Spot Metering

[dbose]

I think I am not doing this correctly...

I have a Nikon D90. When I use spot metering (and say I want to meter for two parts of a shot without altering the composition and the camera position - the highlights and darkest spot), how do I do It. What am aiming for (in terms of the focal points that I can see in the viewfinder)? Is it that when I change the focus points (Nikon has 11 points visible from the viewfinder) does it also use the same focus point for spot metering or is it something else that I need to use as my pointer to spot meter off a particular point? It also gets confusing as when I have auto focus on the camera automatically picks out a few points as it focus points - in that case how will I use spot metering (which is my pointer)?

Not sure if my question is clear but any help would be great...:confused013:confused013:confused013

[Suter200]

The spot meter is always in the centre no matter which focus point you select. You can lock in your exposure with the exposure lock button in a simmlar way to the focus lock. Int the menu you can set which focus point you want to use ie. centre, selectable or auto.
Hope this helps.

[arthurking83]

The spot meter is always in the centre no matter which focus point you select. ...

Not on a Nikon.

Spot metering is determined by the focus point you choose.

I do this all the time(where practical).

In a landscape scene, I use the focus points for my spot meter readings.
I'll set the camera up for the scene, and then use the rear control pad to move the AF point around to get various meter readings.

Eg, I'll spot meter on the sky for a max exposure value, then take a reading in the shadow area. I'll add a filter or two to balance the exposure difference, get it as close as I can to balanced, and take more spot readings once the filters are added.

D90 uses the D200's CAM2000 AF/metering system, which means you get a choice of 11 AF points. While each AF point has it's own ability as an af point, they each spot meter as well.

(I THINK!!) that centre weighted only works on the centre area of the AF point zone.. but I dunno! I don't really use centre weighted enough to figure out exactly how it works.

Also note! When using Matrix mode, the AF point used will also be used to determine the exposure required. So if you matrix meter a scene that has both a dark shadow area and a bright highlight of much higher Ev, when you place the AF point on the dark area the matrix meter seems to be 'protecting' the shadow and will cause the camera to expose differently(brighter) than if you point the AF point to the brighter area, which will then try to protect the highlight as best as the metering can determine.

As for metering on one point and focusing on another:

Quickest method is to set the AF point where you want it for the scene.
Initially compose the image to get a spot reading, immediately press the AE/L button(locks the exposure value, and then recompose and focus.
This is OK if you only want a single exposure, but if you want to bracket, it only locks the metering for the first exposure. Each subsequent metering values will be determined by the AF point used.

best method!
Switch to Manual, set aperture to your desired value, and use shutter speed to expose to the value that you require. If you want a bit of under or over exposure, then you set the meter bar to accommodate that requirement.
Of course you can do the same thing in either Shutter or Aperture priority modes too, where you take a meter reading from a predetermined point, use the correct 'quick exposure compensation' control wheel to effect your correct exposure.
Quick exposure compensation is by default turned on.

if you use Aperture Priority, the shutter wheel(Command Wheel) is you quick exposure compensation adjustment dial. If you use Shutter priority, then the aperture control wheel(Sub Command Wheel) is the exposure compensation dial.

[etherial]

Not on a Nikon.

Spot metering is determined by the focus point you choose.


Another thing I wish Canon had. :(

[fillum]

It also gets confusing as when I have auto focus on the camera automatically picks out a few points as it focus points - in that case how will I use spot metering (which is my pointer)?In this case it sounds like you have the camera in "Auto-Area AF" mode which lets the camera select the focus points. In this AF mode with spot metering the camera uses the centre of the frame to meter. (This is how it works on the D300 so I'd assume D90 is the same). Therefore in this mode you would need to meter using the centre of the viewfinder and then either set aperture and shutterspeed in manual ("M") mode or use exposure lock before recomposing and shooting.

In "Single-Point AF" mode it works as AK described. (I dunno what happens in "Dynamic-Area AF").


(I THINK!!) that centre weighted only works on the centre area of the AF point zone.. Yes, as the name implies it meters at the centre of the view frame. There may be a few options to vary the size of the centre-weighted area. I often use centre-weighted metering when shooting footy.


Cheers.

[dbose]

Not on a Nikon.

Thanks a ton mate - this is exactly what I was looking for - it'll make my life a lot easier now.

I am also thinking, that if I initially meter off a focal point which I might not use for the actual focal point for the composition, I can simply recompose without moving the camera and just shifting the focal point to the area I like to focus on - as long as I DO NOT alter the shutter speed I should be fine even if I have not locked the exposure.

I think I have got this clear now - thanks again.