Can anybody help me with metering?

That was the question asked by Matt Spracklen Photography on the Flickr group Nikon D300 Users/Discuss. Matt’s really intelligent question got a whole lot of online responses.

You don’t need to own a Nikon D300 to benefit from Matt’s question and the replies and it got me thinking about metering.

Back in the old days (here we go again) I used to shoot four or five rolls of black and white Tri-X film everyday for the daily newspaper. I got so good at shooting at ASA 400 (which was considered really fast back then) that I could, and often did, shoot without metering the scene.

I had a Leica M4 and a bunch of lenses that I used exclusively for shooting available light work. The Leica (one of the most expensive of 35mm cameras) had no light meter. Oh sure you could buy a really expensive Leica light meter that attached to the flash shoe (which I can’t remember was even a hot shoe as I never used on camera flash but a BIG Metz 403 (no longer made) that had a potato-masher head and an external battery that was the size of a motorcycle battery and weighed as much but that was rare. It could light up a stadium.

When it came to accurate metering I used a LunaPro that my dad bought me as a birthday present. I’ve still got it and it still works.

So I learned how to meter with an external meter. You can do the same thing with your digital SLR and I explain how in a moment.

The Luna Pro would allow you to do reflected metering or incident metering. It’s important here to know the difference.

In reflected metering, the meter (whether the one in your camera or an external handheld meter) “sees” the light that reflects off your subject and based on the ASA (film speed) or ISO (digital sensor speed – or sensitivity for digital cameras) gives you a bunch of correct readings. You see there is no such thing as a correct light meter reading.

Matt asked about metering a bride in white dress. Let’s make this even more extreme by saying our bride is a black woman and she’s wearing a really white wedding dress.

Let’s avoid the complication of what mode your digital camera is in for now and set it for manual shooting mode. Put the metering system on spot metering (as opposed to matrix or overall metering) and meter on the woman’s face. The meter will provide you with a bunch of meter readings all of which will create a properly exposed image of this bride’s face. For example, let’s pretend the meter says the proper meter reading is 1/250 of a second at f/11 will be perfect. So if you set your camera to these settings (remember we’re on manual right now) the rendition of our bride’s complexion will be perfect.

But so will the following settings as 1/250 and f/11 is the equivalent of the following:

1/60 – f/22 – (harder to handhold due to the lower shutter speed but huge depth of field)

1/125 – f/16

(1/250 – f/11) – (our initial metering)

1/500 – f/8

1/1000 – f/5.6

1/2000 – f/4

1/4000 – f/2.8 (Easy to handhold due to high shutter speed but very shallow depth of field)

Wonderful….but the dress in the image is blown out. You can’t see the expensive brocade that the bride’s mother paid for. So let’s meter again. This time we’ll meter on the dress. This time we get new readings. Let’s pretend the meter now says the “correct” reading is 1/250 of a second at f/22 (remember the dress is white and very reflective).

1/60 – f/64 (hard to hand hold to avoid blur but huge depth of field. Might want to use a tripod.)

1/125 – f/32

1/25o – f/22 (our initial meter reading)

1/500 – f/16

1/1000 – f/11

1/2000 – f/8 (Easy to hand hold and fair amount of depth of field)

1/4000 – f/5.4

1/8000 – f/4

1/4000 – f/5/6 (Stop a jet fighter in flight but not much depth of field)

Now we can see the detail in the dress at all these settings as what changes is not the overall exposure (this isn’t exactly accurate but will do for the purpose of talking about metering) but the depth of field and shutter speeds. But what happened to our bride’s face. It’s so under exposed that there isn’t any detail to be seen. Trust me, nobody but the dressmaker will buy this image.

So what happened and what can we do about it?

You’re going to read people using other numbers but the principal is the same. The human eye can see about 20 stops of light (a stop is the combination of shutter speed and aperture on a camera) but the best film cameras only see around 10 stops and digital cameras only see 5 to 6 stops. This is why high dynamic range photography is so much the rage right now. Bracketing our digital cameras to shoot five or more frames of the same subject at different exposures allows special HDR software (Love HDR EFEX PRO from NIK.) to create images with greatly enhanced dynamic range (often with disastrous consequences when over used).

So you could shoot a series of images of our bride by putting your camera on a tripod and having the wedding party stand absolutely still. Then in software you could produce an image that had sufficient dynamic range to create an image where the bride’s face and wedding dress where properly exposed. But in real life (especially after a couple of celebratory drinks) this isn’t going to happen.

This is why most wedding photographers use a BIG honking flash unit. (Read more at David Ziser’s Digital Pro Talk blog.) It allows them to balance the light more evenly over their bride’s face (regardless of colour) and the white wedding dress. David sometimes brings his workshops to Buffalo and it’s worth the drive.

But let’s get back to metering.

So when we meter a subject by pointing our camera’s light meter which sees through the lens or our handheld meter we’re metering reflected light. Now especially for landscape photographers, there is another way to meter. It’s called incident light meter reading and uses a plastic hemisphere which goes over the light meter element itself. The lightmeter is then carried to where the subject is and the actual meter is pointed back towards the camera. The meter now meters the light coming through the hemisphere and sees the same thing the camera sees but this time instead of metering light being reflected off the subject (who may have a white complexion or black complexion which would change the reading dramatically as we’ve seen), the meter “sees” the light that is incidental to the subject. Incidental light meter readings are very useful for shooting landscapes.

Ansel Adams developed a system called the Zone System that used a spot meter. He pointed the meter at the darkest area in his frame and took a meter reading. Then he pointed it at the lightest area and took a second meter reading. Then he compared the meter readings to see if the dynamic range was within or outside the capture range of his film. You can do the very same thing using your meter in spot-metering mode.

Speaking of modes (and this is a big problem with digital cameras as everything is called a mode of one sort or another) now we come to shooting modes. For absolute control of your digital image shoot in manual mode using your internal camera meter or your external handheld meter to guide you in finding the proper settings.

Now as a special events photographer I almost (note almost!!) never use manual shooting mode unless (here it comes!!) I get into a situation that where the metering is tough. An example would be a shot where light was being reflected off a building or glinting off water). I used (and some of you might need to take a deep breath right now) Program mode.

There I’ve said it. i shoot in Program mode a lot just like my hero Joe Buissink who is one of the best photographers I’ve ever met in my life – period. (This is a shot Joe did of Rebecca Romijn who is the most beautiful woman in the world —err next to my gorgeous wife – and Rebecca’s husband what’s his name.)Joe gave a workshop in Toronto some months back and it’s the only one I cried my eyes out over the passion and sensitivity of his images…and Joe shots in Program mode!!

If you ever get a chance to attend a workshop by Joe, I guarantee it will make you both a better photographer and a better human being. After all, anybody who gets to shoot images of Rebecca has god-like status in my eyes. Oh yes, back to photography…

Why Program mode? Because it allows the camera, working with light meter in matrix mode, (see what I mean about this mode thing!) to respond accurately and lightening fast to any exposure changes. In other words you capture the image you want. All the rest is just photography.

Now I could (and often do) use Aperture mode as it allows me to control my depth of field (when that’s important to the image) but it means the camera is making decisions based on the meter reading that can adversely affect the shutter speed. If there’s a black wall in the background (or a white one for that matter) I’m likely to miss the exposure.  If I’m shooting really, really fast the camera can set a shutter speed that is so slow I get blurry pictures. This is a bad thing.

I could use (and rarely do) Shutter mode. I rarely shoot sports but when I do I use Shutter mode to force the camera to shoot at a pre-selected speed where I know I won’t get blurry images. My aperture might be pretty wide (requiring accurate focusing on the subject I want) resulting in shallow depth of field and I might have to boost my ISO to help achieve the proper exposure but my images will be sharp.

Now let’s get back to the light meter modes. I use matrix (my cameras are Nikons) most of the time. Why? It works! But I use spot metering when I get into trouble metering a subject that has lots of dynamic range. Now I want to take total control over the meter. There are other metering modes like averaging which are useful especially if you’re using filters or polarizers but I don’t do this much myself.

So how do you learn how to meter?

Shoot lots of photos. Shoot images with dark backgrounds. Shoot images with bright backgrounds. Look at your LCD display. Shoot in manual shooting mode with the meter on spot. Then change it all up.

And if you want to learn about exposure, go buy an external light meter. It doesn’t need to be expense. I’ve got a couple of Sekonic light meters (L-398A and a L-358 which will also meter flash in the studio setting) plus the Luna Pro. 

Also by a grey card and figure out why it’s important to exposure.

Best of all: Have fun.


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