{"id":166,"date":"2008-04-05T07:20:11","date_gmt":"2008-04-05T12:20:11","guid":{"rendered":"http:\/\/blogs.scienceforums.net\/swansont\/archives\/166"},"modified":"2008-04-05T07:20:11","modified_gmt":"2008-04-05T12:20:11","slug":"dont-waste-your-money","status":"publish","type":"post","link":"http:\/\/blogs.scienceforums.net\/swansont\/archives\/166","title":{"rendered":"Don't Waste Your Money"},"content":{"rendered":"

Sunny Kalara at “Talk Like a Physicist” wants a 576 MegaPixel camera<\/a>, and while the post talks the physicist talk, it doesn’t walk the physicist walk (if there is such a thing).<\/p>\n

And the gauntlet has been thrown down \u2014<\/p>\n

Next time a person tells me that I don\u2019t need a digital camera with more than 6-10 mega pixel resolution, I am going to hit him\/her on the head with the sharp corner of my camera<\/p><\/blockquote>\n

it appears I am risking photogricide by saying, “But that might actually be true. More pixels do not necessarily make a better picture.”<\/p>\n

A further claim is:<\/p>\n

Apparently, if you converted the resolution of what an eye can perceive in to mega pixel, it turns out that an eye can see at 576 Mega pixel. So, I want my camera to be at least 576MP camera; is that too much to ask?<\/p>\n

When I look out, I see in stereo; with full depth – is it too much to expect that my camera does the same?<\/p>\n

I want to take pictures for the unknown technology that will be available to me in 20 years, not for the 3\u00d74 print that can be printed now! <\/p><\/blockquote>\n

Both the 6-10 MP claim and the 576 MP claim are based on a few assumptions, and as any good physicist knows, you have to make sure these assumptions are not violated in your analysis. So let’s put the Pentax down and talk about this.
\n
\nFirst of all, there is a difference between a compact digital camera and a digital SLR that has interchangeable lenses, and it’s not clear that everyone who is risking a Canon to the cranium here is talking about all cameras. When context is given, the 6-10 MP admonishment is often in terms of the compact cameras, i.e. the ones you can carry around in your pocket.<\/p>\n

The assumption here is that the quality of the picture is proportional to pixel count. Picture quality is not limited by just the resolution of the sensor, though that’s one factor. First of all, size matters (c’mon, you knew it all along). Compact digital cameras do not all have the same size sensors, and they are generally smaller than the sensors on a digital SLR, which are smaller than 35mm film. If you add pixel count but keep the sensor the same size, you must have smaller pixels. For the same exposure, you now have fewer photons collected, so your signal\/noise ratio and dynamic range have gotten worse. This has implications to the aperture, too, since you need more light but the diffraction limit means you are blurring the image onto more pixels. And there’s more to this than pixel size, there’s the lens: cheap, small cameras have cheap, small lenses, and this limits the quality of the picture that hits the sensor in the first place. Imperfect focusing becomes more of a problem with smaller pixels, too, since the light is spread out over more pixels. So more pixels isn’t necessarily the answer \u2014 a small sensor with many pixels is just going to result in a faithfully reproduced crappy image stored on your memory card in a large file. The one redeeming part of all this is that you tend to naturally crop your picture with the small sensor, and the image from the edge of the lens is the lowest quality.<\/p>\n

One more thing that will risk a Nikon to my noggin: 576 MP. The cited article<\/a> lists this as the equivalent of the human eye, but it also assumes a 120\u00ba field of view, and guess what \u2014 most pocket digital cameras don’t have anywhere near this field of view! Even a 35mm camera with a 50mm lens on it has a field of view that is about 1\/15 of that area \u2014 that brings us down below 40 MP \u2014 and a compact digital camera with a much smaller sensor has a smaller area still, though you can compensate for this by using a shorter focal length lens to replicate the angle of view, but these generally aren’t as high a quality. You’d have to be using a very wide wide-angle lens to be needing such a large pixel count.<\/p>\n

There is some further reading here<\/a> and here<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Sunny Kalara at “Talk Like a Physicist” wants a 576 MegaPixel camera, and while the post talks the physicist talk, it doesn’t walk the physicist walk (if there is such a thing). And the gauntlet has been thrown down \u2014 … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[39,53],"tags":[],"class_list":["post-166","post","type-post","status-publish","format-standard","hentry","category-physics","category-tech"],"_links":{"self":[{"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/posts\/166","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/comments?post=166"}],"version-history":[{"count":0,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/posts\/166\/revisions"}],"wp:attachment":[{"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/media?parent=166"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/categories?post=166"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/blogs.scienceforums.net\/swansont\/wp-json\/wp\/v2\/tags?post=166"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}