Wikipedia:Reference desk/Archives/Computing/2019 June 21

= June 21 =

Blurry background
Most search results are about how to obtain a blurry background in photos and it seems to be something people actually want, which I really don't understand. I then found out front cameras of modern smartphones apparently can't focus on both your face and the background due to technical limitations. I simply don't get it. What's the point of taking a selfie when you can barely make out where you actually are? After all, you want to show your friends the places you've been to. While the rear camera is a little bit better, finding passersby that take photos to your liking is actually quite rare. What's the obsession with the trend of blurring out the background and why don't companies improve the front camera besides from adding more megapixels? --94.134.89.230 (talk) 21:58, 21 June 2019 (UTC)


 * The article Depth of field may help. Bubba73 You talkin' to me? 22:18, 21 June 2019 (UTC)


 * A pinhole camera may be of interest to you, as everything is in focus in one. Then why don't we all use those, you might ask. Well, since very little light makes it past the pinhole, you either need a very long exposure, which leads to motion blur, or you need very sensitive photoreceptors. If you have a 20 Mpixel camera, then each pixel only receives at most 1/20 millionth of the light that makes it through the pinhole (probably less, because a circle of light makes it to the photreceptors, but they are normally in a rectangular array). A very bright scene helps somewhat. But, until we get those ultra-sensitive photoreceptors, the best a single lens camera can do is autofocus on whatever is in the center, and blur out everything at different depths. Or, using multiple lenses, it may be possible to create a composite photo by combining images taken at different focus depths.


 * As for why you would intentionally blur things, that can be done because those items are not of interest. For example, if you and your significant other are at a party, and don't know anybody else there, you might blur them all out, so you don't waste time looking at them and trying to remember who they are, when you look at the pic years from now. It's basically the reverse of circling the object(s) of interest.


 * As for front cameras versus rear cameras on cell phones, the front camera is for selfies, with the focal length set short so the user is in focus, while the rear camera allows a wide range of focal lengths, depending on if the subject is near or far. This means it may occasionally auto-focus on the wrong subject, and it takes time to allow it to settle into the proper focal distance. SinisterLefty (talk) 22:54, 21 June 2019 (UTC)


 * As to why blurring is desirable, see bokeh. 85.76.66.99 (talk) 10:25, 22 June 2019 (UTC)