HDTV Lies, False Claims and Nonsense
Shopping for an HDTV can be a confusing and bewildering experience. The HD Guru is here to help. For the past eight years he has come across many lies, false claims and utter nonsense regarding HDTV. This propaganda has been spread by manufacturers and many Ã¢â‚¬Å“so calledÃ¢â‚¬Â tech journalists.
Here is part one of The HD GuruÃ¢â‚¬â„¢s list of common lies, false claims and nonsense about HDTV. (Part II will be posted later)
Item 1-Contrast Ratio
Is a measurement of the difference in light intensity between the darkest black and the whitest white a display is capable of producing. High contrast ratio numbers are thrown around in the marketing of HDTVs. A display with a contrast ratio of 3000:1 will create a better image when its compared to one with a lower rating, i.e. 800:1.
Choose the HDTV with the best contrast ratio numbers. It will provide the best image with whiter whites and blacker blacks.
There is no industry standard of measurement of contrast ratio and manufacturers come up with their own ridiculous schemes to create the highest ratio they are willing to print. ITÃ¢â‚¬â„¢S ALL NONSENSE. Do not believe any contrast ratio specification for a moment, they are all worthless.
What to do about it?
Perform your own simple test. The ratio part of contrast ratio is the difference between black (darkest) and white (lightest and brightest). The light part is not an issue. All HDTVs are bright enough for normal viewing environments and none is bright enough for direct sunlight. (Read my LCD vs. Plasma section for more on their brightness). The part of the ratio you should be concerned with is how dark can the darkest image be. Here is a simple test. Bend your hands facing together to let your fingers and palms form circle. Place the pinky side of your hands against the HDTV you are evaluating to form a tunnel from the screen to your thumbs and index finger. This is to block out the storeÃ¢â‚¬â„¢s ambient light from hitting the screen. Let the storeÃ¢â‚¬â„¢s demo HDTV content fade to black as it does between scenes or commercials. Note how dark the screen gets and see if it is shaded towards specific color such as blue or purple. Repeat with a different display.
How to Compare
The display with the deepest and most neutral blacks will have the best contrast ratio in normal room lighting conditions. Bright retail showrooms tend to mask poor black levels. This will cause many consumers to favor the display with the brightest picture. Some retailers have very bright demo material such as beaches, sports and flowers without scenes that fade to black. If this is the case, ask the sales clerk to change to different demo content. If you are told that is not possible, the HD Guru suggest you shop elsewhere, for you will never have any idea how deep and neutral a given set makes black.
Here is the order of the different display technologies ability to make black from best to worse
1) CRT (direct view picture tube)
2) Microdisplay rear projector (LCoS/SXRD and DLP)
4) LCD flat panel and rear projection
CRT direct views are limited to 34Ã¢â‚¬Â screen size. DLP or SXRD (LCoS) microdisplay rear projectors come in screen sizes up to around 70Ã¢â‚¬Â. Currently, Panasonic plasma has the best black level of any plasma I have measured to date. LCD while improving, still does not produce the black levels I have obtained from the Panasonic plasma, CRT or Microdisplay (DLP and LCoS) rear projection.
Within all technologies (except CRT) there are great variations in black level performance from model to model, so check carefully. Showroom settings may not always have the set adjusted for the deepest black without burying dark detail. You may want to twiddle with the TVÃ¢â‚¬â„¢s brightness control, which is technically called the Ã¢â‚¬Å“black levelÃ¢â‚¬Â control to find the point of deepest black without losing low level detail.
Item 2-Response Time
Response time is the amount of time it takes for a display to change (on a pixel level) from one level of brightness to another. Response time is not an issue with any rear projectors, direct view CRT or in most cases plasma. However it is a big problem with LCD flat panels. If the response time is too slow youÃ¢â‚¬â„¢ll see the image blur when the subject is in motion. It could be seen as the blurry legs of a football player running down the field or an ice skaterÃ¢â‚¬â„¢s body blurring as sheÃ¢â‚¬â„¢s spinning.
Choose the display with the fastest response time. Many claim an 8 milliseconds (ms) is fast enough.
Lets first look at the math. A HDTV LCD panel has a frame rate of 60 frames per second. If the display completely changes every frame in (refreshes with a new image every frame), in 16.666 milliseconds (ms). This time is more than twice as long as the so called recommended 8ms safe level. All 8ms rated LCD panels I have tested blur fast motion. How can that be? Just like with our contrast ratio there is no industry specified standard to measure response time. Some companies test by going from one level of gray to the next (called gray to gray) others measure from black to white (how much change must occur to come up with a number for the spec sheet, no one knows). Every company does it their own way. What ever number a set maker prints in its spec sheet is meaningless as there is no standard test procedure to back up any claim.
What to do about it?
TV retailers tend to use flowers, trees and talking heads as demo material in part because they do not have fast motion that may show the blur on LCD flat panels. The HD Guru suggests bringing a DVD into the store (with a player if necessary). Pick a disc that has a fast scroll of the ending credits and use this to compare different displays. How blurry do the letters get with each display? The blurrier, the slower response time. If you canÃ¢â‚¬â„¢t read it, youÃ¢â‚¬â„¢ll probably be unsatisfied with the blur during sports. If all LCDs are too blurry for you, pick one of the other display technologies and look again at the rolling credits.
The HD Guru has rated three LCDs that have acceptable motion response. They are the JVC LT-37X987 37-Inch HDTV. HD Guru Rated Ã¢â„¢Â¥Ã¢â„¢Â¥Ã¢â„¢Â¥Ã¢â„¢Â¥/Hitachi UltraVision DirectorÃ¢â‚¬â„¢s Series 37HLX99 37-Inch HDTV. HD Guru Rated Ã¢â„¢Â¥Ã¢â„¢Â¥Ã¢â„¢Â¥Ã¢â„¢Â¥/ and the Philips 42PF9831D/37 42-Inch HDTV.HD Guru Rated Ã¢â„¢Â¥Ã¢â„¢Â¥Ã¢â„¢Â¥
Copyright 2006 HD Guru (SM) All rights reserved.
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