Sharp focus for the sharp eye

One of the most important systems in an actual digital camera is the autofocus (AF). In any recent cameras, even on the simpler ones, this is one of the most complex characteristic to use well. For most of the newcomers to the photography world autofocus is just as simple (and wrong) as half pushing a button and wait for a blink or beep confirmation. Then they take the picture without even analyzing if the focus was really achieved where it was supposed to. Even for the more experienced photographers, after checking the point and taking the picture surprises may arise, as sometimes focus is not exactly where it was supposed to… Perhaps not very displaced but just enough to transform a great picture into a mediocre one.

In order to achieve a better focus on important pictures, some tricks are worth knowing. Here is a little review of some of them.

 

You, Live View, my dear friend

Even if we tend to think that the most precise way of achieving focus is using the autofocus, it happens that one of the most precise ways to have a great focusing is using the manual mode… As long as your camera supports it (many compact cameras don’t), and you have a tripod or other stable surface to put the camera, and also a camera supporting Live View Mode, and time enough to play with the camera, and a still target… Too many “ands”, right? But it’s worth the effort.

Live view allows us to preview the image we are going to take before actually taking it. In fact, it can usually also predict the final exposition and other post-effects. This is a very handy tool because it can also magnify the image (perhaps by 2, perhaps by 10) on screen. Once you have the camera and target still on their place it is rather easy to focus on the right spot just using the live view as a guide and gently turning the focus ring on the lens. The extra magnification provided by the Live View Mode increases the precision as you will see the spot much larger than the real size. This way you can focus on the exact place you desire.

This is a very convenient way of focusing on studio, photographing still life, as nothing will move and you will have enough time to play with focusing. In this kind of photography quality is a necessity, as they are usually used for catalogs, fine art photography or perhaps illustrations for books. In any case, the increase on quality is usually an important request that a bad focus can ruin.

Another place where this trick is really useful is in nocturnal photography, perhaps stars or perhaps a still object in a very low light environment. In these cases the low light conditions imply that the autofocus won’t receive enough light to do its job. If you are taking a picture of the sky: focus on the brightest star on the firmament (even if it isn’t your desired target, the star will be almost at “infinite distance”, just as any other object in the sky, you just have to recompose after that). If you are photographing an object: aim for the most illuminated part. If the illumination is not enough you can use a small flashlight as a test light while you focus, or perhaps a laser pointer (the laser pointer is great even for the stars, as long as it is not very powerful; less than 10 mW is safe, never try with more than 20 mW).

Stadtflucht Lindabrunn

Example of how a low power laser pointer can create a point on the surface of interest that allows for a simple focusing on low lightning conditions. (Picture by Christian Benke)

 

Hold the shake

Sometimes the focus is good and all seems nicely configured, but still the picture is blurred and not perfectly sharp. If the entire image shows this pattern the focus is not the problem, as the lack of focus blurs on one point but another one must be sharp. The problem is motion blur. Motion blur can happen, amongst others, for two reasons: The shutter is making the camera tremble when is actioned, or the lens is moving while the sensor is exposed.

The first situation happens when using a not-too-fast and no-too-slow shutter speed, between 0.3 and 5 seconds approximately. In this range, when the shutter is triggered, the mirror flips so the light can reach the sensor, and this sudden movement can make the camera vibrate. To avoid this problem, a function called mirror-lockup is recommended. When activated, the first time you push the button the mirror will flip, and the second time the sensor gets exposed. To avoid moving the camera while pressing the button a remote trigger is recommended (if you don’t have one it’s the first accessory you should get, they are relatively cheap and very handy). If you don’t have a remote trigger, activate the countdown: the mirror will flip and start counting and the camera will have a few seconds to stabilize before taking the picture.

The second situation is more subtle. Sometimes, when a lens has a stabilizer, it will try to stabilize the picture even if the camera is completely still. Trying to compensate something that is not there makes the system mad and it shakes a little bit trying to find the movement; this shake blurs the picture. This doesn’t happen on all lenses, many stabilizers nowadays are smart enough to detect that there is no movement and just enter in stand-by mode, but it can happen. The solution is very simple: If you are working with a tripod or other stable surface, just turn off the stabilizer. Even if your lens is of the smart kind it won’t do any bad.

 

Stand still laddie!

Sometimes the motion blur is not caused by the camera itself, but by the photographer. When the shutter speed is longer than the actual focal length of the lens, blur movement is likely to happen due to the small involuntary movements we all do. Avoiding this for very long shutter speeds is difficult, but when moving on the frontier speeds trying to stabilize ourselves might help.

Try to relax while taking the picture, open your feet a little bit and get sure they are completely stable on the ground. Sometimes the position can help: if you have a wall try to put at least one side of the camera against it as a support, and if you don’t, try to make a “surface” with one of your arms and rest the camera on it, controlling it with the free hand (like the way they shoot pistols and Tommy guns on old gangster films).

Also breathing control can help. Instead of just breathing normal, try to make a couple of deep, intense breaths. After exhaling the second time just don’t inhale again and press the trigger. The inhalations will oxygenate your blood enough for a few seconds, and not inhaling again will slow down a little bit your heart. This will minimize the movement you get from your pulse and breathing for an instant, giving you an opportunity to take a better picture.

Photographing the Cherry Blossoms

The heavier the camera, the easier it will be to hold it stable in our hands. Don’t be afraid of adding an external flash, a grip or a heavy lens. Holding it with both hands also increases stability dramatically and reduces the blur-motion. (Picture by Susanne Nilsson)

 

I’m cold, I’m wet and I just want to go home!

Finally, if nothing of the above is applicable, you are in an unpleasant place or simply just tired and willing to finish and go home, remember some of the rules that apply to any camera: Closing the aperture will increase the length of field, decreasing the chances of not getting the focus on a good enough place. Increasing the shutter speed will reduce the chances of motion blur (at least the one produced by your movement, and reducing the blur caused by the target being on movement) and a high sensibility will favor both of the parameters above (but you pay in a noisier picture). You can also use a test light to achieve focus in case illumination is not enough for the autofocus to work well.

First Person Shooter in the Rain

Bad weather can be a challenge for a photographer, especially on long sessions. Always wear good protection against water or cold and do it with the help of an assistant if possible. Trying to achieve precision in hard conditions without proper equipment is a recipe for disaster. (Picture by Thomas Hawk)

 

Do you know any other tricks that might be interesting? Just tell in the comments! Perhaps they can be included in the next post about tricks.

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