In the last episode of our metering serial, we talked about what type of meters were available (excluding in camera matrix mode metering) and how they piece of work. Nosotros also covered the basic ideas behind the subject effulgence range.
In summary, we have spot meters that have a reading of a specific small area of a scene and incident meters that measure the light falling on a scene. The typical discipline brightness range (SBR) of a non cogitating scene is from -3 to +3 stops.
Now we’ll take a look at how you lot would employ each type of meter to measure the brightness of a scene and how you would cull an aperture and shutter speed based on this.
Firstly, to make this simpler, we’re going to work in EVs (actually LV but we’ll explain that in a bit).
An EV translates as an ‘exposure value’. It’s an arbitrary unit of measurement that is 1 when the discontinuity is 1, the shutter speed is 1 and the ISO is 100. Real EV values vary when you modify the ISO but near light meters that read EV’s don’t change when you lot change the ISO and for definiteness we should say that these are measuring LV (lite value). The advantage of LV is that if y’all take a given value of LV it defines the intensity of light and hence becomes a single value that you tin can remember in the future (after some time working with meters you’ll know what the LV of a white cloud is on a sunny day for instance).
NB: Mod calorie-free meters similar the Sekonic use EV instead of LV. If yous desire to work in EV then alter the ISO to 100.
OK, at present we know we’re working with accented light levels in units of one f/stop nosotros can look at how each type of light meter works.
The incident meter should exist considered your go to meter for typical photography. Information technology is more probable to produce a well exposed picture than any other form of metering. This is because, as we have learned before, the typical brightness range of a non-reflective subject is +/- 3 stops and nearly all moving picture is capable of recording +/- 3 stops of light; hence if an incident meter is placed next to a non-reflective object and in the light that that object is illuminated by, then you will get an exposure reading that will requite good exposure from shadows to highlights.
The problem starts when your subject thing is sitting in a unlike light than that in which y’all are currently standing. This is why you should walk up to the subject area and place the incident meter equally shut every bit possible to the subject with the meter pointing dorsum at the camera. This is what you will typically meet in most portrait photography – the lensman will walk up to the model and place the meter in forepart of their face with the meter pointing back at the camera.
In many situations you have a problem that you can’t walk upwards to the field of study and perhaps the subject is being lit by point light source or sources. Allow’s take these one at a fourth dimension
Y’all can’t walk upwards to the bailiwick
In this case you have a couple of options.
If your subject in the altitude is in the same calorie-free every bit yous
Y’all can just take an incident reading where you are.
If your discipline is in straight sunlight
Then find a bit of direct sunlight and place your incident meter in information technology (pointing dorsum at the camera)
If your subject is in the shade
You can just cast a shadow on your meter (try to cast a shadow with your hand at a altitude from the meter – we’ll come back to why in a chip). This should work as long as the type of shade is the aforementioned.
How practice I know if the type of shade is the aforementioned?
Well, you need to work out in your head where the majority of the low-cal is coming from.
For instance, on a cloudy day, the primary light will be coming from all parts of the sky and then you need to brand sure your light meter sees all of the sky (autonomously from the direct light).
However on a blue sky solar day in desert canyons (for a somewhat forced example) the bulk of calorie-free for shaded areas is probably reflected from the ground effectually you; the bluish sky won’t exist contributing much at all.
Your bailiwick is lit past bespeak light source(s)
This could exist problematical, especially if the the lighting is indicate source based which falls in intensity as you get further away. Your all-time bet is to find a light nearby which you tin place your meter under to go close to the values. This is where you lot could exercise with a spot meter..
The biggest problem with incident meters
As landscape photographers, the biggest issue with incident metering is that yous tin’t take a reading of the sky (or part thereof). There are heuristic workarounds for this but they’re not simple and will be part of a time to come instalment.
In reality, if you’re taking pictures that include the heaven and you want to be accurate then you really demand a spot meter.
NB If y’all’re using colour negative picture show, you probably don’t need to worry most the sky readings every bit colour negative has such a large dynamic range. As long as y’all get the shadows correct you should be fine and so it’s best to take a shadow reading. If you’re worried about underexposing, shade your incident meter and use that reading.
The Spot Meter
The spot meter is undoubtedly the best way to take readings of scene luminosity. A one degree meter can accurately place tones throughout the range of your scene and you lot tin await around for the darkest and lightest parts of your scene and identify them according to your film or sensor.
The biggest problem with spot meters
The main problem with spot meters is working out a good exposure point. It’s easy to measure highlights and shadows merely to work out where mid-grey is can exist very hard. This is considering there are rarely nice grey areas in a landscape and our eyes/brain are notoriously bad at working out the relative luminosity of different colours. Even if y’all have a gray, people are notoriously bad at guessing a 12% (or should it exist 15% or 18%) grey (more than on that later).
The main way to resolve this is to conduct your own heart grey with you. This doesn’t need to be amazingly accurate but if you can easily afford i, an X-Rite Colorchecker Passport is useful in many other ways. Otherwise yous can pick upwardly a grey card set from ebay for 99p.
If you lot hold this facing the camera and take a spot meter reading from information technology, information technology’s a good substitute for an incident meter reading.
A Practiced Workflow for Exposure Metering
After speaking to a range of photographers, nosotros would highly recommend that you lot purchase a spot meter and, if possible, purchase one that has an incident meter built in besides. If not it’south not the finish of the globe every bit yous tin ever use a grey card as mentioned in a higher place.
Using both incident and spot metering your workflow would go similar this.
- Have an incident reading in the same light as the subject you want to be normally exposed.
- Mensurate the brightest highlight and work out whether it will stop up overexposed on your pic/sensor or non. If so, change your exposure or use a graduated filter.
- Measure the darkest shadow that you lot don’t want to be black. Piece of work out whether it will exist underexposed based on the meter reading from step 2
And there you have information technology. The real world often doesn’t carry and we’ll come back to some of those bug in hereafter installments. In the meantime the best way to describe the procedure is past showing example photos and the steps I took to get them onto film.
This was taken using a 5×4 camera on Fuji Velvia so non much dynamic range to play with – for most uses nosotros would say between -4 EV and +2 EV
Equally I was waiting for the best low-cal for virtually an hour, I was more often than not keeping an heart on which graduated filter I was going to demand.
Firstly I took an
reading with the meter held in the air and then information technology defenseless the
direct sunlight. This gave me a reading of11 EV
Then I took a reading whilst
by the dunes behind me. This gave me a reading of9 EV
This suggests a
effulgence range from vi to 14
The nighttime area in the shadow is ix EV and the darkest function of that will be iii EV below so will exist six EV
The brightest reflected area in sunlight is 11EV +3EV which gives 14EV
This gives a total dynamic range of viii stops (EV6 to EV14) and it suggests that a 2 stop graduated neutral density filter is needed.
If we look at the spread of these values on our exposure scale it may make more sense.
At present we tin can make some spot meter readings to check the darkest and lightest values and as well see what value the sand and grass has.
- Darkest (Sand in corners) =
- Brightest (Light patch in heaven) =
- Grass =
So if we put these on our chart we can see that we need to have at least a ii end filter.
In my case I used a ii finish and adjusted the exposure downwardly some other stop to catch the light in the heaven as I knew blueish over exposes easily on Velvia 50 (and looks ugly when it does). I also knew that I have a drum scanner and should get abroad with -5 stops on Velvia 50.
In this case I only had ane blazon of low-cal to deal with and this was the dawn glow almost half an hr earlier sunrise. The incident reading gave me a value of
six EV. This suggests that the dynamic range of the normal parts of the scene range from
Using my spot meter I read the following values from the scene.
This gave a couple of values outside that range, although not by much. I think the
in the lesser correct is because it’s totally shaded from the lite (i.e. it’s both night AND shaded).
The big trouble is the directly source of light with
ten⅔ EV. Here are the values placed on our Velvia fifty range.
In order to bring the brightest part of the heaven downward to within the Velvia 50 range, we’ve had to use a two stop graduated ND. This brings the
value downwards to
and given this we only lose the very darkest parts of pictureblack by ⅓ of a stop (which actually turned out OK on a pulsate scanner).
I could have forgotten about the incident reading for these tests simply adjacent consequence I’ll evidence some situations where having an incident reading gives extra information about where to identify your tones. Mostly, in these cases, the incident reading gives y’all skilful feedback on whether your overall exposure volition look ‘correct’.
You may have noticed that in both examples you could have about gotten abroad with only the incident reading, using a ii stop graduated filter and underexposing slightly. For many cases where yous aren’t looking straight into the sun or you have bright sunlight on white clouds, this quite often works. These sorts of ‘heuristics’ are something we plan to await at in future articles.