Make Telescopes: Make Them, Use Them
The history of the telescope makes for interesting reading from a theoretical perspective, but also from the perspective of someone interested in beginning to make a telescope. During the development of the telescope, practical experiments with reflectors had already begun in 1639, but it was not until 1663 that they gained any prominence.
The Gregorian Telescope
High magnification could be had with this instrument, the second reflection amplifying the focal length of the primary in the ratio of fs to Fs.
He began to make telescopes, but whatever chance it may have had of performing creditably was lost by polishing the speculum on a cloth lap – putty (tin oxide) being used as the polishing agent. The Cassegrainian Telescope
Sieur Cassegrain, a Frenchman, in 1672 designed a second compound reflector, differing from Gregory’s in that it employed a convex secondary, to be of hyperboloidal figure, placed inside of the focus of the paraboloidal primary .
The Newtonian Telescope
The history of the telescope takes an interesting turn at this point. In the same year, Newton designed and began to make telescopes that had two small reflectors, of the type so popular with amateur astronomers today and which still bears his name. They were not large, as we know telescopes today, the effective apertures of the concave specula being about 1 1/3″. Their focal length was 6″, making the focal ratio f/4.5.6
Newton, according to his Opticks (1704), polished his specula on pitch, using putty as the polishing agent. It might be concluded that if the center of the mirror were properly deepened, that is, given a shorter radius, or if the radii of the outer zones were progressively lengthened, or if a little of each were done, all the reflected rays could be brought to a common focus. The standard practice is to deepen the spherical mirror so that, for a 6-inch f/8 mirror, the glass removed in the operation is but half a wave length of light in thickness at the center. The field lens, like Galileo’s concave lens, is placed before the focal plane of the objective.
Ever since Galileo took a Dutch invention and adapted it to astronomical use, astronomical telescope making has been an evolving discipline. Many astronomers after the time of Galileo built their own telescopes out of necessity, but the advent of amateurs in the field building telescopes for their own enjoyment and education seems to have come into prominence in the 20th century.
Today telescopes of the size and technicality used by NASA experts are out of an amateurs grasp (and price range), but an amateur can easily begin to make telescopes of the kinds mentioned above both inexpensively and easily.
Photography Lighting & Equipment Tips : How to Use Light Reflectors in Photography
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New 600 Watts HPS + MH Dimmable Digital Ballast Grow Light Kit Reflector 600W $189.95 |
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400 Watt Digital Ballast Grow Light Kit HPS and MH Bulbs Bat Wing Reflector 400w $0.01 |
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600w Digital HPS+MH Grow Light Kit Air Cooled Cool Tube Reflector Hood 600 Watts $199.95 |
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1000 Watt HPS MH Tube Reflector Air Cool Grow Light Kit System 1,000 1000w W $213.80 |
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6″ x 27″ COOLTUBE AIR COOLED GROW LIGHT REFLECTOR COOL TUBE 4 HPS MH HYDROPONIC $65.99 |
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1 Pair Lighthouse Hydro Yo Yo Adjustable Grow Light Reflector Hangers – 24LB Cap $11.95 |
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New 2pcs 1/8″ LED Grow Light Rope Ratchet Reflector YoYo Hanger for Grow Lights $0.01 |
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2 Pair Lighthouse Hydro Yo Yo Adjustable Grow Light Reflector Hangers – 24LB Cap $18.99 |
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1000 Watt HPS+MH Grow Light 42″ HV Reflector Magnetic Ballast Sun Lamp Kit 1000W $249.95 |
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NEW HYDROFARM RD6AC Radiant 6″ Air Cool Grow Light Reflector Unit w/Cord $123.62 |
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400 Watt Digital HPS+MH Grow Light Sun System 400W Hood Reflector Lamp Ballast $144.95 |
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2 Pair Lighthouse Hydro Yo Yo Adjustable Grow Light Reflector Hangers – 24LB Cap $18.99 |
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NEW HYDROFARM RD6AC Radiant 6″ Air Cool Grow Light Reflector Unit w/Cord $123.62 |
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600W HPS Grow Light Premium System XL Hood Reflector 600 Watt Digital Ballast $164.95 |
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Cub Cadet Pulling Tail Light or Reflector Replacement Tread Brite Plates $5.00 |
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1000W Digital Ballast HPS + MH Grow Light set Reflector $219.95 |
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600w HPS Grow Light Kit Air Cool Tube 2-in-1 Reflector 600 Watt Digital Ballast $219.95 |
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12X Adjustable Yoyo HPS MH Grow Light Roller Reflector Hanger 3 Pair Hydroponics $39.95 |
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T5 8 bulb Grow light reflector for Greenhouse & Indoor Gardens $49.00 |
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1000 Watt HPS MH Tube Reflector Air Cool Grow Light Kit System 1,000 1000w W $213.80 |
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Sun System Agrotech Magnum Reflector Grow Light Fixture Hood Hydroponic MH HPS $109.50 |
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Sun System Agrotech Magnum Reflector Grow Light Fixture Hood Hydroponic MH HPS $109.50 |
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Sun System Agrotech Magnum Reflector Grow Light Fixture Hood Hydroponic MH HPS $109.50 |
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Sun System Agrotech Magnum Reflector Grow Light Fixture Hood Hydroponic MH HPS $120.95 |
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1000 Watt Digital HPS Grow Light Cool Tube Reflector 1000W Air Cooled Hood Gift $244.95 |
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Virtual Sun 600W HPS MH Grow Light Tube Reflector Hood Digital Kit- Dimmable $239.99 |
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Virtual Sun 1000W HPS MH Grow Light Winged Reflector Hood Digital Kit – Dimmable $279.00 |
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Virtual Sun 400W HPS MH Grow Light Tube Reflector Hood Magnetic Kit – 400 Watt $189.99 |
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Virtual Sun 1000W HPS MH Grow Light Tube Reflector Hood Digital Kit- Dimmable $309.99 |
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Virtual Sun 1000W HPS MH Grow Light Winged Reflector Hood Digital Kit -1000 Watt $269.00 |
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Earthmate EP085250 8-Watt, Dimmable BR30 2700K Bulb, 6 Pack $146.94 … |
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Hydrofarm SBM175H 175-Watt Mini Sunburst Metal Halide with Lamp $86.89 Plug-and-play: comes with cord and lamp.Highly reflective European specular.Magnetic 175W MH Super quietEasy to hang lightweight and compactIncludes instructions hangers and lighting recommendations… |
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MollaSpace While You Weren’t Home Reflector Keychain, Drunk Rabbit $5.95 As you walk home in the dark, these reflectors will shine bright when hit by a light. At the same time, it’ll show what your adorable pets may be doing at home when you’re out of the house!! Comes with a keychain and a hook ring! Designer: Arthur Yung… |
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Mag-Lite ST3D016 3-D Cell LED Flashlight, Black $23.32 … |
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Bird-X TAPE-25 Irri-Tape Bird Repellent Ribbon $5.65 Holographic iridescent diffraction foil drives away birds. Repel birds holographically, Irri-Tape bothers all of a bird’s senses: Visual Scare: birds are scared by the material’s sheen, as the light causes constantly changing reflections and shadows. Sound scare: birds are rattled by the fierce metallic noise irritape makes as it blows in the breeze. Physical Deterrent: birds are blocked by Irri-T… |
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Emergency Sleeping Bag, Survival Bag, Emergency Zone Brand, Reflective Blanket $2.79 Emergency Zone Brand. The Emergency Sleeping Bag is made of the same Mylar material as our emergency blanket but is formed into a sleeping bag to prevent heat loss even more efficiently. The bag retains 80 percent of body heat and is wind and waterproof. The bag measures 36 x 84 inches…. |
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Sylvania 14502 50 Watt PAR20 Narrow Flood Light Bulb / 30 Degree Beam Spread / 120 Volt 50 watt 120 volt PAR20 Medium Screw (E26) Base 2,950K Narrow Flood Capsylite Halogen Incandescent Sylvania Light Bulb… |
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Sylvania 15172 65-Watt 130-Volt BR30 Indoor Flood Light, 6 Pack $10.25 … |
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GU10 120v 50w MR-16 50 Watts JDR C Halogen Bulb Lamp $0.01 GU10 120v 50w MR-16 MR16 Long Life Lamp Premium quality by Divine Lighting This is 50 watts, 30 degrees. We also sell 35-watt and 75-watt versions. Integral rounded cover glass, slightly rounded. Manufacturer : |
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Planet Bike Beamer 1 and Blinky 3 LED Bicycle Light Set $24.99 Offering long runtimes and exceptionally bright LED light, the Beamer 1 Light Set from Planet Bike is a great choice for daily riders, commuters, and pleasure riders alike. The Beamer 1 headlight provides four times brighter light than prior models with an eXtreme V2.0 genuine Nichia LED bulb that will not dim with age. The Beamer 1 mounts easily to your handlebar and the beam can be aimed where y… |
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100785 Zoom Reflector 2 $214 The Profoto Zoom Reflector 2 is a smoother more accurate reflector with an integrated grid holder that accepts Profoto grids directly with no more need for you to purchase the expensive extra grid holder. The light from the reflector is smoother yet more precise and the fall-off is more even as well. It offers a more dynamic range. Stray light is almost completely eliminated . The Zoom Cap, which is an optional protection cap, fits on top of the reflector, even while it’s holding a grid or if the reflector is mounted on a lamp head. |
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SOLAR REFLECTOR LIGHT ON STAKE $54.98 The Solar Reflector with Shepherds Stake will illuminate outdoor spaces with soft ambience. Antique style solar lantern hangs on a classic shepherds hook garden stake. During the day the solar panel absorbs the suns natural energy. As the sun sets the |
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Solar Reflector Light On Stake $54.98 The Solar Reflector with Shepherds Stake will illuminate outdoor spaces with soft ambience. Antique style solar lantern hangs on a classic shepherds hook garden stake. During the day the solar panel absorbs the suns natural energy. As the sun sets the |
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Chameleon 42 5-in-1 Reflector $64.94 Chameleon 42″ 5-in-1 Reflector 42″ diameter 5-in-1 Reflector and case. The Chameleon 5-in-1 panels are a light weight, circular, spring-steel reflector system. Each 5-in-1 includes a zippered carrying pouch for easy storage and transportation. The panels fold conveniently into the pouch which is a smaller disk approximately 1/3 the size of the open reflector. The Chameleon reflectors provide five functional surfaces – Silver, Black, White, Gold and Translucent. |
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Chameleon 32 5-in-1 Reflector $53.94 Chameleon 32″ 5-in-1 Reflector 32″ diameter 5-in-1 Reflector and case. The Chameleon 5-in-1 panels are a light weight, circular, spring-steel reflector system. Each 5-in-1 includes a zippered carrying pouch for easy storage and transportation. The panels fold conveniently into the pouch which is a smaller disk approximately 1/3 the size of the open reflector. The Chameleon reflectors provide five functional surfaces – Silver, Black, White, Gold and Translucent. |
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Chameleon 22 5-in-1 Reflector $43.94 Chameleon 22″ 5-in-1 Reflector 22″ diameter 5-in-1 Reflector and case. The Chameleon 5-in-1 panels are a light weight, circular, spring-steel reflector system. Each 5-in-1 includes a zippered carrying pouch for easy storage and transportation. The panels fold conveniently into the pouch which is a smaller disk approximately 1/3 the size of the open reflector. The Chameleon reflectors provide five functional surfaces – Silver, Black, White, Gold and Translucent. |
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100624 Magnum Reflector $309 For maximum output with a normal beam spread. The Magnum Reflector provides strong, smooth light. Although this is not a true focusing reflector, zooming it across the focal point does create interesting lighting effects. To achieve precise control over direction of the light, the Magnum can be supplemented by the ProTube, Honeycomb Grid or Barn Doors. The crisp character a high output makes this reflector very popular as fill-in light source against direct sunlight. |
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Exo Terra Light Dome Aluminum UV Reflector Lamp $28.69 Exo Terra Light Dome Aluminum UV Reflector Lamp |
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20 in BI-LIGHT II INC STRIP REFLECTOR 2 BULBS $29.28 20 in BI-LIGHT II INC STRIP REFLECTOR 2 BULBS |
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Ideal Studio Equipment 5in1 Elliptic Type Reflector $42.99 Ideal Studio Equipment 5in1 Elliptic Type Reflector. The 5in1 reflector kit is ideal as a fill light for portrait photography. We use this self standing reflector kit for continuous light diffusion like a softbox and for a soft reflected fill light off the main key light. The Reflector lect sunlight to create professional image. |
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5in1 Elliptic Type Studio Equipment Reflector $41.99 Ideal Studio Equipment 5in1 Elliptic Type Reflector. The 5in1 reflector kit is ideal as a fill light for portrait photography. We use this self standing reflector kit for continuous light diffusion like a softbox and for a soft reflected fill light off the main key light. The Reflector lect sunlight to create professional image. |
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Lastolite TriGrip 33 Photographic Reflector $78.99 This reflector can be held in 1 hand for convenient, accurate positioning and features a double-sided design for harsh or softer light. |
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Studio Equipment 80cm 2in1 Folding Reflector $11.99 The reflector kit is ideal as a fill light for portrait photography. We use this self standing reflector kit for continuous light diffusion like a softbox and for a soft reflected fill light off the main key light. The Reflector lect sunlight to create professional image. |
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Studio Equipment 5in1 Elliptic Type Reflector $47.69 The 5in1 reflector kit is ideal as a fill light for portrait photography. We use this self standing reflector kit for continuous light diffusion like a softbox and for a soft reflected fill light off the main key light. The Reflector lect sunlight to create professional image. |
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Mini Elliptic Type Collapsible Reflector(White) $4.19 - Collapsible reflector – White produces an even, neutral-colored bounce light that works beautifully as a fill light source |
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100794 D1 Spill Kill Reflector $114 Profoto’s D1 monolight has a compact form factor with a built-in 77° reflector. The D1 Spill Kill Reflector is specifically designed to offer additional control of stray light when using the D1 250 / 500 / 1000W/s monolights with umbrellas. |
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30-inch Light Multi Collapsible Disc Reflector $22.04 - It comes with silver, gold- Those are the most popular reflector in photograph. – It is a must for studio or outdoor photography. – It also folds into a easy carrying pouch. |
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Finger Shaped Car Mark Light Reflector Blue $8.49 Description:Easy to install and use, adds elegance to your carThis is non-OEM generic productBlue Reflector made of acry plastic materialsBee eye finger shaped Car Light Reflector for your cars!Safety Car Reflector will reflect lights from other cars, warn the other driversWidely used on cars, motorbike and other vehiclesDouble side adhesive tape on the back of the Car Stop ReflectorDimension: 13 x 7 x 0.8cm(each one)Color: blueWeight: 90gPackage included:2 x Finger Shaped MarkDirection:Unsteady surface and unpainted resin can not be attachedMake the surface clean and dryDry the surface, rip the protector paper and then stick to the surface firmly |
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Studio Equipment 60cm Double Colour 2in1 Folding Reflector $13.99 Studio Equipment 60cm Double Colour 2in1 Folding Reflector. The reflector kit is ideal as a fill light for portrait photography. We use this self standing reflector kit for continuous light diffusion like a softbox and for a soft reflected fill light off the main key light. The Reflector lect sunlight to create professional image. |
