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Digital Photography Explained

The "Nuts and Bolts" of Everyday Digital Photography

Digital photography is the process of capturing images electronically rather than by analog methods such as film or instant Polaroid's. A digital image is captured to a solid state sensor containing an array of photodetectors or pixels. The digital images are then stored as a type of computer file* that can be processed, edited and corrected using software such as Adobe Photoshop.

*These computer files are generally captured as JPEG or RAW files. JPEG's are a more basic and simplified file that holds less digital information. However, a RAW file captures a huge amount of captured information meaning processing can be more extensive and creative.

Digital Photography Explained

Do you KIND of understand it, but would like digital photography explained a little bit more? Well, without getting into the technical jargon, I will try and explain the basics. If you understand digital photography at a certain level, you then begin to understand how to manipulate each and every pixel to your advantage.

Traditional Film Photography

With film photography, the light falling through the lens would create a "negative" image on the film plane. For example, the brightest light would BURN a darker area onto the film. Then when printing this image, light is shone through the negative, onto photographic paper. This is highly sensitive to light. So, the darker areas on the film would block the light hitting the paper during exposure of the paper. This would then re-create the original lighter image that was recorded onto the negative!

Make sense? No, read it again ; )

Now digital photography is radically different, but based on the same principles of light. There is no negative image formed, just a replica of what you see through the lens. Each digital camera has what is called a *CCD or *CMOS sensor in place of the negative. This is where the Mega-pixel war is fought. Each individual pixel (Up to 100 million pixels at the time of writing this) records the amount of light, including the full colour spectrum, that hits it. It then converts the whole thing into an image.

CCD and CMOS Sensors

CCD stands for Charged Coupled Device. This  records photons as electrical charges in every photosite or pixel. After exposure, all of the charges and information is taken as a whole to a built-in amplifier which then converts the analog signal to a digital one. It is then stored on your memory card or external recorder.


CMOS sensors or Complementary Metal-Oxide Semiconductors work slightly differently and more efficiently. CMOS sensors have solid state circuitry on every photosite which means all the work can be done there and then. Right on the sensor itself. Because each photosite can be accessed and worked on individually, it can respond more effectively that a typical CCD sensor.


I guess this is why some of my earlier digital video cameras had 3 CCD sensors as opposed to one CMOS sensor. Isn't tech amazing?


Make it Simpler for me!!!

Ok. Imagine you had millions of square Lego blocks covering 256 different colours and all the shades of the spectrum. If you were able to make these into a picture, using say, a football pitch as a template, that is the basic principle. Now, if you were standing on the pitch, it wouldn't look like a photograph at all, just lots of squares. However, if you were to fly over the pitch at a great height, it would start to look good.

There is a reason I am explaining it like this. When you use photo-editing tools such as Adobe Photoshop or Elements, what you are actually doing is this. You are:

  • Going back down to the football pitch
  • Re-arranging the colours, shades and tones of each block
  • Then floating over the pitch again to check the image

Obviously you don't alter each pixel individually, the editing program takes care of all the donkey work. Although for serious work, I have, on occasion, altered individual pixels!!!

If you understand this, it should make your transition into digital a little easier. In order to alter a photograph in the past, you needed to acquire some serious darkroom skills. That was time-consuming and messy, believe me!

How many pixels do I need?

It is quite important to understand that it isn't the AMOUNT of pixels on a sensor (e.g. 16, 21 or 36mp), but the sensor size itself. It is the sensor that creates a bigger and better enlargement. For example, take the 8 mega pixel CMOS sensor on the now quite dated but still fantastic Canon EOS 20D (DSLR circa 2004). It will produce better results than the 8 mega pixel CCD sensor on a smaller compact digital camera or 12 megapixel camera phone.

Why? I hear you ask! Simply because it is bigger. Let's dig a little deeper…

Imagine the sensor is a net and each pixel is a square in that net. For argument sake, we are comparing two 24 square nets! I.e. Each net has 24 squares, 4 high by 6 long and they are made of the same material. Now you have to imagine this…

One net is 6 inches long, and the other is 12 inches long. How big can you stretch the 6 inch net before it becomes too tense? How big can you stretch the 12 inch net? A lot bigger right? They both have the same number of squares but one will stretch bigger.

That is the (really) basic way of explaining digital sensors.

Choosing a camera

Digital Photography Explained Sensor Sizes

When choosing a digital camera for yourself, remember that digital compacts have the smallest sensors. Semi-Professional Digital SLR's are substantially bigger. Most Professional Digital SLR's have the same size sensors as 35mm film.

See the diagram to the left (or above if you are on a Smartphone).

For the utmost in quality, medium format digital cameras have the largest sensors of all (check out the Mamiya Leaf Phase One cameras). The quality of prints from these has easily surpassed film quality in many people's opinion. However, unless you have a budget in excess of £10,000+, you may have to start a little smaller!!!

So, I hope that has shed some light on digital photography for you. It is a great time to be alive and have an interest in digital imaging. Technology is moving at incredible speed and I always look forward to seeing how cameras evolve. If you enjoyed this page or found it useful, please be sure to comment below and share with friends. Thank you.

​Further learning:

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