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PostPosted: Fri Jul 17, 2009 5:27 pm 
3D Colour Matrix, Center Weighted & Spot Metering. What they are for and in which situations to use them.

Also regarding exposure compensation it states in the Nikon manual:

"Only the exposure information shown in the electronic analog exposure display is affected, shutter speed and aperture do not change"

...when clearly in the viewfinder illustrations the shutter speed and aperture are affected, they are also in the top screen of my D90. This is confusing me because at first I didn't think exposure had any link with shutter speed or aperture as when using live view you can change the exposure and see the difference, but when you actually take the shots higher exposure setting will use longer shutter speeds, and lower the opposite.

Is the live view dimming when lowering exposure just a preview of what the end photo will look like? So technically Nikon could also make it so that you can preview the results of longer shutter speeds in terms of brightness (by increasing the amount of light in the LCD)?

Thanks.


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PostPosted: Fri Jul 17, 2009 5:36 pm 
So, if my last paragraph is true, the benefit I can think of for exposure compensation is tweaking the shutter speed (by raising or lowering exposure) relative of the one calculated by the camera automatically, as in contrast with manually adjusting shutter speed which would be absolute, with no anchor point.


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PostPosted: Fri Jul 17, 2009 7:39 pm 
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mm66554 wrote:
3D Colour Matrix, Center Weighted & Spot Metering. What they are for and in which situations to use them.

Also regarding exposure compensation it states in the Nikon manual:

"Only the exposure information shown in the electronic analog exposure display is affected, shutter speed and aperture do not change"

...when clearly in the viewfinder illustrations the shutter speed and aperture are affected, they are also in the top screen of my D90. This is confusing me because at first I didn't think exposure had any link with shutter speed or aperture as when using live view you can change the exposure and see the difference, but when you actually take the shots higher exposure setting will use longer shutter speeds, and lower the opposite.

Is the live view dimming when lowering exposure just a preview of what the end photo will look like? So technically Nikon could also make it so that you can preview the results of longer shutter speeds in terms of brightness (by increasing the amount of light in the LCD)?

Thanks.


Basically the camera uses each of it's "zones" (Nikon has about 500 compared to Canon's 30 or Pentax's 77). It then determines the amount of light each zone is giving off or requires. When you do the "Color Matrix Metering" it evaluates every zone and averages them together to create an "even" image. This is probably useful for landscapes or city-scapes where you want every part as evenly exposed as possible.
Center weighted is the same, except there is a slight emphasis on the center portion of the image.
Spot weighted is the VERY VERY center (about 1% of the frame) is metered. This works well with portraits where you want the center of the image to "POP" out and have the background under exposed, however, spot metering doesn't work with certain focusing screens.

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PostPosted: Sat Jul 18, 2009 7:58 am 
GLXLR wrote:
This works well with portraits where you want the center of the image to "POP" out and have the background under exposed, however, spot metering doesn't work with certain focusing screens.


The focusing screen used shouldn't have enough effect on the metering as the camera's metering sensors bypass the focusing screen. They are underneath the mirror whereas the focusing screen is above.


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PostPosted: Sat Jul 18, 2009 10:41 am 
Thanks, great explanation.

So basically metering is an automatic process which alters the shutter speed based on light reflecting off all or part of the scene framed. Would this mean that changing the metering has no effect in manual modes?

Does anyone have an answer to my other question of what exposure compensation is, or is it a really silly question?


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PostPosted: Sat Jul 18, 2009 4:24 pm 
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mm66554 wrote:
Does anyone have an answer to my other question of what exposure compensation is, or is it a really silly question?


well the camera doesnt allways get it right, so if you take a pic and its to dark or to light, you have the ability to overide the camera and dial in + or - compensation.


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PostPosted: Mon Jul 20, 2009 5:08 pm 
Yer I understand what it does but I meant how does it work... like is it the same as manually adjusting shutter speed, just with a reference to the current settings, or does it +/- the brightness by adding or removing gain or something.


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PostPosted: Mon Jul 20, 2009 5:20 pm 
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mm66554 wrote:
Yer I understand what it does but I meant how does it work... like is it the same as manually adjusting shutter speed, just with a reference to the current settings, or does it +/- the brightness by adding or removing gain or somet

Depending on your priority, the camera alters the other factor. Say, in aperture priority, the camera alters the shutter speed. You dial -1 stop exposure compensation, the camera doubles your shutter speed. :)

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