Hi everybody and welcome to another episode of Exploring Photography right here on an
AdaromaTV. I am Mark Wallace and we are dedicating a few episodes of Exploring
Photography to basic studio lighting techniques. In this episode I'm going to
show you how to use a light meter. Now last episode we talked about something called
sync speed, thats the fastest shutter speed we can use with our flash, and that helps
us to understand how a light meter works. How you set it all up in. A light meter
basically you set up your ISO and your shutter speed and it tells you what
aperture to use when you're taking a photo. Why is that? Why is it always
telling you the aperture setting and nothing else.
Well to understand that we need to understand the different kinds of metering. The
through the lens metering our cameras used and the meeting that we use in a
studio with a light meter. S to understand all that here's a cool animation that I made
just for that.
There are two basic methods of metering light. Incident
metering and reflective metering. Your camera's built-in light meter uses
reflective metering. Here's how it works
Light travels from its source and reflects off the subject and into your
camera's lens. When the light enters your camera it travels down the lens and then
hit's a mirror, the light is then reflected at a 90 degree angle up into
the pentaprism and finally out the eyepiece. The mirror and pentaprism allow us to
see exactly what's coming through the lens. Your cameras light meter is inside
the pentaprism.This built-in light meter is what your camera uses to show
you meter readings in the viewfinder. Some of the light is allowed to travel
through the main mirror and hit a secondary mirror. This smaller mirror
reflects the light onto the autofocus sensor. This sensor is what your camera
uses to focus the lens. When you press the shutter release button both of these
mirrors move out of the way, the shutter opens and the exposure is made. When
you're using flash heads that are synced to your camera they don't fire until the
shutter is completely open.
Which means that your built-in light meter has no way of seeing and metering
this light. For studio work you'll need an incident light meter. Instead of
metering light that reflects off the subject, incident metres measure the
light that is actually falling on the subject itself. You simply place the
meter next to your subject and take a reading. In a normal studio setup you'll
set your camera and light meter to the same shutter speed and ISO setting. When
you take a meter reading, the light meter will tell you the correct aperture value
and you'll set your camera accordingly. Once you're all set up you only have to
worry about the aperture value. Well now we know about some of the theory that is
involved in using a light meter now let's put that into practice and get
some handle on how to actually works. Now the question that you might be asking
yourself is ‘Mark, which aperture value is the correct aperture value?' Well that
depends on what you want to do. So to walk through that and how to adjust all
this stuff I'm going to ask Kelly to join us and since Kelly is the tallest
model in the world I'm going to have you actually sit right there and we're gonna
go through some of these things. Now when we use a light meter if you go back a few
episodes of Exploring Photography you'll understand that you need to point this
lumisphere at that camera when you're starting out and so that's what we are doing.
As far as the settings go I have told my light meter that I'm shooting at ISO 200.I have
set it to my camera sync speed which is 180th of a second.
I have also set my camera to ISO 200 and a 180th of a second.
All that remains is the aperture value and so what I'm doing here is I have a little
remote. When I push the test button that makes my flash fire and so I can push
the button on the side of my meter and then push this and then my meter tells
me that this light is metering at f/2.0. That is not the aperture
value that I want. Why is that?
Well f/2.0 has really shallow depth of field, in fact her entire face is not
going to be in focus and so for this portrait what I want is an aperture value of
about f/10 maybe f/11 because that will give me everything in focus, from her nose all
the way to the back of her head and that is what I want. So what I need to do is I
need to go from f/2, which isn't very much light, that means our aperture has to be
really wide to bring in that light. I need to increase the power of this flash
until it gets to f/11. Now on every single flash speedlite, studio, strobe doesn't
matter there's some way,
read your user manual, there is some device some dial that will allow you to
increase or decrease the power. On this Profoto B2 it’s just this big dial here.
So I’m going to increase that and so i'm going to put that up a little bit more and then
hit this little test button and come back over here. We're going to see where we
are now.
Now we're at f/5.6. So not enough. I have to keep going. So I'm going to keep
going until I have this set to more power and then we'll meter at this one
more time and now I am metered at f/11. Once you use a flash for a
little while you'll get to the point where you know pretty much know exactly where
you need to be every time to hit f/11 or f/4.5 or f/22 and it's really fast
and so you don't have to worry about that, with a little practice you'll be there. So now
we're set at f/11. So what I did, let’s review. ISO set on the meter the same as
in the camera. Shutter speed that’s set on the meter same as in the camera and
then I metered and adjusted this until I got it to an aperture value that I
wanted, which was f/11. Now the only thing that's left for me to do is set my
aperture to f/11 on my camera and take some pictures. So let me do that and I’ll
show you the results.
There you have it using a light meter in the studio is pretty simple. Remember you
set your camera and meter to the same ISO and shutter speed which is our
cameras sync speed and then you meter and adjust your flash until you get to
the aperture value that you want. Now of course there's more to metering than
just that but the good news is over at the Adorama Learning Center we
have hundreds of videos about shaping light using light ratios, light modifiers,
bouncing light, anything you can think of its over there and it's absolutely free
so check that out.
Also don't forget to subscribe to AdoramaTV it's free and that way you get all
the good stuff from me and everybody else that contributes every single day, so do
that right now. Thanks again for joining me and I will see you again next week.