For most people, the simple answer is: No.
But let’s consider this from a mathematical and scientific point of view. In this video (slightly NSFW) by YouTuber “mediocre man”, he uses his knowledge of printing to explain this concept. Now, he’s European and it’s fairly focused on the metric system. His “1”‘s are kinda odd. You’re welcome to watch it, but I’ll translate it:
It’s pretty well known that the human eye can resolve 300 ppi. Most photo lab printers print at 300 ppi. Your home inkjet will tell you it has more DPI, but that’s ink droplets per inch, not pixels per inch. Modern inkjets will print dozens of droplets to generate the millions of colors needed to print, but at the end of the day, they generally work to print around 300 pixels per inch. For this post, we will use ppi instead of dpi to avoid this confusing difference.
Why 300 ppi? Well at 12″, the human eye can resolve 300 ppi. The further away from the image, the less ppi you need to see the image. The key to this is an expectation that you wish to view the entire photo, not a section of it. At 12″, the largest print you can see in its entirety is a 17×12″ (17×11.3 is a 4×6 shape, but let’s stay with 17×12 for ease of math). This is the common A3 paper size. It’s also the size of an 8.5×11 double-truck magazine spread. 17″ X 300 ppi = 5,100 pixels. 12″ X 300ppi = 3,600 pixels. 5,100 X 3,600 is 18.3 megapixels. For the actual A3 paper size, it’s 16.8mp but who’s counting?
The further away the image is from your eye, the fewer pixels per inch you need. Since people view photos on a wall from a distance, you don’t need 300 ppi to print them. 8x10s and smaller are common desktop prints or photos you might view while holding in your hand, so 300 ppi is useful. The common 8×10 (8×12 in a 2:3 aspect ratio) needs is 8.64 mp.
There are several reasons why you may need higher resolution images. They include:
- Critical copy work, like photographing fine art or documents, digitizing negatives and slides
- Extreme cropping
- A client that requires large files
- Your photo lab encourages the larger files for ultra-large wall prints (like 4 x 6 feet or larger)
- Pixel peeping
- Very large groups where the photo will be printed very large
Extreme cropping is related to pixel peeping, except that the goal of extreme cropping is to provide an image that someone will view as a whole.
Pixel peeping is zooming in to see the fine detail of the image. That’s okay. Many photographers get enjoyment by zooming in to see that detail. In the video above he talks about architectural photography needing high-resolution. This is another industry that being able to zoom in is important.
Macro photography lives somewhere between extreme cropping and pixel peeping. I know I love to zoom in to 100% or 200% and see all the details in the bugs I photograph, which is pixel peeping, but at the same time, I would likely want to actually crop to that detail, producing an image that will be seen in its whole.
Some people will argue you need high-resolution cameras for portraiture. I’m certain there will be some people who want to print out a 24×36 portrait, but realistically 16×20 is about the maximum size and they will be viewed on a wall at a distance where you can see the whole. You need 34.5 mp to print 16×20 at 300 ppi, but they are rarely viewed at 12″. People who walk up to large print to view the detail is analog pixel peeping.
Yes, it’s nice to see all the detail in the eyelashes and hair, but you’re going to be spending time smoothing out the skin anyway and you can’t see that detail when viewed at distance anyway.
I see a lot of wedding photographers shooting 40+mp images for weddings. That’s just clobbering your workflow and eating up storage. Like portraits, some wedding photos might be printed at 16×20, which are typically bridal portraits. Most other prints from a wedding will be 8×10 or smaller, and even more likely being shared on social media where 2.7 megapixels is about the maximum Facebook wants or most websites need.
The very large group photos printed at wall sizes is an interesting use case for high-resolution sensors. If you think about a team photo of a high school football team that has dozens of people in it. The school may print a large 3×4 foot print. At viewing distance, 24 mp will be plenty, but this is where people will walk up close to the print to find themselves, family members or friends in the photo. Again, this is a use case where the viewer is intentionally not looking at the whole photo, but a portion of it.
So buy that 40+ mp camera if that makes you happy, or it solves a problem listed above. But for most common photography uses, the 24 mp class cameras will provide you plenty of pixels to work with.