A photometer is an instrument used by photographers to measure the intensity of light and give us the best exposure in a photo or video session.
This accessory is essential to work with the correct lighting for that; today we will tell you how to use a photometer.
But first, a little history
The photometer emerged in England in the late nineteenth century as a replacement for the previous measurement method, when they were made with chemical products. This process was very complicated, since everything was done for the photographer’s consideration and required a lot of experience.
At the end of the decade of the 20s, the need for instruments for the measurement of light began to emerge, allowing a study of the most limited photography. The first photographers used selenium plates, but these were limited to a quantity of lighting, not being able to measure environments with low light such as sunset, candlelight, etc if they had the advantage of being able to be used in totally mechanical and manual cameras.
Then the silicon sensors that needed the use of batteries appeared. These could indicate the measurement with a needle or an LCD screen. They are still in use in all types of cameras.
What is a handheld photometer?
Modern hand photometers are divided by different types and utilities:
- Integrated photometers or exposure meters: Today, most digital cameras come with integrated photometers that greatly help to give us a correct exposure, aided in many cases by the histogram. However, professionals require a handheld photometer to work better, with greater precision when it is necessary to control the light. Especially when combined with the use of flashes or you need to get or keep a special color.
- Handheld photometer: The handheld photometer serves as a light measuring tool, especially if you need to analyze certain areas of light concentration. In the work of professionals, this tool is essential, especially in photography sessions, wherever you use it.
- Spot photometer: With this type of photometer, you can take different measurements of light from different specific areas, called points or spots. Point photometers allow measurements of different areas to be combined and even in some models that indicate medium exposure or that indicate areas where detail is lost. Some cameras and photometers have this type of measurement as the Sekonic Speedmaster L-858D
- Incident light photometer: This meter can make more precise measurements of light by calculating the amount of light that falls on the subject or object you want to photograph, measuring light, both flash and ambient light. Only available for handheld photometer models.
- The photometer of color: The photometers of color are of a special type, they measure the intensity of the color that radiates an object. They are ideal for those who seek to balance the saturation of color and tonality in photographs or need a maximum precision between shots. It is widely used in product photography and advertising.
Types of lights that measure photometers
On the other hand, there is another classification that is taken into account when talking about photometers, from the kind of light they measure: Photometers for reflected light and incident light.
The photometers of reflected light
They measure the light that reflects the objects or people you want to photograph. They are usually the most used by the initiates thanks to the fact that they are incorporated in the cameras. We can also call them exposure meters.
They indicate the amount of light that reaches the subject. They are not very precise because they usually cover more air than we need and can give us the wrong result. They have the advantage that it does not take much experience to interpret them. Especially if we put the camera in automatic. (Something we should not do if we need to learn something)
It must be said that some cameras bring advanced exposure meters with different measurement options, even with precise 10º or 5º point reflected measurement.
In digital cameras we will usually have these exposure meters:
- “Matrix” Matrix or Evaluative Measurement with an advanced comparative algorithm that will indicate the most appropriate balanced measurement for the scene in question
- Measurement to the center. We will give priority to the measurement of the central area of the scene.
- Spot or Spot mode. Called Spot Meter, these will measure a very specific area of the scene and give us greater precision in the exhibition. This option is more recommended for those who control exposure manually
The photometers of incident light
These models, placed just in front of the subject, looking towards the light source, measure the amount of light that reaches the objects and people you want to photograph, regardless of the percentage of light that reflects. In other words, it will always measure the light that reaches the white sphere regardless of whether what we are going to photograph is white or black.
This type of measurement is used mainly for when working with flashes. Due to the short duration of the flame, the camera can not read the exposure. Except in digital cameras with their compatible automatic flashes with a direct connection or wireless with the camera that will always do so reflected.
It is worth mentioning that many of the hand photometers can measure both types of lights mentioned above very easily. These are very useful accessories when working in the studio or outdoors, where lighting can become a problem that changes the idea of lighting you want to achieve.
How to Use a Sekonic Light Meter
Place your camera in Manual mode. Select the ISO you are going to use and open. Place the same aperture and ISO in the photometer that you placed in the camera. Position it in front of the subject, as close as possible, without obstructing the light that reaches the semi-white sphere and presses the button to know the correct exposure.
You will not need to retake a measurement unless you change the light, the modifier you use, or the distance between light and subject.
If you are going to work with flash either hand or study, the photometer will indicate the amount of light that is reaching the “Lumi sphere” in steps of diaphragms or EV values. The speed does not affect the flash, so we recommend you start placing your camera at the maximum synchronization speed you have that is usually around 1/160 to 1/250 of a second.
The incident measurement is very useful to control the contrasts between more than one light source. Knowing the diaphragm of each one of them we can know that it adjusts how much light we want to give.
To make correct measurements, place the photometer in front of the subject pointing the sphere towards the light source. Measure the main light and it will give you a diaphragm (example f / 8). To measure another (secondary) light, reposition the photometer in front of the subject and turn the head by directing the half sphere towards the light source to make the new measurement it will give you another diaphragm (example f / 4). This will indicate that the secondary is two steps below the first or what is the same ratio of 4: 1. If it were only one step, we would say 2: 1 and if there were three diaphragm steps, it would be 8: 1.
If we have a light that acts as a backlight, place the handheld photometer attached to the subject, and place the half sphere facing the light source. Try the result in this example of f / 11 for this one step above the main light. If it is a dark hair, you may have to increase the power of the flash somewhat.
Measurement of handheld flashes in automatic mode and HSS
If you intend to work and measure the light of automatic TTL flashes placed in the camera’s shoe or that is working by means of radio systems shooting with the photometer in an incident way, it is very likely that you will not obtain a correct measurement since many flashes of this type launch a pre-flash control , and then the main flash.
This leads to an erroneous measurement, usually to sub expose because the pre-flash flash is very short and not very powerful, almost invisible to the human eye.
The automatic mode is not infallible, but you can help in a simple way considering this.
If you measure the reflected light of a white object add the flash between +2 to +2 2/3 of the diaphragm to get a white tone and not medium gray:
If, on the other hand, you measure a very dark or black object, the power decreases to -2 to -2 2/3 depending on whether you want more or less detail.
If you want to measure in HSS, you should know that by July 2017 only the advanced model Sekonic L-858D is available that can give you this correct information.
Can you photograph without the help of a photometer?
The answer is yes if you can. Even more now with the help of the histogram of digital cameras. There you can see a simple but effective video of José Antonio Fernández
Measurement of flash without photometer
Demonstrative video of the use of the digital camera histogram to obtain a correct flash exposure.
How to use the photometer with reflected light
A photometer measures the reflected light of a subject or incident that reaches your photosensitive cell and reads it (as if the image were in black and white) in an 18% gray tone, closer to the tone gray 12-14% ) so if for example photographs with a measurement “reflected” to a polar bear in the snow the result that will give you will be a gray bear on a gray background or if you photograph a black object on a dark background also the result will be gray medium with the background in the same color.
To get the picture back to its intensity and original color in the previous examples to a white tone you will have to increase the original exposure in 1 – 1/2 to 3 steps of diaphragm and if on the contrary you want the black tones to look as they are It decreases in 2 steps to have detail or up to 3 for a black solid tone without details.
You can use this technique to get high or low key photographs to get photos in High Key (White) or Low Key (Black).
Lighting Tutorial: Using the photometer, Low key and high key
Demonstration video of the use of the high-key and low-key photometer in the study with Antonio Garci.
Since having only the photometer attached to the camera is somewhat inaccurate in several situations and directly non-functional when used with a flash, it is necessary to know how the hand-held photometer works. Doing so will allow you to have greater control of the exposure, contrast ratios, measurement of the envelope and sub-exposure, the balance of light and to help you pre-light a session before having the camera ready.
With a handheld photometer, you will have great control in your photo sessions with a single flash or more than two.
Measure the Incident Light
When you use the measurement of incident light, you will measure contrasts more than anything between the different points of light that you use. In this way, when you are preparing a session with studio flashes, you can adjust the lights according to what you want or need. Knowing which diaphragm is each study light, you can have greater control than if you did it “by eye.”
To, for example, measure the main light of a portrait, you would have to direct the white sphere of the photometer towards the main light that illuminates the portrait. As a trick, remember to cover with your hand any light that could affect the measurement. Once the measurement is made, the photometer will recommend the most suitable diaphragm with which to work.
However, if you want to measure the shadows in the same portrait, for example, you would have to move the white sphere towards the shadow and you would have to cover with your hand, the possible lights that will come to effect. Then, the photometer will tell you by how many diaphragms below the main light is the shadow.
You can do this same exercise on the backlight to take more tight control of the studio lighting. This is usually at least two diaphragms above the main light although it may be somewhat less if the photographed subject has light or very light hair.
What should I take into account when buying a photometer?
When you have to invest in a photometer, you can not just guide yourself by the brand, but by a series of parameters to follow that will help you find the one that is right for you. Some of them can be:
- Utility: If you are an amateur photographer venturing into professionalism, or if you work a lot doing photo sessions in studio or outdoors, then a photometer will be a good accessory to incorporate into your work team. However, if you are still learning, you may not need it as much, although it is a great help to learn to light. The most basic of high quality and advanced options are the Sekonic L-308S Flashmate, a reference among all those who start in the control of light.
- Reading capacity: Some photometers can measure flash, HD, cinema, etc., so if you are going to work with different types of lighting, you will need your photometer to have the greater reading capacity. Some high-end models like the Sekonic Speedmaster L-858D can even measure HSS fast synchronization, but this is something you will not need if you are just starting or just need to control the light.
- Functionality: The ease of use is essential for the photometer to be useful since you are supposed to buy it to make your work easier and faster. Therefore, consider factors such as whether the screen is touch if it is easy to read if it has a good memory capacity to remember measurements, USB input, etc.
- Lumisphere: The Lumisphere is the white sphere used to measure incident light, so its ability to rotate and if it allows its removal to place other accessories, is also something to take into account when buying a photometer.
- Ability to shoot wirelessly (Wireless): Another facility that photographers look for when looking for a photometer is the ability to shoot wirelessly with equipment from different brands. This helps to have a more relaxed working environment, without wires, and without so many complications, because there is direct communication between flash and photometer.
- Quality: Within the quality, you can include, not only the material with which the photometer is made but also the duration of the batteries (in any case, it is always necessary to have batteries on hand, especially in long sessions). Although some like the Sekonic L-398A do not need them thanks to the use of an amorphous photoelectric cell. Very useful in certain environments where you can not work with devices that use batteries or in the cinema.
If you are interested in having more information about a more exhaustive control of the hand-held photometer, we recommend the book ” The Hand Exposure Meter Book ” (in English).
Recognized brands that make photometers of great quality and precision that we have tried:
- Minolta (Old models that you can find second hand)
When you start to enter the world of photography, the most useful thing is to get a handheld photometer that helps you take control over the lights and you can put into practice all the combinations that you can think of, even more, if you work in a studio with flashes.