To Be Sharp or To Be Blurry, which is it to be?

To Be Sharp or To Be Blurry, which is it to be?

One of the many things to consider when composing your picture is deciding on what part of your subject/scene/composition you want as sharp as possible.

A Tilt/shift lens mounted on 35mmcamera
A Tilt/shift lens
Technical Camera with full movements
Technical Camera with full movements

The Theory

With the exception of the Lytro camera there is only one Plane of Sharpness that will be in focus and, unless you use a tilt/shift lens (assuming you’re using DSLR or other non-technical camera), the plane of sharpness will always be parallel to the focal plane of the camera (we’ll ignore LensBaby lenses for now).

There will be zones before and after the plane of sharpness where the sharpness is acceptable. Depth of Field (DoF) is the distance between the beginning and end of acceptable sharpness – This also depends on the amount of enlargement you intend to use on the image. The impression of  greater DoF comes from small enlargement  compared to a larger image size when viewed from a normal distance for the size of display/print.

You need to do a combination of things to guarantee sharpness in your shots, namely;

  • use a rock solid camera support, which could be a tripod (for portability) or
  • any support you can put the camera on such as a “bean bag” to cradle the camera on a solid surface.
  • Ensure there is no subject movement.

Tripods are just three legs with a top to hold them together and provide a camera connection.

Some doe’s and don’ts of tripod usage are:

  • Try and avoid extending the center pole as this negates the ‘solidness’ of the three legs on the tripod.
  • Use a ball type for the tripod head. Pan and tilt are really best for movie cameras.
  • Use a remote shutter release – wirelesspreferred or connected cable type.

    Diagram showing plane of fous perpendicular to focal plane of camera
    There is only one plane of focus.
  • When no remote shutter release is available use  the camera’s self timer. Some cameras have a “shutter delay” menu setting that delays firing the shutter until a small time after the mirror rises to absorb mirror slap vibrations.
  • Use the mirror lock up function, if available, which may be manually operated (count about 3 seconds before using shutter release for vibrations to cease) or, as noted before, you may be able to program a delay after shutter release is pressed and the mirror is raised before the shutter operates, some cameras refer to this function as Exposure Delay Mode.
  • For lenses with with Vibration Reduction (VR) or Image Stabalization (IR) test to see if this needs to be OFF when when camera is not hand held.
  • If your VR or IS system has two modes then one of them is for when you are in a moving vehicle. Learn which is for what situation.
  • Zone of Acceptable Sharpnes is called Depth of Field
    Zone of Acceptable Sharpnes is called Depth of Field

    Regardless of the quality of the VR/IS system it is of no use when your shutter speed is faster than 1/300 to 1/500 sec. You will need to experiment but  turn it off when the shutter speed is faster than the threshold speed you have determined. Otherwise you may find the VR?IS system degrades the sharpness!

  • Unless other composition reasons demand it use an aperture that is two/three stops down from wide open. This reduces to a minimum any lens aberrations that exist. And in any case for small sensor (this means anything including or smaller than FX size (24x36mm /1×1.5”) as diffraction becomes apparent at smaller apertures.
  • It’s axiomatic to say but use a good quality lens in the first place.
  • Select the lowest ISO the camera has (often called it’s native ISO) – when using a camera support the resulting slow shutter speed should not pose a problem unless your subject is moving.
  • If your camera supports Live Mode and you can zoom in on the image, use this feature to check focus or take a test shot and using Zoom on the image in Playback mode to check focus and DoF is what you want.
  • Post Shooting – if your image edit program supports luminance sharpening use that in preference to the RGB layer sharpening.

Hand Holding

If a camera support is not available or viable for the shot then the following tips should give you a greater percentage of sharp shots.

Diagram of The  ratio of acceptable sharpness in front and behind plane of cus
The ratio of acceptable sharpness in front and behind plane of cus

Use the fastest shutter speed with the aperture that reduces aberrations (generally one or two stops down from wide open), unless you are looking for a blurred foreground/background to make the subject standout.

The minimum shutter speed that you can use is dictated by the focal length of the lens you are using. Note the focal length you are using and the shutter speed is its reciprocal. For example, 300mm focal length means a minimum shutter speed of 1/300 sec, 150mm == 1/150 sec. If the calculated shutter speed is not available use the next fastest one. This assumes a stationary subject. For moving subjects use the reciprocal of the lens and adjust according to the table of speeds below.

Of course if you have a very fast ISO set you will be able to use faster speeds.

Subject @ 15m

Subject Speed (km)

straight on

Oblique 

Lateral

Pedestrians

3   6 1/20 1/40 1/60

Foot races

32 1/100 1/250 1/400

Swimming

6 10 1/250 1/400 1/800

High Diving

80 1/300

1/400

1/500

Bicycle racing

40 1/150 1/400 1/1000

Trotting horse

8 16 1/80 1/150 1/250

Racing horse

40 48 1/150 1/300 1/900

Train

60 1/150 1/300 1/500

Fast train

90-120 1/300 1/600 1/900

fair weather waves

8 20 1/200 1/400 1/600

Waves in gale

100 160 1/600 1/800 1/1000

Slow cars

8 16 1/50 1/100 1/150

Racing cars

130 320 1/500 1/1000 1/2000
  • What if you have set the optimal aperture but with the current level of light and ISO you cannot use a suitable shutter speed? Increase the ISO until you get the shutter and aperture values you need.
  • Try using Continuous Shooting mode (set to 3 shot burst), you may find that the middle frames of the triplet will be the sharpest.
  • Wrap the camera strap around your forearm or around head to provide extra steadiness.
  • Lean on something solid, which may include a person.

If you have your bean bag support that can be placed on a railing or post to support the camera

But the most important thing is to practice any and all these tips and techniques before you need to really use them. When you do need to shoot The Great Shot you wont have to worry about blurry or un sharp shots.

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