Controlling the point of focus

I was walking around the countryside when I turned a corner and seen the most amazing site – a farmer fighting a real life dragon! so I took out my camera and quickly snapped a picture before the dragon has a chance to fly off (or set me on fire), I got home with the picture that would make me rich and famous, quickly loaded the picture on the screen and – the farmer and dragon are both completely blurry because the camera focused on this stupid cow at the distance – so much for fame and fortune  and back to blogging about photo techniques.

A more common version of the same problem (for people who don’t get a chance to meet a dragon) is a photo of a couple at a wedding or similar event where the couple is blurry but some aunt in the distance that is visible between the two people you are trying to photograph is crystal clear.

There are actually two easy ways to completely control the camera’s point of focus:

Focus and recompose

“Focus and recompose” is the oldest, quickest and simplest way to control the point of focus.

You start by setting your camera to always focus on the center point of the picture, check your camera manual about how to do that – for simple cameras and cell phones that don’t let you preset the focus point you can skip to the next technique.

Now, to photograph a lion wandering into a quiet farmyard point the camera strait at the lion (the composition is way off and we see stuff that is supposed to be out of the frame – but we don’t care at this point we’re not taking the picture just yet):

Half press the shutter button and hold- this will make the camera focus but not take the picture:

Now, with the shutter button half pressed, move the camera so that you see the picture you want to capture (but don’t move closer, back up or zoom in/out as those will change the focus) and press the shutter all the way:

And we get the exact picture we are looking for – the lion is in sharp focus and the farm animals blurry – who are both closer to the camera and near the center – so if we leave it to the camera they will be the most obvious point of focus (note that resizing pictures to smaller size makes them sharper and so the farm animals don’t look so blurry in the small version, to better see where the focus is note the difference in the level of detail between the face of the lion and the face of the cow).

It’s important to know this technique does fail miserably in one situation – when you have a very shallow depth of field (when the subject is very close the the camera, you set a very wide aperture or you are using a long lens) in this case the area of focus is so small that by moving the camera you are moving the focus enough to blur your subject – for those cases we have the next technique.

Choose the focus point

Here instead of focusing and then moving the camera we just tell the camera exactly where we want it to focus.

For cellphones, point and shoot cameras, DSLRs in live view mode usually focus by using the image captured by the sensor, there will be a frame on the screen that tells you where the camera will focus, just move this frame (usually by using the arrow keys, or tapping the screen for touch screens) so it covers the area of the picture you want to be in focus:

For DSLRs using the viewfinder and other cameras that have the faster and more accurate “phase detect” auto focus method the camera has actual multiple special focusing sensors and you can choose which of those sensors to use – if you look trough the viewfinder you will see black dots on the image, each of those dots represent an auto focus sensors, and when you half press the shutter button a dot that is in focus will glow red, you can tell the camera to use just one specific auto-focus sensor) (or, in more expensive cameras, to use only part of the sensors) – here is the focus point selection screen on my camera with the top left point (that is right on the lion) selected :

This technique is more accurate than “focus and recompose” but is slower because you have to mess with the camera settings.

That’s it for today, next week we will talk about what you can do when auto focus doesn’t work at all.

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