Lens' maximum aperture & AF sensitivity


TBing

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Feb 10, 2011
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#1
Dear expert,

Who could explain what is lens' maximum aperture & AF sensitivity??? How it helps in photo shooting?
 

Irvine

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Jan 1, 2010
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#2
Dear expert,

Who could explain what is lens' maximum aperture & AF sensitivity??? How it helps in photo shooting?
when the lens is mounted on the camera, it will be switched to maximum aperture to maintain a viewfinder as bright as possible. this also helps the AF points to detect contrast n focus more accurately. so from this theory alone, bigger aperture = more light enters thru the lens, n u will get a brighter viewfinder + the AF points receive more light for focusing. since there's more light available, it will be easier for the AF points to detect the contrast n focus accurately. this is particularly useful when tryin to focus in low light situations.

otherwise, smaller max aperture = less light enters the lens = dimmer viewfinder and the AF system will hunt more than usual in dark situations.

hope this helps
 

TBing

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Feb 10, 2011
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#3
I read from manual saying that "max aperture up to 5.6 the cross-type AF sensitive to both vertical & horizontal lines are possible". What does this mean???

"With 2.8f, the center AF point's sensitivity to vertical & horizontal lines is about twice as sensitive as the other AF points". What does this mean as well?
 

Irvine

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Jan 1, 2010
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#4
I read from manual saying that "max aperture up to 5.6 the cross-type AF sensitive to both vertical & horizontal lines are possible". What does this mean???

"With 2.8f, the center AF point's sensitivity to vertical & horizontal lines is about twice as sensitive as the other AF points". What does this mean as well?
this will help u understand better:
http://www.cambridgeincolour.com/tutorials/camera-autofocus.htm
 

icy55

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Mar 13, 2011
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#5
I just bought my 50mm camera. Sometimes when I get too close to the subject, i am not able to press the shutter. Why is that so? Is there a min distance to shoot from? Thanks!
 

daredevil123

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Staff member
Oct 25, 2005
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lil red dot
#6
I just bought my 50mm camera. Sometimes when I get too close to the subject, i am not able to press the shutter. Why is that so? Is there a min distance to shoot from? Thanks!
Read up on MFD - Minimum focusing distance.
 

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