Using a hand held Meter for Flash 

A hand held light meter can improve picture quality in environments that require flash.

Even when using digital cameras, a hand held light meter gives superior exposures. When taking pictures with a flash, you adjust aperture for exposure, and shutter speed for ambient light exposure. A camera light meter measures the average light of the scene sampled. Any scene will actually have a number of different inputs that are calculated together to produce a single brightness value.

However, the camera system can sometimes over compensate when there is too little contrast between objects in a scene. With a hand held meter you can point the meter in a direction that measures the light shining on the subject, rather than the light reflected off the subject. This type of measurement is known as an incident reading and it often produces superior results. Advanced hand held meters can measure values with an accuracy of 1/10th of a stop.

Working with ambient light
In ambient light conditions, set the film speed on your hand held meter. Activate the meter to take measurements. Some meters allow you to take continuous readings as you walk around the subject. Other more advanced models allow taking readings from different angles after which an average value is calculated.

The default shutter speed for most cameras using flash is 1/60th to 1/200th sec in auto mode. In situations in which the ambient light is too low, the background will be dark and lack detail. The photographer must balance the ambient light with the flash. This is accomplished by slowing down the shutter speed, also known as “slow sync.” By dialing down the shutter speed, the camera takes in more ambient light. You can also increase ambient light by using a higher speed film, or when using digital cameras, you can set the ISO higher.

Using spot metering
Some hand held meters have spot meters that allow you to focus on specific locations within a scene. Spot metering is a reflective type of reading and should be used by those familiar with the compensation that occurs with these readings. The normal practice is to take several spot readings and then work out a rough average of the right exposure.

You can also estimate exposures using reflective readings using the Zone System developed by photographer Ansel Adams. In such cases, you attempt to assign the subject a greyscale value. A Mono View filter can help you in distinguishing brightness in black and white when using this metering method.

Adjusting Aperture
To change the exposure when using flash, you change aperture i.e. the diameter of the hole in the lens that allows light into the camera. Lower aperture numbers result in a brighter picture, while higher numbers create a darker image. Adjusting aperture also changes depth of field. By adjusting the aperture to a higher number you create a larger depth of field, and vice a versa. A greater depth of field means that objects farther from the plane of focus will still be in focus themselves because they are in the depth of field. You can also adjust depth of field by changing the distance of the flash, adjusting ISO setting, or adjusting flash intensity.

So, for portrait and other photography when you do not want the background to distract from the subject, you would set the lens aperture very wide placing the background out of focus. For landscape and similar types of photography when you want both the foreground and background in focus, you set the lens aperture to a small diameter to capture as much of the scene as possible.

Filters and exposure
Using filters changes the quantity of light that enters the camera. SLR cameras have “through the lens” (TTL) meters that automatically adjust for light differences caused by filters. When using a hand held light meter, you need to ascertain the filter exposure details, which may be found on the filter’s rim, in the container or in the instructions. You will have to adjust readings taken with the hand held meter by the number of stops suggested by the filter manufacturer.

EV numbers
Highly-experienced photographers may use something known as an EV or “exposure value” number. The EV number uses both the aperture and shutter speed to create an exposure value. Some types of professional hand held light meters give readings in EV numbers that can be translated to give both shutter speed and aperture.

Hand held light meters allow you to get perfect exposures to within 1/10th of a stop. However, this type of precision requires more time and work. You must learn how to use the meter correctly to achieve the best results. With some study and practice, hand held light meters provide the photographer with the ability to create the highest quality picture possible.