Matrix Metering – The Silver Bullet?

This post was inspired by a conversation I had with another photographer recently.  He had taken some outdoor portraits and placed his subjects in a shaded area.  The background was in sunlight.  He used flash to light the subject but the background was, predictably, still quite bright.  He spot metered on his subject to come up with his exposure settings.

After the session he spoke to another photographer whose work he admires.  This other photographer told him that spot metering was the wrong approach and that matrix metering would have been a better choice.  I cringed a bit when he told me this.

Let’s recall what meters do and how they work.  In an earlier article in the Photo Basics series I discussed metering.  I also discussed metering extensively in my book The Digital Zone System.  Light meters, come in two basic types; reflected and incident.  Reflected meters read the light that is reflected by a subject.  Incident meters read the light that is falling on a subject.  Meters that read flash are a type of incident meter.  Hand held reflected meters can’t read flash.  The reflected meters in our cameras have an advanced TTL flash metering function as well.  Reflected light meters are pretty stupid and can be fairly easily fooled.  How?  Check out the earlier article or Chapter 3 in my book.

Matrix or multi-segment meters are an advanced version of an average meter.  The difference is that the metering system uses reference exposure information that is stored in the camera’s onboard computer to come up with an exposure.  But these meters can still be fooled just like any other reflected meter.

The first shot below is close to what the photographer I spoke with was shooting in.  Subject in shade with a bright background.  I spot metered off the grass, in the shade, locked the exposure, recomposed and shot.  I don’t have buxom models at my beck and call so I use my idiot dogs.  They work cheap, are fairly compliant and take direction about as well as most models I’ve had experience with.

Spot Meter

We get what we would expect to get; a subject that’s pretty well exposed but a background that is way overexposed.  Not good.

Now let’s switch to multi-segment metering.  This should, according to many, fix all the ills that exist with this scenario.  Let’s see.

Matrix Metering

Matrix Metering

In the immortal words of cartoon dog Scooby Doo, ‘ruh roh Shaggy’.  What happened? We now have a background that is well exposed but the shadowed area is way under.  But isn’t the fancy multi-segment meter supposed to fix this?  Isn’t it the photographer’s silver bullet?  A panacea for all complex exposure situations?  No, it isn’t.  The focus point for this shot was on the dog, so that’s where the major weighting of the meter should have been but it still underexposed.

Matrix or multi-segment meters are no different from any other reflected meter.  They can be fooled just like a spot meter or a centre-weight meter or an average meter.  The photographer needs to understand his/her tools, how they work and how to adjust to conditions.

So what could the intrepid photographer do in this case?  As the photographer in question did, use flash.  But, the other component of that is to use Manual mode and dial in a shutter speed that effectively overpowers the background, bringing that exposure down and the shaded exposure up via flash.  In this case, the exposure for the background was 1/320 sec.  What?  That’s faster than the sync speed of the camera?  Of most cameras?  Yes, it is.  Today’s advanced interchangeable lens cameras and flashes have a clever mode called high-speed sync; however.  This allows you to use flash at higher shutter speeds and still get the entire subject illuminated by flash.  They work by firing a rapid burst of stroboscopic flashes that cover the entire frame as the thin slit of the shutter moves by.

High Speed Sync

High Speed Sync

That’s what I did with this last shot.  I used the same 1/320 shutter speed and turned on high-speed sync for my flash.  I get a background area that’s well exposed.  It could be a bit darker, but it’s OK.  And I get a subject that is also exposed well.

You do lose flash power with high speed sync so you may need to move your flash closer to the subject to get a proper exposure.  The big white shed in the background is always going to be difficult to overpower because it’s just a huge reflector and you wouldn’t have something like this in the background of your shots.  Right?

So, in answer to the question in the title of the article, is Matrix metering the silver bullet?  No, it is not.  Know your tools and how you need to compensate.




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