This is a question I read a lot on different forums, groups and pages, and the answers people give vary. Camera manufacturers still have a megapixel war going on, to see which brand can make the highest megapixel camera. This is fun to watch, but does it really matter? Well, the short answer is, yes. The longer answer is, it depends. So let me explain to you what the advantages and disadvantages are, so you can deside for yourself, it you need a high megapixel camera.
“High megapixels are only good to print billboards”. That’s one of the things I read a lot, but it’s not true. There are a lot of advantages to a high megapixel camera, even if you don’t print billboards. And the funny thing is, most billboards don’t even need high megapixel images. FStoppers made a video and article about that here. They proof that some HUGE billboards only use a very small amount of megapixels. This has to do with how far away you are from a print to actually see pixels. So for what kind of print would we need high megapixels? If you’d make a large print where you would stand in front of, let’s say a museum print, you would definitly benefit from higher megapixels, because the pixels per inch would need to be a lot higher.
High megapixels mean sharper images (*in most cases). This is plain logics, because there are more megapixels to capture more details, in the same field of view than a lower megapixel camera. So you capture more resolution. Images are devided in more and smaller parts, which all contain their own details. With a lower resolution camera you would capture less details, because there are less and bigger pixels. Even if you would resize the high megapixel image to a lower resolution, the sharpness that has already been captured is still there. It’s like downscaling a 4K image to a 1080p image. The downscaled image will look sharper then when you would shoot directly in a 1080p resolution. If you are looking for ultimate sharpness, which I know you pixel peeping nerds (I’m one too) do, than higher megapixel camera’s will do that for you.
TimeInPixels wrote an article about this (4K vs. 1080p), I snatched this image from their article, you can read their article here.
But, with more detail you also need better quality lenses, otherwise the faults of a cheap lens, and slightly misfocus, will be more visual than with a low megapixel camera. With a low megapixel camera you can get away with slight misfocussing, or cheaper lenses, because you would’nt see the difference if you’re not a pixel peeper.
Pixel density* and ISO
There is a but, for the above. The point where higher megapixels are useless, or even an disadvantage, is when you have a very high pixel density, or a very low pixel density. Pixel density is how far the pixels are from each other on the sensor. For example, the pixel density on a fullframe 24mp camera is lower, than on a APS-C 24mp camera. That’s because the sensor of the APS-C camera is smaller, but containst the same amount of megapixels. Megapixels are actually receptors on the sensor which capture the light and send it to a chip which translates it to pixels. When there is a very high pixel density, the receptors are very small to fit on that sensor. Thereby it’s harder for the receptors to capture light which introduces a higher “signal to noise” ratio. When a receptor fails to capture the light correctly, it becomes noise. When a receptor captures the light correctly, it becomes a signal. The bigger the receptors, the smaller the chance that it fails to capture the light. So with a higher pixel density, there is a higher chance to get more noise. That’s why my Huawei P20 Pro with 40 megapixel camera, can NEVER beat my fullframe camera. It’s sensor is so small, and therefore pixeldensity so high, that even the pictures in native ISO are noisy and muddy.. This article is more about high graded camera’s though, like fullframe or medium format.
With a very low pixel density, the receptors would be huge, and therefore register a lot less noise. But with that, it also captures less detail because that receptor will only transfer one light, one pixel, from a certain area. The image will be cleaner, but less sharp.
So in theory, a high megapixel fullframe camera, would produce a lot more noise on high ISO, than a low megapixel fullframe camera would do. Well, the theory is correct, BUT.. The resolution of the high megapixel camera is much higher than the resolution of a low megapixel camera. When we review a picture on our monitor, in the resolution of the monitor, we wouldn’t see much difference. That’s because the noise in the high resolution image, is much smaller in the resolution that we review the image. It’s when we would zoom to a 100% where we would see a big difference between the two.
Yes, high megapixels also mean bigger files. A lot bigger. Definitly when you are like me, and don’t throw any file away. You would need tons of storage, and like me, have tons of external HDD’s lying around. If you are on a very low budget and can’t affort multiple SD cards or bigger SD cards, of more storage on your computer, don’t bother buying a high megapixel camera. But, if you can afford a high megapixel camera, you can probably affort more storage too. SD cards and HDD’s are cheap now, unless you go for the Sony Tough cards, or UHS-II cards with lot’s of storage. Then again, if you buy a high megapixel camera, you’re probably serious about your photography and don’t bother buying expensive cards for it. Believe me when I say, you want the best of the best when it comes to storage. You don’t want to wait for a few seconds on a job because your card is still writing, and you certainly don’t want a card to be corrupted, when on the job. Don’t go for cheap, go for mid-range or pro-range. I personally use the Sandisk Extreme Pro UHS II SDXC cards and never have any issues with them. Before that I used the Sandisk Extreme Pro UHS I SDXC and SDHC cards and also never had issues with them. But with that I have to say that I buy new cards every year to be assure.
Bigger file sizes also means that it will be harder to process for your computer. Your computer will struggle a lot more with a 40MB file than a 12MB file, I think we can agree on that. Assuming you don’t shoot in JPEG, which limits your editing. If you like to do some post processing with your RAW files, you need a powerful computer with the larger files, otherwise it takes a lot longer to import the files, to post process them, and to output the files. Smaller size files are much more forgiving, you can easily do that on a normal laptop or tablet.
With a high megapixel camera you can crop your images without ending up with a low resolution image. Well, at a certain point it will be a low resolution image offcourse, but you get my point. Now I know, as a photographer you need to get the image right in camera, but there are situations where cropping comes in handy. If you just don’t have the reach with your lens to capture a certain object far away, you can crop the image later and still have a decent resolution image. Or when you’re not certain about your composition, do I want that extra space in the image or not? You can capture that extra space and crop the image later if you change your mind.
You can also put your camera in APS-C mode to get extra reach and still get a decent resolution image. If you would do that with a normal resolution camera, you’ll end up with a low resolution image.
With higher megapixels you need to be more careful for camera shake. Camera shake will be a lot more visual in higher resolution. There is the reciprocal rule for taking images handheld, where you need to have at least the same shutterspeed as your focal length, to get sharp images. So if you shoot at 50mm, you need to shoot it at at least 1/50 ss to not have camera shake in your image. With high megapixels, you need to even go further, increase your shutterspeed with 1,5 from the focal length. So as the example above, you need to shoot at 1/75 ss. Camera’s these days have image stabilization though, so you can bring the shutter speed down a notch, but still have to take into account that camera shake will be more visual.
This is also the case with astro photography. For astro photography you have the 500 rule, which means you need to devide 500 with your focal length, and devide that with crop factor (fullframe is 1, aps-c is 1,5). With this calculation you get the longest recommended shutterspeed, at which you can’t see the stars moving in the image. When exposing longer, you will get startrails. With higher megapixels it’s also different. You need to do the same as with the camera shake, devide the outcome with 1,5. So with a normal fullframe megapixel camera, with a 24mm lens, the recommended shutterspeed would be 20 seconds. With a high megapixel camera it would be 10 seconds. This means you need a faster lens, or set your ISO higher, to get the same exposure.
So to sum everything up:
Detailed art prints
Cropping / Down sampling
Huge files / storage / editing
More expensive lenses
More camera shake
If you’re a professional photographer, and really know what you are doing, the higher megapixels can be a good option for you. If you just started your photography or do not consider yourself a professional yet, the higher megapixels sound cool, but are actually more of a hastle than an advantage. I hope this article helped you in any way. Please leave a comment if you have any questions. You may also leave a comment if I missed something or even when I misinformed you.