using f2.8 or brighter lens will FOCUS well ?


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S11loop

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Feb 11, 2005
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#1
will it focus well like in low lighting ? coz i realise that my f3.5 lens at times when in low light condition cant really focus well sometime subject will go OOF :(
 

wiz23

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Jun 20, 2005
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#2
S11loop said:
will it focus well like in low lighting ? coz i realise that my f3.5 lens at times when in low light condition cant really focus well sometime subject will go OOF :(
How low is the low lighting u're referring to?
 

ricohflex

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Feb 24, 2005
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#3
short answer. yes
depends on your camera's focus sensor sensitivity too
some better than others
 

denniskee

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Oct 26, 2003
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#5
from my experience @ esplanade outdoor theater

In low light

50mm f1.8 + D60 = cant focus

50mm f1.4 + D60 = can focus

50mm f1.8 + 1v = can focus
 

surge

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Mar 17, 2002
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#7
AF works by phase matching, in others its like overlapping 2 lines, once the 2 lines overlapped exactly they are in focus.

thats why patterns can cause AF to hunt or mis-focus even under broad day light.(same pattern means hard to determine which pattern overlap whcih)

back to the focusing problem, try finding strong lines along the same plane of focus and ths will allow the focus to lock. (e.g the outline of the ear cos it usually stands out quite nicely against the dark back ground for focus.)


festures of the face under low light has too little contrast for the camera to detect.

AF works under a certain range of EV( light values). eg EV1 -21. means brighter lens will work better cos allows more light in and thus easier to get at least EV1

more importantly to work around the problem be focusing on strong lines then getting brighter and brighter lenses. 2.8 is already pretty good for most situation even outdoors at night.
just my 1 ct worth:)
 

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