Nick Carver Photography Blog

Photography Tips, Tutorials, & Videos


How Many Megapixels Do You Really Need?

With the recent announcement of the 36.3 megapixel Nikon D800 and D800E, I figured it was high-time I write a blog post about megapixels and how many you really need.

First things first: You should understand that I'm not a gear head. I love my equipment as much as the next guy, but to me, these are just tools in the hands of someone who knows how to use them or not. I don't care about Nikon vs. Canon, I don't need a coffee mug shaped like my favorite lens, I don't want a wrist-band that looks like the lens barrel of my 24-70mm and I'm not about to wear a t-shirt that announces my brand-loyalty to the world.

So when I talk about gear and camera specs, I'm looking at it from a realistic, practical application type viewpoint. No MTF charts, no side-by-side images, no bias towards one brand - I'm giving it to you straight. I'm also trying to talk you out of spending more money, so listen up 😀

Alright, so let's get down to the nitty gritty: How many megapixels do you really need?

To put it simply, it all boils down to how big you want to print. Or better yet, how big you will print. That's a more realistic way to look at it. Because I would love to print gallery-quality billboards, but let's be honest, I'm not going to.

Let's look at some common print sizes and see how many megapixels you'd need to print that size natively (meaning straight out of the camera with no "blowing up" the image). These calculations are done with a 300 DPI print quality for all prints below 20" in the long edge and at 200 DPI for anything above 20" in the long edge. Why? Because that's how photo labs work.

But really, where do most people's images end up? Facebook, email, Flickr, etc. Not many people print very many of their images. It's almost all digital sharing now. So let's look at the megapixels required for some common digital sharing avenues.

So think about all your pictures and where they all end up. How often do you print 24x36? What about 16x24? How about anything above 8x12?

The truth of the matter is most people's pictures rarely end up larger than 8x12. Even fewer go above 16x24. Hardly any print at 20x30 or larger. Of course I'm not talking about professional photographers, but even then, anything above 16x24 isn't the lion's share of their work.

But let's say you do want the ability to print all the way up to 30x45. Does that mean you need a 54 megapixel camera? No! Of course not! 54 megapixels is what you'd need to print straight out of the camera at 30x45 with loupe-worthy detail. You don't need that. With just a little blowing up of the file using software like Alien Skin Software's Blow Up (that's what I use) or Photoshop's built-in resizing tool, you can get great results from 18 megapixels. I know that sounds hard to believe, but I've printed at 30x45 from my 12.8 megapixel camera with results that were good enough to sell as fine art pieces to an art buyer.

The quality of a blown-up file definitely isn't as good as a native 54 megapixel file, but trust me, the difference in quality isn't worth the $31,000 price tag. Plus, you have to realize that larger prints are always viewed from further away. A huge 30x45 print isn't meant to be viewed from 3 inches away. People will look at it from whatever distance allows them to see the entire image. The bigger the image, the further back they need to be. And the further back the viewer is, the better the quality will look.

I print gallery-quality 20x30 prints all the time from my 12.8 megapixel files. That means I blow my files up to nearly double the original size and the results are great!

But if you have the money, why not buy the highest-megapixel camera you can? Well, there are a couple drawbacks to having a ton of megapixels. The first is measurable and obvious: more megapixels means bigger files. Bigger files means more memory cards and more hard drive space. For instance, my 12.8 megapixel camera produces RAW files in the neighborhood of 13 MB. So, I can fit around 79 photos in 1 GB. A 21.1 megapixel RAW file is around 25 MB. So, you could fit 41 images in 1 GB. And the Nikon D800 with its 36.3 megapixel sensor will produce RAW files around 40 MB. That will give you a mere 26 images in 1 gigabyte. That's less than a roll of film!

Given that memory cards and hard drives are pretty cheap nowadays, that might not be a big deal to you. But the other thing that people fail to acknowledge is the extra strain on your computer. Processing 36 megapixel RAW files will take quite a bit more computer power than processing 12 megapixel RAW files. Your computer will act sluggish when you work and you'll have a harder time running multiple programs at once. You may have to get a new computer altogether.

Another drawback to ultra-high megapixels is a little less measurable but, ultimately, much more expensive.

An ultra-high resolution sensor will create ultra-high resolution images that, when viewed 100% on the computer, will reveal every single little flaw in your lenses, subjects and your technique. Your 18-135mm lens that looked great on your 18 megapixel camera suddenly looks a little soft at 36 megapixels. Also, all those little blemishes that make us all human now look like huge blemishes!

This will lead to new, more expensive lenses in that never-ending quest for perfect sharpness and lots of extra Photoshop time removing blemishes. And it will all be for nothing, because although now your 36 megapixel images look great at 100% on your computer, all of your money spent on top-notch lenses and Photoshop plugins will be lost on the 0.7 megapixel file you sized-down for email and Facebook.

So really, don't put down a deposit on the D800 just yet. You probably only need about 18 megapixels at most. No reason shelling out $3000-$4000 so you can throw away half your megapixels with every image you take.