Wednesday, July 29, 2015

Mega Pixels, do I need them?

I like browsing the internet, I can easily ‘waste’ hours during a day looking at new technology and searching out the best way to integrate it. In fact I usually spend so many hours and days researching combinations that when I’m actually ready to buy the product is no longer offered… I’ll leave that topic for another day. One thing I have recently come across over and over is the new High Mega-Pixel Cameras. Cameras such as: Hasselblad’s 200-megapixel H4D-200MS, the Pentax 645Z 51.4 MP CMOS Sensor, the EOS 5DS and EOS 5DS R 50.6-megapixel CMOS sensor, Sony’s a7R II 42.4 MP full-frame sensor, Nikon’s 36.3-megapixel D810… Do you need that many MegaPixels?
Well that is what people are arguing about on forums across the internet. My stand is simple, you might not need it, but I want it, so you should probably buy any of the above now and sell it to me in a month or two at significant discount when you decide it’s just too much of a camera for you.

Alright, I acknowledge that the above statement is neither helpful nor likely to happen, so I’ll explain what Megapixels are and what they might be good for.

A Megapixel is roughly one million pixels, and a pixel is the smallest unit of information that makes up a picture. The more information you capture in your image the more options you have as far as what you can do with it. The easiest visualization is your computer monitor- although not exactly the same the principle is the same. I am running dual monitors, a 24” Dell from 6 yrs ago that has a resolution of 1920p X1080p , and a 28” Asus from last year on highest setting would be 3840px2160p. To fill the screen on the Dell I need a camera image of 2.1MP (1920×1080=2073600). To fill the screen of the Asus I need an image of 8.3MP. So if you plan on only using the images on your computer a 10MP camera will more that meet your demands.

How about printing?
When printing an image we refer to the output of your printer, DPI or dots per inch. High quality images are generally printed from 240 to 300 dpi. How does this relate to our camera pixels? Each dot can be represented by a pixel. PPI is the effective resolution of the image we wish to print, three common sizes printed at home are 4×6 , 5×7, and 8×10. Using 300 dpi for our calculations, a 4(300dpi)x6(300dpi)= 1200X1800 = 2160000 ≈ 2.2 MP, 5X7 ≈ 3. 2MP, 8X10 = 7.2MP. You can print up to 9.5×11.9 with a 10 MP camera.
So again it looks as though you only need a 10MP camera.

These are the arguments people have for the lack of need for high megapixel cameras. Where this falls apart, in my opinion, is that you are limited to exactly what you take in camera.

More of my opinion below.

I prefer to have some flexibility; perhaps I shot the image vertical, but decide that when I crop in it looks even better as a landscape. Or perhaps I just want to print larger without up-scaling. Printing a 11X17 requires 16.8MP, a 16X20 requires 28.8 MP, now to go really big 20×30… 54MP … Ok you don’t need all 54MP unless you intend for your image to be viewed from less than 2 feet you can have a very high quality print with up-scaling from a 20MP camera, but back to the flexibility. If you’ve captured more information you will likely have more details in the shadows, the same image you capture with 20MP will simply look better with 54MP.

Sample image 5X7 ratio shown @ 1500 pixels wide

Image taken with Canon 7DII

Original Size 18.24”X12.16” @ 300ppi — 5472px X 3648px = 19.96 MP