When shooting a close-up of people’s face, it is highly desirable to have their eyes in sharp focus and at the same time render the background blurry to avoid distractions. This situation typically requires accurate focus and large lens aperture. Here are some tips on how to focus on the eyes.
Focus-and-recompose technique should typically work fairly. On many cameras, the center focus point is the most sensitive and accurate. Therefore it may be the best option to simply focus on the eyes and recompose the frame. Be aware that focus-and-recomposes can have some pitfalls.
If you are concerned about focus accuracy using focus-and-recompose technique, another way is to use a off-center focusing sensor point. Many cameras have multiple focusing sensor points. Choose the one that’s right over the eye when the desired composition is achieved. If no focusing sensor point is exactly over the eyes, just select the one that is nearest to the eyes then do the focus-and-recompose. This will minimize the focusing error. Or you can compose loosely so there is a focus sensor point over the eyes, then crop the photo to desired composition.
Finally, you can always try manual focus if the light is not too dim.
If you still cannot get a good focus on the eyes, you may need to increase the depth of field (DOF) by stopping down the aperture. What may happen then is the shutter speed becomes too slow. In this case, you will need to either increase the ISO or shoot with flash.
Posted in
Tips and techniques on October 29th, 2007.
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This is a very well presented video tutorial of the important photography concept depth of field (DOF). Enjoy!
Posted in
Tips and techniques on October 25th, 2007.
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What you see is not what you get. When it comes to shooting with a SLR camera, this is usually true. The camera keeps the lens at its widest aperture for metering and focus operations. It only stops down the lens to the aperture you want when the shutter release is pressed to take the picture. This is typically desired because the viewfinder would otherwise be too dark and the auto-focus sensor would have trouble acquiring focus.
The problem is that the depth of field (DOF) is directly related to the lens aperture. How could the photographer know if the end result will have the subject captured in acceptable sharpness before taking the picture? To solve this problem, most SLR cameras are designed to have a depth of field preview button that allows the photographer to stop down the lens temporarily to preview the depth of field. Is depth of field preview the only function of this button? Read More…
Posted in
Tips and techniques on October 14th, 2007.
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What is depth of field (DOF)? Here are some definitions. People seem to have formed some customary notions about this term but may not really understand it. Examples of them are:
- Lens with shorter focal length (wide angle lens) has more depth of field (or less background blur) than a lens with longer focal length (telephoto lens)
- Camera with larger sensor has less depth of field compared to camera with a smaller sensor
- Depth of field can be calculated precisely from a formula and it won’t change from person to person
- …
While these are true to some degrees, or in certain circumstances, it is not the case for all situations. If you are still confused by this subject or just want to refresh your understanding, please read the excellent article by Paul van Walree.
As Paul pointed out, the depth of field has a lot to do with human perception. Viewing conditions, distances, visual acuity, etc have significant impact on depth of field. When comparing depth of fields, it is very important to establish a comparison framework, otherwise the comparison will be meaningless. For example, wide angle lens has the same depth of field as telephoto lens when the subject is framed the same (with different perspective due to different subject-camera distance). It is also quite eye-opening to know that the lens design also affect the depth of field: some lenses with longer focal length may yield more depth of field than a lens with shorter focal length.
I hope you enjoy the reading. For more information on depth of field:
Posted in
Tips and techniques on October 9th, 2007.
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This YouTube video teaches you how to simulate the shallow depth of field effect using Photoshop.
Blurring the background is a very commonly used photography technique to emphasize the subject and to avoid busy or distracting background. In photography term, you want to have a shallow depth of field (DOF) that only allows a narrow range of sharp focus. Here are a few very easy tips:
Get closer
Focusing at a closer distance will reduce the DOF. The focal length of your lens may limit how close you can get. For example, it is preferred not to get too close to for a portrait photo with a wide angle lens to avoid odd-look distortions.
Use lens with longer focal length
At the same camera to subject distance, lens with longer focal length will produce shallower depth of field. An added benefit of long lens is that it also has a narrow angle of view, therefore making it easy to avoid background distraction, such as a power pole, trash can, or hash reflection spot, etc.
Open up the lens aperture
The wider the aperture (the small the f-stop number), the shallower depth of field is. Professional grade lenses can typically open up to f/2.8, or even f/1.4. Some budget lenses may not have such large aperture so you just have to open as wide as possible if the DOF is not shallow enough. In many practical cases, you do not want to use maximum aperture for a couple of reasons: first, the DOF may be too shallow to contain all parts of the subject that need to be sharp; second, the image quality may be degraded due to distortion and chromatic abbreviation. You may want to know more about your lens to make a decision on whether the image quality is good enough.
Use the depth of field preview button
Many digital single lens reflex (DSLR) cameras have a DOF preview button. In typical photo-taking process, the camera sets the aperture wide-open to give user a bright viewfinder. When the shutter release is pressed, the camera will set the aperture to the intended f-value. If the intended aperature is already the maximum aperture of your lens, pressing the DOF preview button has no effect, although you may still hear a click.
The above are the basic tips of taking photos with less distracting background. Please comment below or drop me an email at picmax at gmail dot com. The excellent photo in this post was taken using a 90mm lens at f/3.8.
Posted in
Tips and techniques on July 11th, 2007.
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