Is all the data necessary? - Home Theater Forum and Systems -

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post #1 of 3 Old 09-11-08, 09:54 AM Thread Starter
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Is all the data necessary?

Or... Do I really need to know how a cake is made to know it tastes good?

Aside from the common questions about screen recommendations I often get asked or read posts saying all the data and testing is cool that it's being done, but is it really necessary? The answer is yes.

One thing I want to point out is the data and tests can be complicated and complex, but that doesn't mean the end solution is complicated.

Sometimes easy takes a lot of thought and work to make it easy and still exceptional.

Huh? Is also a common response. Color science is a little bit more than what we were taught in grade school art class, in fact that is only half the story when it comes to colors (subtractive, the other half is additive- if you want a real mind blower I can show you how to make gray with just Blue and Yellow, and we always were told they make green ). Don't worry, I'm not going to go into a long boring lecture on color theory, but I do want to take a moment to explain why we do all this work.

First and point blank and brutal... screens are actually simple to make. With a can of good quality paint and for a few bucks and a little time and effort (no more time than it takes to paint a room though) a person can have a decent screen. For some, they may never go beyond that level. For others... they will always be looking for the holy grail of screens and won't be satisfied by anything whether it's DIY or commercial.

So what is all this data and why is it important? Simple, without the readings and testing done to color balance screens nobody would ever be able to tell (or prove) that one screen is really better than another. Screenies are eye candy, plain and simple. By the time a person looks at a screen shot on their monitor it has gone through so many layers of compression and is subjected to so many different variables that it is just a picture and nothing more. Some people rely solely on screenies as 'definitive proof', however they are subjective at best. Even a person's monitor can make a difference depending on whether it's calibrated or not.

Screen shots are first altered in the camera. Most people don't shoot in RAW format and let the camera make its own auto adjustments. Two camera's can produce two totally different looking images and very few consumer level camera's will look alike, even a different model from the same company can look totally different. Then there is compression and conversion. Every screenie is compressed at least once, often several times. The camera compresses, and depending on the resolution setting it can be a lot right there. Then usually the image is resized by the shooter so it can be uploaded to a hosting service. Sometimes the hosting service then resizes it again, and often the hosting service will even change the file format as well. So there are a lot of variables going on.

That leaves the final image and then the person's observations and opinions. Some people are honest, others like the subjective world and use that to their advantage.

So where does all this data come into play? As I mentioned getting a decent screen is easy. It's as simple as a $10-$12 OTS neutral gray or white paint. Squeezing out those last few extra percentage points of performance is the hard part. The data is mainly for color balance of the screen, more appropriately how neutral the screen is. Without getting all technical and boring, neutral is not a color. Colors are hues and they will impact the overall screen image to some extent where as a neutral palate will not.

Now when two screens are compared that may look close in shade, they can actually be ranked as to their balance, and the more neutral the screen is the better it will perform. Even two basic OTS (Off The Shelf) paints that look close to the same can perform differently. Image colors can be affected, but also brightness as well. A neutral screen is more effective and efficient at reflecting all spectrum's of light, where as a color will absorb certain light spectrum's. In some cases the extra brightness is noticeable, in others not so much. Without the numbers though nobody would be able to rank anything.

Color balance isn't the only factor though. Sheen, texture, and even what the material or paint is made of can all be factors. Some materials refract light and as much as it is argued, that is just the nature of those materials. Others are purely reflective and do not allow any light to pass through so they cause no refraction. The former is an interference method (iridescence), the latter is a non-interference method. Think of it like this... do you want something that 'interferes' or something that doesn't? All of this is taken into consideration with the color science. Actually when we combine everything it can actually be called screen science!

The best way to look at it is like this- Anytime a person buys something they check the specs and details of it. How many watts is that new AVR? Can it handle the new HD audio formats? How many HDMI inputs does it have... and so on. Nobody would spend $2grand on an HDTV and not even ask if it is 720p, 1080i or 1080p (well, I dare say nobody on these forums would!). From things like cars to microwave ovens... people look at the specs and and compare prices and performance. Screens are no different. In that sense all these numbers do (or should) mean more than to just us developers, they are the hard specs just like the features and wattage on that AVR mentioned... Or how many Lumens or what the CR is on that new projector a person just bought.

Sure something can have great numbers but be ugly as sin, or something can look/sound exotic and sexy but perform horrible. (Take the Delorean for example, very cool looking for for a sports car but it has terrible performance)

I am working on a thread that ranks all known screens. I am working out some metrics- performance, specs, and cost will be taken into account, as well as difficulty to construct. I'll even include actual real world user experiences.

The bottom line is that all these numbers may be boring, and to some may even be meaningless, but it is necessary to move to the next level of screen performance. We've come a long way by eye and through empirical testing. Moving to the next level of performance is where people (developers) are going to have to set aside any bias and egos and accept some common standards and even start working together. We have a good crew here though but DIY is still a long way from being universally accepted... we're working on that though!

"Make everything as simple as possible, but no simpler." - Albert Einstein

"If all else fails, spin the cat."- Grzboken
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post #2 of 3 Old 09-11-08, 11:44 AM Thread Starter
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Two Types of Developers

There are basically two types of DIY developers- Casual developers that do this for fun and a hobby, and then Hard Core Developers... who also do this for fun but tend to be perfectionists and are always looking for better ways.

Nobody expects a casual developer to run out and buy a bunch of expensive equipment. In fact now there are numerous people with the gear that can take accurate readings for others. All that needs to be done is just to ask. Still though, nobody expects someone just having fun to write a thesis on their screen or be like Sam Becket and be able to build a quantum accelerator! This is after all a hobby for most people.

Even the more seasoned hard core developers don't all have a spectrophotometer, but again they know the people that do have them. So requesting some readings to tweak things in can and should be done.

Where things start to break down though is when ego's and claims come into play. It's one thing to say hey look what I found, this works pretty good! It's something totally different when a person claims their method is the best and better than anything and everything out there. That's when people really want to see more than just subjective proof and opinions and many forum wars have been started over claims and hype.

Like the saying goes, if something sounds too good to be true it usually is. Ask for some proof. If someone says they have a 1.8 gain screen, ask to see the data and charts and how they did the readings. Interestingly you'll find a lot (not everyone mind you) of people simply put a screen sample up and then say 'Hey, my screen is brighter... so it must have a higher gain!' That very well could be true, but it can't be said as a fact without actually testing and verifying it. There have been times though when this is exactly how a person 'determined' their gain, yet they state it as a fact and like it was done by actual testing and readings.

Some developers have a whole witches brew of ingrediants in their mixes, and they talk a good talk and have the banter to convince people it was specially designed to have each and every ingrediant in the exact proportions listed- but usually the fact is it was nothing more than trial and error, add this, try that. These are usually easy to spot because over the course of time you can see how many changes are constantly being made. The reason for the changes is simple, they are still trying to balance the mix out by eye. Thing is, maybe they might have actually hit the perfect screen but they'll never know since there is no data to compare it to, so they continue to add things even though they just had the perfect mix and never knew it.

Some people actually thrive on 'subjective'. By remaining in that realm they never have to 'prove' anything, they can just say whatever they want. That's like playing a game with someone that constantly changes the rules in their favor. After awhile a person figures out what's going on and stops playing, but there is always someone new that comes along and is willing to sit down and play the game with them.

Educate yourself a little. By that I don't mean go to school or even crack a tech book. If you're just looking for a screen, nobody wants to be expected to get a PHD in order to sift through everything. A person can however look at previous threads and get a feel whether a person has a history of constantly changing things, or making wild claims that never seem to get backed up with anything other than personal opinions. I'm definitely not saying this scenario means a bad screen. Just ask for some proof is all.

I think what really makes DIY confusing to people is they read about so many different methods and naturally each developer always says theirs is the best. How is a person to really know? Ask others that have the same projector as you do as well as ask the developer for some proof to back up the claims. When you start doing that sifting through everything becomes a lot easier.

"Make everything as simple as possible, but no simpler." - Albert Einstein

"If all else fails, spin the cat."- Grzboken
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post #3 of 3 Old 09-11-08, 01:12 PM Thread Starter
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How to select a screen

Actually the process is often done in reverse. Typically a person buys their projector first and then worries about the screen. It really should be done the other way around.

The first thing anyone thinking about getting into the world of projectors needs to do is to conduct an honest evaluation of the room that the projector is going to be setup in and how they intend on using the projector. Some people use their projectors as a huge TV and watch everything on it from sports, to movies, to network sitcoms. Others only watch movies, while others watch movies and sports. Each of these types of viewing usually have very different lighting conditions.

Once the room conditions have been determined and the type of viewing a person intends on doing, then a screen that matches those conditions can be recommended. At that point a projector can be mated to the room and the screen with an extremely high confidence rate that the owner will be more than happy with their setup.

What happens though more often than not is the projector comes first, and unfortunately it is not always the right projector for the setting or type of viewing habits a person may have. That's when giving screen help and recommendations can become interesting and sometimes even tricky.

Here is a good rule of thumb.
  • 12fL is the minimum requirement for a unity gain white screen in a dedicated HT room with total lights out viewing. If you have less than 12fL then you need a screen with some gain to bring you up to the recommended minimum screen brightness.
  • Gray screens help with percieved contrast as well as perform better with ambient lighting. Since they help the percieved contrast they also are good for lights out viewing for certain projectors and setups.
  • 14fL is good for some low mood lighting and even higher levels of lighting as long as the light does not shine directly on the screen. Keep in mind though that even one lit candle in a room is enough light to completely crush those amazing CR specs some projectors have. One candle will render a projector with a CR of 5000:1 or higher down to the same as a 500:1 projector. Note: some projectors produce their own ambient light from the adjacent walls and ceiling.
  • 15fL can handle an N8 shade of gray with relatively no problems at all. This will allow using the projector with low to medium lighting.
  • 16fL is the sweet spot for ambient light viewing and will produce very bright and vivid screen images during lights out viewing even with a darker screen (N8). This can also accomodate higher levels of ambient light and can even produce a watchable image during the day as long as there isn't direct sunlight hitting the screen. The image won't be spectacular during the day and nothing like when the lights are out at night, but it is watchable.
  • 20fL plus is enough for very high amounts of ambient lighting, including sunlight (not direct though)

Old CRT TVs put out between 20-25fL of brightness, but keep in mind the light is from a tube and isn't being affected by sunlight, not the way projectors are. Plasma HDTVs are in the 40-50fL range, and LCD HDTVs are even brighter.

So it's easy to see that projectors simply cannot match the type of brightness of a Plasma or LCD projector at the screen sizes being used in HT setups. Even if you could, hot spotting would be a major issue with all but the darkest of screens, and bulb life for projectors that bright generally is short and expensive. However many people are surprised at how watchable a projector can be during the day under the right conditions and with the right screen and projector. Just don't expect it to look like an LCD or Plasma HDTV on a Sunday afternoon for the game.

If you haven't purchased your projector yet... do what the pros do and conduct a full room evaluation of your setting and viewing preferences, research the best type of screen for those conditions, and then go projector shopping. If you already have a projector, give us the make model and room setup as well as the desired screen size and we'll help to determine what is the best recommendation for your setting.

Coming up... The Placebo Effect and Screens

"Make everything as simple as possible, but no simpler." - Albert Einstein

"If all else fails, spin the cat."- Grzboken
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data , necessary?

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