Lens Reflector
2009
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Lens Reflector
Spotlights and Ellipsoidal Reflector Spotlight
A spotlight is general term for any lighting instrument used in theater to create a pool of light on the stage.There are many different types of spotlights which break down into three general areas:
Fresnel lanterns or Fresnels (US) are small fixtures giving a soft-edged spot or pool of light. Their name comes from the distinctive ridged Fresnel lens used on the front. recommend directory: 5050 SMD Flexible Strip with non-waterproof 5 Meter 150 LEDS.
Profile spots (UK) or ellipsoidal reflector spotlights (US) tend to be longer fixtures containing convex lenses and having a gate at their focal point which enables the insertion of gobos or irises to shape the beam of light. They give a hard-edged beam most often associated in the public mind with "spotlights". Large versions are operated by a technician as a 'followspot' to follow performers on the stage.
Pebble Convex lanterns (or "PCs") are similar to Fresnels, but use a plano-convex lens with a pebbled effect on the planar (flat) side, resulting in less
"spill" outside the main beam.[16] They are used much more widely in Europe than North America.
A Fresnel lantern (UK), or simply Fresnel (US), employs a Fresnel lens to wash light over an area of the stage. The lens is named after French physicist Augustin-Jean Fresnel, and consequently pronounced with a silent "s". The distinctive lens has a 'stepped' appearance instead of the 'full' or 'smooth' appearance of those used in other lanterns. The resulting beam of light is wide and soft-edged, creating soft shadows, and is commonly used for back light, top light, and side light. Another method of controlling the spread of light is to use either a top hat (also referred to as a snoot), which generally limits the light coming out, or a barn door, whose flaps work as though they were shutters on an ERS (shown on the right). These methods limit light output and keep excess light from spilling into the eyes of audience members or where it is not desired. Fresnels use a spherical reflector, with the lamp at the focus point. The lamp and reflector remain a fixed unit inside the housing, and are moved forward and back to focus the light. This is accomplished using a slider on the bottom or side of the lantern, or using a worm track. At very tight focus, the lanterns are the least efficient, as the least light can escape the housing. Therefore Fresnels are not good for tight focus on small areas. They are most often used at medium distances from the stage for area lighting.
In 1999, ETC introduced a new lighting fixture, the Source Four PARNel, which combined the design of the PAR fixture with that of the Fresnel. The fixture is more versatile, allowing for a flood or a softer spot.
The ellipsoidal reflector spotlight (ERS), also known as profile (after its ability to project the silhouette or profile of anything put in the gate) (UK) and PC (French), is the most abundant instrument type currently in theatrical use. The flexibility of the ERS allows it to fulfill the bulk of lighting roles in the theater. They are sometimes known as a profile spotlight (in Europe) or by their brand names, especially the Source Four (a popular lantern from ETC) and the Leko (short for Lekolite, from Strand lighting).
The major components of an ERS light are the casing in which the internal parts are mounted, an ellipsoidal reflector located in the back of the casing, a lamp mounted to position the filament at the rear focal point of the ellipsoid, a dual plano-convex lens (two plano-convex lenses facing each other in the barrel), and at the front, a gel frame to hold the color gel. The light from the lamp is efficiently gathered by the ellipsoidal reflector and sent forward through the gate, shutters and lens system. recommend directory: 3528 SMD Flexible Strip with waterproof 5 Meter 150 LEDS.
ERS or profile lanterns have many useful features. One of the most useful are the metal shutters at the focal plane of the lens to shape the beam of light. The original shape of the beam is round, but with the use of the shutters one can limit the beam to avoid obstacles or parts of the set that should not be illuminated in a specific look. Another feature is a gate, also in the focal plane, for sliding in gobos (also known as templates or deckles). These have patterns cut into them, much like a stencil. These patterns are projected onto the stage. An iris can be also be inserted in this position to make the beam smaller in diameter, reducing the light cast without the sharp edges of the shutters. ERS instruments from ETC, Altman, Selecon, and a variety of others have interchangeable lens tubes (or barrels) which can both create a very sharp or very soft beam as well as alter the beam spread. The barrel sizes can range from a narrow, long distance 5- or 10-degree spot to a broad and short-distance 50- or even 90-degree. The first 90-degree profile lantern was developed by Selecon Performance Lighting as part of their "Pacific" range of products. Since its introduction many other manufacturers have introduced their own 90-degree barrels.ERS instruments allow many different lens tubes to be used with the same body. This makes them more versatile, since a venue can purchase varying degrees of barrels without buying as many instruments. Many manufacturers also produce zoom lenses which offer the ability to change the beam angle. However, some zoom ranges have a poorer optical quality making them difficult to use in sharp focus.
The field angle of an instrument is the angle of the beam of light where it reaches 10% of the intensity of the center of the beam. Most manufacturers now use field angle to indicate the spread that the fixture has. However, older fixtures are described by the width of the lens x focal length of the instrument. For example, a 6x9 ellipsoidal would have a 6" lens and a focal length of 9" (creating an approximately 37° beam angle). This nomenclature was used because traditionally a larger lens directly equated with more light output. This is no longer necessarily true, so most manufacturers now identify their fixtures by beam angle and light output. As the field angle narrows, the instrument can either be used further from the stage to create a similarly-sized beam as a closer, larger instrument, or it can be used from the same distance to create a smaller beam. recommend directory: 3528 SMD Flexible Strip with Non-waterproof 5 Meter 300 LEDS.
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can only see white through EDU-SCIENCE 600 power telescope?
the finder scope works great. I line the finderscope up and get it focused and I can see the object great, but when I go to use the telescope it looks like i am looking at a lightbulb and it doesn't matter how much I try to focus it. when I take the eye pieces (it came with 4) out and look that way I can see the object but also see the reflector lens . does this make since. can anyone help.
Try it in daylight first, if it has a barlow do not use it.
Use the longest focal length eyepiece, the one with the biggest number on, probably the 25mm one and rack the focus in and out.
If the best focus is at the end of the travel try sliding the eyepiece out about 10mm
point it at something a long way away, at least 400 yards. it will not focus on nearby objects.
If you look without the eyepiece in all you should see is the "spider" that supports the secondary mirror (the small one at the front
LED test without red lens/reflector
