| json_metadata | "{"app":"Musing","appTags":["camera"],"appCategory":"camera","appTitle":"Why can not a camera film movies in the same resolution as still photos?","appBody":"<p><br></p>\n<p><img src=\"https://posterjackcanada.files.wordpress.com/2013/12/silhouette-photographer-tripod-sunset-sunrise.jpg\" /></p>\n<p><br></p>\n<p>Although the wording of the question is quite convoluted, I think you understand that your question is: Why is it not possible to take moving images with the same resolution as a still image?</p>\n<p><br></p>\n<p>Well, first you are making a statement in your question that is false at the beginning. Yes you can. Second, forget about the movie, there are only James Cameron and Steven Spielberg who record in film what is not 3D animation, and they respect it because they are them, since enough problems originate.</p>\n<p><br></p>\n<p>If you do not register on film, it is recorded on an analog device called MOS (CMOS, PMOS, NMOS) which is a very peculiar chip. It has a series of \"wells\" or \"pits\" that have a positive charge. Each pit is covered by a microlens that concentrates light on it. They are not pixels, but photos. A pixel is a minimum unit, usually square or rectangular, that is part of the image.</p>\n<p><br></p>\n<p><img src=\"http://ilovehatephoto.com/wp-content/uploads/2015/06/sony-a7rii-gapless-design-sensor.png\" /></p>\n<p><br></p>\n<p><br></p>\n<p>On the cmos there is the Bayer filter so that the photosites (which are color blind) get the photons corresponding to the primary colors plus the luminance: Red, Blue and Green plus luminance</p>\n<p><br></p>\n<p><br></p>\n<p>There are more photos for green because they are the ones that determine the biggest part of the spectrum plus the nuances that go from black to white.</p>\n<p><br></p>\n<p><img src=\"https://www.sony.jp/products/overseas/contents/web_contents/avchd_hdd_hdr_xr500v/48239hd_2_1_1_exmor_r_cmos_sensor_r/images/exmor_r_cmos_11.jpg\" /></p>\n<p><br></p>\n<p>The light enters through the nano-lens condensate.</p>\n<p>The amount of photons with a certain wavelength corresponding to each color converts the charge of that piletón, or photosito. The more photons, the positive charge (luminosity) is reduced, the fewer photons, the positive charge will be higher (dark).</p>\n<p>Then it goes through a filter that determines by comparison with the neighboring photosites, what is noise of what is image. In this process, we try to eliminate as much noise as possible from the analog image that is latent in CMOS charges.</p>\n<p>Since these are charges, they can be measured in fractions of volts for each photosite, and the voltage can be converted into digital signals.</p>\n<p>That's what an analog / digital converter does. That can have a depth of 1 bit (1 and 0), for many years it was 8 bits. To have a gamut (visible light spectrum), 13 bits of depth were required. That is to say that from white to black there were at least 13 steps. That was already achieved and the most professional cameras are in the 14 bits and to have 12 or 25 k resolution is required, in addition to more photos, that the stair from white to black is 18 or 24 steps.</p>\n<p><br></p>\n<p><br></p>\n<p><img src=\"https://www.ledtuning.nl/sites/all/modules/modledtuning/cie/CIE1931_ledtuning.png\" /></p>\n<p><br></p>\n<p><br></p>\n<p>To go from analog to digital, they take, as I said, samples that can be from 1 to 16 bits in the present:</p>\n<p><br></p>\n<p>The problem is that when more samples are taken to convert into bits, very fast sampling clocks are required which means more speed and quantization capacity. Higher sampling and quantization capacity means more processing capacity at ever-increasing speeds, which means higher power consumption, more heat and more complex cooling, which is sometimes loudly noisome in addition.</p>\n<p><br></p>\n<p>As there are no free lunches, the greater quantization implies more diversity of tones (gamut) as a final result, but also fewer photons that enter each photo. All this results in the photocaptor being very wide in its colorimetry, but not very sensitive. The solutions are several.</p>\n<p><br></p>\n<p>The first solution is to open the diaphragm between 1 and 3 points. But a DF, which likes to shoot with an f 12, you will not easily conform to film af 5.6, or worse af 4. Then prime lenses do not reach and you have to resort to the Super Prime and already to the Ultra Prime (designs are already being developed for some huge Hyper Prime pans), which includes more photons without violet vignetting.</p>\n<p><br></p>\n<p>Returning to the question, the problem is the speed of the electronic shutter, which from the moment it is closed until it is opened, all this must happen:</p>\n<p><br></p>\n<p>More the return to zero of the photosito.</p>\n<p><br></p>\n<p>As CMOS and its external controllers are faster and more efficient, they consume less current, heat less (there are fewer fans), process faster and allow the electronic \"shutter\" to exceed 1/24; 1/25; 1/50; 1/60; 1/120; 1/200 and up to 1/500 of a second. It is said that in a second 500 images with resolutions of 4.5k pixels from north to south and 13.5 k pixels from east to west of the sensitive surface.</p>\n<p><br></p>\n<p>The higher the shutter speed, the fewer photons enter. At 1/500 of a second, the number of photons that enter is 1/20 of the normal speed of 24 frames per second. That means that the photocaptor has the ability to capture more photons, that the microlens do not reject them or swallow them down the road, that the pit is sensitive to all the few photons that arrive, that the Bayer filter is something subtle and minimal , that the double process of noise reduction is not wrong and that processing, for now only 12 or 9 bits.</p>\n<p><br></p>\n<p>There are not many cameras that can reach 4500 x 13500 with a depth of 12 bits. We're?</p>\n<p><br></p>\n<p>There are cameras that can register in RAW up to 1 / 20,000 of a second, but with a depth of 8 and 10 bits and with later processing in PC or Mac.</p>","appDepth":2,"appParentPermlink":"p3lk8z79x","appParentAuthor":"seeee3","musingAppId":"aU2p3C3a8N","musingAppVersion":"1.1","musingPostType":"answer"}" |
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