ANSI Lumens
ANSI (American National Standards Institute) lumens refers to the brightness of a projector. Fundamentally speaking, the higher the number, the brighter the projector. How bright the projector is governs how big a screen it can be used on and/or how much ambient light is bouncing around in the room. If you are projecting onto a 6’ wide screen a 2000 lumen projector should be perfectly adequate even in normal office lighting conditions but if you had a larger screen or much brighter room a more powerful projector would be necessary. As a rule of thumb, to achieve a bright image with good contrast in normal office lighting, allow about 500 lumens/meter2. Typically home cinema projectors range from 1000 – 2000 lumens because most people don’t have a screen any bigger than 6’ – 8’. Our Panasonic PT-AE3000E projector is 1600 lumens and looks amazing on a 10’ screen in a fully darkened room! The same is true if you need to hire a projector for your office meeting but because there is likely to be more ambient light a more powerful projector may be required. We have 2000 lumen Sanyo XW57 projectors for hire, ideal for our 6’ screens and 3500 Lumen Sanyo XP41 projectors for larger screens and/or more ambient light. If you need to hire a projector to be used on a much larger screen we have Panasonic DLP projectors that go up 10000 lumens, Sanyo LCD projectors up to 15000 lumens and Christie DLP projector up to 18,000 lumens. If you require brighter projections than a single projector can provide, it is possible to double stack projectors, effectively doubling the brightness.

Aspect Ratio
The Aspect Ratio of an image is the width divided by the height and are expressed as x:y. The most common today are 1.33:1 also known as 4:3, TV format and 1.75:1, commonly expressed as 16:9 or HDTV which are found in both projectors and computer monitors. Even wider formats such as 2.35:1 are also used in feature films. We supply both 4:3 and 16:9 projectors and screens as well as 2.35:1 and custom screen sizes.

Bi-directional Microphone
A microphone's directionality or polar pattern indicates how sensitive it is to sounds arriving at different angles about its central axis. The above polar patterns represent the locus of points that produce the same signal level output in the microphone if a given sound pressure level is generated from that point. How the physical body of the microphone is oriented relative to the diagrams depends on the microphone design. For large-membrane microphones such as in the Oktava (pictured above), the upward direction in the polar diagram is usually perpendicular to the microphone body, commonly known as "side fire" or "side address". For small diaphragm microphones such as the Shure (also pictured above), it usually extends from the axis of the microphone commonly known as "end fire" or "top/end address". Some microphone designs combine several principles in creating the desired polar pattern. This ranges from shielding (meaning diffraction/dissipation/absorption) by the housing itself to electronically combining dual membranes.

Cardioids, Supercardioids and Hypercardioids
Cardiods are named because the sensitivity pattern (see diagram above) is heart-shaped. A hyper-cardioid microphone is similar but with a tighter area of front sensitivity and a smaller lobe of rear sensitivity. A super-cardioid microphone is similar to a hyper-cardioid, except there is more front pickup and less rear pickup. These three patterns are commonly used as vocal or speech microphones, since they are good at rejecting sounds from other directions and also help to reject feedback when used in a live situation A cardioid microphone is effectively a superposition of an omnidirectional and a figure-8 microphone; for sound waves coming from the back, the negative signal from the figure-8 cancels the positive signal from the omnidirectional element, whereas for sound waves coming from the front, the two add to each other. A hypercardioid microphone is similar, but with a slightly larger figure-8 contribution. Since pressure gradient transducer microphones are directional, putting them very close to the sound source (at distances of a few centimeters) results in a bass boost.

Condenser microphone
In a condenser microphone, also known as a capacitor microphone, the diaphragm acts as one plate of a capacitor, and the vibrations produce changes in the distance between the plates. If a D.C. voltage is applied to the circuit, the voltage across the capacitor varies as the sound pressure varies. Condenser microphones can range from cheap karaoke microphones to extremely high quality and expensive recording microphones. Condenser microphones require a power source which is necessary for establishing the capacitor plate voltage, and also for internal amplification of the signal to a useful output level. This can be provided either from microphone inputs as phantom power which can be found on most mixing desks or from a small battery. Condenser microphones are also available with two diaphragms, the signals from which can be electrically connected such as to provide a range of polar patterns (see below), such as cardioid, omnidirectional and figure-eight.

DLP Projectors
Digital Light Processing (DLP) was originally developed by Texas Instruments, in 1987. DLP projectors produce the image by using thousands of microscopic mirrors laid out on a semiconductor chip called a Digital Micromirror Device (DMD). Each mirror represents one or more pixels of the projected image. These mirrors can be repositioned rapidly to reflect light through the lens. Rapidly shifting the mirrors produces grayscales, controlled by the ratio of on time to off time. Colours are produced in a DLP projector in two ways; In a Single-chip DLP projectors colours are produced by placing a spinning color wheel between the lamp and the DMD wheel is usually divided into four sectors, the primary colours; red, green, and blue, and also an additional clear section to boost brightness. In a three-chip DLP projector a prism is used to split the light from the lamp, and each primary colour of light is then routed to its own DMD chip, then combined before coming out through the lens. Three-chip DLP projectors have finer graduations of shades and colours than single-chip projectors, up to 35 trillion! This is because each colour has a longer time available to be modulated within each video frame; furthermore, there won't be any flicker or rainbow effect like with the single chip solution. All of our Sanyo projectors are LCD and can be found here. Our Panasonic projectors are all DLP and can be found here with the exception of the PT-AE3000E. Our Christie projectors all use the latest in DLP technology and are found here.

Dynamic microphone
Dynamic microphones work via electromagnetic induction by detecting changes in sound pressure to move a coil of wire in a magnetic field. When you speak into a dynamic microphone the variations in the air pressure cause a dyaphram whcich is connected to the coil to move. The difference in voltage at either end of the coild is detected. Dynamic microphones are robust, relatively inexpensive and resistant to moisture. This, coupled with their high gain before feedback makes them ideal for on-stage use.

Keystone
When a projector is physically positioned, depending on the angle that it is to the screen, the image projected may not be square. Digital projectors have keystone adjustment to correct this. A typical example would be a projector on low table, projecting onto a screen that is higher. In this instance the image would be distorted. The top of the image would be wider than the bottom and a trapezoid shape. This is easily corrected on a projector by just pressing the keystone button that shrinks the image at the top to square it up again. This is referred to as vertical keystone and is a feature on all of our projectors. Some projectors, usually the more expensive and higher spec models have horizontal keystone too. This means that you can also correct the left and right sides of the image giving even more flexibility in positioning.

LCD or DLP Projectors?
We have both LCD and DLP projectors for hire but it’s a common question; which one is best? The answer is it depends on the application. Here is a list of pros and cons of each system. This is not a definitive list and as technology progresses the pros become greater and the cons are being rectified all the time. If you’re not sure which is best for you, please give us a call and we’ll help you decide. Three chip DLP™ — Pros: Perfect color accuracy. Good contrast; much greater than film theaters. Good shadow detail. Can provide high brightness compared to the limited brightness of single chip versions. Overall image quality deemed as the best of any type of micro display technology. Same technology as projectors installed in digital theaters. Pure digital technology. Three chip DLP™ — Cons: Very expensive compared to the other technologies. Lower contrast than single chip versions. Generally larger and always louder than single chip versions. Lamps usually don't last as long. Single chip DLP™ for home theatre — Pros: Fantastic color accuracy. The best contrast ratios and shadow detail. Generally very quiet. Very little space between each pixel creates a very smooth image, even when using lower resolution projectors. Very few, if any, dead pixels. Light engine failures are very rare so repairs are less costly than other technologies. Technology doesn't degrade over time. With proper routine maintenance, DLP™ projectors consistently provide just-out-of-the-box performance. (DLP™ is the only technology that makes this claim). Color uniformity is the best of the technologies. Single chip DLP™ for home theatre — Cons: It is more expensive than LCD technologies given comparable projector resolution and brightness. Home theater DLP's only reach a maximum of 1500 lumens of brightness. On some DLP™ projectors, viewers can detect a color breakup effect called the "rainbow" effect. This rarely occurs with home theater DLP's. Single chip DLP™ for business — Pros: Provides higher brightness than home theater DLP's. Excellent contrast and shadow detail. Generally produces reduced noise levels. Very little space between each pixel creates a very smooth image even when using lower resolution projectors. Very few, if any, dead pixels. Light engine failures are very rare so repairs are less costly than other technologies. Technology doesn't degrade over time. With proper routine maintenance, DLP™ projectors consistently provide just-out-of-the-box performance. (DLP™ is the only technology that makes this claim). Color uniformity is the best of the technologies. Cheaper to purchase - based on resolution and brightness - than true home theater DLPs. Single chip DLP™ for business — Cons: Color saturation is not as good as LCD or home theater DLP™ machines. Color separation effect, AKA "rainbow effect," can be apparent on these projectors and can be distracting to watch, although most people don't notice the effect. Advanced menu screens for image adjustments are rare in business machines, although some manufacturers do offer them. Most, but not all, business machines won't offer HDCP enabled digital inputs. These machines are only offered in 4:3 aspect ratios. True 720p resolution projectors not offered. LCD — LCD or liquid crystal displays are the oldest type of micro display technology used in front projection. Since the only real differences between an LCD projector for home theater and one built for business are the resolution and menu options, we won't differentiate between the two here. LCD Projectors - Pros: Can be very bright even in home theater applications. True high definition models are the least costly of any technologies. Great color saturation. Home theater models are usually feature-rich. 1000 lumen and lower models will usually have long lasting lamps. LCD Projector - Cons: Dead pixels are common. Contrast ratios are usually lower than those on DLP™ projectors although by using recent dynamic iris technology much grater contrast can be achieved. Shadow detail and absolute black levels fall short of DLP™ powered projectors. Panel convergence problems (where the three LCD panels don't align properly producing a noticeable color halo around each pixel) are common in cheaper machines. LCD panels are organic and lose image quality over time. The less the machine is used each day, the less of a problem this is. Projectors that are used for over eight (8) hours a day can exhibit problems fairly quickly. Color uniformity across the image is lower than that of DLP™ powered projectors. All of our Sanyo projectors are LCD and can be found here. Our Panasonic projectors are all DLP and can be found here with the exception of the PT-AE3000E. Our Christie projectors all use the latest in DLP technology and are found here.

LCD Projectors
All of our LCD (liquid crystal display) projectors are 3 LCD models and work by splitting the light using a series of mirrors and prisms through three LCD panels, one for each colour of the spectrum, red, green, and blue. The light is split into the 3 colours by a polariser and as the light passes through each of the three LCD panels individual pixels can be opened or closed to allow light to pass through or not. The combination of these open and closed pixels across the 3 LCD panels can produce a wide range of colors and shades in the projected image. Most LCD projectors use Metal Halide Lamps because they output an ideal colour temperature and a broad spectrum of color. They are also extremely efficient so LCD projectors are often fairly small and portable. All of our Sanyo projectors are LCD and can be found here. Our Panasonic projectors are all DLP and can be found here with the exception of the PT-AE3000E. Our Christie projectors all use the latest in DLP technology and are found here.

Lens Shift
Lens Shift is not too dissimilar to keystone correction as it allows flexibility in positioning a projector. As you might expect, lens shift refers to the physical movement of the lens inside the projector housing. This has the effect of moving the image left or right and up and down on the screen without having to move the whole projector and is a godsend when trying to ceiling mount a projector and can also help to reduce hot spots created when using high gain screens.

Microphone
A microphone, (mic or mike) is a device used to convert sound into an electrical signal which can then be processed, mixed and amplified before being sent to the loudspeakers where it is converted back to sound. Used in many applications from telephones to hearing aids, we will concentrate on the application that our customers and ourselves at Event Projection will use them, namely live and recorded audio engineering. Microphones are most commonly used to pick up speech from a singer on a stage for example but they can also be used to pick up (mic-up) instruments or in fact anything that makes a noise! There are many different types of microphone but the most common design today uses a thin membrane that vibrates in response to sound pressure that is then translated into an electrical signal. Most microphones in use today for audio use electromagnetic induction (dynamic microphone), capacitance change (condenser microphone, piezoelectric generation, or light modulation to produce the signal from mechanical vibration. There are many different types of microphone and ways in which they work but we will concentrate on the main types that we would use.

Microphone Capsule Design and Directivity
The shape of the microphone defines its directivity. Inner elements are of major importance, such as the structural shape of the capsule. Outer elements may include the interference tube. A pressure-gradient microphone is a microphone in which both sides of the diaphragm are exposed to the incident sound and the microphone is therefore responsive to the pressure differential (gradient) between the two sides of the membrane. Sound sources arriving edge-on at the diaphragm produce no pressure differential, giving pressure-gradient microphones their characteristic figure-eight, or bi-directional patterns. The capsule of a pressure-transducer microphone is closed on one side, which results in an omnidirectional pattern, responding to a change in pressure regardless of the direction to the source. Other polar patterns are derived by creating a capsule shape that combines these two effects in different ways. The cardioid, for instance, features a partially closed backside. Microphone polar patterns Omnidirectional Subcardioid Cardioid Supercardioid Hypercardioid Bi-directional or Figure of 8 Shotgun The diagram above illustrates a number of these patterns. The microphone faces upwards in each diagram. The sound intensity for a particular frequency is plotted for angles radially from 0 to 360°.

Omnidirectional
An omnidirectional microphone is designed to respond to sound from all directions like a sphere in three dimensions. In practice, this is not the case. As with most microphones, the body will obstruct frequencies reaching it over part of it’s axis therefore, the smallest microphone body will give the best omnidirectional characteristics at high frequencies.

Piezoelectric microphone
A crystal microphone uses the phenomenon of piezoelectricity — the ability of some materials to produce a voltage when subjected to pressure — to convert vibrations into an electrical signal. An example of this is Rochelle salt (potassium sodium tartrate), which is a piezoelectric crystal that works as a transducer, both as a microphone and as a slimline loudspeaker component. Crystal microphones were once commonly supplied with vacuum tube (valve) equipment, such as domestic tape recorders. Their high output impedance matched the high input impedance (typically about 10 megohms) of the vacuum tube input stage well. They were difficult to match to early transistor equipment, and were quickly supplanted by dynamic microphones for a time, and later small electret condenser devices. The high impedance of the crystal microphone made it very susceptible to handling noise, both from the microphone itself and from the connecting cable. Piezoelectric transducers are often used as contact microphones to amplify sound from acoustic musical instruments, to sense drum hits, for triggering electronic samples, and to record sound in challenging environments, such as underwater under high pressure. By using changes in sound pressure to distort a piezoelectric element the piezoelectric element produces a small voltage when distorted, and this varies as the sound pressure varies.

Resolution
Resolution dictates the definition and detail of an image and refers to the number of pixels in each dimension, horizontal and vertical, that a device can display and is simply the physical number of columns and rows of pixels creating the display (e.g. 1024×768). Various resolutions are typically referred to by standards such as VGA, XGA etc. In terms of projector hire or plasma screen hire, what you are looking for when deciding on a projector is the “Native Resolution�. This is the physical number of pixels that the machine actually outputs onto the screen. All of our projector resolutions on the site are shown as native resolutions. Many projectors and video displays can process higher resolutions from an input device such as a computer but they cannot output higher than their native resolution. When hiring and projector or plasma screen, you should take into account what you are going to be showing. For example if you are looking for a projector to hire for a Microsoft PowerPoint presentation where the content is usually big bold text and graphics you probably do not need a particularly high resolution projector. If you are showing photographs that have lots of detail or screening a film, particularly if it is from a HD source such as a Blu ray player, then a projector with higher resolution will give you a far more detailed image. We have a range of projectors with various resolutions. The lowest resolution machine we supply is 1024X768, known as XGA. This has been the most common computer screen resolution for several years and is more than adequate for most users. We do not supply projectors with lower resolutions than this such as SVGA (800X600). We also have SXGA+ (1050X1400) Panasonic projectors which are an excellent choice for users wishing to show very fine detail and a range of full HD (1080X1920) projectors for the latest in digital cinema such as the Panasonic PT-AE3000E and Panasonic PT-DW10000E.

Unidirectional Microphones
A unidirectional microphone is designed to be only sensitive to sound from one direction. There are various types, Cardioids, Supercardioids and Hypercardioids that you can read more about on this page.

Vision Mixer
A vision mixer, also known as a video switcher, video mixer or production switcher is a device used to select or mix two or more different video sources and in some cases to add special effects. This is similar to what a mixing console or DJ mixer does for audio. There are various types of vision mixers that accept different video inputs from composite video (BNC/RCA/Phono), S-Video, SDI or even FireWire. Typically a vision mixer would be found in a professional television production environment such as a television studio, commercial production facility, outside broadcast van or linear video editing bay. The switchers and vision mixers we hire can be used for presentation switching, in a conference environment for example, for switching between a number of live camera feeds and for VJing to create visuals in night clubs or for live music. Besides hard cuts (switching directly between two input signals), mixers can also generate a variety of transitions, from dissolves to pattern wipes. Additionally, most vision mixers can perform keying operations and generate color signals (called mattes in this context). Most vision mixers are targeted at the professional market, with newer analog models having component video connections and digital ones using SDI. They are used in live and video taped television productions and for linear video editing, even though the use of vision mixers in video editing has been largely supplanted by computer based non-linear editing.

26/09/2009
Cinema in the Woods.
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