Canon EOS-1D Dicas e técnicas - Página 10

Procurar online ou descarregar pdf Dicas e técnicas para Software Canon EOS-1D. Canon EOS-1D 35 páginas. For macintosh
Também para Canon EOS-1D: Manual de instruções (28 páginas), Manual de instruções (41 páginas), Manual do software (2 páginas), Gestão do ponto Af (2 páginas), Manual do utilizador do software (50 páginas), Catálogo de peças (38 páginas)

In One-Shot AF, it can take as long as a full second or more for the camera to achieve

focus completion in extremely low light without a focusing aid. Even with a Speedlite

featuring an AF-Assist beam, low-light AF will be slower than bright-light AF. This is not a

design flaw or manufacturing defect; it's related to the sensitivity of the AF sensor.

Remember that the AF system is always passive, even when using an AF-Assist beam;

AF search in low light can be faster with an AF Assist beam than without one, but bright

light AF speed will always be faster with a readable subject.

In AI Servo AF, the camera samples the AF detection data at varying rates of frequency

depending on the light level. The brighter it gets, the higher the sampling rate and

therefore AF performance improves. But as light levels drop off, the sampling rate

decreases and a point is reached where the tracking ability of the AF system is

diminished. In other words, it's unrealistic to expect AI Servo AF to track fast-moving

subjects as well in low light as it does in bright light.

Again, you may not always have control over lighting conditions, but it is important to

understand that there are limitations to AF performance according to the level of

available light.

Shutter Release

Another factor that has a lot to do with AF performance is shutter release technique. In

Techniques:

order to achieve the greatest possible performance from your EOS camera, it is essential

Half-Press vs. Mash

to press the shutter button halfway and hold it there until the instant you are ready to

shoot, especially in AI Servo AF with moving subjects. No other way is nearly as effective

in terms of maximizing AF performance.

There are two issues at stake here: the first is focus tracking and the second is a

phenomenon known as "release-time lag" or "shutter lag." In One-Shot AF, pressing the

shutter button halfway locks the focus. When the camera is set for AI Servo AF and the

shutter button is pressed halfway, the AF system begins tracking the subject. If you

simply press the shutter button down without waiting for the AF to function, the shutter

release might lock up or be delayed in One-Shot AF. Under the same conditions, the

shutter will release without focusing in AI Servo AF. This is true with or without the use

of an AF-Assist beam. Conversely, pressing the shutter button halfway and holding it

there until you are ready to shoot allows the focusing system to lock focus in One-Shot

AF or start tracking the subject in AI Servo AF. Pressing the shutter button down all the

way once focusing has been established will release the shutter in the shortest possible

time, thereby increasing the odds of capturing "the decisive moment."

I. CAMERA FEATURES AND OPERATION

focus manually until you are "in the ballpark," then try using AF for fine-tuning.

Additionally, this is an instance where the distance range selector switch on "white"

lenses like the EF 70-200mm f/2.8L USM can reduce the length of time the AF system

spends hunting for focus, if your subject distance happens to be beyond the range

stated on the lens switchboard.