in order to sketch it. Meanwhile, Jupiter's rapid rotation would have taken the impact scar closer to the planet's preceeding limb and shortly thereafter onto the far side of the planet.

Sunspots: 9 July 2009

Today's sunspot observation was made with the help of Buttercup, a 60mm achromat refractor. The above photo of Buttercup was taken shortly after I had completed today's sunspot sketch. The short cardboard tube visible on the front of the telescope is a home-made solar filter utilizing safe, Baader Solar Filter material. Permanent eye damage or blindness is likely to occur if proper safety procedures are not followed when observing the sun. The telescope's finder has black covers over both ends as a further safety measure.

Today's sketch, shown above, has north up and preceeding to the left. The image is mirror-reversed due to the use of a star diagonal. A magnification of 70x was utilized. The sketch shows just a small region within the telescope's field of view.

When sunspots are observed near the limb of the sun one should always look for faculae -- areas that appear brighter than the background solar surface. Faculae were noticed and sketched today, but those regions do not show up well in the scanned image.

July 7th Sunspot Group

The above sketch shows the sunspot group observed from 15:54 until 16:04 U.T. on 7 July 2009. A 60mm f/11 achromat refractor (Buttercup) was used at 70x for the observation and sketch. Use of a star diagonal resulted in a mirror-reversed view. North is up and preceeding is to the left. It's good to finally see some sunspot activity on our nearest star!

Moon Occults Venus

The above sketch shows Venus and Earth's moon after sunrise, but just before the moon passed in front of Earth's sister planet on Earthday morning. The sketch is a fairly close approximation of the view through 20x80 binoculars. East is toward the lower left. North is toward the upper left.

Later in the day I showed students our moon, Venus, and the sun using Buttercup (a 60mm refractor) at 28x. Some of the students managed to see the moon and Venus in the daytime with their unaided eyes! By this point in time Venus was a fair distance west of the moon.

Buttercup views Saturn: 16 March 2009

Saturn and Titan were sketched last night while observing with Buttercup, a 60mm refractor. The planet was tiny at 28x and still rather small at 70x -- the magnification used for the above observation. North is approximately up. Preceding (west) is to the left. A subtle, slightly darker band was just visible (or suspected) north of and running parallel to the ring plane. The point of light to the left of Saturn is Saturn's largest moon, Titan.