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March 25, 2011 / arthill

Are your photos as sharp as you’d like?


You’ve probably seen pictures on the web or in one of those craft show booths or even on TV and thought, “Wow that is sharp”.  Or maybe you’ve gone through your own photos and wished that they were sharper.

Well there are several factors that affect how sharp your photos will be.

  1. The lens
  2. The subject
  3. Camera movement
  4. Subject movement
  5. How you focus

I’ll touch briefly on the first 4 and talk about #5 in more depth.  I think the first four are well understood and there isn’t a heck of a lot to say about them. 

The lens

Expensive lenses are sharper than cheap lenses.  That plastic lens in the disposable camera just can’t compete with a $1500 prime lens from a well known camera manufacturer. But this post isn’t about that.  You have your camera with the lenses you have and that’s it.  We’re going to talk more about how to shoot sharp photos with what you have.  I would caution you to read reviews on the web before you plunk down your hard earned cash for a third party lens.  Some of them are fantastic and some are mediocre.  I bought a lower priced telephoto a few years back and was never happy with the pictures so I got rid of it and moved up to a Canon lens.

The subject

Windows and the atmosphere itself can give you problems with sharpness.  If it’s hazy or misty or foggy you just won’t have a sharp photo.  Sometimes that’s fine, foggy shots are often very dramatic. A polarizing filter can help you shoot through glass.  You can compensate for some of that atmospheric haze with your photo editing software later.

Camera movement

Modern cameras with vibration reduction or image stabilization have helped here but you can still cause blur with camera movement. Higher shutter speeds help, especially with longer lenses.  With slow shutter speeds you need a tripod. Without one, try to brace the camera on something, a railing, a street post, a car.  Take a breath and hold it before you shoot and try to squeeze the shutter button – don’t push it or punch it.  Even with a tripod you may need to use the self timer so that the camera stops vibrating from your pushing the shutter button.  If your camera has a viewfinder, use that and not the LCD screen.  Alas, the trend with point and shoots is to eliminate the viewfinder.  You just can’t hold a camera steady at arm’s length.  If you must use the LCD, pull your elbows in to your sides and hold the camera just far enough away to see it (i.e. don’t extend your arms out in front of you).

Subject movement

This can be tough.  Definitely use a higher shutter speed. For fast moving subjects like cars, horses, runners, etc you may have to learn panning.  This is a technique (which requires practice) in which you move the camera on purpose in the direction of the moving subject.  You’ll get a blurred background but a sharper subject.  We think of moving subjects as cars and birds and kids but don’t forget that a breeze can turn a flower into a moving subject.  And subject movement is magnified when you are in close or using a telephoto lens.

Focus

Nothing spoils a picture worse than an out of focus subject.  So I’m going to spend most of this post talking about focusing.  If you’re like me you rely on the camera’s autofocus system. You activate this by depressing the shutter button half-way.  You should get some sort of autofocus confirmation – a beep and a green light in the viewfinder are common.

Today’s cameras do handle focusing pretty well but your camera also supports manual focus.  While you may not have to rely on manual focus often you will need to use it when shooting extreme closeups (macro).  There may also be times when the autofocus will just not work.  You will not get the beep and green light that indicate successful focus.  This can occur in low light situations or even when the subject has no contrast i.e. just shooting a picture of the sky.  If you switch to manual focus it means you look in the viewfinder (or LCD screen) and turn the focus ring until the image appears sharp to your eye.  That’s it!  So we’re going to concentrate on autofocus.

Even when you’ve set the camera to autofocus you may have two other choices to make

  1. Single shot or continuous focusing.  On my old Nikon point and shoot they used these two terms. On my fancy Canon DSLR they use the confusing terms One Shot and AI Servo. Regardless of terminology the two “modes” are for stationery subjects or moving subjects. In the single shot and One Shot modes the camera focuses on something in the scene when you press the shutter halfway and LOCKS that setting.  You get the familiar beep and or green light.  In continuous or AI Servo (c’mon Canon) when you depress the shutter button halfway the camera achieves focus but then keeps on focusing anew all the while you keep the shutter button depressed halfway. So, as the subject moves closer to the camera or further away the focusing mechanism adjusts until you push the shutter button all the way to take a picture. Note that in continuous focusing mode you do not get a visual or audible focus confirmation.
  2. Select AF point.  You can set this to automatic or manual.  NOT to be confused with auto or manual focus.  (Of course it’s confusing but it is what it is.)  The idea is this.  In auto mode the camera will select the best of 5 or 7 or 9 “points” in the image and set that as the focus point.  In manual mode you tell the camera which of the available points to use.

With my Canon T1i the screen that shows up is like this.  All of the nine possible autofocus points are shown in blue.  So, in this mode the camera will choose one (or more) of these to calculate the correct focus.

DSCN0049

When I press the shutter button halfway down red lights will come on in the viewfinder showing me which points the camera has selected.  Your camera will have something similar.  Take a good look at those.  Does it make sense?  Has the camera correctly identified the important items in the shot. If not, release the shutter button, move the camera a little and try again.  Check the focus points again – this may have fixed it. If it is still not right, you may want to tell the camera which point to use.  When I’m shooting close ups of faces I nearly always switch to the focus point shown below

IMG_2062

This tells the camera to only use the center focus point.  I then position this point over the subject’s eye, press the shutter button halfway and then recompose the shot to get the eyes where I want them to be in the shot.  I suppose I could just as well set it to use the top focus point but I’m just used to doing it this way.

Here’s an old shot I took with an earlier Canon (that only had 7 focus points).  Notice that the camera chose Jake’s ear as the proper focus point.  I failed to notice this and got a shot where they eyes were not in focus as well as they should have been.  I should have moved the camera around to get a focus point right on his eye or even set the focus to just the center.

image

On my old Nikon Coolpix 8800 if I leave the autofocus set to auto (I know auto to auto?) the camera shows the point it has selected this way

IMG_8939

If I set AF to manual the screen changes to look like this

nikon manual focus IMG_8929

and I can move that red bracket around to wherever I want it.

How important is all this?  Well, it depends Smile.  In my post on Depth-of-Field I explain that in some cases a lot of what’s in front of and in back of the focus point is also in focus. If DOF is shallow though, then it is critical to focus precisely on your subject.  So, before you shoot ask yourself the following questions

  1. Am I shooting with a telephoto lens (or zoomed in with my zoom lens)?
  2. Am I within a few feet of my subject?
  3. Am I shooting with a relatively wide open aperture (f-stops like f1.8, f2.8, f4)?

If even one of these is Yes then you’ll want to pay close attention to focusing.  If you answer no to all of these you’ll probably be okay with the camera’s autofocus decisions.

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3 Comments

Leave a Comment
  1. anna fowler / Mar 25 2011 6:29 am

    I do agree to u. The factors explained by you often cause a problem to look photo dull.

  2. Howard / Mar 25 2011 12:34 pm

    Very good info, Art. I believe I generally get the subject in focus but there are too many times when I don’t. It’s always good to learn and yes, even review what might have been forgotten, at least in my experience. Thanks!

  3. Maryann Goldman / Mar 25 2011 9:00 pm

    There were a few times lately that I could not get the S3 to autofocus. I tried moving around, changing to center spot focus, focusing on something bigger at the same distance and moving back over…no luck. It can be frustrating. I need to read how to use MF. I have it. I have never taken a manual focus shot with the S3. My eyes don’t focus good anymore. I’m not sure how much we want to rely on what I think is sharp:-) Thanks for all the reminders in this post of what to consider when it comes to sharpness.

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