Posted by dap

Taking a picture

When you take a photo, whether you realize it or not, you’re making dozens of artistic and technical choices that determine how the final image looks.  These choices are tradeoffs: there’s rarely a single correct choice.  And there’s a wide spectrum between using a compact camera in automatic mode (in which case you may not directly make any of these choices) and using a DSLR in fully manual mode (in which case you’re directly making almost all of them).  If you take the time to understand each of these in depth, you’ll understand more about photography than most amateurs and many professionals.  With the magic of modern technology, you can also make pretty good photos without understanding much of the technical considerations.

Below is a non-exhaustive list of the choices that go into every photograph, as well as useful resources for understanding each one in depth.  I try to organize these subjects logically, but there’s a lot of overlap between disparate categories.  This page is a work in progress.  As I learn more about photography, I expect to continue updating this page.

  • The physical space: the subject and the camera (point of view, not the device). What you’re shooting and where you’re shooting from.  See Composition below, too.
  • Camera and lens.  Cameras and lenses have their own effects on the image, including various types of noise and distortion and levels of sharpness, but most people make these choices based on what they have and what focal length and apertures they want for a particular photo (see below).
  • Lighting. Hard vs. soft light. Colors (white balance/color cast).  Artificial lights (including on-camera flash, as well as flash timing). Reflections. Filters: polarizing (reduce reflections), netural-density (reduce overall light level), colored.
  • Composition.  What’s in the frame?  Where does the viewer look first?  Where do they look next?  I use this as a catch-all for other artistic considerations, summarized best by asking how does the photo make the viewer feel?
  • Focal length.  This determines the field of view in the photograph, or in common terms, how “zoomed in” the photo is.  (While lay people use the term “zoom” to mean “magnified”, photographers use it to refer to a lens’s ability to change focal lengths at all.  A 10-24mm lens is a zoom lens, even though the most “zoomed in” it gets is further zoomed out than most compact cameras can do, and a 200mm fixed lens is not a zoom lens even though it’s more “zoomed in” than most cameras can do.)
  • Exposure (overall light level in the image).  This is comprised of essentially three components, each of which defines its own tradeoffs:
    • ISO: camera sensor’s sensitivity to light.  Higher ISO means more light, but also more noise in the image.
    • Aperture: how large of a hole in the lens the light passes through to reach the sensor.  Larger apertures allow in more light and reduce depth of field.  This can be a good or bad thing.
    • Shutter speed (actually a time interval): how long the shutter remains open to allow light in.  Slower shutter speeds allow more light in but over a longer period, so if a subject is moving it will appear blurred in the image.  Related: vibration reduction / image stabilization.
    • Exposure compensation: tells the camera to increase or decrease the exposure from what it believes is “correct”.  In manual mode, this doesn’t mean anything, because you’re controlling all of the above variables.  In semi-automatic modes where you control only one or two of the above three variables, this is how you tell the camera to adjust the other variables (without needing to understand those variables).
  • Metering: measuring the amount of light in a scene to determine proper exposure (see above).  I consider this separately because DSLRs have several built-in algorithms for determining the proper exposure: “evaluative” (i.e. “let the camera figure it out as best it can”), center-weighted, and spot metering.  Other methods are also possible, including several that require external equipment.
  • Vibration reduction / image stabilization.  This feature of a camera or lens reduces motion blur due to motion of the camera (not the subject).  Speculation suggests this can actually make things worse on a tripod, but generally I just leave this on.
  • Focus.  This is more complicated than you think.  Several choices here include automatic focus (which works poorly in many situations, including low light levels) vs. manual focus, static vs. continuous focus, the focus-and-recompose technique, which focus points to use (or whether to let the camera decide), and where you actually focus (the focal point).  Since the closer your focal point is to the camera, the smaller the depth of field, you don’t always want to focus on the subject itself.  In some cases, focusing on your subject throws the background out of focus, while focusing on midground keeps both the subject and background in focus.  This is related to the choice of aperture and exposure.  In the above example, you might start simple by choosing a small aperture and focus on the subject for maximum depth of field.  But if the required shutter speed for that aperture is too slow for what you’re doing (because you would have motion blur), then you could increase the aperture to increase the exposure and focus past the subject to maximize your depth of field.
  • Picture settings.  You usually make the same choices here for all photos.
    • Image quality (e.g., low, medium, fine).  I always pick “fine” because storage is cheap.
    • File format (RAW vs. JPG).  I always use RAW these days because Lightroom makes it as easy as using JPG, but using RAW enables you to manipulate the image much more extensively without losing quality.
    • Color space (e.g., Adobe RGB or sRGB).  How colors are represented in the final image.  This is a very complex topic.
  • Camera technique, including grip, which top-level shooting mode you use (typically program, aperture-priority, shutter-priority, or manual), whether to use bracketing, single-shot vs. continuous, and how you focus before taking the shot.