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Focus – A Key To Sharp Photos

One main reason pictures turn out unsharp is because they are out of focus.

Seems simple enough? Well, there are several reasons this can happen, most of which have nothing to do with the camera being broken but all have to do with taking sharp photographs.

Too close the the subject

I have seen literally thousands of pictures ruined because of this one cause. A large portion of these are of newborn babies. Why? While we are trying to fill the frame with those tiny faces, we simply get too close to the subject to focus. Different cameras have different minimum focus distance (how close you can get).

The first step to fixing this problem is finding out how close your camera will focus.

For this we check that little book that came with your camera known as the instruction manual (you may see this theme repeated a lot here). You can usually find it (the distance – I can’t help you figure out where you left the manual) in the section that tells you how to focus the camera or listed in the camera specifications at the back of the manual.

After you know the distance, it can help to use a yardstick (or meter stick for those of you used to the metric system) or tape measure just to get a good idea how close that is and how it looks in your viewfinder. You can also use it to measure baby’s current height while it’s handy and you may want to write it down in your scrapbook next to baby’s picture. This has nothing to do with focus but you may appreciate it a few years from now. Anyway, it can be a little easier to know if your too close once you have a good idea what is too close.

Most, but not all, autofocus cameras will give you some kind of confirmation if it is focused or not or maybe if you are too close.

I know, now I tell you after you had to go search for a tape measure. Again, check your manual to find out.

The camera has focused on the wrong subject

A second reason pictures are out of focus (not sharp) is the camera has focused on the wrong subject. A common situation when this occurs is trying to take a picture of two people and there is a space in the middle between them.

Most cameras focus (or most reliably focus) on a spot in the center

Most cameras focus (or most reliably focus) on a spot in the center of the viewfinder (the little window you look through to “compose” you picture. If that spot happens to be a different distance than your subject (perhaps distant mountains), your subjects will be out of focus.

Lock focus by holding the shutter button halfway down

“So,” you say, “what’s the trick this time and do I need to look at that silly manual again?” Most cameras will let you lock the focus on a subject by holding the shutter button down halfway and recompose (fancy word for moving the camera) before pressing the button all the way to take the picture. And yes, you may want to check your manual and see what it says (besides they usually have a picture to demonstrate). Some cameras can sense if you have a subject not centered (maybe your friend is just too-way-out-of-line in which case this may not help). Maybe they use “the force”?

Some cameras have a mode that will force the camera to only focus at a farther distance

A very similar situation is when you try to take a picture through a fence or window and you have a sharp fence (or sharp reflection of you) and your subject (that million dollar horse in the field behind the fence) is not sharp. This can be a bit trickier of a situation. If you can use the recomposing method you are ok. If not, you may have to jump over the fence or break the window (I suggest to try opening it first-and don’t blame me if someone gets angry at you, I am not advocating vandalism just good photography). Some cameras have a mode that will force the camera to only focus at a farther distance. This may even make that fence magically disappear (you’ll need a magician to make the horse disappear-if you broke the window, maybe he could help you disappear). This is usually symbolized by a little picture of a mountain (but not always, sometimes the mountain picture means a wider depth-of-focus range which I’ll talk about in a second-don’t you wish we could all be more consistent with these symbols). This is definitely something you want to check that good old manual for!

One more note on recomposing. In most cases, the little changes in camera angle required to recompose will not make a difference in your focus distance. If you move too much though (step forward or backward) you may change the distance and move out of focus. It is important not to move too much when you do this.

Depth-of-field

A final focus related problem to sharp pictures is called depth-of-field. Depth-of-field refers to the total area that is in focus. This is a complicated subject that has to do with: focal length of the lens, aperture, focal distance and planet alignment (ok, planet alignment has nothing to do with it or with anything else for that matter, but focal distance does have a lot to do with physics, which is kinda like rocket science, which may have something to do with getting to planets). I’ll try to make some simple instructions.

Lens focal length refers to the length of the lens. Ok, what does that mean? Simply, a telephoto lens (or a zoom lens when you “zoom in”) has a long focal length and a wide angle lens (or a zoom lens “zoomed out”) has a short focal length. At long focal lengths, less area will be in focus

At long focal lengths, less area will be in focus. A good example of this is the lenses sports photographers use when they cannot be close to the action. The athlete or part of the athlete (lets say a close up of a baseball left fielder catching a game winning out) is in focus while the background is out of focus (fortunately we can’t see the overweight fan who is not wearing a shirt). At short focal lengths, larger areas can be in focus (allowing the photographer about to stepped on by a basketball player to have almost everything in focus (and a footprint on his forehead because everything looked so far away in the camera). If you want to have a subject close and a subject far away in focus a wide angle lens will help (in case you want that fence and the horse both in focus).

Aperture has to do with the size of the opening of the lens. This is measured in something called f-stops and to confuse you more smaller f-stop numbers mean a larger opening and larger f-stop numbers mean a smaller hole. A larger f-stop (smaller number) will mean less is in focus. A smaller f-stop (larger number) will increase depth of field and more will be in focus. Unfortunately (or fortunately, if you find this confusing), unless you have a SLR (single lens reflex) or DSLR (digital single lens reflex) you probably cannot adjust the aperture of your lens directly anyway.

 If there is lots of light your camera will choose a smaller f-stop and you will have more in focus.

What will affect the aperture is how much light is available. If there is lots of light your camera will choose a smaller f-stop and you will have more in focus. If there is not a lot of light (brightness-while technically 40 candles on your birthday cake is more light, it probably is still dim compared to the sun) less will be in focus.

That pretty much covers how focus affects sharp pictures. Next we’ll look at how camera movement causes blurry pictures.

About James Thoenes

James has spent most of his life involved in photography. He is now dedicated to producing portraits that his clients will treasure for the rest of their lives.