Depth of field.

Two weeks ago I was approached by my friend who said that his dad was wondering how do I make my subjects sharp while the rest of the photo is blurry.... About eight years ago when I started taking photos, I asked someone the same question.

Every lens has a certain aperture (indicated by a letter 'f'... followed by a number. In fact you can see it in description of lenses all the time. Like Canon 135 f 2.0). 

Aperture is a hole in the lens that lets the light in. The more open it is (eg f 2.0), the bigger the whole, the more light comes in. The more closed it is (eg. f 8), the smaller it is, the less light comes in through the lens. Simple as that.

If you are wondering how is it that sometimes the whole picture is in focus and sometimes only certain parts of it are in focus leaving the rest of it blurry... then the word you're looking for is the depth of field which comes hand in hand with the aperture. 

If your aperture is open (eg. f 2.0) the zone of sharpness between the subject you focused on and the rest of the photo will be be very small. This will allow you to make that creamy blurred background that most people love to have in their photos.

And vice versa. If your aperture is closed (eg. f 8) the zone of sharpness on your photograph will be greater making it mostly sharp.

Have a look at this:

In this photo the depth of field is indicated by a sharp line that runs across the mat where the flowers lie. The actual area around the point where I focused, before and after, is approximately 1.5 - 2cm wide altogether. It's quite a small area! This means that all the subjects in the photo that are out of this depth of field (the sharp area) will be blurry. In this particular photo I had an aperture of  f 2.0.

I don't shoot at closed apertures such as f 8, but if in this particular moment I did, my whole bouquet of flowers would have been in focus. I would also be able to see the background clearer.

Closed apertures (bigger f stops ... from around f 5.6 up to f 22) are mostly used in interior photography and landscapes, as well as studio photography.

So in order to have a nice blurry background giving your photo some volume, you can shoot at low apertures. Most of the lenses that have low apertures are quite expensive. Because remember... Photography is all about the light and the more light you can let through your lens, the higher the quality of the picture you will get.

Practice it, compare it and find your own preference of depth of field because it can be quite subjective.


Please leave your thoughts, comments and questions below... lets engage and be friends :)

... you're simply extraordinary ...