Having troubles with setting up the lights we provide in our studio? No worries. Mastering exposure with studio strobes is no-brainer. In fact it will not take more than 10 minutes in order to calculate right settings for your camera depending on the strobe lights, the distance of the light from a subject, kind of modifier and a power level on the strobe. Now we will not go into details of science behind these calculations as we strive to provide a concise, easy to digest guide of how to get you set up quick. No expensive tools, light meters or such required. Let’s go.
Before you take your first shot here are the initial steps for the light set up
Turn on the strobe lights, set it to full power and click a test button to make sure it works.
Use the remote control trigger that our staff member provides for free. Place it on your camera’s hot shoe.
Settings: Set your camera to manual mode, your shutter speed to 1/125th of a second, and your ISO to 100. Now the only parameter you’d have to deal with is F-number (aperture).
Runa calculator app on your iPhone/Android.
Think in full stops – 1- 1.4- 2- 2.8- 4- 5.6- 8- 11- 16- 22- 32. Most cameras have much more precise tuning with numbers in between this pattern. Yet for this guide you would not need to worry about it.
The guide number is a child of complicated math formulas and calculations based of Inverse Square Law. Long story short, it is used to calculate the F-number depending on the distance from the subject to the light and the kind of the light. Here, at FD we mostly use Paul C Buff Alien Bee 800’s which have a guide number 109 when used with 7 inch modifier ( in feet).
There are two main ways to use this guide number, that will be useful to you. You can choose your aperture based on the desired outcome of your photo and calculate where to put your strobe, or you can place your strobe for a desired lighting effect and calculate the correct aperture.
Find out your Aperture
Some lighting effects require strobes to be in certain positions, and distances from your subject and other strobes. In other circumstances, your strobe might be in a fixed position and it cannot be moved.
In this case, the easiest way to figure out your needed aperture is to measure the distance from the light to your model (in feet) and then divide the Guide Number ( 109 ) by that distance. For instance, if your distance is 7 feet then: 172 divided by 7 for a result of 15. Take the closest number in our pattern – f/16 is your correct exposure.
Taken by: @josefjassophoto
Find out your Strobe Distance
Conversely, if you know your desired aperture, simply divide the guide number by it. For example, if you want to have f/11 aperture then: divide the guide number 109 by 11 and get 9.9 as your result. So, for a correct exposure place your light 9.9 feet away from the model. That is it. Easy.
Attention: If you want to decrease the power of the strobe light then the guide number will decrease accordingly – half power of the light is a half of the guide number.
Working with different modifiers
The output of the strobe light in terms of exposure depends of the kind of modifiers you use:
Modifiers that decrease the amount of light on the model and require larger aperture or closer distance:
-Soft boxes
-Translucent Umbrellas
Modifiers that increase the amount of light on the model and require smaller aperture or further distance:
-beauty dishes
-silver umbrellas
Taken by: @jonsams.jpg
Although the modifier influences the aperture, it rarely changes it by the full stop. Thus, if you choose to alter your aperture in these situations, feel free to use F numbers in between our 1- 1.4- 2- 2.8- 4- 5.6- 8- 11- 16- 22- 32 pattern.
Changing your aperture depending on the modifier and getting that into a habit would not take long for you. Soon enough you will be adjusting it on the fly.
Although this guide is created to aid your studio set up and save up some time, the creative process sometimes requires to step outside the precise math and make decisions based on emotion or concept. In no way we want you discourage you in experimenting. Our main advise is to have fun with your projects and make some great photos!
**Cover photo is courtesy of @nikavphoto, @nastya_atanession, @makeupbyevelyn
*** All photos were taken at FD Photo Studio.
