The WAP-LARP Principle in Photography

August 12, 2021August 12, 2021

What is the WAP-LARP principle

WAP-LARP is an acronym for as Wide As Possible – Low AS Reasonably Practical. ‘WAP’ refers to using the widest aperture on your lens to gather more light, and ‘LARP’ to keeping your ISO as low as practical in controlling and selecting your desired shutter speed.

It provides a way to control all three elements of the exposure triangle whilst exploiting your cameras semi-auto modes, and in particular, working in Aperture Priority mode.

How does it work

Most photographers are introduced to the exposure triangle at some point, and know that there is a correlation between aperture, shutter speed and ISO. WAP-LARP exploits this relationship and the semi auto modes of your camera to give you, the photographer, a practical way of working with the exposure triangle.

The theory

ISO – adjusts the gain or sensitivity of your cameras sensor. In bright conditions we generally work with lower ISO settings and as the light dims we may be forced to use higher ISO settings to arrive at a suitable aperture / shutter speed combination.

When we meter a scene, based on our ISO setting and the overall brightness of the scene, and depending on what shooting mode we are in, our cameras do one of the following

Full auto mode – set ISO, aperture and shutter speed.
Semi auto mode
- Aperture priority – we set the aperture, camera sets the shutter speed.
- Shutter priority – we set the shutter speed, camera sets the aperture.
Manual mode – we set both the aperture and shutter speed based on our meter reading.

Our camera meter determines the brightness of the scene and then provides us with an exposure value (EV), which, based on our ISO setting, provides us with a combination of aperture and shutter speed values that can be use to arrive at the correct exposure for our scene.

With WAP-LARP method, we work in aperture priority mode, set our ISO to manual, and use our ISO setting to adjust both ISO and shutter speed to arrive at a suitable ISO, aperture and shutter speed combination.

Principle of operation

Set your initial working ISO based on brightness of scene.
Use the widest aperture of your lens to gather the most light.
Meter the scene and make a note of the shutter speed.
Adjust your ISO as necessary to balance out your shutter speed and ISO
- Keeping your ISO as low as practical to arrive at your desired shutter speed.

We set our aperture to what we want it to be, the principle being that we work as wide as possible to gather the most light into the lens but you can choose whatever aperture setting meets your needs.

Once the aperture is set, we have metered our scene and based on our ISO setting, our cameras will then provide us with a correlated shutter speed, if the shutter speed does not match our needs, we can adjust our ISO up or down until we arrive at our desired shutter speed.

We work on the principle that we want our shutter speed to be high enough to freeze our subject matter and we want our ISO to be as low as reasonable practical in relation to the brightness of the scene.

Working in aperture priority mode and setting your ISO to manual, means that you can control all three variables of the exposure triangle as you would in manual mode. Except that, as the brightness of the scene changes and based on your aperture and ISO setting, your shutter speed will vary accordingly with the changes to the brightness of the scene.

By keeping an eye on your shutter speed, you can adjust your ISO up or down to keep your shutter speed within a desired range and maintain correct exposure for your subject.

You can fine tune your exposure by using your cameras exposure compensation function.

Working like this is much quicker than working in manual mode and you are less likely to miss a shot through poor exposure as your camera is continuously metering and adjusting exposure for you.

Here are the steps summarised making it easy for you to follow.