All that is right, but economics are economics, and for how long will the "film manufacturers" will continue manufacturing film ? I gave up all this debate a long time ago, i'm not insisting on a technology that is going away, but i know the risks and prepare for them. As other member said, a good idea is always a good idea, even if it is produced with low budget elements. Mário Pires http://www.retorta.net http://www.esteticafotografica.net ________________________________ De: owner-photoforum@xxxxxxxxxxxxxxxxxxxxxx em nome de lookaround360@xxxxxxxxxxxxxxxxx Enviada: dom 21-05-2006 15H37m Para: List for Photo/Imaging Educators - Professionals - Students Assunto: more "future proofing" I forwarded Karl's article RE "future proofing" to a quite knowledgeable friend in the biz and this was his reply (Again, the conclusion is the important part): There are a number of fundamentally incorrect assumptions made in this guys' article. He talks about resolution and I do give him credit for explaining how it is measured, but he misses a major point with regard to resolution of HD video cameras. A typical 2/3" 3-chip HDTV camera has sensors with 1920 pixels across a 9.6mm wide area. In order to make any measurement of resolution of such a chip, one must divide the pixel count by 2. This, because a single pixel (picture element) is a photo site that can have only one single luminance level at any given time. In order to discern the finest bit of detail that any optical imaging system is capable of, you minimally need two pixels or you will have nothing against which to contrast a single pixel. So, with every other pixel being black and rest being white, the 1920 pixel wide chip is optimally capable of 100 lp/mm or 960 tvl/ph in video terms. This is on a good day and with sampling at the highest level and no compression and a recording medium that is lossless and with a monitoring system that is at least an order of magnitude higher in resolution and considering that the test source (all the stuff in front of the chip) is a laser generated pattern. In other words, it can't happen. Now we have to consider what the lens does. Funny that the lens is considered more of an accessory than the key component part of the entire system that it is. The very best HDTV prime lens ($20,000 - $30,000 for one focal length) may have a resolution of around 80-90 lp/mm. This is excellent optical performance and can even be achieved without closing the iris down in some cases. So given that, no, lets be real generous and say it's equal in theoretical resolution to the chip at 100 lp/mm. This makes the math easier. So if we use one of two common formulas for calculating sy stem resolution, we come up with the combined performance of at best, 50 to 70 lp/mm. I won't bore you with the formulas, but take my word for it as I have calculated this quite a few times. The rule is this: The combined resolution of lens and sensor (film) can never be any greater than the weaker of the two links in the chain and will ALWAYS be less. So now that we know what is possible in an optimal situation, let's examine how people are really doing HDTV. They use much cheaper zoom lenses with maximum resolution of around 56 lp/mm at perhaps just one focal length and with the iris closed a bit. They typically don't spend the money for the right charts or learn how to properly back-focus their lenses and so performance at infinity focus is compromised reducing resolution at the very focal lengths where it is most needed (most are still using back focus charts designed for LowDTV or none at all). They don 't use matte boxes or if they do, don't really understand how to properly use them and so compromise dynamic range and apparent sharpness further. They stick el cheapo Tiffen window glass filters in front of their lens, screwing up the lens file (assuming they know what one is and have gone to the trouble of creating one) and undoing the effects of having a multicoated lens (for which they paid a premium). And lastly, they are judging focus with a resolution limited viewfinder as opposed to using a high resolution monitor, so they can't really see when stuff is in focus anyway. So anyone that thinks that the average user of even a $100,000 Sony Cine Alta HD-F900 is getting the most out of their camera is probably smoking funny cigarettes. While the Japanese (and a couple of domestic chip manufacturers) continue to cram more and more pixels onto silicon, film continues to get better and better with each new generat ion of emulsion that Kodak and Fuji bring out. And all but the most serious cinematographers continue to ignore the role that the lens plays in all of this. It's a numbers game and the specs are the manufacturers bragging rights, nothing more. Another thing. The beam-splitter prisms used in all 3-chip cameras are and will continue to be source of uncorrectable chromatic aberration. I can look at a film/HD comparison and pick the video every time because of this alone, forgetting all the other differences. Since this fellows' article was written, there have been a number of 35mm size single chip HD cameras introduced that use real film lenses. Their performance is outstanding, although it has less to do with resolution than most people realize. And lastly, with proper storage, a film original can be turned into anything it needs to become down the road without much worry about archival permanence. The problem with electronic formats is that they need constant monitoring to make certain they are a file type that can still be read or played back in something. The maintenance implications over time are enormous. Bob Zeichner, MFSO -end- AZ Build a 120/35mm Lookaround! The Lookaround Book. Now an E-book. http://www.panoramacamera.us <http://www.panoramacamera.us/>
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