How big can I print?
The first thing that people like to find out about a digital camera is it’s megapixels. It seems there’s some sort of megapixels fetish that consumes the world of digital photography. Unlike popular believe, however, megapixels is not the be-all-and-end-all of digital photography. Unless of course you’re planning to print giant billboards it does not matter whether you’re shooting with a Canon 5Ds or with a D3200.
However having said that some photographers who shoot professional photos and want their pictures to be able to retain a lot of detail even when cropping would love the idea of being able to shoot with 24 megapixels or even 36 megapixels.
Viewing distance & print size
There is some relationship between print sizes and the megapixels. Look at a billboard from a distance. It looks bright and sharp. Can you take a guess what is the dpi (dots per inch) at which it may have been printed? About 72! I hear you say but that’s going to be pixilated? Not really, if you’re looking from a distance. The minimum distance at which a billboard is seen is more than 20 feet. At that distance it is impossible to notice the pixels. If there is a picture on a wall and you are looking at it from a distance of say one meter, the ideal dpi is 200. A magazine is normally printed at a resolution of 300 dpi.
Enough said about dpi but what is the relation between dpi and megapixels? Let’s say you need a print out of 8 x 12 at 300 dpi. What is the perfect megapixels count that can give you that 300 dpi resolution without burning a lot of useless megapixels? Multiply 300 x 8 that gives us 2400 pixels and multiply 12 x 300 that gives us 3600. So 2400 x 3600 pixels is the exact pixel size of the image that you need in order to print an image with 300 dpi.
Do we really need 300 dpi?
If you have a 16 megapixel digital camera & the maximum image size it offers at 4608 x 3456 pixels settings. Means, it is perfect for a print size of 15.36” x 11.52” at 300 dpi resolution. Certainly more than what an average user would ever need for printing everyday photos. If you want to print a billboard at 72 dpi, the same image size will be good enough for a 64” x 48” print. Photo labs recommend at least 250 dpi input for normal prints.
Megapixels vs. Print Size Chart
As you can see there are some grey areas here.
- 280 dpi & up = Excellent. Average person won’t see “dots” at a few inches away
- 180 – 287 dpi = Good quality.Will not show visible pixels at normal viewing distances
- 179 dpi or less = Poor quality.Will show visible pixels at normal viewing distances
Image quality vs print size
But megapixel is not the end of the story here. there are few other factors may influence your printing capability. In real life situations, properly exposed, clean noise free sharp images can be upsized about 2x more than the theoretical print size, before any image quality degradation become truly noticeable at usual viewing distances. Using good optics, low ISO setting, correct exposure, proper depth of field, keeping camera shake free and proper post processing is critical to get quality print out. If you follow good shooting practices, virtually any of the currently available DSLRs on the market should be able to produce quality prints to match the maximum size a consumer inkjet can produce. Offcourse starting with high megapixels will always give you a good start.
Image sensor vs print quality
There is another factor that can affect your print quality as well as print size is the Image sensor and it’s processing power. For example, a 8 megapixel mobile camera sensor won’t be able to produce same image quality as a 8 megapixel DSLR does. Here sensor size & pixel density are important factor. In general, bigger sensors produce better image quality. Because, their pixels or light sensor are bigger and can gather more information than the smaller one. Which results cleaner and better images. You can read more on various sensor sizes here.
Professional cameras like the Nikon D810, Sony α7R ll & Canon EOS 5Ds can shoot at 36, 42 and 50 megapixels respectively. With this massive 50.6 or 51 megapixels EOS 5Ds offers very high quality 30″X20″ prints at 300 dpi, perfect for coffee table books, professional journals, magazines or even for huge billboards. But for everyday shooing needs, and especially if you’re looking to print, a small 12 megapixels camera is all that you need. Read more on megapixels here