One would imagine that after nearly 20 years of digital cameras being the mainstream photography tool, the subject of pixel count and maximum print size would be well understood by the photographic community. Sadly, many camera websites, writers and photographers seem to cling to old misconceptions, to the point that they often repeat as common knowledge printing misconceptions without providing facts as the basis for their frequently misleading assumptions. I’ve been involved with digital printing since 1981, both offset printing and inkjet printing, the two most common methods of making prints in use today.
My studio produced digital inkjet prints for many years. I dropped out of it because it became unprofitable with so many budget printing services taking over the market. I simply couldn’t compete with the likes of COSTCO and SnapFish, just to name a couple. Sadly, places like COSTCO offered very low cost photographic prints for years, driving commercial printing to the point of extinction, only to abandon their services, leaving a large hole in the industry. Couple that with the fact that inkjet printers are sold at dirt cheap prices, many photographers now make their own prints at home on their own printers, there just isn’t the demand for photographic printing as there once was.
My business was focused on large format printing. Meaning prints that were larger than 8×10 inches. I’m referring to large prints, in sizes that can be displayed on walls and in galleries, and viewed from across a room and could be used to change the mood of a room. Over the years, I have produced prints up to 44×66 inches and even larger.
The common mantra is prints need to be made at 300dpi (dots per inch) and that this was the standard resolution for making high quality large prints.
To clear up another misconception, DPI (dots per inch) and PPI (pixels per inch) are common terms used by the people in the market, but they aren’t the same thing and more often than not, are referenced in an incomplete or inaccurate manner.
Dots Per Inch (DPI) is more of a printer resolution term, whereas Pixels Per Inch (PPI) is more of a photographic resolution term. For the purpose of this article, I’m going to use the Pixels Per Inch nomenclature, as it more accurately describes the resolution of a digital image file related to print size. The general technical question to be addressed is how much resolution a digital photograph has and how large of a print can be made with that resolution before visible degradation of the image occurs. Simplified, I’ll explain how large of a print you can make with a digital image based on the pixel dimensions of the files created by that camera. I’ll also give you a basic idea of how much cropping you can do to any particular digital image file and what size print you can expect to make with acceptable resolution quality. For example, I’ll explain how large a print you can make with a XXX megapixel image.
For starters, I’ll take a 300 PPI image, meaning there are 300 pixels per inch of print resolution. If one uses the 300 PPI standard, the math is simple. Lets assume for the sake of argument that I have an uncropped image file from a Nikon D500. The D500 produces an image file at a resolution of 20.7 megapixels. The pixel dimensions of that image file are 5,568 pixels wide x 3,712 pixels tall. If you multiply 5568 x 3712, you get the megapixel count of the image. To determine the maximum print size using 300 dpi as a basis, you simply divide the width and the height by 300. At 5568 pixels wide/300, you get a print that is 18.56 inches wide. Divide the height, 3712/300, and you get a print that is 12.37 inches. Using 300 ppi as a resolution, your print can be made as large as roughly 12 x 18 inches, rounding to the most convenient print size. A 12″ x 18″ print is a nice size print, but it’s not that large that I would consider it a centerpiece on a wall. What if I want a poster size print, say a print that is 24″ x 36″, how many megapixels does my camera need to be to make that large of a print. Assuming you are stuck at the 300ppi definition, it’s easy to figure out. You’ll want an image file that is 7,200 pixels x 10,800 pixels, or a 77.76 megapixel image. Not many of those cameras floating around out there, I’m gonna need a bigger camera. What to do?
If you stand 3 feet away from a 36 inch wide print, hold up a tape measure with your arms extended and measure the width of the print, you’ll find it’s close to 22 inches wide from that perspective. If you stand 6 feet away from a 36 inch wide print and repeat the measurement, you’ll find the viewable width of a print is close to 10 inches wide from your viewing perspective. The concept of print size is relative to viewing distance. The required resolution will change with a change of viewing distance. Most of the time, when you look at your large print hanging on a wall, you’ll be at least 3 feet away from the print, unless you have some uncontrollable need to stick your nose on the print. Those of us who make prints may view the print with a loupe (magnifying glass) to discern the microscopic detail being reproduced in the print, but most regular folks are going to look at your print from 3 feet away or more. The human eye can’t make out the fine detail of a 77 megapixel image printed at 300 ppi from 3 feet away. You need to study it with extreme magnification on a table to determine the amount of detail in the print. Us printers study our prints with magnification all the time, we want to get all the detail possible at a microscopic level. That tells us how well our photographic techniques and equipment are working. Your typical art fanatic isn’t going to do that, they just want to look at the print and see that it looks nice. That’s not done with a microscope.
So, my potential admirer is looking at my 24″x36″ print from 3 feet away. What are they seeing? They are seeing an image that to their eyes is about 16 x 24 inches wide. When they move further away from the print, the functional view of the print shrinks even more. I don’t need to have a 77 megapixel camera to make a very nice, detailed print that will be viewed from 3 feet away. All I need is an image that is 4,800 pixels x 6,600 pixels printed at 300 ppi, to give the viewer a high quality visual experience. That equates to a camera sensor resolution of about 31.6 megapixels. Those cameras are available, but you’ll pay a premium for that amount of resolution. You should now see how viewing distance is an important consideration when determining maximum print size.
Lets revisit the 300 ppi standard. I’m not sure where and how 300 ppi became this default standard, but it’s arbitrary and doesn’t reflect reality when looking at photographic ink jet prints from a digital camera with the naked eye.
I’ve done my visual detailed tests on prints of all sizes and resolutions and I can tell you that without a single doubt, 300 ppi is overkill to an extreme. No print needs to be made at 300 ppi to maintain detail, even under microscopic scrutiny. Forget about 300 ppi. So what is a suitable ppi resolution to get a high quality print? From my detailed print analysis and experience, you won’t begin seeing a microscopic difference in detail until you begin printing an image below 180 ppi. From a normal viewing distance of 3 feet away, you won’t see a loss of image detail down to 150 ppi. At 180 ppi, you need a microscope so see even the most most faint change in detail between a 300 ppi image and a 180 ppi image. This is a consistent fact, nothing you can do will make a 300 ppi image show more detaile than a 180 ppi image viewed with a standard loupe at magnification. So, lets take our Nikon D500 with a 20.7 megapixel sensor and see how large of a print I can make at 180 ppi. At 5568 pixels wide/180, you get a print that is roughly 31 inches wide. Divide the height, 3712/180, and you get a print that is 20.6 inches tall. Simplifying, you can print a 20.7 megapixel photograph at 20×30 inches dimension and not see a difference with a magnifying glass. Move to a normal viewing distance of 3 feet or further away from the print, and you have a very high quality print that can be made down to about 150 ppi without any loss of detail to the naked eye at any distance. If you are going to hang a print on the wall, you can take a Nikon D500 at 20.7 megapixels and make outstanding looking prints up to 24″ x 36″. If you have a lower resolution camera, say 12 megapixels, you can make outstanding looking prints up to 20″ x 30″ and even then you can press the print size up to 24″ x 36″ and it would require you to put your nose up to the print to see a difference with your eye. From 3 feet away, a 12 megapixel image will look as good as a 77 megapixel image to the viewer.
When you are considering buying that next camera and what megapixel count the sensor needs to be to print big, don’t delude yourself that buying the most megapixels is the answer. You don’t need 45 or 50, or 100 megapixels to make a large print that looks outstanding hanging on your wall. Any modern camera with 12 or more megapixels of resolution will safely and satisfyingly give you a large print up to 24″ x 36″ which can hang on your wall and wow anyone who looks at it. The quality of your image is going to be determined more by your ability as a photographer to get a good composition and the quality of your lens to create a sharp image. It’s not about megapixels, it’s about your ability to take a good photo. Any modern digital camera with 12 megapixels of resolution has the tool to make a large very large print. Once you drop below 12 megapixels, you’ll still get good prints up to 16″ x 20″ or 20″x30″, but you’ll be pushing the finite details above that. From 3 to 6 feet away, you still won’t see a difference. I have 8 megapixel 16″ x 20″ prints hanging on my wall and they look great too.
My recommendation for those who are sticklers for technical details and have an uncontrollable need to be at the top of the technical specifications, keep your print resolutions above 150 ppi and don’t worry about the difference in resolution between a 20 megapixel camera and a 60 megapixel camera. A 20 megapixel camera is all you’ll ever need to make an exceptionally nice looking large print up to 24″ x 36″. Anyone not believing this has fallen victim to misinformation, marketing and delusional thinking. If you need to do better, save your money on the high resolution camera and buy a better lens. You’ll see more difference in the lens quality than you will in a higher resolution camera. I guarantee it.