![]() ![]() You could zoom in for a close-up in transfer that didn’t cost you resolution. ![]() When everyone shot on film, some telecine devices, like the Rank Cintel Mark III, sported zoom boards that permitted an optical blow-up of the 35mm negative. The first is to shoot 4K for the purpose of reframing and repositioning within HD and 2K timelines. In the case of the ALEXA, ARRI adds some on-the-sensor filtering, which results in a softer image that gives it a characteristic filmic quality. Although the equation isn’t nearly this simplistic, since a lot of color science and “secret sauce” goes into optimizing a sensor’s design, you can certainly see this play out in the marketing battles between the RED and ARRI camps. This roughly correlates to a sensor that’s of high resolution, but a smaller dynamic range (many small pixels) or one with lower resolution, but a higher dynamic range (large, but fewer pixels). For any given sensor of a certain physical dimension, you can design it with a lot of small pixels or with fewer, but larger, pixels. ![]() There’s a loose correlation between pixel size and light sensitivity. The pixels of the sensor, called photosites, are the light-receiving elements of the sensor. The perceived image quality is also not all about total pixels. That’s in part why RED developed 5K and 6K sensors and it’s why Sony uses an 8K sensor (F65) to deliver a 4K image. Green is used for luminance, which determines detail, so you do not have a 1:1 pixel relationship between green and the stated frame resolution of the sensor. The reason is that in many designs 50% of the pixels are green versus 25% each for red and blue. There’s also a very good discussion among top DoPs here about 4K, lighting, high dynamic range and more.Ī lot of arguments have been made that 4K cameras using a color-pattern filter method (Bayer-style), single CMOS sensor don’t even deliver the resolution they claim. It’s worth watching Mark Schubin’s excellent webinar on the topic to get a clearer understanding of this. 4K is also not sharpness, which is a human perception affected by many things, such as lens quality, contrast, motion and grading. True resolution is usually measured in the vertical direction based on the ability to resolve fine detail (regardless of the number of pixels) and, therefore, 4K is only twice the resolution of HD at best. That’s a measurement of area and not resolution. As such, 4K is not four times the resolution of HD. ( Click on any of these images for expanded views.)įirst of all, 4K used as a marketing term is not a resolution, it’s a frame dimension. There’s so much hype around it, though, that you really have to wonder if it’s “the Emperor’s new clothes”. That really doesn’t make a lot of difference, because these are close enough to be the same. 4K means different things to different people and in terms of dimensions, there’s the issue of cinema 4K (4096 pixels wide) versus the UltraHD/QuadHD/4K 16:9 (whatever you want to call it) version of 4K (3840 pixels wide). I’ve talked about 4K before ( here, here and here), but I’ve recently done some more 4K jobs that have me thinking again. ![]()
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