Metering

[BarryG]

I like to think I know what I am doing, in reality I don't!

Metering.

I get the idea and I've seen some fantastic tutorials, but one simple thing escapes me - how do I actually take mater reading?

My understanding is the camera will take the meter reading from the focal point (in centre weighted and spot).

So, if I want to take the reading I set the focal point to the grey area and then compose the shot?

Basics I know, but I just don't know about this essential technique.

Also, are there ant subjects that are good to practice on?

Camera D90, any help really appreciated.

 

[Dredd123]

I think if you are in manual mode, you can spot meter off something which equates to roughly 16% grey reflection (e.g. green grass or grey tarmac) which is in the frame and is lit by the same light as is lighting the rest of the frame which you intend to shoot.

Note that you need to use manual mode for this to work; in any other mode the camera will continuously evaluate the framed shot and adjust the aperture and shutter speed parameters as it sees fit.

 

[HoppyUK]

Metering is actually a two part process - the business of measuring the brightness of the light, and then converting that into a combination of camera settings (shutter speed, lens aperture and ISO). You're talking about the first bit I think.

Basically the camera has to guess what the best exposure might be, and usually has three metering options. Centre-weighted looks at the whole picture, with an emphasis on the middle, scrambles the whole thing and comes up with an answer. Spot reads from the centre circle in the viewfinder, and scrambles only that area.

Then there is matrix metering (Canon's evaluative) which is far more sophisticated. It takes dozens of readings from all over the frame, and in that way it not only knows the average scene brightness, it knows the extremes of light and dark, how large an area they occupy, and where that area is.

From that it can make a much better guess at what the best exposure settings might be, and it can also modify it when it recognises certain characteristics, such as a large bright area at the top of the frame - probably the sky in a landscape.

In any of the auto modes, the camera simultaneously converts the reading into a combination of control settings, and away you go. But digital has given us the gift of an LCD image, a histogram of the actual tones, and also a bit of magic known as blinkies - the highligh over exposure warning that flashes on the screen. And all that is generated off an actual image - no guesswork there, unlike the metering system which is only a guide (and can be easily fooled). So if you want the best exposure, that's what you should be looking at.

 

[ramyad]

If you are finding that you meter at a certain area and then recompose to get a good composition, the settings change and the scene is then under/over exposed when you take the shot. If the camera is in any of the auto or creative modes then it will keep adjusting.

So, use exposure lock to lock the settings at where you metered. I don't know what the button is on the Nikon's to do that, probably on the back of the camera near your right thumb. Check your manual.

The camera then locks the exposure settings from where you metered from and so when you recompose, it won't change any of the settings and so you can take the shot.

 

[jamesoliverstone]

If you are finding that you meter at a certain area and then recompose to get a good composition, the settings change and the scene is then under/over exposed when you take the shot. If the camera is in any of the auto or creative modes then it will keep adjusting.

So, use exposure lock to lock the settings at where you metered. I don't know what the button is on the Nikon's to do that, probably on the back of the camera near your right thumb. Check your manual.

The camera then locks the exposure settings from where you metered from and so when you recompose, it won't change any of the settings and so you can take the shot.

Nail, head.

 

[BarryG]

Cheers guys.

I am mainly using the aperture priority mode, maybe I should spend a week in manual to get a better understanding of whats going on?

I'll also try locking my exposure and see how I get on.