Focus on your focus

Cameras these days are like science fiction devices compared to when I first started taking pictures.  Back then everything was manual; setting the exposure, focusing, film winding.  Now we have all these wonderful automatic tools at our disposal, and auto focus has come on in leaps and bounds since the first, rather clunky, iterations.  That does not mean that it’s foolproof, nor does it mean that you should just let it do its work without any input from you.

Here are three examples of different focus issues.

Some auto focus systems need edge contrast to do their job, and when there’s not much edge contrast they can hunt around for a while.  These clouds with the sun behind them looked very moody when I applied about 3 stops of negative Exposure Compensation, but the auto focus was struggling to lock.  I switched to manual focus and it was easy to get the clouds sharp.

With macro photography the depth of field is low, even with small apertures, so you have to make a judgement about which bits of the subject you want in focus, and which not.  I wanted not only to get the edges of this raindrop sharp, but also to show a sharp image of the house and tree in the background.  The problem was that I could have either/or sharp in one image but not both sharp.  The solution was to take one image with the drop edges sharp and one image with the house sharp and then combine them in post-processing.  The result has both sharp, which is what I wanted.

There are times when you want nothing sharp, such as this image of dewdrops on the lawn a few days ago.  I used a 150mm lens with a 1.4x teleconverter on my Olympus E-M5 camera (equivalent to 420mm on full-frame), and set the Aperture to its maximum of f4.  I then set Manual Focus and defocused the image.  Using Autofocus here would have given a sharp image, and that’s exactly what I didn’t want.  Defocusing made the highlights on the drops render as circles.  It’s a technique called “Bokeh”, and can give lovely, abstract results.

In summary, let the auto focus do its thing when it’s the right thing to do, but keep control so you get the images you want.