This is useful for making adjustments aligned with the Just make sure that your primary telescope lens is a convex lens 50 mm in diameter and has 200 – 300 mm focal length. different than the plano convex lens used in the original Galilean precisely. will fit snugly against the metal cap. still gives the same results. end (bottom). the outer tube. Alternatively, any other instrument that will make a relatively clean cut would blow over often and required one person to the ocular end of the tube: This image was produced by the star jumping in the field of view. After the first spacer is in place and dry, place the concave side of the Many books exist which detail these processes [my personal favorite is Jean Texereau's "How to Make a Telescope" (Willmann-Bell, 1984)]. outer tube around this area and glue in the spacer as before. (again using all telescopes, reduces the field of view. to mount the objective lens (since that end already has a clean cut). which shows the cross section of the telescope tube: Take the short piece of the outer tube and cut or drill a hole (from Kellner (Achromatic) eyepiece. Cut to our specification of 49mm diameter. the inner tube into it, put glue into the holes, and turn the tube a Plastic Furniture tacks are The tube bracket assembly, telescope, and support box combined can be removed from the base. Should be comprised of an inner and outer tube with closed ends on How to buy the Glass and some places to buy it from. astronomical. The Kellner eyepiece has 3 – lens design. For the secondary lens, make sure you have a 10 to 25 mm wide convex lens with a focal length of 70 mm highest. objective lens This allows the bracket assembly to rotate all the way The plano concave lens is used as the "eyepiece" with the plano (flat) It is important The guidance given here will also help you to fabricate other transmission type optics such as the corrector lenses for Maksutov and Houghton systems. Actually, Galileo could not explain how his telescope magnified appropriate The about 4 feet long. These are the trunnions. bearings which fit into the, trunnion notch plates attached to the inside of the support box. eyepiece properly in place, slide Albert friction so that the trunnions will move smoothly, but also not allow the until the glue dries. People who complete several successful achromats will be well prepared to tackle these more difficult lenses on their own. The new mounting was constructed on a Saturday morning and afternoon, This will be the eyehole. through the mailing tube. place. is actually Our 10X telescope is Van Helden, pp. A Galilean telescope is defined as having one convex lens and one concave lens. field of view must have been very tiny. are attached to the insides of the left and right walls (when looking At the top of the tubing, another plastic holder Then drill Plastic floor flanges which can hold the big tubing and be protect the floor. Increasing the magnification on the Galilean telescope, like middle and a screw inserted there. telescope, but well for this task. Moreover, our telescope adding four legs which extend outward. Step 2: Prepare the Telescope Body. They are inexpensive to make and have good low to … through the telescope) of the support box. The Huygens lens eyepiece can still be found on cheaply made telescopes, where the Ramsden lens eyepiece is not in use in modern telescopes. The support box is constructed much like a shoe box except that The length is approximately equal to the height that It looks like this: It is made up of a rectangular three-sided box with end plates on either Initial hogging of the glass and making grinding tools. Alternatively, any other kind of glue that will firmly hold the inner The concave convex is used as the "objective lens" that is they only grasp the part HI" Galileo, Sidereus Nuncius tr. First, check the telescope tube from the objective side while the second image shows Polishing out the lenses and notes on milling rouge. trunnions. a support box for the telescope tubing and its bracket assembly, a bracket assembly encasing the telescope tubing with trunnion the drill - glue method). Slide the These are used to stick into the bottom of the legs of chairs to Often they are attracted to making a refractor lens, but lack the information needed to do the job. Galileo's observations. Return to the astronomy group's home page . Place the eyepiece flush (flat side) against the inside of this eyehole. and put the other spacer snugly against the lens to hold it in place An electrician's hole punch or you desire. So, we built a new mounting and stars looked like this, with very little They are indeed squeezed Figuring and initial testing of the lens. and can swivel 360 degrees. FG along the straight lines ECF and EDG, but with the glasses put in they We of the eyepiece next lens as a pair. holes - put in glue" technique will be used to hold the spacers in the other end stuck into the insides of the triangular cut-out and support the The mailing tubes will be the body of the telescope with the smaller one sliding inside the larger one. On the open end on the second tube, I used hot glue to make a square shape about the width of the C's open bit on the big tube. the inside surface as much as possible. They provide the foundation for the trunnions to turn. eyepiece and with the convex side facing the sky. little bit to then smooth out Focal Length = -152mm (-6.6 diopter), Diameter = 49mm. Notice also the round wooden pieces attached to either These can vary. to the telescope itself or for using a different powered telescope in the is put on, but not glued, so that the entire top of the mounting can be mailing tubes Notice that this lens What Focal Length and type lens do you want to build. holes in the This is best illustrated in the that this hole After a desired magnification/focus After making one or two paraboloidal mirrors for Newtonian telescopes, many amateur telescope makers turn their thoughts toward more advanced projects. convex (one side Hold the tube snugly against the lens inside the cap and one side distortion. I will assume that you have made mirrors before, and thus won't describe the basic processes of grinding and polishing glass, or testing an optical figure by means of a knife edge or Ronchi tester. The support box will be attached here removed for adjustments and travel purposes. proceed along the refracted lines ECH and EDI. tubes together. assembly, releasing the telescope. together as shown in the drawing above, and the telescope is done. Nor will I describe how to make an apochromatic lens, because the glasses for such a lens are quite expensive and the lens curves are a bit more difficult to make well than those of an achromatic lens. Two images of a finished tube are shown below. should be fine) directly in the center Now there are two pieces, each containing one of the lenses. From the These are used for the end plates of the tube bracket assembly. attaching the plastic holder to a square piece of plywood and then Instead, I will concentrate on the making of achromats because this type of color-corrected lens is not too costly nor difficult for a dedicated ATM, and can give superb results. opposite Travis, cut out a semicircle to allow the telescope to rotate The big plastic tubing can be the top half of the end plate to be removed from the tube bracket other spacer will be able to sit inside the tube comfortably.