Earlier this year Sony released the A7R II, which has a 42 megapixel full-frame sensor, replacing the original A7R, which had "just" 36 megapixels. The Nokia Lumia 1020 has 41 megapixels on a tiny 2/3" sensor. Nikon has been using a 36 megapixel full-frame sensor on a couple different cameras, the D800 and the D810.
The camera market seems to be headed towards mega megapixels!
But what does this mean for you? Do you need a 250 megapixel camera? When is enough resolution enough? How many megapixels are sufficient?
The first thing that you need to know is that not all "pixels" are created equal. They come in all sorts of different sizes. Generally speaking, the smaller the light-sensing "pixels" the lower the high-ISO capabilities are and the lower the dynamic range will be. And vice versa. But design differences and processing differences can throw this "rule of thumb" for a loop. For example, the top-rated high-ISO camera at DxOMark is the Sony A7S, which has a 12 megapixel full-frame sensor, but the number two rated high-ISO camera is the Sony A7R II, which has a 42 megapixel full-frame sensor.
It should also be said that it is difficult nowadays to find a camera that doesn't have decent high-ISO capabilities and dynamic range. Even entry-level DSLRs intended for beginners are pretty good. So the differences between the different cameras are quite small, despite what camera magazines (who make most of their money from camera manufacturers' and retailers' advertisements) would like you to believe.
|The Closed Road - Fish Camp, California|
This photograph was captured using the Nokia Lumia 1020. It was included in this post simply because I needed an image to break up the text.
So this begs the question: how much resolution do you need? It all depends on what you will do with your photographs.
If you plan to post your pictures to social media and occasionally make an 8"x10" print, then an 8 megapixel camera is more than enough. Apple has been placing images captured with the 8 megapixel iPhone 6 on billboards and full-page magazine advertisements! For most people, especially those who are not "professional" photographers, 8 megapixels provide enough resolution for your needs.
If you plan to make large prints you'll need more resolution. 12 megapixels are plenty for 16"x20" prints, no problem. 24 megapixels will get you poster-sized prints with resolution to spare. With 36 megapixels you can create murals.
But when was the last time you printed a mural? Or a poster-sized print? Most people don't print that large, or, if they do, it is rare. Most cameras provide excessive resolution for most people. You should consider what you intend to do with the photographs to determine how much resolution you need.
I have nothing against 50 megapixels or even 250 megapixels, because it gives you the freedom to do deeper crops and larger prints. I prefer fine details in my photographs (that most people will never notice), and "mega megapixels" provide that. However, a disadvantage of high resolution cameras is the file size that they produce. Huge files take up computer memory and also make post-processing programs run slower. Another disadvantage is that high resolution cameras tend to cost more money, sometimes lots more.
You have to weigh the advantages against the disadvantage to decide if it is worth having unnecessary extra resolution. Perhaps this is an easy decision for you, one way or the other. If you have the resources and need for a 120 megapixel DSLR, don't hesitate to get it! If not, don't worry about it, because it's just another piece of technology that will be outdated just a couple years after it comes out.