On-camera flash is an indispensable accessory for many photographers as it enables photographers to get clear and bright pictures even in poor or low light. This proves to be advantageous for photographers who are into night photography and need to deal with factors like distribution of light and treatment for certain photo shoots before shooting a particular picture. On-camera flashes are usually the ones that are preferred the most by photographers as it provides additional light when the area is too dark. Additionally, a flash can be used as a highly effective creative tool to establish an aesthetic that elevates your imagery when lighting conditions are considered less than stellar. The benefits of an external on-camera flash far outweigh those provided by a built-in camera flash, while the only drawback is keeping an additional piece of equipment.
IMPORTANT FEATURE OF A FLASH
Guide numbers are the standardized, numerical way of determining the power of a flash, with a higher guide number representing a more powerful flash. To be precise, the exposure constant for a flash unit is depicted by the guide number. The Guide Number (GN) needs to be higher which signifies that the flash is more powerful enough for the photographer's purposes if the subject of photos will be more of interior architecture or any other situation where large spaces need to be illuminated. Otherwise, if the flash is meant to be mostly used for close portraits, then the photographer doesn't need a large guide number.
flash-to-subject distance = guide number / f-stopFor example
The Sync speed indicates the fastest shutter speed that can be selected on a camera when firing a flash simultaneously. When the limit of sync speed is reached, it shows actual shutters on the the photo which is because of the light burst being too quick for the camera. These days most cameras have sync speed at 1/200 or 1/250. Photographers can get faster speeds by selecting the Hi-Speed option on the flash/camera and use it at faster shutter speeds.
For example, if you buy one of the new fancy flashes from either Canon or Nikon, you can use what is called high-speed sync. This turns your flash into a machine gun, but with less destruction. It makes the flash fire several low-power extremely quick bursts of light. The multiple bursts will occur at planned times during the exposure so that the whole frame will be illuminated. With high speed flash sync, photographers can use shutter speeds of over (or faster than) 1/1000th of a second.
The recycling rate determines how much time you have to wait in between flash pops. Being able to rapidly fire your flash will be very helpful especially if you are a fast shooter or are trying to capture action sequences.
One flash: TTL VS Manual
The question of whether one should use TTL vs manual flash output is one that many photographers will experience at one point or another in their careers. Both methods have their advantages and disadvantages.
TTL means Through The Lens metering. When you focus your camera with that half push of the shutter, your camera is not only focusing, but its taking a reading (metering) of the scene and taking a measurement of how much ambient light is being returned Through The Lens to the sensor.
Also, TTL flash uses a series or infrared flash bursts before the flash actually fires. This flash information is returned back to the camera which then adjusts the flash power accordingly to set what it thinks is a well-balanced shot.
Please pay attention that TTL is faster when the lighting or subject distance changes frequently and TTL might work out better unless you can set up your lights ahead of time and anticipate someone coming into the frame, or get good at judging distance of moving subjects.
Manual flash means the user sets the power output himself in order to get the desired amount of flash recorded in the picture. The flash exposure is affected by the available power of the flash, the aperture, the ISO, and the distance of the flash to the subject.
Unlike TTL, Manual flash is better when your lighting doesn't change and when you have full control of all the variables
TO choose a moving flash head or not to choose a moving flash head
The flash head must be able to SWIVEL left-to-right as well as TILT up-and-down because you can suddenly gain much greater control and a variety of options regarding how to direct the light falling on the subject. Light that is pointed at your subject is very harsh light, which producing deep shadows and having a quick light fall-off from your subject to the background. To render a similar scene with softer light, you can tilt and swivel your flash head to bounce your light off a nearby wall or the ceiling in order to broaden its directional quality. After bouncing the light, that surface is being converted into a much larger light source than your flash itself.
The strobes that do not have a moving flash head have the benefit of being more compact, but outside of that their usability is significantly less than that of a strobe featuring a flash head that can tilt, and even better, one that can rotate.
Camera flashes are basically just another source of light that is used to illuminate a scene. The flash power can be controlled easily based on its intensity and direction. Flash power is measured in half increments and are depicted as full power, half power, quarter power, etc. When buying a new camera flash, it is necessary to check out its power that will signify the amount of light the flash can emit at full power.
Wireless Flash Control
Most top-of-the-line flashes allow you to use the main flash (the one attached to the camera) to control other flash units remotely and wirelessly while maintaining the intelligent TTL exposure computation on each flash unit triggered. In theory, you can link up unlimited amount of flash units wirelessly and control each flash's output from the “commanding/master” unit attached to your camera.
Mid and lower-end flashes often do not have this ability to control other flashes but are ready to act as the flash units RECEIVING the TTL signal instructions from the main unit while high-end units can act as both the TRANSMITTER and RECEIVER of TTL signals.
Common types of wireless triggers
An infrared triggering system is similar to an optical method, but it utilizes infrared wavelengths to transmit the flash signal. This has a benefit over an optical trigger that do not need an on-camera or directly tethered flash to trigger exposure, which can affect exposure and limit the means of how you light your image.
An infrared transmitter is essentially a low-powered flash with an IR filter over the front of it; when it emits a burst of light, the IR filter attenuates most of this light and converts it to an infrared signal.
Infrared remotes work best in indoor situations when there isn't an abundance of ambient light to disrupt the infrared transmission, and they also usually require your infrared receiver to be in direct line of sight of the infrared transmitter.
Radio remotes have the advantage of being completely non-reliant on optics and do not require a line of sight or certain lighting conditions to function properly.
They can operate across numerous channels, which greatly enhances photographing with wireless flash in situations where multiple photographers are working.
Their other main benefit is that some radio systems integrate full TTL compatibility, which gives direct connection between the flash and your camera for controlling flash exposure.
Many radio trigger also have dual functionality, deeming them transceivers, which allows the same units to be placed on either cameras or flashes.
Small addition to your flash that enables wireless triggering once the trigger detects a flash of light
These triggers come in an assortment of connections. Remember to determine which connection type is compatible with your specific flash before considering anything else when using an optical trigger.
Additional Battery Power
On-camera flash is a self-contained power source and the power source of on-camera is AA batteries which is stored inside the flash and can be replaced easily during the course of a photo session. The advantage of this power source is that it is convenience when compared to portable strobe packs featuring batteries. But actually AA batteries are not that powerful. Flash is a power-craving tool that requires battery power and quantity in excess of typical camera batteries, so if you choose the right external battery pack for your camera and flash will not only save you money and improve recycling speed, but it will also prevent you from missing shots because your flash is recharging or you've run out of power. All in all, it is beneficial to use battery packs if you use flash on a regular basis.
Flash units have the tendency to get hot when they are in heavy use. On some units this means they may shut down completely or start operating at a lesser power. Know what to expect if you will be putting your speedlight through rigorous shooting sessions.
Types of Lighting
Macro Ring Flash
A ringlight is a unique lighting tool that is donut-shaped and goes directly around your lens. This circular light is perfectly aligned with the axis of your lens and helps to soft, near-shadowless light, which is vital for macro photography. Not only does this eliminate shadows created by your camera and lens, the evenly distributed light wraps around your subject to produce a soft, even light to emphasise detail and colour. When used with more powerful studio strobe battery packs, a ringlight is a popular tool for fashion and portraiture work, but when confined to an on-camera source the light output is typically fairly limited and best suited to macro and close-up applications. The more important, reason that ringlights are best suited to macro work is that they constitute an effective solution that provides even lighting to subjects where your own or your camera's shadow would be in the way if you were using off-camera lighting. Since the light is positioned on the same plane as your lens, you are able to light anything that your lens can focus on. Furthermore, Some ring flashes actually have a pair of tubes, one at each side, which can be fired at independent flash power ratios to give a more three-dimensional feel to shots.
Things to consider
Guide number (GN)
The guide number measures the reach of the flash, and is given in metres at ISO100 at f/1; to find the true range, you need to divide the GN by your actual aperture. As ring flashes are used at close range, you don't need anything too powerful so the GN will be small, typically between 14 and 16.
Most ring flashes fit to the lens via adapter rings that screw onto the lens filter thread. Some ring flashes come with a range of adapter sizes, whereas others will only include a couple of options, so you may need to purchase additional adapters separately.
Other Functions And Features
Auto-Focus (AF) Assist Beam
Most external flashes offer an external AF-assist beam that is significantly brighter, less intrusive, and more effective than what's equipped on the camera itself. The AF-assist beam on external flashes often use bright red beam patterns that the camera's AF sensor is sensitive to. These assist beams can help you lock focus in practically zero light conditions without blinding your subject with a bright flashing beam from your camera's pop-up flash or AF assist lamp.
Most flashes can zoom in an out automatically according to your lens' focal length. As you zoom your lens from 24mm to 70mm, for example, the flash automatically adjusts its beam pattern to ensure maximum coverage and efficient light usage. Newer flashes have the capability to detect whether the flash is mounted on a full-frame 35mm sensor camera or a crop-sensor camera to adjust its beam pattern accordingly.
Auto zoom heads can be manually set as well, allowing you to change your light pattern from wide to narrow, depending on the lighting effect you want on your subject.
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