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AVCHD Format Discussion
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Old July 17th, 2008, 12:45 PM   #46
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Originally Posted by Kevin Shaw View Post
We have a 42" 1080p display in our living room, and while it's a little on the small side it looks fine at our main viewing distance of ~11 feet. According to Carlton Bale's chart I shouldn't see any difference between 480p and HD at this distance on this TV, but I just did some tests and the difference is visible.
Like with everything else, the resolving power of peoples' eyes varies. According to my optometrist friend, many people are only correctable to 20/30 or so with lenses, while many others are correctable to 20/15 or better. That's a 2:1 range of resolving power which falls within the range of the "normal" population.

I wouldn't be at all surprised if statistically, the people who value resolution more in a video image (or still photo for that matter), are the folks who tend to have better visual acuity and are used to seeing a sharper world in general.
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Old July 17th, 2008, 01:02 PM   #47
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Like with everything else, the resolving power of peoples' eyes varies. According to my optometrist friend, many people are only correctable to 20/30 or so with lenses, while many others are correctable to 20/15 or better.
That occurred to me after I wrote my last post, and my vision is better than my wife's when we're trying to read road signs and such. But given that I can see a difference where Carlton's chart indicates there shouldn't be one, the chart leaves something to be desired.

SD video is sooooo 20th century...time to move on! :-)
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Old July 17th, 2008, 02:45 PM   #48
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Originally Posted by Kevin Shaw View Post
That occurred to me after I wrote my last post, and my vision is better than my wife's when we're trying to read road signs and such. But given that I can see a difference where Carlton's chart indicates there shouldn't be one, the chart leaves something to be desired.

SD video is sooooo 20th century...time to move on! :-)
I agree. The difference between 480p and 1080p even on a 42" monitor at 11 feet is so pronounced that even those 20/30 people should be able to see it. This may be another case where you have to be careful how you interpret numbers. 20/20 visual acuity is based on the ability to resolve 1 arc minute, so you could translate that to lines on a screen at a given distance and come up with a chart of what an average person should be able to see at various screen sizes and distances. But, visual perception is subject to a lot of processing in the brain, and even though someone might not be able to resolve two lines at a given distance, they might still be able to perceive a difference in edge sharpness.
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Old July 20th, 2008, 10:34 PM   #49
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By the way, just another data point, I've found over the years that two cams of the same company, same model, can have somewhat different AWB setups. My video buddy and I have tended to get the same cams over the years and rarely did the colors look exactly the same on the same display pointing at the same scene. The same was true of sharpness. So I even take some of those 'exact' charts with a grain of salt. They may be accurate for THAT particular unit, but should not be taken as gospel for any other unit.
Would you hazard a guess as to why this is? With modern manufacturing techniques I would have expected AWB, color and sharpness to be pretty darn close for a given cam model. Apparently that's not the case.

Good luck.

Dennis
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Old July 21st, 2008, 05:09 AM   #50
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A couple of things -tolerances, meaning that the individual components can have a slight variation, as well as a tolerance in any adjustable internal settings.

On top of that add that as components age, there is some drift and things can slowly go out of alignment...

Finally, to add another layer of complexity, most modern cams have heavy reliance on firmware, which can be "upgraded", as can design specifications over the course of a production run...

I find that two cams purchased around the same time from the same vendor typically will be pretty close. I saw a wide variation in output between the HC7 and the CX7, even though the guts were supposedly nearly identical - the HC9 was more like the CX7, but still slightly different... again, the HC9 was just an updated HC7...
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