Flash photography has a lot of advantages but has its share of disadvantages as well. A lot of Photographers do not find flash photography very easy and hence, it is not a part of their regular workflow. However, once you know how to handle it well, you can easily adapt it to your photography style as if you have not even used a flash. There are different kinds of flash units. While the mains powered are stronger and come with a whole lot of light modifiers, the ones to be fixed on the camera are relatively weaker but are more portable and versatile. So, here are some of the typical problems faced in camera Flashes and the remedies for the same.
The level of light produced, with the built-in flash may often not suffice for good pictures at distances of over 3 meters (10 ft) or so. Dark, murky pictures with excessive noise or "grain" will result. In order to get good flash pictures with simple cameras, it is important not to exceed the recommended distance for flash pictures. You get this information in the camera booklet or calculate as per the flash guide number. To get better results, even with external dedicated flash units, it is not a very good idea to use very long focal lengths. Most of the strobes work well up to about 100 mm at the max.. If somehow the subject or the background, which may be further back from the subject is still underexposed, it is best to move closer to the subject while changing the focal length. this way both the subject and the background will be well within the range. keep in mind that you move closer only to the extent that you are still using a relatively long focal length. i.e you may come down to maybe 70mm from 100mm but not all the way to 28mm!
Do not use a very Long focal length, with the subject too far away from the reach of the flash
Be closer to the subject but still use a relatively long focal length so as to not cause any distortion.
A Good flash will take into account the background and try to balance out the exposure when set on Automatic dedicated mode.
Prefer a strong flash unit with a higher Guide number as you can always reduce the power of a flash but not increase it if the flash is not powerful.
Red Eye effect
The Red eye effect is another problem. Since the retina of the human eye reflects red light straight back in the direction it came from, pictures taken from straight in front of a face often exhibit this effect. Modern cameras have a Red Eye reduction mode and this helps reduce it to some extent. It's a pre-flash that makes the subject's irises contract and get adjusted to the upcoming actual flash so that it's not unexpected.
However, very good results can be obtained only with a flash unit that is separated from the camera, sufficiently far from the optical axis, or by using bounce flash, where the flash head is angled to bounce light off a wall, ceiling or reflector.
Use Red-eye reduction mode
Physically move the flash away from the optical axis of the lens - Possible only with external flash units.
Delay due to Red-eye reduction mode
When you shoot in this mode, the camera fires some pre-flashes to eliminate or reduce red-eye leading to a delay in the actual flash. This delay is particularly noticeable in compact cameras.
The camera's flash exposure measuring logic fires a pre-flash very quickly before the real flash. In some camera/people combinations, this will lead to shut eyes in every picture taken. The blink response time seems to be around 1/10 of a second. If the exposure flash is fired at approximately this interval after the TTL measuring flash, people will be squinting or have their eyes shut. Many compact cameras suffer from this problem.
One solution may be the FEL (flash exposure lock) offered on some more expensive cameras, which allows the photographer to fire the measuring flash at some earlier time, long (many seconds) before taking the real picture. Unfortunately, many camera manufacturers do not make the TTL pre-flash interval configurable.
if your subject is too close to the background or a wall you may get a hard shadow on the wall. You may bounce the flash from the ceiling or soften the flash. Otherwise, simply ask the subject to step ahead away from the wall. since the wall is now quite far away the shadow is lost in midair because the shadow is formed only on a certain surface.
Having a hard shadow on the background is perfectly all right but for everyday photographs, it is best to avoid it.
Mostly, it is the human psychology that a person, when asking someone to click a picture, moves closer to the wall behind. Simply ask him or her to step closer to the camera and away from the wall behind.
Soften the flash using readymade softboxes for flash,
Diffusing sheet at a little distance from the flash, (if it is close, touching the flash, it may burn due to heat of the flash if fired continuously)
Bounce the flash if using an external one,
Create distance between the subject and the wall.
Shutter speed limitation
Electronic flash units have durations so short that a shutter speed of 1/60th of a sec or slower must be used on focal plane shutter cameras. The flash must fire when the first curtain has fully opened and uncovered the sensor and the second curtain has not yet closed and covered the sensor. The flash must fire during this brief period when any of the shutters is not blocking the sensor. In DSLR cameras, the maximum duration when the sensor is fully exposed is 1/60th of a second. As the shutter speed increases, depending on how much of an increase it is, a part of the sensor is blocked by the shutter, leading to that area being dark due to no light falling on the sensor.
If your budget allows buying cameras that have a higher synchronisation speed. Usually in more modern cameras, there is an option up to 1/250th of a second as well. so, one can use 1/250th sec and 1/125th sec as well besides 1/60th sec. This opens more possibilities to shoot handheld with flash.
Play around more with the aperture when you shoot outdoors as the only option to control light is via closing down the aperture and not by moving to a higher shutter speed. The opening can be controlled towards the minimum aperture to allow less light to enter but the shutter speed cannot be be moved beyond 1/60th or 1/250th sec as the case may be. That is the duration of exposure cannot be reduced.
Modern Dedicated flash units and their counterpart camera models allow High-speed Synchronisation. This is a feature in modern cameras that helps use even a higher shutter speed conventionally not possible. The flash unit fires a series of flashes instead of one single burst of flash. This corresponds with the slit between the two shutters as it travels across the frame. In other words, the open exposed area of the frame continuously gets the flashlight because it is bursting continuously instead of a single burst.
The disadvantage of High-speed synchronisation in most cases is that the flash unit fires at reduced strengths. For example, if the flash can produce a maximum of 100 units and it needs to be firing for 4 bursts to keep pace with the shutter, it will have to fire these bursts at a power of 25. This is just a simplified example. The higher the shutter speed being used, the thinner is the slit for exposure and the more of the power is divided and distributed to ensure that there is an equal amount of light produced during every opening
This limitation is a big drawback especially for photographers who use the flash outdoors as a fill very often. This can also be used creatively for the "Day to Night" effect. This involves, leting the ambient light be uderexposed, lets say by one stop and then compensating the flash output by a positive one stop. So the subject exposed by the flash is correctly exposed but the sky or the background in general gets its deeper tones due to underexposure.
You need to learn how to balance the flash lighting with the ambient lighting so that both kinds work together. On camera inbuilt flash generally results in flat lighting as the hard light is coming from the camera axis.
Use an external flash and still better, use it off the camera hot shoe.
The external flash is relatively higher than the camera lens and falls from a higher angle in comparison to the inbuilt flash. Further, you may use the external flash off-camera with the help of synchronization cords or wireless remotes enabling you to set the flash at the desired angle. This will add modeling to the subject resulting in a pleasing photograph, unlike regular flash pictures. But you need to see what works for you in general. Most of professional cameras do not have an inbuilt flash and you may add a good professional flash to your photography gear. I generally carry a small flash unit as well when traveling so that the camera setup gets more portable, lighter and compact. This allows me to carry a small flash instead of not being able to carry any flash.
In-built flashes generally do not have a very fast recycling time in comparison the external flashes. This happens when the flash is firing at its maximum capacity and you are shooting a bit too fast. Move closer if shooting slower is not possible. The flash will need to work less hard and not use its full capacity to fire, leading to faster recycling as it needs to recharge only the used charge and not what is left out from the previous flash.
Always buy the most affordable flash with a fast recycling time. Depending on the genre you cover, fractions of seconds matter too.
Shoot at open apertures so that enough light reaches back on the sensor.
Use a Dedicated flash so that the unused charge from the previous flash is added on to the next flash.
Shoot slower if possible so that the flash gets enough time to recycle.
Increase the ISO a little bit so that the flash does not need to fully recharge before the next exposure.
The basic idea is to put less strain on the flash to fully recharge before the next shot. Dedicated flashes are able to save the unused charge from the previous flash and carry it on to the next one and this helps save all the time it needs to recharge.
The subject is too bright or in other words, the background or the part of the subject further away from the camera is too dark. Although there is not much that can be done with a built-in flash but with an external flash on the camera you may tilt the head towards the neutral ceiling which will act as a large light source redirecting the flashlight. This will result in almost uniform light all across a large area resulting in a very uniform exposure. You should have a strong enough flash for the purpose as you will lose a lot of light.
Reduce the distance between the nearest and farthest subject in the frame being photographed. if shooting two people standing apart, simply ask them to get closer so that it still appears that there is a gap between them but good enough to be covered by the flash.
Bounce the flash from the ceiling or the wall around if it is a neutral tone. This will ensure that almost the same light falls on the subject who may be closer and far off.
Remember the inverse square law. The light falls off much more than we imagine. if the distance from the camera is doubled the light does not get half but gets reduced by one-fourth. Making it 3 times reduces the light and makes it fall by 1/9th of what it was.
Lost Ambient Light mood
You don't have to use the flash as the main light source but learn to use it as a fill giving more importance to the ambient light. With dedicated external flashes and some experience, you can learn to strike the right balance between the two lighting kinds so that your pictures look natural.
If you are not too technical, always use a Dedicated flash which will give you perfect exposures for the subject as well as the ambient illumination of the area.
Even Dedicated flash units have all the control in your hands. You can simply reduce the flash output as suggested by the camera or change the ambient light exposure as suggested by the camera's exposure metering.
Explore the option of shooting at a higher ISO. Higher ISO helps cover the detail of all the background areas where the flash is not reachable.
Shoot with a wide open aperture as this helps include the influence of the natural light as well.
whenever possible set the shutter speed at 1/60 instead of 1/250. These extra two stops will help record the influence of the ambient light as well and it will be easier to balance the flash and ambient exposures.
Actor Ranvir Singh at the NDTV face of the year awards was photographed with an off-camera flash with canon 5D mark III | ISO 1250. | 200mm | f4.5 | 1/125 | Aperture Priority. | Canon 600EX -II RT
The subject is properly illuminated with the people in the background, visible as well.
The flash light was bounced from the ceiling of the room which allowed the side lamp also be visible the way it would be without the flash. The warmth also is added in the photograph due to the colour of the walls as well as due to the tungsten light. Shalini Khanna is a well known talented fashion Designer.
Unwanted Colour cast
while a warm colour cast is always welcome to a certain extent, the colour cast can be quite cold and unpleasant especially if the light is bouncing off a Blue or Green wall.
Ensure that the colour of the walls is neutral. If not add a neutral reflector so that the light bounces off the surface of the reflector and not the coloured wall. Sometimes, to avoid too much of a warm or orange cast you may partly add a reflector inbetween so that you just reduce the cast a little bit while still retaining the warmth.
Burnt out Details
Although this is less likely to happen with a dedicated flash as the output is thoroughly calculated and controlled through the lens. Known as TTL metering ( Through The Lens metering) the camera measures the actual light which is making the exposure and hence chances of any over or under-exposure are less likely. However, sometimes the subject is so close to the camera/flash unit that the flash may have fired at its minimum strength but still, it was overexposed as the light could not be reduced further.
Most of the time, being a dedicated flash this is very less likely to happen and is more of a problem of a manual flash.
Bounce the flash to reduce the strength.
Use a diffuser in front of the flash to soften and reduce the amount of light.
Keeping the flash off the camera, lets you have the required distance from the subject. You may be shooting with the camera very close to the subject but you can always shift the flash a bit away.
The dedicated flash units adjust the zoom of the flash in accordance with the zoom of the lens being used. If these are not set correctly, there may be a problem. If you are shooting with a wide-angle lens and set the zoom of the flash to a longer focal length, the flash will produce more light assuming that the light has to travel far off with a narrow throw of light. The middle area of the frame may get overexposed with the corners rendered dark
Interesting many creative photographers intentionally use this technique to highlight the area in the center to be highlighted with proper illumination and the edges be registered as dark. This brighter portion maybe anywhere in the frame and not essentially be in the center. The flash head can just be specifically pointed towards that area.
Due to Mirrors and DJ lights in the frame, the dedicated flash can miscalculate the exposure as it is unable to correctly calculate the distance and the existing light levels.
Avoid Mirrors and High intensity DJ strobe lights directly in the frame so that the light from the flash is not directly falling and bouncing off a mirror.
Adjust the Aperture if you are too much at an extreme. If the aperture is fully open and your images and too bright, just close down step by step. The flash might already be firing at its weakest power, so the only option would be to move away or close down the aperture. On the other hand if the exposure is too dark and you are shooting at a closed aperture, simply open the aperture or move closer to the subject.
Try to play around with the ISO, keeping in mind that in terms of the quality, lower ISO is always better. So, increase it to compensate for underexposure if other options are exhausted.
Flash Light is unable to reach a macro subject
You cant use a conventional flash for macro photography as you are using the lens and the camera very close to the subject and this moves the flash unit quite away from the subject. There are specialized flashes that are fixed around the lens so that the illumination is close to the lens and the subject gets properly and uniformly exposed.
This system has two small yet powerful flash units which have some sort of adjustability that allows better control on the way a very close-by macro subject is illuminated.
A typical Macro flash is fixed around the lens and the illumination comes from very close to the macro subject.