How Much Depth of Field

Hale, Cornwall. Sony RX10, ISO80, f/5.6, 1/50".
Hale, Cornwall. Sony RX10, ISO80, f/5.6, 1/50″.

Last week I took a well-deserved break (at least in my eyes) and went on holiday to Cornwall. Whilst away I took this photo that I wanted to share with you. The reason for sharing is not that this is a great Landscape image (I have a much better one taken at sunset rather than on an overcast day, that I will share soon). No the reason for sharing this is that it illustrates just how much depth of field can be achieved with smaller sensor cameras.

This image was taken using a Sony RX10 which has a 1” sensor. This is slightly smaller than the micro 43 sensors but somehow Sony has managed to cram 20Mpixels onto it. If you were looking at the print of this scene you would say that the image was in focus from the foreground to the background. It’s only when you view the image at 100% magnification on the screen that you see the distant lighthouse is very slightly outside the depth of field but is still acceptably sharp. Also the flowers nearest to the camera (literally inches from the camera) are out of focus but again this isn’t objectionable. Interestingly you don’t notice either of these points on the print as the image appears very natural.

What really makes you stop and think though is that the Aperture used to achieve this is f/5.6. The trick to this if there is one, is where you place the point of focus. Here I was focussing on the hillside just beyond the foreground flowers (probably around 10 feet from the camera. Had I tried to get all the flowers in perfect focus I would have lost the distant lighthouse. This compromise appears to work very well.

I hope this gives you food for thought about depth of field and needing to use very small apertures.

9 thoughts on “How Much Depth of Field

  1. Indeed, this is one significant advantage of smaller digital formats (although sometimes a disadvantage). When we add sophisticated IBIS with longer shutter speed capability in sharp handheld shots, the advantage is heightened. This is what makes some of the new top Olympus and Sony cameras so attractive and easy to use. Nevertheless, experience is the best teacher and practice makes perfect.

    Using old film cameras, I would often use manual zone focusing working on a tripod. Although there are manual focus prime lenses for digital that offer a focusing scale with aperture DOF markings, they are few and far between. Therefore, it’s necessary to be very familiar with the DOF characteristics of a particular lens at any focal length. For my zoom lenses, I carry a little book with DOF data for several focal lengths of my fav zoom lenses (I could also put them into my smartphone). That helps me to learn so that it becomes more intuitive where to focus and what aperture to use.

    One other factor with some WA and UWA lenses is curvature of focus field, where it may be necessary to focus farther back (esp near the center of the frame) than expected in order to get everything in focus out to the edges. For WA lenses with AF capability, cameras with a larger number of AF sensors have an advantage because the camera is able to nail focus for the largest number of AF points. Some excellent UWA lenses were faulted in past reviews for having soft corners (the Oly ZD 7-14mm f/4 comes to mind) due to an older camera’s inadequate AF system.

    1. Hi John, you have presented some great technical information here. For a while I was using a DOF calculator on my phone but then I ealised that I was terrible at estimating distances in a scene and surprisingly made a better job of just guessing where to focus and reviewing the results at full magnification on the camera screen. The point about the curvature of the focus field is one that I run into regularly when shooting Infrared. There are very few wide angle lenses that will give a sharp image in the corners.
      Thanks for sharing the information.

  2. On M43 for landscape I switch to manual focus, turn on focus peaking and enable DoF preview. Then it’s a simple matter of rolling the focus ring to get as much of the scene peaking as possible. Generally with a 14/15mm it’s possible to have acceptable focus with just f/4 and critical sharpness at f/8.

    1. Focus peaking is a good tool to help with depth of field but I have to admit that my eyesight sometimes struggles with it. I also find that on the Sony RX10 the areas that the peaking say are in sharp focus aren’t. Good approach though and thanks for sharing.

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