Flash
Turn off the Darn flash!
14/09/10 08:22
This article is divided into three parts. Part one is a simple explanation of the problem and one quick solution. For a more detailed explanation and additional solutions read parts two as well. Read part three for when to break the rules.
Turn off the Darn flash!
Part 1: Short and Simple
I see it every Superbowl, every swim meet , and every school play. We all see it. What is it? It is the built in flash firing on everything from a camera phone, point and shoot, and even a DSLR. I see it and I wish there was some way to make it stop. The built in flash on almost all cameras is maximally effective in ranges between 3 and 9 feet depending on the camera model, aperture settings and ambient lighting. To get the most out of your camera, turn off the built in flash if your subject is more than about 9 feet away.
A typical image taken at a school assembly from the audience, about 30 feet away, using the built in flash, zoom lens, and the camera set to auto.
A detail from another photo from the same school presentation. This time the flash was turned off the camera was set to auto but the distance to the stage was reduced to about 12 feet. Note that even with these adjustments, the focus is a bit soft but the image is usable. In these conditions it would be ideal to have used a lens with a large aperture and to have manually focused. In fact I did do that for the rest of the performance.
This an example of a time when a flash would have ruined the photo. My wife was reading something on her iPod and her table lamp was serving as a backlight. I shot this with a 50mm prime lens at f2. I adjusted the ISO to 1600 and set the shutter speed to 1/20s. I got lucky on this one because I did not have my tripod handy and was forced to hand hold the camera.
Part 2: The Reasons Why and What to do About It
The built in flash is a miracle of modern convenience. When I was a child the only way to have a flash on a point and shoot was to use flash cubes. These were one-time use flashes. There was no way to control the strength of the flash, duration of the flash, diffusion of the flash, or even know if the flash was going to fire at all. These flash cubes were expensive and as a result many people just never used them. In retrospect I think that was a good thing.
The flash cube and the built in modern electronic flash have a few things in common. They are both poor sources of artificial light and they were both meant primarily for indoor use over a short distance.
A flash is rated by guide numbers (GN). A guide number represents the relative strength of the flash and you can calculate the effective distance of a flash if you know the guide number. Guide numbers are generally calculated using an ISO of 100.
The guide number(GN) is a derived number that is represented by the following formula:
GN = distance * fstop.
The average point and shoot camera will have a guide number between 9 and 18. The average DSLR will have a guide number between 12 and 18. So, what does that tell the photographer? It tells the photographer that the built in flash is going to have a very short effective range.
My wife’s point and shoot has an fstop of between f2.5 and f5.6. Her camera has a guide number of about 16.
Let’s do the math.
GN = distance * fstop.
16 = d * 2.5
Solve for d (distance) and the distance of 6.4 feet is obtained.
So, what does this tell us? It tells us that if my wife is indoors and her subject is more than 6.4 feet away from her then she needs to turn off the flash.
When the camera lens is zoomed all the way out, the f number goes to f5.6, so the distance needs to be calculated again.
Let’s do the math.
GN = distance * fstop.
16 = d * 5.6
Solve for d (distance) and the distance of approximately 2.9 feet is obtained. This means that her flash has a maximum effective distance of 2.9 feet at f5.6.
Turning off the flash should be the first thing a photographer learns to do on a new camera, after learning to turn the camera on. Camera phones, point and shoots, and DSLR cameras set to auto mode will all automatically fire a flash when a scene is too dark to be exposed correctly without additional light. This is where the photographer has to decide whether to let the flash fire or not. If the subject is farther away than the guide number will allow, then the decision is easy: TURN OFF THE DARN FLASH!
You might be asking: Why should I turn it off if it is not effective anyway? The answer comes from the way a digital camera and flash work together. When the digital camera fires a flash, the computer on the camera also sends a signal to the shutter to increase the shutter speed so that it syncs with the flash. Shutter/Flash sync speeds are usually 1/150s - 1/250/s If you are indoors shooting a distant object, you will most likely need a shutter speed of 1/4s - 1/60s to correctly expose an image. If the flash fires, then the camera will use the faster shutter speed and your image will most likely be so underexposed that no useful information will be captured.
Now is when you say to me: 1/4s compared to 1/150s seems awfully slow. My kid will be blurry. I would rather have an underexposed picture than a blurry mess! What am I supposed to do?
Here is a list of things you can do:
1) Find out the distances that your flash can cover. You will need to find what is the guide number of your flash. This will most likely be in the user manual for your camera. If your manual does not list a guide number, then guess the guide number based on the size of a flash as follows: a small point and shoot or cell phone will be in the neighborhood of a guide number between 9 -12 and the bigger the physical size of the flash, the bigger the number up to a guide number to about 18 on a large point and shoot or DSLR. Do the math and know your flash distances.
2) Get closer to the action.
3) Don’t use the zoom feature. On almost all cameras the more you zoom, less light gets to the camera sensor.
4) Use a tripod. This allows for longer exposure times without camera shake.
5) Dial up the ISO number. High ISO numbers allow the camera sensor to be more sensitive to the light entering the lens. Remember that with high ISO numbers there is a price to be paid for sensitivity. That price is noise. If you are using very high ISO numbers you might want to consider switching your camera to black and white image recording. Noise in a black and white image is often considered artsy when the same noise in a color image is just distracting.
6) Shoot in manual or aperture priority mode. Set the aperture to the lowest number that your lens will allow. Remember an f1.8 lets in much more light than a f16.
7) Look for times when people are standing still. This will allow for longer shutter speeds and reduces blur.
This photo is demonstrating the use of Black and White with high ISO, motion blur, and waiting for someone to be still.
In this photo I was trying to catch the watchful eye of the teacher while the children played. I had to wait for just the right moment when the teacher was staying very still and then I snapped the shot.
ISO 3200, 85mm, f/32, 1/3s, no flash.
8) Set your exposure for the main subject of the scene.
9) Shoot it with the blur. This can be a very effective way of conveying the frenetic energy contained in a scene.
Here is an example of letting the blur happen. I took this shot at the state fair (This shot was taken outside, but the same guidelines apply to outdoor nighttime photography). I used a longer shutter speed and held the camera above the crowd to capture the angle a child might have when riding on a parent’s shoulders.
ISO 400, 50mm, f/2, 1/13s Purchase this print here:
http://williamburnettgalleries.zenfolio.com/statefair/h3d1b2e27#h3d1b2e27
This image also makes use of blur to capture a moment.
ISO 100, 50mm, f2.2, 1/6s Purchase this print here:
http://williamburnettgalleries.zenfolio.com/statefair/h3d1b2e27#h263aa99f
10) Buy a more powerful external flash if your camera will except one, and recalculate the flash coverage distance.
11) Get the right lens and/or camera for the job. This is an expensive solution but really the best solution. For indoor shooting you want a lens with the largest aperture you can afford and in most cases that is going to mean a prime lens. I will discuss prime lenses in a later article so stay tuned.
Part 3: Breaking the Rule
As with most things in life, rules need to be broken at times and this rule is no exception. It is possible that an underexposed and grainy photo is better than no photo at all and the only way you are going to freeze the action is to get a faster shutter speed. If you are shooting an advanced point and shoot or DSLR then the solution is simple. Switch to manual or shutter priority mode and set the speed of the shutter at the speed that freezes the action and under exposes the image the least possible. However, many point and shoot cameras and camera phones lack this level of control. In these cases it becomes necessary to force the camera into having a higher shutter speed. As discussed earlier this can be done by forcing the flash to fire and thus forcing the shutter to operate faster. Just remember that this will result in a dark and poor quality shot. But, in the end a poor quality shot is better than no shot at all.
So, turn off the darn flash, get out there and start shooting.
Turn off the Darn flash!
Part 1: Short and Simple
I see it every Superbowl, every swim meet , and every school play. We all see it. What is it? It is the built in flash firing on everything from a camera phone, point and shoot, and even a DSLR. I see it and I wish there was some way to make it stop. The built in flash on almost all cameras is maximally effective in ranges between 3 and 9 feet depending on the camera model, aperture settings and ambient lighting. To get the most out of your camera, turn off the built in flash if your subject is more than about 9 feet away.
A typical image taken at a school assembly from the audience, about 30 feet away, using the built in flash, zoom lens, and the camera set to auto.
A detail from another photo from the same school presentation. This time the flash was turned off the camera was set to auto but the distance to the stage was reduced to about 12 feet. Note that even with these adjustments, the focus is a bit soft but the image is usable. In these conditions it would be ideal to have used a lens with a large aperture and to have manually focused. In fact I did do that for the rest of the performance.
This an example of a time when a flash would have ruined the photo. My wife was reading something on her iPod and her table lamp was serving as a backlight. I shot this with a 50mm prime lens at f2. I adjusted the ISO to 1600 and set the shutter speed to 1/20s. I got lucky on this one because I did not have my tripod handy and was forced to hand hold the camera.
Part 2: The Reasons Why and What to do About It
The built in flash is a miracle of modern convenience. When I was a child the only way to have a flash on a point and shoot was to use flash cubes. These were one-time use flashes. There was no way to control the strength of the flash, duration of the flash, diffusion of the flash, or even know if the flash was going to fire at all. These flash cubes were expensive and as a result many people just never used them. In retrospect I think that was a good thing.
The flash cube and the built in modern electronic flash have a few things in common. They are both poor sources of artificial light and they were both meant primarily for indoor use over a short distance.
A flash is rated by guide numbers (GN). A guide number represents the relative strength of the flash and you can calculate the effective distance of a flash if you know the guide number. Guide numbers are generally calculated using an ISO of 100.
The guide number(GN) is a derived number that is represented by the following formula:
GN = distance * fstop.
The average point and shoot camera will have a guide number between 9 and 18. The average DSLR will have a guide number between 12 and 18. So, what does that tell the photographer? It tells the photographer that the built in flash is going to have a very short effective range.
My wife’s point and shoot has an fstop of between f2.5 and f5.6. Her camera has a guide number of about 16.
Let’s do the math.
GN = distance * fstop.
16 = d * 2.5
Solve for d (distance) and the distance of 6.4 feet is obtained.
So, what does this tell us? It tells us that if my wife is indoors and her subject is more than 6.4 feet away from her then she needs to turn off the flash.
When the camera lens is zoomed all the way out, the f number goes to f5.6, so the distance needs to be calculated again.
Let’s do the math.
GN = distance * fstop.
16 = d * 5.6
Solve for d (distance) and the distance of approximately 2.9 feet is obtained. This means that her flash has a maximum effective distance of 2.9 feet at f5.6.
Turning off the flash should be the first thing a photographer learns to do on a new camera, after learning to turn the camera on. Camera phones, point and shoots, and DSLR cameras set to auto mode will all automatically fire a flash when a scene is too dark to be exposed correctly without additional light. This is where the photographer has to decide whether to let the flash fire or not. If the subject is farther away than the guide number will allow, then the decision is easy: TURN OFF THE DARN FLASH!
You might be asking: Why should I turn it off if it is not effective anyway? The answer comes from the way a digital camera and flash work together. When the digital camera fires a flash, the computer on the camera also sends a signal to the shutter to increase the shutter speed so that it syncs with the flash. Shutter/Flash sync speeds are usually 1/150s - 1/250/s If you are indoors shooting a distant object, you will most likely need a shutter speed of 1/4s - 1/60s to correctly expose an image. If the flash fires, then the camera will use the faster shutter speed and your image will most likely be so underexposed that no useful information will be captured.
Now is when you say to me: 1/4s compared to 1/150s seems awfully slow. My kid will be blurry. I would rather have an underexposed picture than a blurry mess! What am I supposed to do?
Here is a list of things you can do:
1) Find out the distances that your flash can cover. You will need to find what is the guide number of your flash. This will most likely be in the user manual for your camera. If your manual does not list a guide number, then guess the guide number based on the size of a flash as follows: a small point and shoot or cell phone will be in the neighborhood of a guide number between 9 -12 and the bigger the physical size of the flash, the bigger the number up to a guide number to about 18 on a large point and shoot or DSLR. Do the math and know your flash distances.
2) Get closer to the action.
3) Don’t use the zoom feature. On almost all cameras the more you zoom, less light gets to the camera sensor.
4) Use a tripod. This allows for longer exposure times without camera shake.
5) Dial up the ISO number. High ISO numbers allow the camera sensor to be more sensitive to the light entering the lens. Remember that with high ISO numbers there is a price to be paid for sensitivity. That price is noise. If you are using very high ISO numbers you might want to consider switching your camera to black and white image recording. Noise in a black and white image is often considered artsy when the same noise in a color image is just distracting.
6) Shoot in manual or aperture priority mode. Set the aperture to the lowest number that your lens will allow. Remember an f1.8 lets in much more light than a f16.
7) Look for times when people are standing still. This will allow for longer shutter speeds and reduces blur.
This photo is demonstrating the use of Black and White with high ISO, motion blur, and waiting for someone to be still.
In this photo I was trying to catch the watchful eye of the teacher while the children played. I had to wait for just the right moment when the teacher was staying very still and then I snapped the shot.
ISO 3200, 85mm, f/32, 1/3s, no flash.
8) Set your exposure for the main subject of the scene.
9) Shoot it with the blur. This can be a very effective way of conveying the frenetic energy contained in a scene.
Here is an example of letting the blur happen. I took this shot at the state fair (This shot was taken outside, but the same guidelines apply to outdoor nighttime photography). I used a longer shutter speed and held the camera above the crowd to capture the angle a child might have when riding on a parent’s shoulders.
ISO 400, 50mm, f/2, 1/13s Purchase this print here:
http://williamburnettgalleries.zenfolio.com/statefair/h3d1b2e27#h3d1b2e27
This image also makes use of blur to capture a moment.
ISO 100, 50mm, f2.2, 1/6s Purchase this print here:
http://williamburnettgalleries.zenfolio.com/statefair/h3d1b2e27#h263aa99f
10) Buy a more powerful external flash if your camera will except one, and recalculate the flash coverage distance.
11) Get the right lens and/or camera for the job. This is an expensive solution but really the best solution. For indoor shooting you want a lens with the largest aperture you can afford and in most cases that is going to mean a prime lens. I will discuss prime lenses in a later article so stay tuned.
Part 3: Breaking the Rule
As with most things in life, rules need to be broken at times and this rule is no exception. It is possible that an underexposed and grainy photo is better than no photo at all and the only way you are going to freeze the action is to get a faster shutter speed. If you are shooting an advanced point and shoot or DSLR then the solution is simple. Switch to manual or shutter priority mode and set the speed of the shutter at the speed that freezes the action and under exposes the image the least possible. However, many point and shoot cameras and camera phones lack this level of control. In these cases it becomes necessary to force the camera into having a higher shutter speed. As discussed earlier this can be done by forcing the flash to fire and thus forcing the shutter to operate faster. Just remember that this will result in a dark and poor quality shot. But, in the end a poor quality shot is better than no shot at all.
So, turn off the darn flash, get out there and start shooting.