[Explainations:] Metering Mode

• Interception_7

  19 Jun 09, 21:06

  Hi Guys,

  Would like to open up a question for different metering modes..

  As for now, I'm shooting in Average. My camera has 2 other settings I can choose, Multi or Spot.

  What's the difference between each of them...

  Thanks :D

• Gedanken

  20 Jun 09, 21:43

  Average metering is a fairly basic mode of metering whereby the camera takes an overall reading of brightness across the image space and sets exposure to suit the average level of brightness across the picture.

  Spot metering takes a specific spot in the centre of the image (usually less than 5% of the total image area; in some cases it may be as small as 1%) and sets metering according to the brightness at that spot.

  I'm taking a guess at Multi here, but it's probably sensing brightness across multiple preset spots or zones across the image and adjusting metering according to the brightness of those zones.

  Apart from the above, there are a few other forms of metering.

  Centre-weighted average metering is similar to average metering, except that the exposure setting is influenced more by the centre of the image than by the outer edges.

  Partial metering is similar to spot metering but it utilises a larger spot at the centre of the image, typically covering about 15% of the inage area.

  Evaluative metering assesses the image, estimating the position of images in the foreground, middle and background and attempting to find a balance of correct exposure for all three.

  So, what does this all mean?

  I've taken four identical shots, each using a different metering mode.  Now depending on your screen settings the differences may be pretty subtle, but pay particular attention to the three areas in red boxes indicating the foreground, middle and background:

  

  Here's the first shot, taken with evaluative metering:

  

  Overall, not too bad.  The image is reasonably bright, and you can see the microphone in the background.  On the other hand, the foreground is overexposed, so that the detail of the table surface is whited out.

  Let's try partial metering now; the exposure is pretty much set according to the light surfaces of the lens:

  

  Now you can see thatthe wood grain in the foreground is more visible, but the red word "Ultrasonic" on the top of the lens is still a little whited out.  Let's just expose on the word "Ultrasonic" using spot metering:

  

  That's much better, but if you look at the background, going from the spot-metering photo, to partial and then back to evaluative, you'll see that the microphone in the back gets harder to see as the "Ultrasonic" gets clearer.

  Just for one more contrast, let's try centre-weighted average:

  

  The background's great because the averaging algorithm has taken it into account more than the other metering modes, but it's come at the cost of detail in the middle and foreground.

  So which is the best metering mode to use?  It depends on what you want to shoot and how you want the picture to turn out,  but if you're not sure what you're doing, use the evaluative mode - it's the default on most automatic systems.

• Interception_7

  21 Jun 09, 10:10

  Thanks for the detailed and precise information.

  It gave me a clear understanding about the different metering modes.

  :D

  Thanks again..!

• technoboy

  21 Jun 09, 13:18

  I realise you have the "Understanding Exposure" book by Bryan Peterson. Heard that it's a good book and I just ordered one which will probably arrive on Monday! Sorry for the off topic.

• Interception_7

  23 Jun 09, 20:10

  Decided to sticky this topic so that others would benefit.

  Thanks Gedanken! (:

• Gedanken

  23 Jun 09, 20:33

  My pleasure, I7 - glad I could contribute.  I was actually thinking of putting something together about sensor sizes and the myth of megapixels.  Let me know if you think that'll be useful.

  Understanding Exposure is a very good introduction to photography, techno.  I would also recommend John Hedgecoe's "The New Manual of Photography".