Setting up your screen Your first step towards setting up a perfect home cinema is to properly calculate the viewing distance. Our projector screen calculator will automatically determine the following values: Minimum viewing distance : the minimum distance between you and the screen to ensure the whole picture is in your field of view.
Don't place any seats closer to the screen, as it will be uncomfortable to watch the movie for the viewers. Maximum viewing distance : the maximum allowable distance between the audience and the screen according to THX an American audio-video company. For the movie theater to obtain the THX certification, the audience must sit at this distance or closer to the screen. Optimal viewing distance quality-wise : regardless of the field of view, this value specifies the distance between the audience and the screen that ensures you see all available detail.
The higher the resolution, the closer to the screen you should sit. Hence, if sitting at the optimal distance would mean you sit too close to the screen to get the whole picture in your field of view, you can decrease the image quality without any consequences for viewing quality.
You can also open the advanced mode to get more information on recommended viewing distances: Maximum viewing distance recommended by THX : apart from setting a maximum allowable viewing distance, THX also specifies the maximum recommended distance. They suggest that sitting at this or closer distance to the screen will result in optimal viewing conditions. Determining the screen brightness The next step in setting up a perfect home cinema is choosing the proper projector to ensure correct brightness levels.
First, you need to input the following values: Projector brightness : you can find it in the manufacturer's specifications of your projector model. It is expressed in ANSI lumens and describes how bright is the image projected by the device. Screen gain : if you use a special material for your screen, it can increase or decrease the brightness of the projected image. For example, the Stewart FireHawk screen provides a maximum gain in brightness of 1. The brightness levels are as follows: Brightness lower than 12 fL is not acceptable, even in totally dark rooms - your audience will have problems with watching a movie that dark.
You should consider a brighter projector or a smaller screen. Brightness between 12 and 16 fL is better, but still too low for dark rooms. For environments without ambient light control the important thing is to maintain a good contrast ratio. For movie watching a minimum contrast ratio of is recommended.
Based on this Digital Projection , a manufacturer of projectors, recommends 40ftL for environments with some ambient light and 60ftL for high ambient light locations. For this reason LCDs are often used in locations with high ambient brightness such as family rooms with lots of windows. For projection systems we need to calculate luminance to ensure the combination of projector, screen material and screen size will provide enough light output to meet targets.
A big screen with unity or negative gain like the wide viewing angle, acoustically transparent types we like to use will need a high light output projector to meet brightness targets. There are two factors which might increase the luminance target we aim for when designing a projection system for a home theater:.
Need help designing a projection system or choosing a screen, projector, masking system or anamorphic lens? Contact us now! Any further comments are welcome, thank you……….
You should also factor in loss of brightness over the lifespan of the bulb, so that even near the end of the lifespan you are still within targets. That seems to be within the capabilities of the X, though as you will note where you mount the projector does make some difference to the light output…closer to the screen provides more output as there are less losses in the lens.
May I ask two questions about that luminance formula you used? First, when doing 2. You should use the D Gary - Sorry I wasn't clear enough in my article. Now assume we change nothing except a larger screen and then adjust lens zoom and position to fill the new larger screen. We have diluted the available light to cover the larger screen area. The foot-lambert reading will be lower less light per sq.
Numerator lower - CR lower. Had we made the screen smaller, CR would have gone up. Because they all seems to interpret "ansi lumen" quite differently.
To answer your Q, you have a very large screen - and I don't know the gain, if any. And you are correct, ANSI lumen ratings are not consistent. At the cost of those projectors, you might consider a smaller screen. Spot on,once I viewed the contrast of an image from a JVC projector never went with anything else. Brighter is better but contrast is best by far. Now on my third one. Terrence S. The Projector Central "Projector Throw Distance Calculator" linked to most of their projector spec pages calculates foot-lamberts on screen for a specific model, based on sliders to input projection distance and screen size.
Things could change once a projector is calibrated, but it's a good starting point for Harris and Gary's questions. Harris- Foot lamberts lumens are just the square footage of any screen divided by the post-calibrated lumens of the projector in use.
So, if you have a projector which delivers 1, lumens, post calibration, and you have a 60 square foot screen, you have 40 lumens per square foot, or 40 ft lamberts. This is how most reviewers determine the actual light output from a projector post calibration. They measure the light at the screen, then multiply it by the size of the screen, and that's the projector's light output at the lens, post calibration. HCD- So, with your " diagonal screen, which is FAR larger than a typical home theater setup, you have about a square foot screen.
Just multiply that times the desired lumens per square foot. At 40 lumens, that's a 4, lumen projector. At 20 lumens, it would be a 2, lumen projector. Keep in mind ALL numbers are post calibration, not advertised. Though this is similar to a Lumen , as alluded to above, there is a key difference , which primarily focuses on the fact that a Lumen is a measurement of the light emitted from a source, while a Foot - Candle is focused on the amount of light that impacts a surface a given distance away from a light source.
A general rule of thumb is to use to lumens per square foot of work space. For example, a watt fluorescent bulb puts out about 2, lumens. A watt incandescent bulb puts out about lumens. How bright is a lumens? One lumen is about the same brightness as a one birthday candle from a distance of one foot from you.
To put it another way, a standard 60 watt light globe produces around lumens of light. For the average space of square feet , you'll need roughly 5, lumens as your primary light source 20 lumens x square feet.
In your dining room, you'll want about 30 lumens per square foot on your dining table to see, not examine, food , so if your table is 6 x 3 feet , that's lumens. It measures illuminance by using your device's light sensor. Features of this product include: Ability to calibrate your device with the multiplier. Once you've found those two numbers, simply divide the number of lumens by the number of watts.
That will give you the standard measure of light bulb efficiency, which is the lumens per watts. It's best to use the actual wattage of the bulb, not the so-called "equivalency" value.
It is far short of what you need in a commercial cinema, where typical projectors output 20, to 30, lumens.
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