Assembling the Galileoscope
When I first heard of the Galileoscope, I knew I had to have one. I have been on the waiting list for an Astro-Physics Traveler for many years now but who knows when they will make another 105mm refractor. I’m more of a reflector guy anyway, but I have always appreciated the view through a refractor.
I thought it would be neat to look through a telescope about the same size as that used by Galileo 400 years ago and compare what he saw versus what I can see with my reflector. I know there won’t be any comparison, but it will be interesting to see the differences.
I received my telescope many months after it was promised, but I wasn’t in that much of a hurry so it didn’t matter. When it did show up, I was excited, because in addition to looking through it, you also put it together! It is a kit. It would be the first telescope I built myself.
There are some simple instructions that come with it, but more extensive instructions are available on-line. I’m glad I got these.
I carefully followed the steps for unpacking the box. The 2” 50mm objective lens was heavy and the six eyepiece lenses were small and light.
The objective lens is actually two lenses cemented together. One lens is thinner and the other thicker.
The telescope tube comes in two halves. The kit comes with handy v-shaped blocks for supporting the tube while you are assembling the telescope. I rested one half of the tube on the blocks and carefully inserted the objective lens in its groove (thin lens out). I only touched the lens with the tissue paper it comes wrapped in. I didn’t want to get any fingerprints on my brand new lens!
The telescope mounts on a standard tripod ¼” threaded screw, so the next step was inserting a ¼” nut into a special slot that keeps it from turning.
The focuser is a drawtube and that needs to be put together before the other half of the telescope is placed. The drawtube also comes in two halves that are cleverly held together with o-rings. The assembled drawtube is placed in the bottom half of the main tube.
After affixing the mandatory “Don’t look at the sun!” sticker, I placed the other half of the main tube on top and secured it by sliding the lens shade/dew cap on the front and a clamp ring on the back. I made it extra tight with another set of optional o-rings. It fit very snugly.
Now that the telescope was together (about 15 minutes of careful work), it was time to make the eyepieces. The barrels for these came in two halves, just like the telescope and drawtube.
The main eyepiece consists of four lenses. The lenses are paired like the objective lens, but not cemented together. In addition, these are plastic rather than glass. One lens of each pair is flat on one side and convex on the other, while the other is convex on both sides. The convex side of the double convex lens fits into the concave side of the other. Together, these pairs create a Plossel type eyepiece. You have to be careful to put the flat sides of the two lens pairs to the outside.
Next comes the field stop; a ring of plastic designed to provide a sharp edge to the field of view. Other plastic rings press fit on the front and back of the eyepiece to hold everything together.
The main eyepiece provides a magnification of 25x and a true field of about 1.5 degrees: the width of three full Moons.
I couldn’t resist trying it immediately, so I inserted the eyepiece into the telescope, held it up to my eye and pointed it at the flowers across the street. The drawtube slid smoothly, bringing the flowers into clear focus. It worked! It was upside down of course… :)
Galileo didn't have too many choices when it came to eyepieces. The images his produced were very small and full of aberrations. On the plus side, the images were right side up.
The kit allows you to build this type of eyepiece, or use the same lenses to make a 2x Barlow. Very clever!
I started out with the Barlow configuration and was able to these the flowers across the street twice as big. It was very difficult at this magnification (50x) to hold the telescope steady.
Then I decided to try the Galileo eyepiece. All you have to do is remove the lens assembly from the Barlow and add another ring to make it into an eyepiece that will insert into the drawtube. The field of view is very narrow and the magnification is less than the main eyepiece (17x versus 25x), but the image is upright. It is like looking through a soda straw.
So what I put together is not really the same as what Galileo had; it was far superior! Imagine what Galileo could have seen with a modern day Plossel!
I feel fortunate to live at a time when an affordable telescope can show people the night sky so they can expand their imaginations up to the stars and beyond.
First Light: I used it to look at Jupiter tonight and at 25x, I could easily see all four Galilean moons. Using the barlow (50x), I could see Jupiter’s cloud bands when the seeing was steady. I reconfigured the barlow lens to act as a Galilean eyepiece (17x – very narrow field of view) and saw the moons of Jupiter much like Galileo did.
I learned recently that on Sept 2nd, there will be a “moonless” Jupiter. All of its moons will be either eclipsed by the planet or in its shadow. Guess which telescope I’m going to use to observe that? :)
I thought it would be neat to look through a telescope about the same size as that used by Galileo 400 years ago and compare what he saw versus what I can see with my reflector. I know there won’t be any comparison, but it will be interesting to see the differences.
I received my telescope many months after it was promised, but I wasn’t in that much of a hurry so it didn’t matter. When it did show up, I was excited, because in addition to looking through it, you also put it together! It is a kit. It would be the first telescope I built myself.
There are some simple instructions that come with it, but more extensive instructions are available on-line. I’m glad I got these.
I carefully followed the steps for unpacking the box. The 2” 50mm objective lens was heavy and the six eyepiece lenses were small and light.
The objective lens is actually two lenses cemented together. One lens is thinner and the other thicker.
The telescope tube comes in two halves. The kit comes with handy v-shaped blocks for supporting the tube while you are assembling the telescope. I rested one half of the tube on the blocks and carefully inserted the objective lens in its groove (thin lens out). I only touched the lens with the tissue paper it comes wrapped in. I didn’t want to get any fingerprints on my brand new lens!
The telescope mounts on a standard tripod ¼” threaded screw, so the next step was inserting a ¼” nut into a special slot that keeps it from turning.
The focuser is a drawtube and that needs to be put together before the other half of the telescope is placed. The drawtube also comes in two halves that are cleverly held together with o-rings. The assembled drawtube is placed in the bottom half of the main tube.
After affixing the mandatory “Don’t look at the sun!” sticker, I placed the other half of the main tube on top and secured it by sliding the lens shade/dew cap on the front and a clamp ring on the back. I made it extra tight with another set of optional o-rings. It fit very snugly.
Now that the telescope was together (about 15 minutes of careful work), it was time to make the eyepieces. The barrels for these came in two halves, just like the telescope and drawtube.
The main eyepiece consists of four lenses. The lenses are paired like the objective lens, but not cemented together. In addition, these are plastic rather than glass. One lens of each pair is flat on one side and convex on the other, while the other is convex on both sides. The convex side of the double convex lens fits into the concave side of the other. Together, these pairs create a Plossel type eyepiece. You have to be careful to put the flat sides of the two lens pairs to the outside.
Next comes the field stop; a ring of plastic designed to provide a sharp edge to the field of view. Other plastic rings press fit on the front and back of the eyepiece to hold everything together.
The main eyepiece provides a magnification of 25x and a true field of about 1.5 degrees: the width of three full Moons.
I couldn’t resist trying it immediately, so I inserted the eyepiece into the telescope, held it up to my eye and pointed it at the flowers across the street. The drawtube slid smoothly, bringing the flowers into clear focus. It worked! It was upside down of course… :)
Galileo didn't have too many choices when it came to eyepieces. The images his produced were very small and full of aberrations. On the plus side, the images were right side up.
The kit allows you to build this type of eyepiece, or use the same lenses to make a 2x Barlow. Very clever!
I started out with the Barlow configuration and was able to these the flowers across the street twice as big. It was very difficult at this magnification (50x) to hold the telescope steady.
Then I decided to try the Galileo eyepiece. All you have to do is remove the lens assembly from the Barlow and add another ring to make it into an eyepiece that will insert into the drawtube. The field of view is very narrow and the magnification is less than the main eyepiece (17x versus 25x), but the image is upright. It is like looking through a soda straw.
So what I put together is not really the same as what Galileo had; it was far superior! Imagine what Galileo could have seen with a modern day Plossel!
I feel fortunate to live at a time when an affordable telescope can show people the night sky so they can expand their imaginations up to the stars and beyond.
First Light: I used it to look at Jupiter tonight and at 25x, I could easily see all four Galilean moons. Using the barlow (50x), I could see Jupiter’s cloud bands when the seeing was steady. I reconfigured the barlow lens to act as a Galilean eyepiece (17x – very narrow field of view) and saw the moons of Jupiter much like Galileo did.
I learned recently that on Sept 2nd, there will be a “moonless” Jupiter. All of its moons will be either eclipsed by the planet or in its shadow. Guess which telescope I’m going to use to observe that? :)
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