Buffer

3 September 2010

After the sensor in the camera is exposed, the image data will be processed and then written to the storage card. The buffer inside a digital camera consists of RAM memory which holds the image information before it is written out to storage card. This process makes the time between shots shorter and allows burst (continuous) shooting mode. The very first digital cameras didn’t have any buffer, so after you took the shot you had to wait for the image to be written to the storage card before you could take the next shot. Now most digital cameras have relatively large buffers which allow them to operate as quickly as a film camera while writing data to the storage card in the background (without interrupting your ability to shoot).
The number of images that can be shot in continuous (burst) mode is affected by the location of the buffer within the camera (which normally is not specified by the producer). The buffer memory is located either before or after the image processing.
Before Image Processing Buffer
In this method no image processing is carried out and the RAW data from the CCD is placed immediately in the buffer. In parallel to other camera tasks, the RAW images are processed and written to the storage card. In cameras with this type of buffer, the number of frames which can be taken in burst mode cannot be increased by reducing image file size. But the number of frames per second (fps) is independent of the image processing speed (until the buffer is full).
After Image Processing Buffer
With this method the images are processed and turned into their final output format before they are placed in the buffer. As a consequence, the number of shots which can be taken in a burst can be increased by reducing image file size (e.g. shoot in JPEG, reduce JPEG quality, reduce resolution).
Smart Buffering
The “smart buffering” combines elements from the above two buffering methods. Just like in the “Before Image Processing Buffer” the unprocessed image data are stored into the buffer allowing for a higher fps. They are then processed and converted into JPEG, TIFF or RAW. But instead of writing the processed images to the storage card they are stored in the buffer. Therefore, the image processing is not bottlenecked by the writing to the storage card, which happens in parallel. Moreover, it constantly frees up buffer space for new images since processed images takes up less space than RAW once, especially in the case of JPEG. Just like in the “After Image Processing Buffer”, the output images are then written from the buffer to the storage card. But an important difference is that here the image processing happens in parallel with writing to the storage card. So the image processing of new images can continue while the other images are being written to the storage card. This means that you do not necessarily have to wait for the entire burst of frames to be written to the CF card before there is enough space to take another full burst.

 | Posted by Andrei | Categories: Camera System | Tagged: , , , |

Batteries

30 August 2010

Disposable AAs
Given the high power consumption of digital cameras, it is economically and environmentally unjustified to use disposable batteries other than in emergency situations when your rechargeables are depleted. Disposable Lithium AAs are more expensive than Alkalines, but having about three times the power packed in half the weight, they are ideal to carry with you as a backup.
Rechargeable AAs (NiCd and NiMH)
NiMH (Nickel Metal Hydride) rechargeable AA batteries are much better than the older NiCd (Nickel Cadmium) AAs. They have no “memory effect” (explained below) and are more than twice as powerful. Capacities are constantly improving and differ per brand.
Rechargeable Lithium-ion Batteries
Li-ion (Lithium-ion) rechargeable batteries are lighter, more compact, but more expensive than NiMH batteries. They have no memory effect and always come in proprietary formats (there are no rechargeable Li-ion AAs). Some cameras also accept disposable Lithium batteries, such as 2CR5s or CR2s via an adapter, ideal for backup purposes.
Charging
Fully charged batteries will gradually lose their charge, even when not used. So if you have not used your camera for a few weeks, make sure you bring a freshly charged battery along on your shootout. Charging NiCD batteries before they are fully discharged will reduce the maximum capacity of subsequent charges. As the effect gets stronger when repeated often, it is called “memory effect”. It is therefore recommended to recharge the batteries only after they are fully depleted. To a lesser extent, this is also useful for NiMH or Lithium-ion batteries, although they have virtually no memory effect. Doing so will also increase the life span of the battery which is determined by the number of “charge-discharge” cycles that depends on the type and brand.

 | Posted by Andrei | Categories: Camera System | Tagged: , |

Los Angeles Insurance

29 June 2010

This days I found something interesting for all of us, a very useful insurance website. The Los Angeles Insurance website is unique in that it doesn’t simply stick to one kind of insurance carrier, but it brings you the best deals from many online insurance carriers. This way, you have offers from multiple carriers all in one place – the Los Angeles Insurance website!

Phone: 1-800-475-6840 (toll free number)
Los Angeles Car Insurance
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Los Angeles Auto Insurance

 | Posted by Andrei | Categories: Others | Tagged: , |

Autofocus

15 February 2010

This feature can be found in all digital cameras. In autofocus (AF) mode the camera will automatically focus on the subject in the focus area in the center of the LCD or viewfinder. Many digital cameras allows the user to also select other autofocus regions that will be indicated on the LCD/viewfinder.

AF Area

In “single AF” mode, the camera will focus when the shutter release button is pressed halfway. Some cameras offer “continuous AF” mode whereby the camera focuses continuously until you press the shutter release button halfway. This shortens the lag time, but reduces battery life. Normally a focus confirmation light will stop blinking once the subject in focus. Autofocus is usually based on detecting contrast and therefore works best on contrasty subjects and less well in low light conditions, in which case the use of an AF assist lamp is very useful. Some cameras also feature manual focus.

 | Posted by Andrei | Categories: Camera System | Tagged: , |

AF Servo

13 February 2010

This system allows the camera to maintain focus on subjects that are moving. It is a very useful feature for sports or wildlife photography and it is normally found on digital DSLRs.

Autofocus Servo is normally triggered by switching focus to “AI Servo” on Canon, or “Continuous” on Nikon, followed by half pressing the shutter release. The camera will continue to focus on the subject as long as the shutter release will be half pressed or fully depressed (actually taking shots). The Autofocus Servo usually also puts the camera into “release priority” mode so that the camera will take the shot when the shutter release is depressed, regardless of the current AF status.

 | Posted by Andrei | Categories: Camera System | Tagged: , , |