AF points.....

[jks_photo]

a lot of new model cameras lately have been sporting a high number of AF points 7D, 50D, 1 series all have a lot of points.....


I personally use ony the Center AF point..... am I losing some of the beneifts that the other AF points offer???


Also, it is said that the 7D or 1 series will focus fatser [assuming all use 2.8 lens or higher]...... using the the 7D or 1 series and having only CENTER AF active... will they focus slower????

[andnowimbroke]

am I losing some of the beneifts that the other AF points offer???

When I had my 40D I just used the center mainly. The 7D gives me a better chance of gettingan eye locked in one of the little squares without recomposing.

only CENTER AF active... will they focus slower????

If I get what your asking, the answer is no. The center AF point is the only one that is 2.8 (which is good) with the rest being 5.6 I think.The camera as a whole is better at focusing. Didn't I read that you shot Nikon before? The digital versions of Nikonhave a crazy amount of focus points. Too many if you ask me. Rather than actually using all of them individually and scrolling across to get to the right one, you'dprollyclump them together in groups so I don't think you actually gained anything.


Take everything I say lightly. I'm stil pretty new.


Greg

[HDNitehawk]

using the the 7D or 1 series and having only CENTER AF active... will they focus slower????

The 7D will focus faster. For my shooting I keep my 5D and 7D on center point single shot only. And then change it if I want to do something else with it.

[andnowimbroke]

will they focus slower????

The other thingwhen talking aboutfocusing speeds, and I believe I'm correct in saying this, is Single Shot Mode happens to be slower but more accurate, and the Servo Modesare faster but maybe a little less accurate due to what your asking it to do. But getting back to your 7D and1 series, their fancy math stuff (algorithms and other words I can't spell)they use in finding focusis better than some of the other cameras on the lower end.

[tkerr]

I personally use ony the Center AF point..... am I losing some of the beneifts that the other AF points offer???
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IMHO, Yes.


When I am out shooting Birds, and especially Birds In Flight I will leave it on the center focus point using Spot metering mode just because it is faster and more convenient for that particular situation. Otherwise what focus point I use depends on the effect I want to capture within the complete picture/scene. When choosing a focus point you also have to consider the metering mode and f/stop as well.
Composition (Framing) How do you want to frame the picture and what part do you want in focus, to draw attention to? You don't always want the center only in focus. E.g. Rule of thirds!


http://www.digital-photography-school.com/digital-photography-composition-tips


http://www.cambridgeincolour.com/tutorials/camera-autofocus.htm

[MattG]

IMO center is the best for single shots. The only time I have ever used automatic (utilising all focus points) is when I am trying to catch moving subjects and have it on Servo. The 7D has quite a few different AF options but i only use the center. 7D has always been notable for better action photography with the super-fast burst and i guess AF options.


Good question as I have always wondered the same thing.

[elmo_2006]

Typically the centre focus point is the most sensitive as it is a *cross-type* sensor and as such focusing will be much quicker than let

[Sheiky]

Typically the centre focus point is the most sensitive as it is a *cross-type* sensor and as such focusing will be much quicker than let's say the outer focusing points. Bryan's review of the 7D and 1D MIV describes this.
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It is more accurate, but really is it faster? I thought AF speed waslimited by the lens's AF motor? I'm not sure, but it seems logical to me. I don't think anylens will focus faster on a 7D then on a 5D2, but I might be wrong [A]

[elmo_2006]

Hi Jan and thanks for chiming in.


You are correct, I should have listed *more precise* than faster. My apologies.

[HDNitehawk]

It is more accurate, but really is it faster? I thought AF speed waslimited by the lens's AF motor? I'm not sure, but it seems logical to me. I don't think anylens will focus faster on a 7D then on a 5D2, but I might be wrong

When I bought my 7D to use with my 500m F4 L, instead of my 5D Mark II, it seemed that the 7D was slower. So I tested this, on singe point single shot focus the 7D was indeed slower than the 5D Mark II by 1 tenth to 2 tenth of a second.