Combining flash with daylight

Combining flash with continuous light (like daylight)

Indoors, it often works best to use a light modifier like an umbrella but there is nothing against an open flash. Especially outdoors the daylight can provide a lot of fill light. Outdoors I rarely use umbrellas, because then the slightest bit of wind will blow over your light stand and it may damage your equipment or models.

When you take the flash off camera, you need to go to manual exposure: the light meter does not see the flash, so it will make mistakes if you rely on automatic.

You simply make a test photo, and check the histogram. The image on the lcd screen is good for composition and to a certain degree the placement of the light. But it does not show the exposure reliably: when you see it in bright light everything seems dark, when you see it in the darkness everything seems bright. So the histogram can tell you the right exposure.

When you combine continuous light with flash, it is important to keep this in mind:

·         Shutter speed (should be below the flash sync speed): influences the daylight, but not the flash. It does influence the way motion is rendered by the daylight, but the flash freezes everything except the fastest motion like a bullet. This gives interesting options when you photograph a concert with a light show: you can make a sharp image with the flash and light streaks from the light show.

·         Aperture: influences both flash and daylight exposures, as well as depth of field.

·         ISO setting: influences both flash and daylight exposure, higher iso settings give lower image quality, depending on the quality of the camera.

·         Flash output: influences only flash exposure, not daylight exposure.

Eustina posed for these test photos (thank you).

·         Photo 1: no flash, 1/100 @ f4.5 is correct exposure, but Eustine does not stand out very much from the background.

·         Photo 2: I added flash to make her stand out. Also I exposed at 1/250 @ f4.5, so I darkened the background by over 1 stop. She stands out strongly against a darker background.

·         Photo 3 has the same flash setting as before, and the same aperture, so the flash is the same strength. But I exposed at 1/125, so the background, that is lit by daylight becomes one stop lighter than in photo 2

·         Photo 4: 4.5 @ 1/60. Now the background is again one stop lighter than in photo 3. Also you see that the shadows in her face are less dark. Because the daylight comes in stronger. The flash is again the same strength.

·         Photo 5: 4.5 @ 1/30. The daylight is so strong it takes over from the flash, and it overexposes the photo. 

Off-camera flash 2

More on off-camera flash

Syncing your flash with the camera:

When your flash is on the camera, the camera communicates with the flash to make it flash at the right moment: when the shutter is open. When your flash is off-camera you need to sync it, so that it will flash at the right time.

There are several ways of doing this. In the old days we did it with a cable. Then, earlier or later, someone will trip over the cable, and take a flash on a stand with him. The person can get hurt, and so can the flash. A wireless system is better.

You can use a built in system like the Nikon CLS (Creative Lighting System). This has the advantage that you don’t need to buy any new equipment. Also you can control the flash settings from the camera, so you do not need to move to the flash every time you want to change a setting. You can even use ttl light metering, and automatic settings on your camera (like aperture priority A, or shutter speed priority S, or T. Even program P works. The disadvantage of ttl light metering when using multiple flashes is that the output of one flash influences the metering for the other, so when you change one setting, all the other flashes may change their output, and you go crazy trying to find out what every flash is doing. The CLS works with pre-flashes, which make some models blink right at the time you make the photo. This can be overcome by using an infrared filter over the master flash on the camera. (By the way: it took me a while to realize that it only works when the flash on the camera is tipped up!). For using this system refer to the camera and flash manuals. It seems complex at first but pretty soon you will figure out your favorite settings. I rarely use this system for the reasons explained.

optical trigger

Indoors I usually use an optical trigger (or optical combined with radio triggers). They are cheap and robust, less chance of anything going wrong than with more complex systems with batteries and all. Some flashes even have a built in optical trigger, so then you do not need any extra equipment. To trigger the remote flash you need a master flash on the camera. When you use a modern flash, turn off the ttl, set it for manual. If you use ttl, the flash gives off pre-flashes to meter the light output, and the optical trigger will trigger your remote flash on the pre-flash, before you make the photo. It is perfectly possible to use an old fashioned cheap flash for triggering. It is important to not get the light from the master flash in the photo too obtrusively, so I usually point it away from the subject. For this you do need a flash with swivel head. Before I had two good flashes I did use a cheap flash reversed on the camera, so the light would be directed away from the subject. In my (then) living room in Amsterdam with white walls this worked fine. Outdoors or in a really big hall you may have to point the master at the optical trigger for it to see the master, and trigger your remote flash. My optical trigger can easily be overpowered by light outdoors, on a sunny day even in the shade. 

radio trigger

For that reason outdoors I usually use radio triggers. Mine have several channels, so when several photographers use radio triggers in the same space, they can use different channels to avoid triggering each other’s flashes. It also means that you have to make sure your transmitter is set for the same channel as your receiver. Also you need to make sure that both transmitter and receiver have fresh batteries. My radio triggers do not work with rechargeable batteries. On the up side: the power they use is very limited, so your batteries have long life. It is perfectly possible to combine radio triggers with optical. Then you radio triggered flash will trigger the optical triggered flash. All this is fast enough, this equipment is much faster than your shutter.

There is one thing with the shutter, that you need to be aware of: a focal plane shutter (most of our cameras use these) has a flash sync speed. This is the fastest speed at which you can use it with flash.

A focal plane shutter opens one curtain. Then, after the time of your shutter speed it closes with the second curtain. For fast shutter speeds, the second curtain starts closing before the first curtain has opened all the way. So then a slit moves in front of the sensor to expose every part of the sensor for only a very short time.

A modern camera does not allow you to use a faster shutter speed then the flash sync speed when it detects a flash on the camera. But it may not detect your radio trigger, or very old flash. Then you may have set your camera for a very fast shutter speed, and only part of your image will receive flash.

Example of flash sync speed:

In image 1 the subject (woodcarving) is in the shade, while the background is in sunlight. This happens a lot when people sit in the shade because it is too hot in the sun. Then the subject comes out too dark. If you compensate with the exposure, you find that the background will be overexposed and you may even get lens flare around your subject. The solution is to add light to the subject, in this case with a flash. 

In image 2 I added off camera flash, to the right/above the subject. You can see a small shadow on the lower part of the wood carving. The subject and background are correctly exposed. Here the shutter speed is 1/250s, which is the flash sync speed of this camera. 

In image 3 the shutter speed is 1/500, faster than the flash sync speed of this camera. You see that only the top part of the wood carving receives flash, and is correctly exposed, the bottom part receives no flash and is under exposed. 

In image 4 I tilted the camera for a vertical image to show that the shutter turns with the camera. At a shutter speed of 1/500, twice as fast as the flash sync speed, only the left side receives flash and the right side is underexposed.

Off-camera flash

Taking your flash off camera

This post will be more technical info for photographers. Let me know if you enjoy this, and if you do I’ll write more for you.

Too few photographers take their flash off the camera. With flash on the camera the photos usually do not look good. The flash is small which results in hard light, the light source is close to the lens which results in very small shadows. There is simply no way to get the shadows in the right place with the flash on the camera.

The alternative is available light, and that often looks great. But sometimes you want something different or the light in a location is not what you need. Then it’s time to take your flash off the camera.

To get it to flash at the right time you need some way to sync it with your camera. Nikon has CLS for this built into their modern cameras and flashes. It works with pre-flashes, which may cause your models to blink at exactly the time you’re making a photo. I rarely use it, I usually use an optical trigger, or radio trigger. Both have their pros and cons:

Optical trigger: simple, cheap, uses no batteries but you need a flash from the camera to trigger it, which does cause a certain amount of fill light, which you may like or dislike. In bright sunlight or at a distance from the camera the optical trigger may not see the master flash and it may not flash.

Radio trigger: more complex system, needs batteries, needs no master flash. This means you have to introduce the fill light separately if you need it, they work at a longer distance than optical triggers, and they have no problem with bright sunlight.

Once you take the flash off your camera, either on a stand or handheld by an assistant, you can move the light source, and with it the shadows. This introduces an infinite number of interesting options, and with more than one off-camera light you can make complex set ups that give interesting effects. For a beginner I recommend to start with one off-camera light to not over complicate things.

Simply put: the wider the angle between the camera angle and the light angle, the bigger the shadows will be. If the light is close to the camera (frontal lighting) the shadows are small, if the light lights the subject from a wide angle compared to the camera, (side-lighting, or in extreme cases back-lighting) the shadows are big.

Once the flash is off-camera you can modify the light: an umbrella or soft box will make the light soft. This means the shadows will have soft edges, and usually the shadows will be less dark but that does not always go: in a very big room or a room with dark walls, or outdoors at night it does not fill the shadows with light. A few quick examples to show the effect. (Nathan of FD Communicatons posed for these demonstration photos.)

 flash about 45 degress left/above the camera.
bounced off a white umbrella:
soft edged shadows on the right, that are not very dark

Flash at the same position as the previous photo, but here it is direct, not via an umbrella:
hard light, with deep shadows, you eve see a shadow on the wall in the back. A very strong reflection off the face is visible. This can be prevented with makeup (powder)














                            A different use of direct flash. Here the flash is all the way to the left side with no umbrella: big, deep shadows, hard edges to the shadows. This way I like the hard light, it gives a bit of a mysterious effect. IMO this photo is more successful than the previous. It is very different from the first, but both have their merits.

commercial photography

My colleages Frank Jomo and Nathan doing an interview at JTI

Im in Lilongwe doing corporate photos for JTI, mostly portraits. Going smoothly, and thanks to their clear photo guidelines I can do them in the right style, and their guidelines leave room for creativity. Actually creativity is required in many cases. Nice type of job!

BOOKS!

I went to the second hand bookstore today. New books are expensive here in Malawi and the choice is limited. With used books you have to be lucky to find something. Today was great!

Eyewitness, 150 years of photojournalism, that is a great book that will keep me busy many hours. Then there is the catalogue to the great photo exhibition: “the family of man”. I already had it, but such a unique book, I cannot leave it in the store, so now I have two.
ON top of that, I found two books of the Time/Life library of photography. Very influential in the 1970s when photography started to get a mass following. These are about “the Studio” and “Colour”. Very dated info and photos, but great documents, and I am sure I will learn a thing or two from them.

And then I got some great art books, about Titiaan, Hieronymus Bosch, the Rijksmuseum in Amsterdam, my hometown, and a few more great books.