Do You Need 50+ Megapixels?

How Many Megapixels Do You Need? 

Just a cell phone photo I use in an example later to calculate megapixels.

 

For those who may be unaware, digital camera manufacturers have been engaged in an all-out megapixel war.  The opening salvos of this battle had probably began back in the 90’s with the first consumer digital cameras, and at one point they marketed the number of megapixels down to two digits. An example would be my ancient Nikon Coolpix 900 with 3.34MP – wow those last .04 MP were really important! Nikon’s last generation of cameras upped the ante with 36MP D800 which eclipsed Canon’s 5D Mark III with a measly 22.3MP.  Canon answered in their latest line up with the 5Ds and 5Ds-R monsters which feature a 50.3MP sensor (not sure why we need these decimal points any more).  The “-R” signifies that the low pass filter was removed to improve fine detail sharpness. So of course now everyone is speculating when Nikon will release their next assault.  Sony, who makes most if not all of Nikon’s sensors, has a 44MP camera locked and loaded in the chamber ready to be unleashed on the world, which means the next Nikon body will likely have at least that.

Megapixel is a marketing companies dream because it’s this number that seems to equal the “goodness” level of a camera. If a 8MP camera is good a 10 is better. At first this was kind of true but are we now getting to the point of diminishing returns?  A long time ago, I read some photography magazine (it’s like a blog but it was printed and you had to buy them at stores) article, and they wanted to find out how many megapixels you needed to equal 100 ISO film.  I am giving only a brief overview because various films had different properties and so did different speeds – but basically they concluded that 35mm 100 ISO film was about the same as 10MP.  So what are megapixels and how many do you need?

If we want to know what a megapixel is we need to define what a pixel is – its the smallest spec of color in a digital image. Mega, that means million, so a megapixel means a million pixels.  Hence, a 14 megapixel camera captures images that have 14 million pixels.  Its actually pretty easy to figure out how many pixels or mega pixels an image is.  I got the new Samsung S6 phone and I don’t know how many megapixels the camera is.  Now I could be boring and look it up with google or something but I can just as easily figure it out on my own.  I have a photo  that I transferred to my computer.  In Windows you can select the file and it will tell you its size (see screenshot below). Its 5312 pixels x 2988 pixels. Multiply the two number together, divide by 1,000,000 and you get 15.872256 megapixels – but you can round to 15.9 I suppose.  

Circled you can see the dimensions of the image that are used to calculate megapixels.

Now that we have that sorted out does more mean better?  Not really. More means more.  For example, I guess megapixels is kind of like horsepower.  You don’t gage the “goodness” of a car solely on how many ponies are harnessed under the hood and usually higher hp translates to lower fuel economy.  So a 700 hp car would be fun but its not for everyone – many people are quite content with 11-150hp and the better gas mileage.  That’s kind of the same with megapixels – there is a threshold at which point you really don’t need more.  That threshold is different for different people depending on what they do with their photos and there is a down side to getting these giant photos which I will talk about shortly.

If you make prints, especially large prints you are going to need more megapixels than someone who just saves photos on their computer or shares them online.  But you might be surprised how many you actually need. To make a good 8x10, 3MP.  Without cropping, I have printed an 11x14 from a 3.3MP image and it turned out great but I would want to shoot at 6MP just in case I need to crop a little.  The next standard size is 16x20 and since the surface area of that print is about twice that of an 11x14, its nice to have twice as many MP – so I would say 12.  Not many people are making prints this large and I have printed as large as 24x36 with a 12MP image with great results so I think most people really only need 6MP but its nice to have up to 12.  Unless you are always cropping your down pretty significantly or printing banners, anything more than 12MP is unnecessary. 

If you often find yourself shooting at 3200 or more ISO then the extra MP helps hide all the digital noise so I don’t want to forge to mention that.

Now there are a number of reasons why high MP cameras are actually kind of sucky.  The file sizes are huge which means your memory cards don’t go as far as they used to, hard drives fill up faster and general computing power needs to be bumped up to maintain the same post processing time. If you backup your files to the cloud then your upload times will also increase. 

Though I am sure there are a lot of people who will love 50+MP cameras, for most people its more than they will ever use or need.  For the most part I would be content with 12-16, but I don’t see a truce coming anytime soon in this war.