need help


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Aug 16, 2005
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#1
today i was taking pic in my room. it is not will light up.
i was using single point, kit len. i found that i could not focus on a point on the brown cupboard.
it goes forward and back anf the focus confirmation light was blinking. i moved the point of focus able 2cm right or left all can focus.

please advice
 

raptor84

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Dec 6, 2005
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#3
That spot you were trying to focus on problbly was one solid shade of brown with little or no contrast so the sensor was unable to get a 'lock'
 

Aug 16, 2005
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#4
That spot you were trying to focus on problbly was one solid shade of brown with little or no contrast so the sensor was unable to get a 'lock'
so how to over come this problem? is it normal? i looked at the sopt and yes it is like what you say. What other scenero will i c this problem

thanks a million in advance
 

jeremyftk

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Jun 24, 2005
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#5
Eh... Don't quite get your vocab and grammar... But if I'm getting it right, you're saying that your cam could not focus on a certain spot. Correct me if I am wrong.

Anyway, the thing to note about AF is that it tends to need lines or some contrasting object to determine how to focus... So if you're looking at a plain and smooth object, chances are your AF will not work
 

Aug 16, 2005
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#6
Eh... Don't quite get your vocab and grammar... But if I'm getting it right, you're saying that your cam could not focus on a certain spot. Correct me if I am wrong.

Anyway, the thing to note about AF is that it tends to need lines or some contrasting object to determine how to focus... So if you're looking at a plain and smooth object, chances are your AF will not work
sorry for the english, but you are right. btw when you say " it tends to need lines or some contrasting object to determine how to focus ", it is for single point focus?
 

Youhong

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Dec 30, 2004
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#8
when it is too dark... The camera may also find difficulty doing AF... Hence, having sufficient lighting will help one way or the other... (AF illuminator comes into play)
 

Aug 16, 2005
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#9
thanks jeremy

youhong

could you tell me a little more about the AF illuminator?
 

Maltese

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Mar 21, 2005
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#10
if u use spot metering ...and the camera is sensitive to pick up tones difference with the available light, it should focus....I believe your camera is not able to focus because of the uniformity colour, texture of the object. That is the big difference between a pro camera, a sharp lens as well as a good tripod. Theoretically, if you are have a steady hand, tripod mounted, bright enough for the camera to pick up, it shouldn't have a problem. That is why grey cards and white balance card can be focus and snapped as well.

Either go manual focus, brighten the area or focus on a spot nearby that area u wanna capture, lock the focus then go back to snap.

Its good that u found out the limitation of your setup so that in future when u go shooting and faces a similar problem, u know what to do next.:cool:
 

kcuf2

Senior Member
Dec 29, 2005
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#11
to focus properly, u must understand a bit abt how the camera achieve focus.. one of the method the camera uses to achieve focus is thru usage of contrast i.e. if the object has black and white, red and blue etc.. such contrasting colour, the camera will know that the object is there and hence hook focus there.

However if it is a smooth plain colour background, the camera sees no contrast and "feels" that there is "eternity" in that area and hence it zooms back and forth just to hunt for something of contrasting colour so that it can achieve focus.

or imagine this scenario: lets say u are in planet jupiter, whereby the people living there never wear any clothes. To find your friend amidst the huge bunch of people in a place is very difficult right? because all ppl have the same skin tone and colour and hence u can't "lock focus on your friend". But if your friend is in singapore and everyone wear clothes on the street, if your friend tells you he wear red shirt, when u look around and u saw the red contrasting colour from the background, you can "focus" on your friend liao rite?

AF illuminator
works in a dark situation, such that it lights up a area, which enables it to clearly see wat objects are there, and then focus on the item u want to focus inside the illuminated area.

Think of it as u are in a dark cave hunting for dinosaur. If it is totally dark, u cant see anything and thus u cant focus on anything. If u light up a torch, u can see the items in the cave and then u can focus liao rite?
 

Aug 16, 2005
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#12
Thanks kcuf2 & Maltese

i got a better idea now, will try the ways out.
thanks a million
 

raptor84

Senior Member
Dec 6, 2005
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#13
so how to over come this problem? is it normal? i looked at the sopt and yes it is like what you say. What other scenero will i c this problem

thanks a million in advance
As long as the spot you are focusing on lacks some sort of colour / tone contrast the AF sensor is not likely to work. the best you can do is to focus on a object nearby with more contrast then re-compose. Alternatively get a speedlite with focus assist lamps (BBB j/k) that helps alot too.
 

Aug 16, 2005
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Singapore
#14
As long as the spot you are focusing on lacks some sort of colour / tone contrast the AF sensor is not likely to work. the best you can do is to focus on a object nearby with more contrast then re-compose. Alternatively get a speedlite with focus assist lamps (BBB j/k) that helps alot too.
i do have a flash 430EX. but learning how to use it as of now. not good at using flash.
 

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