Friday, July 11, 2014

Do we really need more Mega Pixels?

This is long pending blog which i have been requested few months back from one of a leading Photographer of Pakistan to let amateur photographer the need or no-need of "Mega Pixels" ...

Mega Pixel war is not new .... its bin here since the dawn of the digital photography era. There is a great deal of importance placed on the issue of megapixels in the world of digital photography to the point that it’s the first question you ask: “How many megapixels does your camera have?”  It’s even gotten to the point where “low” megapixel cameras are almost seen as inferior to “high” megapixel cameras. Is this actually the case?

Consumers have come to believe that the more megapixels the better the camera. Is this true? Let’s get the answer to this question out of the way right now: “NO!” A better question to ask is “Do I need a camera with loads of megapixels?” Well, that depends. Let me explain further.

Putting it simply, more megapixels does NOT mean a “better” camera or a give you “higher quality” photograph.  So, what’s the big deal about megapixels?

So, What Are These “Megapixels” Anyway?

In every digital camera, the image is captured by a image sensor. In a digital SLR, when you click the shutter button, light travels through the lens and hits the image sensor at the back of the camera. The image sensor is made up of millions of “pixels”.  One megapixel equals “one million pixels”.  Think of pixels as microscopic “buckets” that capture light. These buckets or pixels are laid out on an image sensor in checkerboard fashion.
For example a typical digital SLR at the lower end of the price scale may have an image sensor with an array of 3,888 pixels by 2,592 pixels. Doing the math, 3,888 x 2,592 = 10,077,696 pixels, which is approximately 10 megapixels.
At the other end of the spectrum, a top-of-the-line digital SLR might have an image sensor with an array of 5,616 pixels by 3,744 pixels. Again, doing the math, this works out to 21,026,304 pixels or approximately 21 megapixels (The famous 5D Mark II) .... or Like Nikon D800/D800E/D810 with whooping 7360 x 4912  pixels equal 36.15 Mega Pixels.

Putting it simply,
  • Megapixels represent how many pixels or buckets are available on the camera’s image sensor to catch the light coming into the camera when taking a picture.
  • The more megapixels, the higher the resolution of the photos, meaning the more “detail” in the photograph

More Megapixels Does Not Necessarily Mean “Better”

So which is better? The 10 megapixel camera or the 21 megapixel camera? Well, the answer is, it depends! Obviously, the more pixels a camera has, the more detail (or resolution) the image will have since there are more “buckets” of light that have been captured. But does this translate to “sharper” images? Not necessarily!

Let’s suppose I took a picture with a 4 megapixel camera and a 10 megapixel camera and then I print both pictures to the size 5 inches by 7 inches. Which picture will look sharper? The fact is that they will both look identical. You will not be able to tell the difference. At this size, it is too small for the number of pixels to make a difference to the naked eye

On the other hand, if I were to enlarge both pictures to 11 inches by 14 inches, the 10 megapixel photo would now begin to look noticeably sharper compared to the 4 megapixel photo which would look grainer or “noisier”. Why is that? Because the larger the printed image becomes, the more the individual pixels begin to show.  If there are more pixels to start with, for example with a 10 megapixel camera compared to a 4 megapixel camera, then the more you can enlarge the photo before each of the individual pixels begin to show. Take a look at the bottom image ....

How many megapixels do you really need?

It depends on how large a sharp print one wants to make. For sharp prints use the formula: print width x 300 x print length x 300. You can relax the quality by changing the 300 value to 240. Much below 240 and the perceived print quality drops rapidly. Megapixel needs are shown in the table:

Number of megapixels for given print quality
Print size
300 pixels/inch240 pixels/inch
4 x 62.21.4
5 x 73.22.0
8 x107.24.6
11 x1413.98.9
16 x2028.818.4

Sensor Size and Picture Quality

The size of a camera's image sensor is the main determinant of picture quality and the larger the sensor area, the higher the potential for producing top-quality digital pictures. Equally important is the size of the actual photosites (buckets as mentioned above) on the sensor that collect the image-making light. The larger the photosites, the more light they can collect and, consequently, the more image data they make available to the camera's image processor. (Details of how to calculate the size of sensor photosites are provided below.

Sensor "Type"Imaging Area dimensions (width x height x diameter in mm)
1/2.7-inch (mobile)5.37 x 4.04 x 6.72
1/2.5-inch (mobile)5.76 x 4.29 x 7.18
1/1.8-inch 7.18 x 5.32 x 8.93
1/1.7-inch 7.6 x 5.7 x 9.5
2/3-inch8.8 x 6.6 x 11.07
Four Thirds (Point and Shoot) 18.0 x 13.5 x 22.5
APS-C (Canon )22.2 x 14.8 x 26.7
APS-C (Nikon)23.7 x 15.7 x 28.4
APS-C (Sony)23.6 x 15.8 x 28.4
(Canon professional DSLR)28.1 x 18.7 x 33.8
Full Frame (=35mm frame)36 x 24 x 44.3

Advantages of having Lower Mega Pixels for better ISO

Now this is noticeable thing .... Why DSLR with much higher ISO range have less mega pixels? Here is the list of the high-end camera with the fewer & higher mega pixels ... along with their highest available ISO ranges. Check it out.

If you notice, the lower the resolution, the better the ISO performance. Why is that??? 

Here is the deal ... what happens is, In above list all cameras are full frame. So it means the sensor size in all cameras are 36mm x 24mm. So what happening is regardless of how many MP are there, they are ending up fitting in into the same 36mm x 24mm sensor. Its like you are trying to push 12, 16, 18, 21, 22 or 36 people into 36 x 24 feet room. The more the people into the room the less the space they will going to get into the room which in this case is calls "Pixel Pitch". 

If you look at the last line which is pixel pitch which is the "width/space" of the photosites (or buckets or simply calls PIXELS) which captures the light. The more the width of the photosites, the better its capture light which means "LESS NOISE". Thats why few years back, many camera manufactures prefer to have less MP for better low light performance of the sensor. D700 is the perfect example of it. Regardless it got the 01st generation of EXPEED processor which was very slow when it comes to Noise Reduction, its pixel width was the biggest from above list which means its sensor was better in capturing low light with less noise in compared to all in the above list. I personally shot D700 at 8000 ISO and still it was less noise even though it got old processor. Imagine if it gets new EXPEED 4 processor. It will blow everything away. Nikon Df is one of the perfect example of it. Though its not a direct replacement of D700 but its more or like it. With no video feature just like D700, and less mega pixels ... in addition to it new EXPEED 3 processor, its ISO capability range shoots upto 204800 ISO makes it equals to D4 which is a Pro Body.  

In opposite to that, logically speaking if we have more mega pixels which will leads to smaller pixel width which means higher noise into the image. How is that possible? more pixel leads to noise !!!!!! 

Imagine, there is a room of 36x24 feet. Instead of 12 people i pushed 36 people into it. What will happen? well at first people will have less space (less pixel width) and if i give them task to do (capturing light in this case) there will be more noise and chaos in the room in compared of if i request the same task to 12 people which leads to the less noise and less Chaotic. D800 is the perfect example of it. But Nikon new EXPEED 3 processor was designed to combat this situation of higher noise and able to control the ISO upto 25,600 but not more. Canon on other hand played wisely and able to balance the higher resolution vs noise factor in their new camera body line up. I personally believe thats one of the reason Canon is not offering anything beyond 22.3 mega pixels because of the higher noise induction factor due to more mega pixels cramping into small space. 

In todays hi-tech world, technology evolved and new micro processor  played a vital role in digital imagining with incredible noise reduction performance. EXPEED 4 from Nikon & DIGIC 5+ from Canon are the leading examples. 

Enough with the pixels vs noise, switching back to the reality. Do we really need higher mega pixels? 

Well if you ask me, 12MP is more then enough. To print standard A4 paper in reality we need only 8MP. You need higher resolution for printing billboards. So dont get into this marketing stuff that higher resolution leads to better image quality. Yes you will get better resolution which you can use to crop the images which often need but not the better image. If you take crappy pictures with 36MP cameras, still it is going to be crappy image :) . 

And practically speaking when the last time you print your image? We always upload our images over the social media where it end up in compressed and less quality format regardless of any higher resolution camera we used .... that includes your 8MP iPhone :) 

So this is to address the question ..... do we really need more mega pixels ..... practical answer .... NO!

Happy learning guys !

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