Pixel size and Megapixels

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  • #54472
    Blessings Captured
    Participant

    I’ve been re-going through the Foundations course and am learning about Pixel size and Megapixels. I understand that the size of the pixels is way more important then having a lots of megapixels.
    But what about this? A Nikon D5000 has a pixel size of 30.5 µm² and a resolution of 12.2 mp. Compare that to the Nikon d3400 having a pixel size of 15.3 µm² and a resolution of 24 mp. If we were only to consider the sensor, which one is better? Is it just the manufactures trying to appeal to people who think more megapixels are better? If you do some complicated math formula do they both come out equal?

    This is really making my head spin, so I hope I explained it so Someone can understand it!

    #54473
    Ezra Morley
    Moderator

    A Nikon D5000 has a pixel size of 30.5 µm² and a resolution of 12.2 mp. Compare that to the Nikon d3400 having a pixel size of 15.3 µm² and a resolution of 24 mp. If we were only to consider the sensor, which one is better?

    There’s one more factor to complicate the situation… 🙂 The age of the sensor is a big factor in its image quality. Theoretically speaking, the D5000 would be better in low light. Practically speaking though, it’s quite possible that the D3400’s sensor (even with it’s smaller pixels) will outperform the 7 year older D5000’s because sensor technology changes dramatically in that period of time. You can download and compare these two images from the D5000 and the D3400 to see for yourself. Here are two more images to compare: D5000 & D3400. These are all at 6400 ISO, so you can asses their high ISO performance. Click here to go to the comparison yourself for lots more sample images. (You’ll have to click on “all” cameras, not just current ones, or you won’t be able to find the cameras you’re looking for in the list.)

    My opinion is that the D3400 clearly outperforms it’s 7 year old competitor. Not because of pixel size, but because of the improvements in technology that we’ve seen in the last several years. To get a fairer comparison, you should compare 2 contemporary cameras which have different sized pixels. For example: http://snapsort.com/compare/Nikon-D5-vs-Nikon-D7200/specs

    #54475
    Blessings Captured
    Participant

    Thank you @Ezra Morley! The comparison website is very helpful. So when you’re comparing cameras from the same year (or close to it) pixel size matters, but not as much when you’re comparing old and new cameras.

    I’ve notices that full frame cameras almost always have larger pixel size. Why don’t manufactures keep a large pixel size for crop sensor cameras and just make less megapixels? Are they just trying to make crop sensors look better then they really are?

    #54477
    Ezra Morley
    Moderator

    You’re very welcome!

    So when you’re comparing cameras from the same year (or close to it) pixel size matters, but not as much when you’re comparing old and new cameras.

    Yeah, pretty much. Keep in mind that age is just one factor though. The pixel size, processor, and pixel density also affect image quality.
    An expensive camera will generally do better than a cheap one even if they have similar pixel counts and sizes, because the higher end cameras have better image processing. Here’s an excellent article on the topic of camera resolution.

    When I upgraded from my cheapie plastic 2011 Canon Rebel T3 (12 MP) to a 2010 Pentax K-5 (16 MP) there was very noticeable increase in image quality at high ISO even though the size of sensor and pixels didn’t change much. In fact, the Pentax’s pixels are slightly smaller, according to Snapsort, yet it runs circles around the T3 in terms of image quality. The Pentax is actually slightly older as well, so it breaks the age rule too. 🙂

    When you really boil it down, it’s really a question of the quality of the electronics. Age and pixel size can be against you, and it’s still possible to get better results from an older camera!

    My ~$120 smartphone takes better pictures than our $400 Canon point-n-shoot camera did 15 years ago, and the smartphone sensor (and pixels, and lens) are many times smaller!!

    Why don’t manufactures keep a large pixel size for crop sensor cameras and just make less megapixels? Are they just trying to make crop sensors look better then they really are?

    That’s an excellent question, and I wish I knew the answer. 🙂 Not ALL Full Frames are low MP though, check out the Nikon D800, or the Canon 5DS! And there is actually a (video) camera that is FULL FRAME, but only 2.2 megapixels! (You can imagine how large each individual pixel is!!) It can go up to ISO 4 MILLION to capture super low-light shots.

    If you’re interested in all the nitty-gritty details, you won’t find a better technical article than this: https://clarkvision.com/articles/does.pixel.size.matter/index.html and part 2: https://clarkvision.com/articles/does.pixel.size.matter2/

    #54479
    David Frazer
    Participant

    Bear in mind that larger pixels being “better” applies notably to a 1:1 (100%) view. So, If you have a 12MP photo taken on a crop sensor and a 32MP photo taken on a crop sensor of equal age and quality, viewed at 1:1 the 12MP photo will be much sharper. I suspect the quality will be nearly identical once both are scaled to 8MP. (such as an 8×10 print) If you are shooting with your longest lens and still need to crop a lot, I would say the 32MP camera would be “better”.

    Why don’t manufactures keep a large pixel size for crop sensor cameras and just make less megapixels? Are they just trying to make crop sensors look better then they really are?

    Marketing. “Everyone” knows that more MP is better.

    For the reference, DXOmark has tested many sensors and have published their results here: https://www.dxomark.com/Cameras/ Notice that the ones with the best scores are all full-frame or medium format. The number of MP makes much less difference. For example, the (2019) Sony A7R IV with 61.2MP gets only a slightly better score than the (2019) Sony a9 II with 24.2MP.

    Of course if you NEED 61MP (and have the budget for the extra hard drives) … Wait, 61MP is enough to print at 300dpi 32 inches wide. I don’t know about you, but I don’t view pictures that big at a distance of 12″ from the photo!

    #54481
    Blessings Captured
    Participant

    Wow! This is a lot to digest. Thank you for the articles!

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