(Editor’s Note: This is a guest post from our friends at MPB.com. MPB is a great place to sell gear that’s no longer in use as well as where to buy quality used photo and video equipment at much lower cost than that of new.)
Photography is completely centered around light: it not affects your photo’s mood, but it also dictates what your settings must be in the camera to record a picture and represent that mood in the picture. Let’s talk about how shutter speed, aperture, and ISO setting affect your image, and then we’ll dive into the light.
Shutter speed will increase or decrease the exposure value depending on the speed setting you choose. The longer the shutter it remains open, the more light will be allowed in, making the picture brighter.
However, this will also have an effect on your ability to freeze the action in your image. So if you take a photo of a person near moving traffic at 1/50 of a second, you’ll be able to keep the person sharp but the traffic will have motion blur as the speed required to freeze a moving car is closer to 1/250th of a second.
So if you prefer to have everything sharp, you’ll need more light to shoot at 1/250 either by adding light or adjusting aperture.
Aperture is measured in f stops, such as f/1.8 or f/5.6. Since this is a fraction, the smaller number, like f/1.8, is a larger opening in the lens while f/22 is a smaller opening in the lens. However, the aperture has another purpose—controlling depth of field. Depth of field will have a significant impact on the look of your images. A shallow depth means less of the picture will be in focus in front of and behind the actual point of focus, while more depth means more will be in focus. The wider the aperture the less depth of field there will be.
So if you shoot a head and shoulders portrait of someone with an 85mm lens at f/1.4, your subject’s eyes will be sharp against a background which will fall out of focus—more so if the background is farther away from your subject. If the same shot was taken at f/11, the near background will be less out of focus. If there isn’t much light, you might have no option but to shoot at wider apertures to let more light in if your shutter speed is already too low to successfully hand hold your camera without creating shake due to your hand moving.
In a nutshell ISO in a digital camera is altering the sensitivity of the sensor to make it more or less light sensitive. In low light, it’s a godsend for getting the correct exposure once shutter speed and aperture options have been exhausted. With modern digital cameras performing as well as they do, ISO has less and less of an effect on your photographs—at least not as much as aperture or shutter speed. With film, higher ISO speed film is grainier (the equivalent of noise in digital) than lower speed emulsions.
A great thing about the digital age is being able to change ISO in camera unlike with film where you are stuck with a roll of film at a definite speed until it’s finished, unless you take it out mid-roll and sacrifice it for a higher ISO speed film as light conditions change, which would waste the rest of the roll.
With all that in mind–and once you’ve sorted out the creative side of how you want your images to look–you need light. How do you find it? Here you have a variety of options.
Flash is a dark art; you can do amazing things with it creatively or use it haphazardly to simply get more light, but then all you’re doing is illuminating. There is a difference. The options with flash are huge and in my experience, takes the most amount of care as flash can spread light a huge amount denying you the control you want.
The best thing to do is to experiment. You’ll find that flash best works when it’s diffused or bounced off another surface. The key is to control the spread of light, and depending on what you wish to photograph—and how—you can go pretty crazy in terms of what you can do to control the spread of light. Most decent flash units like Nikon’s SB900 or Canon’s Speedlight 600 RX will have fully articulating and rotating heads to allow you to point the head where you need to. You can mount them on the hot shoe mount or have them off-camera as slaves. Equally, you can use larger strobes which may afford you more power and will allow you to shoot quicker, albeit at the cost of portability.
LED’s & Constant Lights
Using LED’s is arguably easier than flash photography because with live view you can see the exact effects your efforts have made on your subjects. The downside is that they just aren’t as bright as flashes of the same size. If they are bright and small, then they are not cheap.
Small light sources can be very harsh if pointed directly at your subject, so they require a lot of diffusion to make the source larger or bounce it off a surface to soften the light. Equally, softer light sources can sometimes not have sufficient power for your needs because shining through diffusion materials reduces the brightness by increasing the area being illuminated. Larger sources in relationship to the size of the subject mean softer light–more diffuse shadows.
Obviously your preferences will depend entirely on your subject, purpose, and style of shooting.
If you’re willing to incorporate practical light sources into your shoots—such as lamps, chandeliers, table lights or anything that can be found in the ‘real world’—this may be the way to create not only the right ambiance but also give you a justifiable light source.
Again, this depends entirely on the shoot you’re doing. Practicals tend to be incorporated into video a lot where the light not only serves as a prop but one that may give off light to create the right ratio for a scene. These can sometimes be softened or customized slightly by increasing or decreasing output by changing the lightbulb to something more or less powerful.
Neon & Colored Lights
Time of Day & Time of Year
You might be able to replicate a certain type of light in post-production, but after a very long time shooting, you’ll find that there are somethings you just can’t do in Photoshop. Some light, such as the British summer sun, can‘t be changed to be a British winter sun. The differences may be subtle and you may get 75% there, but it’s not perfectly replicable. Plus, you may have limits as to what you want to do in post-production; some things are just best left to nature rather than recreating reality in front of a computer. Just like the difference between daylight and tungsten light, different times of day will have different effects on your subjects as the light quality/temperature is different. If you’re dead set on a look, all you can do is wait until the conditions are right to photograph your subject. The diffusion and evenness an overcast day provides as opposed to the high contrast look a clear summer day brings are all very specific and often very different looks that can have a big effect on your photographs.