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Whether you intend to volunteer to photograph animals at a shelter, or want to take great portraits of people, off camera flash is the way to do it. The good news is that you do not need to spend lots of money on studio strobes, brand-name TTL flash units or use the advanced features of the Nikon gear that supports Nikon’s Creative Lighting System (CLS). In fact, it is quite straight-forward to get professional results using manual mode on your DSLR and manual power settings with simple speedlight flash units. I have done it and I’m going to show you how … using manual mode.
A great resource for learning all about off-camera flash can be found in the following book by photographer Vanessa Joy:
I have several models of speedlight flash units: my original Vivitar 285 HV that I purchased new nearly 40 years ago (and it still works beautifully), a Nikon SB-28 that I purchased used (to use with my Nikon film cameras), and a Nikon SB-80DX that I purchased used for use with my Nikon D1X about 15 years ago. I still use all of these – in manual mode.
Any speedlight flash will do – yet the more powerful the output (higher guide number) of the flash, the more versatile your light setup will be. The main goal is to use your flash off-camera to avoid the “flat” head-on lighting we see (with harsh shadows sometimes) when a camera-mounted flash is used.
The Exposure Triangle
Most photography enthusiasts have heard of the “Exposure Triangle” and if you have please bear with me in this brief review because there are actually TWO exposure triangles in flash photography. Let’s proceed with one at a time.
Case 1: No flash, ambient light only.
There are three variables we can control: The (film speed) ISO setting, the Aperture of the lens, and the Shutter speed. We can set any one of these to a fixed value (usually we choose ISO for this) and then to get a perfect exposure there are a range of aperture and shutter speed combinations that can be chosen next to get a secondary effect. The secondary effect an be a shallow (or deep) depth of field by opening up or closing down the aperture. Similarly we may want to select a slow shutter speed to convey movement in an image with a partially blurred subject or background.
In a situation where we are at a sporting event and wish to freeze action, a fast shutter speed can be fixed. For example, we can shoot at 1/1000 second to freeze action. Allow the in-camera metering system to set either a floating aperture, or the ISO level dynamically to be confident of shooting subjects in focus with adequate depth-of-field (DOF). The in-camera metering system selects the appropriate ISO for perfect exposure.
As the photographer, we choose what exposure settings we want to capture the image we want.
Case 2: Flash plus ambient light
Two exposure triangles exist when adding flash. The first exposure triangle we just discussed above still exists. However, by adding a flash unit (no matter what type) a second, connected but independent exposure triangle is involved. To understand the connection of these two exposure triangles we must understand the characteristics of flash duration compared to our chosen shutter speed.
Both shutter speed and how long the flash fires during exposure are events in time. The realization that flash duration is much shorter than shutter speed is key to understanding flash operation. As far as the flash is concerned, only the aperture controls how much of the light generated by the flash unit enters the camera.
The entire operation of the flash occurs while the shutter is open. Thus, only the Aperture affects the flash exposure.
The ambient light exposure depends on both Aperture and Shutter Speed. However, since we are selecting Aperture for correct flash exposure, the Shutter Speed we choose determines how much ambient light is mixed with the flash.
Always use Manual Mode!
To really learn how this method works so beautifully you will need to experiment. Use both your camera and flash unit in manual mode. Light stands are not required, but off-camera flash will give you more dramatic images if you are set up to do this. You can still experiment with a hot-shoe mounted flash unit, as long as it is set to manual mode. Avoid any metering adjustment of flash output such as TTL, aperture priority, etc.
First set the ISO of your DSLR to 100 (or 200) and determine proper ambient exposure, using a handheld light meter or the built-in meter of your camera while metering on a 18% gray card. For example let’s say it results in an exposure of 1/60 second at f8.
Verify this ambient exposure by shooting one frame with the flash turned off. You should have a good exposure of whatever subject you choose in that ambient lighting condition.
Most DSLRs will maintain flash synchronization up to 1/200 or 1/250 sec exposure. This will be at least two full stops under exposed compared to the first image shot. With the flash still off, change shutter speed to 1/250 and shoot another frame. Verify the low light condition by viewing that image.
Next turn on the flash and set it to manual, and select 1/4 power (full power output will likely overexpose the subject). Shoot a third frame with the flash at 1/4 output. What does the image look like? Is it overexposed? Is the subject well lit? Is the subject separated from the background?
All these things may be answered by simple adjustment of the flash output, distance from the flash to the subject, and adjustment of aperture and shutter speed. The important thing to remember is that Aperture (and flash output power) determine proper exposure of your subject, while the shutter speed controls how much ambient light is allowed to influence the overall exposure. Shutter speed will have no effect on the flash exposure.
To test this last point, choose a subject that is in a dark or poorly lit room and repeat the exercise. Shoot at 1/250 and then go all the way down to 1/10 second exposure (and use a tripod, please). Notice that the only changes occur in the background, while the subject is consistently properly exposed by the flash.
Why? Because in all cases the flash operation always occurs with a wide open shutter, no matter what the speed (up to the maximum sync speed, of course). If you should exceed the maximum sync speed you will begin to see the front edge of the shutter curtain begin to cover part of your image.
- Lit subject/Dark background (Chiaro Scuro)
- Choose your fastest sync shutter speed (e.g. 1/250 sec)
- Choose a low ISO setting (e.g. ISO 100)
- Adjust your flash power output and aperture settings for a proper exposure.
The fast shutter speed should render a completely blacked-out background. If this is not the case, extraneous ambient lights need to be dimmed to achieve this desired look.
- Visible background darker than the properly exposed subject to provide separation and emphasis on the subject
- Choose an intermediate or low shutter speed (e.g. 1/60 sec or less)
- Use a tripod for your camera
- Choose a low ISO setting (e.g. ISO 100)
- Adjust your flash power output and aperture settings for a proper exposure of your subject.
By lowering the shutter speed, more and more ambient light is allowed to mix with the flash output to establish the overall exposure for the image.
- Fill Flash
- Choose your desired shutter speed and aperture for a proper exposure
- Adjust the ISO setting to obtain proper exposure
- Adjust your flash power output and position relative to the subject to fill any areas of shadow that are desired to be filled with flash lighting
Maintaining off-camera flash, even for fill flash situations, gives you much more flexibility in many lighting situations.
Go have some fun with flash photography and your speedlights.