Flash photography made easy
The world of flash photography can be an intimidating experience for photographers first starting out, however providing you understand a couple of key concepts and learn to deal with them it really isn't that bad at all. Some digital SLR cameras, such as the Canon EOS1000D and the Nikon D3100, have a built in flash that can be used when the need arises and this additional light will get you out of a few situations you are likely to find yourself in, however I would not rely on it. In all honesty, the built in flash on all digital SLR cameras is poor and if you want to get serious about flash photography an external flashgun is required. There are many reasons why an external flashgun is required and one will be a sound investment and addition to your kit bag.
When taking photographs without a flash the exposure is controlled using a combination of the ISO, aperture and shutter speed and changing one, or more, of these variables will lead to a different exposure, unless there are compensating adjustments of course. Flash exposure is different as it is only adjusted by varying the aperture of the lens or the ISO. Shooting wide open, i.e. at small F numbers, requires less power than shooting stopped down to the higher F numbers.
Flash exposure is affected by the distance from the flashgun to the subject. If you find you are underexposing the subject, i.e. it is too dark, move the flash closer to the subject to achieve correct exposure. If you find you are overexposing the subject, i.e. it is too bright, move the flash further away from the subject to achieve correct exposure. Moving closer to and further away from the subject may appear easy but there are issues that need to be considered. The guide number of the flashgun in use needs to be considered, as does the laws of light and how it falls away. There is a finite distance you can move away from the subject and still illuminate correctly. Once this maximum distance is reached it is time to make other adjustments.
Flash exposure is directly affected by the power of the flash. Many external flash guns will have adjustable power. Some of the top end flash guns can be manually set anywhere from full power to 1/128th power. It should be noted that every complete adjustment is a full stop. For example ½ power is a stop less than full power, and ¼ power is a stop less than ½ power and 2 stops less than full power, and so on. Many of the top end external flash guns allow the power to be adjusted in half stop, or even third stop, increments for fine tuning and more control over the exposure.
As previously noted, the flash-exposure is not affected by the shutter speed. The duration of a flash pulse is exceptionally fast and can be up to 1/10,000th of a second, which is much faster than the fastest shutter speed of any digital SLR camera. Whilst the shutter speed will not affect the exposure of the subject it should be noted that in most instances the maximum shutter speed will be controlled by the camera’s maximum flash sync speed, which for most canon digital SLR cameras is 1/200 – 1/250 of a second. Some of the professional use and top end digital SLR cameras have a high speed sync flash feature which allows the use of faster shutter speeds, however using faster shutter speeds drastically reduces the power of the flash. Any shutter speed lower than the maximum sync speed can be used with no problems.
Whilst the shutter speed will not affect the flash exposure it will affect the ambient light exposure. In order to burn on some background detail a shutter speed slower than the maximum sync speed is often required, unless you are shooting in adequate light levels. There may be times when the shutter speed required to burn in some background detail at the desired ISO/aperture combination is faster than the maximum sync speed. Some of the top end flashes have a feature called high sync speed, which allows very fast shutter speeds to be used. This is fine, however when flashes are used in high sync speed the recycle time increases, the power and range decreases and it uses a lot more battery power for each exposure.
If your flash and camera combination doesn’t support high sync speed then you must reduce the shutter speed to the maximum sync speed or lower. This is achieved by decreasing the ISO or closing down the aperture. If a shallow depth of field is required the ISO should be decreased to the lowest. If depth of field doesn’t matter then the lens should be stopped down.
Obtaining the correct flash exposure is only part of the equation. The quality of the light is something that needs to be considered too. The light produced by a flash is often harsh and will create areas of strong shadow, which does not make a pleasing image. When taking portraits the harsh shadows can look very unflattering, which is something no one wants. To overcome the shadows it is important to soften the light by diffusing it or bouncing it off some other surface. There are many different products available to achieve this.
The flash is used for macro photography, portraits, landscapes, product photography and wildlife photography. In fact, nearly all genres can benefit from a bit of flash in the right circumstances. Taking good photographs using a flash is not difficult, however taking great professional looking photographs using a flash is. Flash photography takes practice and perseverance to get good at it, however if you are prepared to put in the time and effort you will reap the benefits in the end.
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Tip to instantly improve your flash photos
One of the best lessons I learned about flash photography is that it is effectively taking two images in one, being an ambient light exposure and a flash exposure. Once I got my head around exposing for the ambient light and adjusting the settings to make the background appear how I wanted it to and letting the flashgun correctly expose the subject I found my flash photographs instantly improved.
When I take a photo using flash I will always meter the background in the first instance and obtain the settings I need to expose the background how I want to expose it. Sometimes I want to make the background darker, and under expose it, since this will make the subject “pop”. Other times I want to make the background brighter and over expose it since this will create a more high key effect. Once I have the ambient light settings to get the background as I want it I then dial in the flash power I need to correctly expose the subject.
If you want to improve your flash photos I recommend the approach above, as it really isn’t that difficult and you won’t be disappointed with the results.