|
Flash Photography (part 3)
Making Flash Light More Natural (Less Harsh)
Even when a separate flash unit is used the flash light may not be quite as appealing as you may wish when fired directly at the subject. There are 3 ways around this:
- you could take the flash off the camera altogether (connected via some form of sync cord)
- you could diffuse the flash using an attachment
- you can bounce the flash off something with a neutral colour like a white wall or ceiling.
Let's start with the most common of these for external flash guns.
Bounce Flash
Most external flash guns (except for the most basic, and to be honest ones not worth having) allow you to swivel and tilt the flash head so that it is not firing the light directly at the subject.
Bouncing the flash is a simple and effective way of diffusing the light. If you bounce the flash off a ceiling you are effectively making your light source much bigger as the light will hit your subject from a larger area than it would if coming directly from the flash head. Bouncing flash of a ceiling can have some disadvantages or complications though. First it only works well with a fairly neutral toned ceiling, a bright coloured ceiling will create a strong colour cast to your picture. With fairly neutral colours you will be able to correct any colour cast in post-processing, especially if shooting RAW. Secondly when your subject is lit directly from above (as would be the case when bouncing flash from a ceiling) shadows will show under the eyes and this is not entirely flattering.
To counteract this "panda eyes" effect when bouncing flash off a ceiling there are a couple of things you can do. A tried and tested method is to use a "bouncecard"; this is a white card that is attached to the flash when in its upright position that directs some light directly forward at the subject. The light from the bouncecard acts as a fill-in for the shadows and the light from the ceiling acts as your main source of light.
 |
This photo was taken with the hotshoe flash aimed directly at the subject. This results in a harsh lighting effect. |
| This photo was taken with the flash bounced off the ceiling. Note the softer lighting but unfortunate and unflattering shadows under the eyes. |
|
This photo was taken with the flash bounced off the ceiling however a bouncecard was used to fill in the shadows under the eyes.
Note how there are catchlights in the eyes too - this is quite desirable in portraiture. The use of a bouncecard has taken advantage of the softer lighting of bounced flash and also benefited from some direct flash to produce the most flattering image of the three. |
Diffuser
Another solution is to add a type of diffuser to the flash such as an Sto-Fen Omni-bounce or lightsphere. These are plastic attachments that go over the end of the flash to ensure that as well as light being sent upwards to the ceiling it is sent in other directions too (including forwards) to ensure that shadows are filled in.
|
A Sto-Fen Omni-bounce - manufactured specifically for each make and model of flash.
|
A homemade bounce-card as referred
to in the previous section.
|
An alternative is to bounce the flash off a wall to the side of your subject to get some side lighting or you can bounce the flash off a wall behind you to get a large diffused light source. The key again is to ensure the wall you choose is a fairly neutral colour, unless of course a bright green light source is the look you are going for.
Off-Camera Flash
The third and final way mentioned above to prevent the harsh direct light typical of flash photography is to move the flash completely off the camera (rather difficult with the built in flash but easy with external flash and the right cable).
One option is to use a standard PC-sync cord provided that both your camera and external flash gun have the appropriate socket. This allows the camera to send a pulse to indicate when the flash shouldl be fired, but unfortunately bo other information about the exposure or the camera/flash settings is communicated. Therefore the flashgun must be used in completely manual model where you will set the flash power usually as full, 1/2, 1/4, 1/8, 1/16 etc.
A better method (assuming your system manufacturer makes one) is to use a dedicated flash cord. One end slots onto your camera hot-shoe, and the other end on the bottom of the flash gun. These usually coiled cables have a range usually between 50cm and 150cm. However the maintain full dedication (i.e. it works as if the flash was mounted on the top of the camera).
Slow Sync, High Speed sync, second curtain sync and the kitchen sink...
High Speed Sync We mentioned earlier that your camera will have a shutter speed which is the maximum speed for taking flash pictures - the flash sync or x-sync speed. Whilst what we said was true there is sometimes more too it than that. Certain cameras when combined with certain flash units may allow you to shoot at faster shutter speeds than the normal sync speed, this is referred to as high speed sync.
High speed sync relies on using a dedicated flash (see above). When high speed sync is enabled on your flash unit you will be able to take flash pictures using any shutter speed of your choosing. The way this works, in a nutshell, is that the flash outputs a series of rapid bursts of light. These flashes are so close together that essentially they can be seen as being one continuous light source, this is the flash's way of guaranteeing that the shutter curtains will be fully open when the flash is lit - i.e. the flash will be lit before during and after exposure to make sure.
The downside of using high speed sync is that it results in a reduction of flash power and therefore a loss of range at which the flash is effective. The upside, however, is that it enables the photographer (i.e. you) to take flash pictures in bright conditions. For example if you want to take a picture of someone and use fill-in flash you may find that the camera is telling you that for the aperture you have chosen (f/4 for example) you need a shutter speed higher than your flash sync speed, without high speed sync the only remedy is to use a narrower aperture. However you may want a wide aperture to control your depth of field; high speed sync enables you to have a fast shutter speed and therefore removes this restriction.
Slow sync It may not be entirely shocking for you to discover that slow sync is the opposite of high speed sync. In other words it is the use of flash combined with a slow shutter speed, it is sometimes referred to as "dragging the shutter". This can be a useful technique that enables you to both freeze action and show it with a slow shutter speed. The flash freezes the action whereas the slow shutter speed introduces blur into the photograph, these two things combined can have an interesting effect.
<example to follow>
Leading on from slow sync we have...
Second Curtain Sync When you take a flash picture your camera or flash may give you the option of using first or second curtain sync. This means that you get to choose whether the flash fires as soon as the shutter fully opens (first curtain) or just before the shutter is about to close (second curtain). This is only relevant when using a slow shutter speed, i.e. slow sync mentioned above, but in this situation it can have quite a dramatic effect on the look of the image.
Let's assume you are taking slow sync flash shots of someone running. If you use first curtain sync the flash will fire as the shutter opens and the subject will be frozen at the beginning of the exposure and their movement will be shown as a blur after this point. This can look strange as you will have a frozen person with a blur ahead of them which seems to imply that they were running backwards.
If you use second curtain sync the shutter will open and the flash will fire just before it closes. This will result in an image where the runner has a blur behind them rather than in front of them and this will appear more natural.
Studio Flash This is a subject worthy of a large book in its own right however we'll cover some basics to get you started. Studio flash is not as complicated as it seems, despite strange terminology such as softboxes, umbrellas (nothing to do with rain) and snoots the principles are not extremely complex.
A studio flash is just a large manually controlled flash unit on a stand, that's all there is to it, they are no more complex than a hotshoe flash in the principles involved. Just like with a manual hotshoe flash you will control exposure using your aperture and ISO and you can just leave your shutter speed somewhere around 1/60 without worrying about it. Studio flash units are not dedicated, they will not automatically adjust their power to give you the correct exposure, that is up to you.
In the good old days when the world was an idyllic place, everyone knew their neighbours and you could leave your front door unlocked without fear of burglars or double glazing salesmen, there was a thing called film. The photographers who used this substance didn't get to see their pictures on an LCD an instant after taking them and their in camera light meter couldn't indicate flash exposure (just like today) so they had to use a device called a flash meter. They would connect the device to a flash cable (called a PC Sync cord and still in use today), tell it what ISO film they were using, point it at the flash and trigger the flash. The flash meter would then tell them what aperture to use. As this is an "incident" light reading rather than a reflected light reading (See metering section) it would give them the correct exposure regardless of the luminosity of whatever they were shooting.
Flash meters are great but expensive. Luckily we can use our camera to tell us when a flash exposure is correct or not without using a light meter. Like this...
- Once your studio flash is (or are if there a more than one) set up place something white but not too reflective such as a white towel where your subject will be.
- Set your camera to ISO 100 with an aperture of say f/8 and take a shot.
- Look at the picture and histogram.
The white towel should appear white in the picture and the histogram should have a peak close to the right hand side but it should not be clipped at the right hand side. The objective is to make the towel white without losing highlight detail, if your camera shows you burnt highlights with blinking patches on the LCD look out for them.
- If the towel appears burnt out, close the aperture, lower the flash power or chose a lower ISO (if available).
- If the towel appears grey and the histogram is not peaking towards the right hand side then open your aperture, chose a higher ISO or increase flash power.
Then try again. It shouldn't take more than 3 or 4 shots to get the towel appearing white without blowing highlights at which point you can replace the towel with your real subject and start shooting using the exposure settings you have worked out.
Of course there is more to using studio flash than just getting the exposure right you can use multiple flash heads, at various angles of your choosing, there are multiple types of diffusers (e.g. umbrellas) and gels of different colours. We will cover more of this in "Beyond the Camera - Studio Flash" but here's a few hints to get you started.
First of all, experiment with a single flash head, use a softbox or umbrella to diffuse it and place it at an angle of approximately 45 degrees from your subject. You can do more with one light than you might expect and you can always fill in the shadows by placing a reflector on the opposite side of your subject. Place the flash above eye level but not so high that it is pointing directly down at your subject
Your main light is your "key light", if you add another on the opposite side of your subject with a slightly lower power (one or two stops) this will be your fill light, add a final light slightly behind the subject and one on the background and you will have a fairly classic portrait setup.
Setting up lighting for studio portraits is the subject of many large books, it is a specialist subject in its own right but don't be intimidated by it, start simple with a single light and a reflector, you can even use your hotshoe strobe on a lightstand with an umbrella and you have a good place to start.
|
Photographs
This is a site about photography so I'm sure you are expecting to see plenty of pictures.
For now, why not take a peek at the flickr galleries belonging to the two authors of this site.
Colin's Flickr Page
Phil's Flickr Page
|
