I have received few questions about depth of field control with micro four thirds cameras after uploading the post about Olympus OM-D EM-5. One concern people expressed when considering a micro four thirds cameras was their smaller sensor size and most of the relatively slower lenses creating a comparatively larger depth of fields and less than pleasing out of focus points (bokeh). While I agree most of those concerns are valid, I think most new photographers keep on forgetting the other methods available to control depth of field.
For those who are interested here’s one of my lengthy posts from the past about depth of field determinants.
Word about bokeh
Bokeh is defined as the way a LENS renders an out of focus point of light on the sensor. In other words, bokeh is the quality of an out of focus point on the sensor as rendered by the lens. While the depth of field directly influences the bokeh, it is actually generated by the shape of the area passing light on to the sensor, which is the aperture. Rounder the aperture more pleasing the bokeh is. This is why lenses with 9 blade diaphragms create better bokeh than the lenses with 7 frame diaphragms.
With that out of the way let’s see how we can overcome the smaller sensor size and the slower apertures to create a ‘narrow’ DOF image with a pleasing bokeh by concentrating on other determinants of DOF . If you want a detailed description on DOF control please read this to have better understanding
- Reduce camera to subject distance
- Zoom in – use the longest possible focal length
- Open up your lens as much as possible – you don’t always have to have f/1.2 lenses
Depth of field of any camera & lens combo at a given focal length and aperture can be calculated by using lens formulae, or more easily by using any decent DOF calculator, but nothing beats a real life example.
Here are two quick examples shots illustrating what Olympus OM-D E-M5 quipped with a 12-50 mm f/3.5-6.3 kit lens can achieve depth of field wise. (24mm-100mm equivalent on 35 mm)
Please note that ‘Princes Dora’ is only about 14cm tall. The distance between the toy and the wall of the playhouse, which is the background, is about 45cm. Subject to camera distance is about 100cm (1m) – Focal length 50mm, Aperture f/6.3 – Note how the background it staring to go blurry from just behind the toy.
This time I have moved Dora to a different location to separate the background and moved the camera in while keeping the focal length and aperture unchanged. What you see as background is a window with partially open Venetian blinds. Focus point was on the closest eye. Distance between two eyes is about 1.5cm. Distance from the doll to the window is about 220cm (2.2m). Camera to subject distance is approximately 50cm.
Note how even the left eye which is only 1.5cm away is starting to go out of focus and almost completely blurred background. (Cropped image at the top of the post illustrates this best)