FOLLOW NEOCAMERA
RSS Twitter YouTube
TRANSLATE INTO

Archive for the ‘Digital Photography’ Topic

2013.11.23

Now that CMOS sensors are incredibly common, even on ultra-compact cameras, many digital cameras can quickly capture multiple frames to produce a single image which cannot be captured in a single shot. Even if the camera cannot do it, software exists to combine multiple images together in different ways.

An exposure is what happens in the camera from the time the shutter opens to the time it closes. Most images are produced from a single exposure which takes a slice of time and dynamic-range and captures it. By taking multiple exposures and combining them, one can produce an image which shows more than what an exposure can capture.

Multiple images can be combined in a number of ways:

  • Panorama Stitching – This produces an image with a wider field-of-view than any individual image can, up to 360-degrees actually.
  • Exposure Fusion – This averages out pixels from different exposures to produce directly a low-dynamic-range image, so there is not need to do the tone-mapping like for HDR images. Tone-mapping is the delicate operation where, without a subtle hand, you end up with the types of images you are talking about.
  • HDR Blending – This takes images from multiple exposures to produce an image which stores more dynamic-range than what the camera can normally capture. These images are often used in 3D rendering to make simulated reflections more realistic.
  • Focus Stacking – Takes images focused at different distances to produce and image with an impossibly deep depth-of-field. Often this is used for macro photography to show entire subjects in focus.
  • Image Stacking – This is one most often used with astrophotography. This creates a long exposure by adding up short ones. You would need to take 525 consecutive exposures and the Image Stacking software will blend them into one.
  • Multi-Frame Noise-Reduction – Averages a number of images to produce one which is less noisy. This can also be used for astrophotography to reduce the noise in long low-light exposures.
  • Multiple-Exposure – Overlays multiple images to artistic effects. This is what layer-blending in Adobe Photoshop essentially does. It shows images as if they were super-imposed.

Note that you can combine techniques which requires even more images. For example, to produce an image which captures a wide dynamic-range and infinitely deep depth-of-field, one may use 5 shot brackets at each focus distance. With 5 such distances, one would need 5 x 5 = 25 shots.

Some artists take this to the extreme by using different combinations of multi-exposure techniques for foreground, middle-ground and background elements and then blending the results together which is yet another similar technique. Images combined from hundres of exposures have been produced!

Neocamera Blog Neocamera.com © Cybernium

2013.07.15

Nearly every digital camera on the market, even most point&shoot models, offer a choice of metering system. This deceptively simple option can completely alter the result of images. Luckily for many compact cameras and a number of mirrorless ones, the LCD or EVF correctly previews the effect of the currently selected metering mode. For DSLR users, it is harder and you need to become familiar with how metering modes behave. Naturally, the question is: When to use a particular metering mode?

Every digital camera has a Multi-Segment metering mode. Nikon calls theirs Matrix. Canon calls theirs Evaluative. They work the same way except that each has its own secret formula. In fact, even different Nikon cameras have different Matrix modes. These modes are generally targeted to the intended users of the particular camera. So a lower-end Nikon tends to produce brighter images compared to a higher-end model under similar conditions. These Multi-Segment modes are very sophisticated and does a good job in most situations.

Spot is used when you know what part of the scene is going to be your midtone, that is the part of the scene that you want to show as 18% luminance which corresponds to a middle tone, hence the term midtone. This is simply based on an old research which concluded that the average scene reflects 18% of light that falls on it.

To use Spot metering, you must point the spot meter at that part and lock the exposure using either the AE-L button or by half-pressing the shutter. Most cameras are setup like this initially but you can change that on certain models. Then, you reframe your subject without releasing the shutter or AE-L button and take your shot. When using the Spot meter, nothing else is considered by the chosen spot.

Many Olympus cameras feature also Highlight Spot and Shadow Spot options. These work similarly to spot except that they meter for a highlight or shadow, respectively. These are generally more convenient to use since it is easier to tell which part of the scene is brightest or darkest, than to tell which one falls in the midtone. Users of other cameras can use Spot in conjunction with Exposure-Compensation to achieve the same exposure. Dialing around -3 EV of EC gives a shadow spot while dialing around +3 EV gives a highlight spot. The exact amount of EC needed depends on the camera’s dynamic-range which is itself dependent on the selected ISO.

Center-weighed is basically the ancestor of multi-segment metering. It tries to make the central part at least 18% bright but will vary the results depending on the brightness of the surrounding areas. Average metering is also simple in that it simply averages several measures which are evenly distributed across the frame.

In most cases, selecting a metering mode to use is easy:

  • Use Spot metering when you know which part of the scene should be your midtone.
  • Use Multi-Segment metering otherwise.
  • Use Center-Weight or Average when Multi-Segment fails.
  • Adjust with EC as needed. No metering system is perfect yet!

Neocamera Blog Neocamera.com © Cybernium

2013.06.17

Blurry images are caused by many things. The most common cause is probably photographer movement. This is exaggerated by high-resolution sensors such as the one on the  just reviewed Nikon D7100, long lenses and dim apertures on typical kit lenses or high-magnification ones.

For better stability while shooting hand-held, turn stabilization on and use this hand-held shooting technique:

  • Assume a stable posture, usually not leaning in any direction.
  • Support the camera’s weight with the left hand.
  • Grip firmly with the right but let the index-finder loose.
  • Press the shutter-release halfway and wait for a focus-lock (When using AF)
  • Breath in
  • Exhale
  • Gently press the shutter-release fully.
  • Wait for the photo to be taken (Most people skip this step)
  • Resume breathing.

A tripod is always best for stability but they can be quite cumbersome, impractical or outright forbidden is some places. Depending on the weight of your camera, a Gorillapod can possibly do. It is a small, cheap and relatively light (How often does that happen?) flexible tripod.

Neocamera Blog Neocamera.com © Cybernium

2013.04.03

Each week, we get a dozen or emails saying how great the image quality is from such an such camera we reviewed. Thank you! One would think this normal of large-sensor cameras such as DSLRs and most mirrorless models, but we even get a similar number of emails for ultra-compacts and ultra-zooms which use relatively small sensors.

Frankly, most small cameras do not deliver great image quality. They cannot but they can produce great images. People often confuse great images with great quality. These are completely different and unrelated things.

Image Quality encompasses all aspects of how a camera and lens capture a scene. There several aspect which comprise image quality and they may be attributed to the camera or lens:

  • Image-Noise – The amount of speckles and random variation in an image.
  • Dynamic-Range – The range of contrast from a scene which can be captured.
  • Color-Depth – The richness and gradations of colors.
  • Color-Accuracy – The accuracy of colors relative to our perception.
  • Sharpness – The definition of edges and details.
  • Resolution – The size of details than can be captured.
  • Distortion – The faithfulness of shapes.
  • Vignetting – The uniformity of illumination.
  • Aberrations – The appearance of colors and light which is not present in the scene.
  • Flare – The reflection of light within a lens.

These apply differently depending on the camera and some, such as color-accuracy, only apply to an image processed in-camera rather than a RAW file. Image quality is a property of the camera and lens at a certain setting. Using a different ISO, shutter-speed, image-parameters (JPEG), aperture or focal-length can result in different image quality from the same camera and lens combination.

Greatness has to do with success as an image. It is much more difficult to quantify and resides in how a viewer relates to an image as realized by the photographer which decides and controls some of the following aspects:

  • Subject – What the photographer wants in the image.
  • Framing – How subjects fir within the image.
  • Light – The light illuminating and reflecting of objects in a scene.
  • Color – Colors present in an image.
  • Moment – The time when a photo is taken.
  • Exposure – How a scene is captured.
  • Rendition – How an image is rendered.

With success, there are far less absolutes than with image quality. Something which may for work for one subject can easily fail for another. Plus, a photograph may appear successful to one viewer while appearing a complete failure to another.

The only way to improve success is to hone photography skills through learning, experimenting and a critical eye.

Neocamera Blog Neocamera.com © Cybernium

2013.03.15

A tripod has real benefits to photography and should be used anytime you can. Here is why:

  • Stability: No matter how fast your shutter-speed is going to be, a good tripod can do better. There is a rule-of-thumb that says you need a certain shutter-speed (1/focal-length) get a sharp enough image but it does not guarantee one.
  • Creativity: A tripod lets you shoot at low shutter-speeds. Even though you could shoot faster, you may not want to. Maybe you want more depth-of-field or blurred motion.
  • Precision: With a tripod you can set your camera position exactly and it stays there. Getting your camera level and keeping it level is much easier with a tripod. Plus, with the camera fixed there, you can take the time to check all your edges and composition without the view shifting as you do it.
  • Repetition: You obviously know that HDR or time-lapse require repetition of precise framing but those aren’t the only case where this can be useful. You may have taken the time to perfectly frame your shot only to suddenly have something unwanted move into the frame. With the camera firmly on the tripod, you can take the same exact shot after the unwanted element has been removed.
  • Self-Inclusion: With a tripod you can put yourself in the frame. You can try camera tossing instead but you cannot control framing that way.
  • Panoramas: Try rotating around the nodal-point without a tripod! It is much easier to get all the shots you need with a tripod and even easier with a specialized head with marked positions.

There are certainly plenty of situation when a tripod is not an option. In some locations, it may be simply forbidden. In others, it may simply be impractical due to size and weight concerns. And finally, tripods are too restrictive when you need to move quickly which is the case for many types of photography.

Neocamera Blog Neocamera.com © Cybernium

BLOG SEARCH

Blogroll

Log in