Focal Points

[monroe]

I have a Canon Xsi. It has 9 focal points. Why would I want to use any focal point or combination of focal points other than the center focal point?

[nathanbarlow]

because most of the time a centrally located subject is the most boring and cliche option.

[teaking]

The main reason is wildlife or sports photography if you use auto continuous focus it will use these focus points and allow you to track the action as some action shots you cant predict where the subject will be or will move to.

Like you say the centre focus point on most camera are the best and re framing is usualy best used for composition although even that is a debate lol.

[kencaleno]

Originally Posted by nathanbarlow

because most of the time a centrally located subject is the most boring and cliche option.

But, You use the centre focus point,because on most entry-level dslrs, it is the only focus point with cross receptors,then you recompose to suit. Peripheral focus points usually only have a single line of receptors,and you need to be at 90 degrees to these to focus properly. Ken

[OsmosisStudios]

Originally Posted by nathanbarlow

because most of the time a centrally located subject is the most boring and cliche option.

Im agreeing with Ken (*GASP*)
Using the centre point to focus then re-composing has been done since... well ever really.

The other points act as helpers to this main point and are good for moving subjects (as teaking mentioned).

[monroe]

Thanks everyone. Your comments have been very helpful.

[Toronto111]

Since light can pass through a lens in either direction, a lens has two focal points—one on each side.
Thin lens have 1 focal length, thick lens have 2 focal lengths.
Read the links in source for details.

[OsmosisStudios]

Originally Posted by Toronto111

Since light can pass through a lens in either direction, a lens has two focal points—one on each side.
Thin lens have 1 focal length, thick lens have 2 focal lengths.
Read the links in source for details.

What?! That doesn't make sense.

[kencaleno]

Hey,I am actually agreeing with Osmosis here,(I'll never live this down!) I don't understand toronto111's point of view. The discussion in hand is about focusing icons seen in the viewfinder,so whatever toronto111 is on about doesn't scan-unless he/she is talking about the point of the focal length of the lens' distance from the sensor plane,which, in a prime lens, is the central point of the lens itself when focused at infinity. Ken