can't auto forcus on white blank object..


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Reportage

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Nov 24, 2008
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#2
minimum focusing length. if you want nearer then need to use manual focus.
 

baggiolee

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Dec 7, 2006
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#3
lol...using minimum 18mm focal length already....can't focus on a white wall, white book 4m away.
 

zac08

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Feb 21, 2005
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#4
YOU CAN'T FOCUS on a white BLANK subject.

The AF module requires CONTRAST. Duh.... Make sure there is enough contrast. If you don't believe, get a white piece of paper and put it in front of you. You'll never be able to lock onto it.

Then draw a cross on the paper, see how easily your camera then locks onto the cross. Always understand you gear first. READ MORE.
 

baggiolee

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#5
lol no wonder...so how can i set custom white balance using white paper method if i can't focus? manual focus?

YOU CAN'T FOCUS on a white BLANK subject.

The AF module requires CONTRAST. Duh.... Make sure there is enough contrast. If you don't believe, get a white piece of paper and put it in front of you. You'll never be able to lock onto it.

Then draw a cross on the paper, see how easily your camera then locks onto the cross. Always understand you gear first. READ MORE.
 

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zac08

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Feb 21, 2005
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#7
lol no wonder...so how can i set custom white balance using white paper method if i can't focus? manual focus?
Do it manually.... the custom white balance does not need the subject to be in focus. As long as they white portion fills the screen, it's more than good enough. ;)
 

ahbian

Senior Member
May 23, 2006
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#10
Might be a bit easier if you shoot RAW?

Edit: This is an alternative to setting custom white balance. Does not address the issue of AF.
 

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#11
anyway the post have been answered correctly. good job. just remember there is "minimal focusing distance" for any lense and it is not always the same..

and dont post garbage. thanks.
 

ahbian

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May 23, 2006
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#13
Might be a bit easier if you shoot RAW?
what in the world got to do with this ****?
The reason why TS is trying to focus on a white paper is to do a custom white balance. My suggestion is that he can adjust the white balance easier in post processing if he shoots in RAW.

It is not a cure all or absolute replacement for custom white balance, but it is convenient.

Your post regarding not posting rubbish, is it directed to me?
 

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catchlights

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#14
Might be a bit easier if you shoot RAW?
doing custom WB is get setting right in camera. and also cutting down post processing workflow.

Not all situation are possible to shoot RAW.

for an instant, if I need to give my customs the jpg right after the photo session, shooting RAW and without custom WB, what kind of benefit and conventient can I get?
 

ahbian

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May 23, 2006
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#15
doing custom WB is get setting right in camera. and also cutting down post processing workflow.

Not all situation are possible to shoot RAW.

for an instant, if I need to give my customs the jpg right after the photo session, shooting RAW and without custom WB, what kind of benefit and conventient can I get?
If we are using Jpeg, then yes, i agree that we need to get it as close to right as in camera.

Post processing wise, for me, its is just two steps, which i can accept may be two steps too many for others.

My suggestion is to open the TS to other possibilities besides struggling with custom white balance.

Your senario of giving jpeg to a customer immediately is valid, but it is not what I need to encounter as I'm a hobbist, hence the different perspective.
 

marboed

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Jan 29, 2009
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#16
YOU CAN'T FOCUS on a white BLANK subject.

The AF module requires CONTRAST. Duh.... Make sure there is enough contrast. If you don't believe, get a white piece of paper and put it in front of you. You'll never be able to lock onto it.

Then draw a cross on the paper, see how easily your camera then locks onto the cross. Always understand you gear first. READ MORE.
yeah right, the AF cannot focus in all white neither all black surface, so you have to search any contrast or doing manual focus.

Might be a bit easier if you shoot RAW?
how come? hehehe...
 

ahbian

Senior Member
May 23, 2006
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#17
yeah right, the AF cannot focus in all white neither all black surface, so you have to search any contrast or doing manual focus.



how come? hehehe...
The reason why TS is trying to focus on a white paper is to do a custom white balance. My suggestion is that he can adjust the white balance easier in post processing if he shoots in RAW.

It is not a cure all or absolute replacement for custom white balance, but it is convenient.

Your post regarding not posting rubbish, is it directed to me?
I understand that I should be more specific in my postings next time. Shooting in RAW helps in the setting of white balance (which was the also one of the intentions of the TS) , not the focusing of the blank object.
 

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