a25 March 2012

Tutorial: Wallpapers and what makes depth-of-field shallow


At the beginning I would like to mention that I made two more changes to this blog. First, I added wallpapers section at the top of the screen. At the moment there are just a few wallpapers in 16:10 ratio but I plan to add more shortly (if anyone will use them :) ) so I'm looking for your feedback. Second change is addition of clouds tag in the right panel of this blog what should make finding interesting content a bit easier.

Now I would like to tell a few words about depth of field and what affects it.


When asked what influences depth-of-field many, if not most, people would answer: aperture. However, this is only partially true as there are much more factors to this. If it wasn't this case the above photo wouldn't have that shallow depth of field as it was shot with aperture of f/4 (BTW I love this painterly bokeh on Canon 24-105 f/4 L).

The factors affecting depth-of-field are:
  1. Aperture - this one is pretty obvious and most of the beginner photographers are more less aware of this. The wider the aperture used the shallower the DOF.
  2. Distance from the lens to the subject - the smaller the distance the shallower the DOF becomes. Also note that to get blurry background it works opposite way. The blur is stronger if background is at a greater distance. Both factors were used in the photo above. I got as close as possible to the flower and at the same time the background was at quite a distance. This way I got both shallow depth-of-field and very nice blurry background. Also this is a problem in macro photography. With just a few centimeters from the subject it's really really difficult to not get ultra shallow depth-of-field. Macro photographers would love to have whole insect in focus but to achieve this they often use a bit different techniques (like focus stacking which I hope to discuss in some time).
  3. Focal length - generally speaking the longer the focal length the shallower the DOF. It is very useful feature for landscape photographers as even at widest aperture at the focal length of 14 - 16 mm it will be relatively easy to get almost everything in focus.
  4. Sensor size - generally the larger the sensor the shallower the DOF will become. That's why you will never get blurry background on iPhone and it will be very hard to obtain on most of point-and-click cameras. Also the full frame DSLR camera will have shallower depth-of-field than crop sensor size.
That's all for today :)


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