I have often been asked about the Megapixel debate, is it some urban legend? Folklore? Or some old wives tale perpetuated by camera manufacturers? But what I am going to say is going to be based on facts, and having worked with Sony's DSLR division, I sort of know the good and bad of the megapixel race. All too often, we find ourselves confronted with decisions on which camera is better based on just the megapixel count of a sensor. Now more megapixel means more detail in a picture but only if it is exposed well. Put that context into a low light scene, the sensor's sensitivity comes into play and this negates any gain in detail. But let's not work on that. Let's assess what more megapixels will do for you.

The Good side of More Megapixels

Henri Cartier Bresson of Magnum, known fondly as HCB, didn't like his photos cropped but with more megapixels, cropping is actually good. Let's use a photo I took as an example. The original is above. Let's do a HCB time lapse into the world of B/W photography and turn this into a contrasty picture of a street scene.

The composition isn't spot on. There is lot of room and in the editorial room, it would be considered a "loose" photo since it is not tightly composed.

Here is the cropped photo, by throwing away rougly 1/3 of the size of the photo, it becomes a better picture. So if you happen to be shooting with a 24 megapixel DSLR, this image would be roughly 24MB in RAW size and after cropping, a third of frame, you are still left with 18MB of image data. Now that is a big image!

The BAD of having More Megapixels

High density sensors cost more to manufacturer and low light handling isn't as good.
Often, dynamic range will suffer as these smaller high density sensors just doesn't have the muscles compete unless helped along with brute force noise reduction steroids. Larger sensors handle light better but large high density sensor cameras also cost a bomb to own.

The UGLY side of More Megapixels

If you look at the above cropped pictures, and realize that you can take a "loose" picture and still rescue it later with cropping, don't you think that you'd be a loose photographer than a tight one? Pros everywhere have one strong point, they don't need any image cropping for it to come out right. Should you rely on more megapixels to save your day, then you will forever be dependent on it. By relying on post production miracles, you'd stop being a photographer and more of an image manipulator. This is the ugly side of photography which we all try to avoid but get sucked into. Cropping your image in-camera is the best way to go if you want to improve your sense of composition.

Conclusions

There is no right or wrong way to see this Megapixel Myth. The more insecure you are about your pictures, then the obvious route to take is to have more megapixels. The more confident you are about your photography, then the megapixel myth would have fallen away from you mind and in essence make you an even better photographer. So learn to work with what you have.

Confusing as it is, you have to understand this and I did the hard way with rolls upon rolls of film but today, people don't seem to care as they leave their cameras running on Auto. The fundamentals of exposure are not understood in the correct context and as such, mishaps will happen the moment you go full manual.

Holy Trinity of Exposure

When I started out, the first thing I had to understand was the correlation between ISO, Shutter Speed and f/stop. I had trouble imaging this because the damn SLR I got was fully auto EOS Canon. And the compact cameras I had didn't help either as there was no way to see this in action. It was that I bought into an old used, Nikon FM2 that I finally understood how they were related.

Everything in camera exposure is related to one another. The moment you preset one value, then you will be able to see how that value affects the others. Should any one of those change, for example, the shutter speed, then the corresponding Aperture and ISO would have to change as well to reflect this. One of the best way to understand this is to fix one of the variables so that you can see these changes.

Exposure Variables through Shutter Priority and Aperture Priority

In fully auto digital camera these days, many would shoot using AUTO mode and rarely will people even venture to P or Program mode. Confusion and madness abound when either Shutter Speed or Aperture is not fixed. This way, you can see how and why it affects exposure. Every scene is dependent on the available light at that moment. This is minimum exposure required to render an image. To learn about exposure, refer to the chart above where we have prioritized either the Shutter Speed or the Aperture's f/stop number. 

In the first example, by keeping the shutter speed at a constant 1/60, you will see how this affects both the ISO and Aperture. Shift the ISO up to 200, and the corresponding Aperture will have to go up to f/8 just to maintain the 1/60 shutter speed. 

The second example is the same, you have the Aperture fixed at f/5.6 but when you start to shift your ISO up to 200, the shutter speed will have to change to 1/125 and so on. 

Why ISO matters

This is a personal preference as some may shoot using high ISO like 1600 to 3200. The rule to remember here is that ISO will affect the quality of the image—giving it a noisy and grainy look as you go up the ISO ladder. So staying low is probably the best way to get good imaging. 

Exposure stacking, which is similar to HDR photography except that you capture only three frames with a 1EV difference between them is probably one of the most effective ways to capture night time photos without high ISO. Trusted that this method works best for scenes without moving objects, I have seen this method applied to model and fashion photography in high contrast scenes. The reason for such a method is to arrest the problems of the sensor's limited dynamic range by clawing that back with a three frame shot. 

High ISO is more effective in situations where there is movement and low light where exposure stacking is not possible due to movement of the subjects in the foreground or background. 

Depth of Field for Bokeh

Aperture control is a deft art. You can't deny its artistic merits but you can use a cheat sheet for this. How it affects exposure and DOF (depth of field) is sublime. 

As much as I love playing with the aperture, you have also got to understand that your choice of f/stop is dependent on exposure. If you want to throw something out of focus, then you need to keep the aperture wide open to let in all the light while throwing the background out of focus. Even during the analogue era, we had to get to grips with DOF for without it, the pictures would look dire. Digital is no different but there are more restrictions, something I will reserve for another article. 

Master of All Exposures

Once you jump over the exposure hurdle by learning how to Aperture, Shutter Speed and ISO affect one another and in turn give you the creative edge in creating a picture, then you have ascended to a new level of photography. 

These basic rules must be understood. Once you have this, you can apply various techniques found in digital cameras to further your imaging goals. 

I didn't have to worry about the transition as I had already grasp the very basics of exposure and applied that to digital. For this, I hope that you will start with manual settings on your digital camera and learn to shoot with it to see the difference. I spent a fortune on film learning the outcome of my exposure experiments but you don't have to once you have a digital camera in tow. For this alone, there is no reason why you can't master this with just a few clicks.