Controlling the Flash

Tivolivakt ved Coney Island, Brooklyn

Do you want to have full control of the flash? Here comes an explanation that will get you on the way to really be able to master the use of flash—at least flash mounted on the camera. There is of course a lot more to flash photography, but that will have to way to another time—and many more posts. This tip here will hopefully without too much work help you understand how you can control the flash in some ways.

Before we start, as you may know; in October last year I started what I called a new instalment for me. On and off I wanted to show and write about simple tips, tips that can improve anyone’s photography. I have written about using long shutter speed to make different photos, I have talked about moving close to the subject to create relationships and I have mentioned how you can using natural reflections—such as sunshine reflected from the streets in through doors—to create beautiful light in your photos.

Alas, I have also had a couple of posts about how to get most out of the camera-mounted flash or the built-in flash on compact cameras. It’s time to take the flash one step further. As written in previous posts you can adjust the amount of flash that is emitted by dialling up or down the flash compensation dial. At the same time you can also adjust the general exposure by the exposure compensation dial where you can make the picture darker or lighter by increments of ⅓ or ½ exposure values (E.V.). The latter will influence both the exposure of the available light as well as the exposure by the flash.

Now this means that you can actually adjust the ratio between the available light and the flash light and thus fine-tune your exposure. This may sound a little complicated, but hopefully it is not. Try to think—when using a combination of both available light and flash—that you are taken two images at once, one with available light and the other with the flash. These two images are then superimposed upon each other (of course this all happens as one exposure in the camera. What I am writing here is just to create a visual image in order to understand how the camera is dealing with the combination of available light and flash).

The flash light has a limited range and will only affect objects closer than one and half to three meters (or yards) away from the flash head depending on the maximum emitted light possible from the flash. The available light, on the other hand, will expose everything within the frame, up front and in the background. Now let’s go back to this idea of two different exposures superimposed upon each other. First the camera takes a photo with the available light and then one, in which it adds the flash (again this is not how it actually happens; it all happens in one take, naturally). Now if the exposure by the available light is correct and makes a perfectly exposed photo, then when you add a flash on top of this the objects that are close enough to be reached by the light from the flash will be overexpose. The rest, further away, will still be perfectly exposed (only by the available light). To compensate for this the camera needs to underexpose the available light on whatever is reached by the light from the flash. However, the camera cannot do this partially, thus everything will be underexposed in the first photo taken only by the available light. And then when you now add the flash, those objects in the reach of the flash will get added light and thus (if everything is correctly added) be properly exposed while the background will be somewhat underexposed—which is generally quit OK.

This is usually done automatically by the camera, and can be used in different ways as I wrote in the previous posts about flash photography.

Now I want to raise the stakes. So far I haven’t been dealing with situations where the available light is different in different parts of the scene. Particularly when the foreground is dark and the background is well illuminated, the use of flash can improve the photo significantly. In this case you can get around the problem by thinking that the background is going to be exposed only by the available light hitting it while the foreground is illuminated by only the flash.

You work it out this way: Figure out the correct exposure for the background. In many ways setting the camera to Manual exposure mode is the simplest in this case, but if don’t want to I suggest selecting Aperture Priority mode (if you have a compact camera set the mode to Slow Sync). You may have to underexpose the subject since the foreground is so dark and will influence the cameras evaluation for a suggested exposure. Maybe start with dialling in –1 E.V. At this point you have a background that is exposed as you want to.

Now it’s time to add the flash. Turn it on. Give it a try without any compensation. Since the foreground is dark, it might be just the perfect exposure. If you are not quite happy with the exposure from the flash, just dial up or down the flash compensation dial till you have what you want. One thing to keep in mind: Sometimes when you are in Aperture Priority mode and turn on the flash the camera will automatically underexpose the general exposure. In this case you will have to compensate for this, by making the available light brighter. For instance, you may have to go from –1 E.V to no compensation at all—or even more like +⅓ E.V. However, since this compensation also will affects the exposure of the light from the flash, you have to do an equal amount of compensation on the flash, but the opposite way. So in the example above, you will either need to set the flash to –1 E.V. or -1⅓ E.V.

The photo above is an example in which I used this technique. I used the available light to expose the background and the sky and then used a flash to light the guy in front. (By the way it’s a photo I have shown before on this blog).

If you have any questions to this technique, please don’t hesitate to ask in comments below. I will answer to the best of my abilities.

For the previous posts on flash photography, please look up: Flash Away the Shadows, A Flashy Look and Flash for the Night.

Facts about the photo: The photo was taken with a Canon T90 camera (with analogue film) and a 24 mm lens. It was captured at ½ a second and f/2.8 (set to expose the background as I wanted it). Flash was added and set to -⅓ E.V. No tripod. Finally the photo was scanned and processed in Lightroom and Photoshop.

Flashed Away





I want to finish up my thoughts about flash photography which I started in my previous post, so I hope you not so technical minded will have me excused one more time – even if it’s going to be less hardcore technical this time. I promise it will be a long time till next before I will do it again. So as to not make it completely worthless to have passed by, I have laid out a handful of pictures to show what you can achieve by using the little shoe mounted flash. I hope those of you who don’t care about technique at least will be able to enjoy those pictures.

Last time I gave the theory behind getting the most out of the flash – and did so by explaining how to use the camera in manual mode. Today I will continue with some thoughts about using flash in automatic mode. One should actually assume that it would be easier and faster – and to some extent it is, but at the same time I have found that it’s impossible to predict how the cameras «think». And unfortunately one camera «thinks» differently than another in automatic flash mode, and one brand seems to «thinks» differently than another. So when going automatic, it’s unavoidable with some trial and error first time out. Anyway the basic idea when going automatic is that the camera itself will do the necessary calculations, as soon as you have put in the ratio of exposure between available light and flash light. Remember the trick to get interesting flash pictures when using a shoe mounted (or handheld) flash is to combine available light with flash light.

On a basic level most cameras «think» that whatever exposure compensation you dial in on the camera will affect the whole exposure – the combined exposure of the two light sources that is, while exposure compensation dialled in on the flash itself will only affect the flash light. So to return to the two basic setups from my last posting: If you want to equally blend available light and flash light, you actually don’t do anything, because the camera will automatically take care of the mix and adjust the exposure – which means underexpose both so as to make the combination come out correctly. The only thing you need to do is make sure the exposure mode of the camera is not set to program, P, green, red or complete automatic mode – whatever you camera has available for you. This will only set the shutter speed to the sync speed for flash photography and thus result in those regular ugly flash photos with a washed out foreground and a completely black background. My advice is to set the mode to aperture priority which means you yourself set the aperture before taking a photo and the camera automatically takes care of shutter speed. Setting the camera to aperture priority mode makes sure your camera can adjust the exposure to any available light situations. If necessary it can use 1 second or it can use 1/1000 of a second when that is necessary. By the way don’t worry about long exposure time when using flash. The flash will anyway freezes the subject and whatever movement cause by the available light exposure will only add some interesting features to the picture.




One more thing: You need to make sure the camera’s focusing point is locked onto the subject in the front when the reading of the flash exposure and the focusing point is connected. Otherwise the amount of flash light on the subject will probably be way too much since the focusing point may be set on the background.

Now to the other set-up I mentioned last time; fill-in flash or using the flash to lighten up dark shadows. In automatic mode you set the flash to -2 or two exposure values down. That’s it, and the camera will supposedly take care of the rest. In another word, you use the exposure compensation on the flash to adjust the ration between available light and flash light, while the exposure compensation on the camera will affect the combined exposure. That is; if you want to make the combined exposure lighter or darker you use the exposure compensation on the camera. If you want to increase or decrease the amount of flash light relative to available light you use the exposure compensation on the flash.

What if you only have a point-and-shoot camera? Can you get interesting flash pictures with those cameras? Quite few actually have a so-called slow sync flash setting, which will do exactly what I have talked about here. You just don’t have equal amount of possibilities to adjust particularly the ratio of light between available and flash light.

One last point: If you use your camera in manual mode and use the built-in exposure meter, be aware of the fact that when you turn on the flash it will most likely adjust the readings to compensate for the added flash. So if you want to work manually, you need to meter the exposure of available light before switching on the flash.

In a Flash of Moment


Today’s blog is going to be more for the mere photographic minded (and I hope the rest of you will forgive me for that). I don’t usually write about technique, because there is plenty of information about how to handle a camera out there – and I am more interested in the creative process of photography anyway. But this time I will make an exception, simply because the technique I am about to describe may boost creativity as well.

This post is going to be about how to make a shoe mounted flash not only work, but give an interesting and quite different look to your pictures. Flash pictures you may ask? That is always gonna be harsh contrast, lousy quality and no control on your part… But really, no! Before the digital era I used to be sharp and very good at using flash. I had to. Back then I was shooting slides, and to get the best quality I would usually use a slow film at 100 iso or even Kodachrome 64. When light went low, you had to be able to either use a flash or set up a whole shebang of lighting equipment. I got good with the handheld flash. At some point I almost as a rule used the flash – day or night. It became part of my signature. But when the digital era took over, suddenly I didn’t need the flash any more, I could just ramp up the iso-setting of the camera, and I was able to shoot in any lighting condition. How cool was that! I packed down the flash, and never look back again. Until recently that is. Not long ago I finally dug into my camera bag again, and found the old flash (and found out that I actually had to buy a new one, too), because it’s not bad at all, but really just another creative device in my toolbox – when I need that special look.

The main factor for success with the shoe mounted flash (or even better if you hold it in your hand with an extension cord) is to mix available light and light from the flash. And the trick to gain control of this mix is to think about the process as taking two pictures on the same frame – even though it happens at the same time – in one exposure. First you take a picture with the available light and then you take the same picture with the flash (or the other way around, if you like to think about it that way, because it really doesn’t matter, it’s only a mental exercise; as I said it happens simultaneous – at least for the argument here). And what happens when you add two pictures on top of each other? The two light sources will add up and make the final picture lighter – too light. Which means you will have to make each captured picture darker, so the total adds up to a correct exposure. Thus you will have to underexpose them.

Let’s see how that works in real life. And I will start with explaining two useful set-ups using manual exposure control. That will make it easier to understand the process, even if you are never going to shoot manually. Let’s say you are shooting indoor. You want to take advantage of the special look you can get from mixing equally available light and light from the flash. To get a correct added exposure you set the camera so that it underexposes the subject lit by available light with 1 exposure value (either stop down the aperture one step or cut the exposure time in half). And you set the flash 1 exposure value down, too. Where the flash hit the subject the total of the two underexposed pictures (which albeit is but one frame) will give you a correct exposure, while where only available light is picked up, the subject – usually the background – will be underexposed and that is fine. It doesn’t sound too difficult does it? Try it out!

Here is the other set-up I mentioned I would explain: It’s midday sunshine. The shadows under the nose and in the eye sockets of the person you want to photograph are black. Not to mention if the person wears a hat. Time to mount the flash again. But this time you will only underexpose the flash. You set it to minus 2 exposure values. The exposure for the available light is as if no flash was added. That’s it; you are good to go with a so-called fill-in flash. Two exposure values down on the flash doesn’t sound like a lot, but it actually brings the light from the flash so much down, that it will only affect the shadows. That’s why you with this set-up don’t need to underexpose the available light. Here is the beauty: You can mix any ration of available light and flash as long as the sum of the two exposure values you step down are -2. In the first step-up the available light was -1 and the flash -1. Hence the sum is -2. In the second setup the available light was 0 and the flash -2. Again the sum is -2. So if you want to give a little more flash than the equal set-up in the beginning, you could for instance go for -½ EV for the flash and -1½ EV for the the available light. The sum is still -2. It works!

I’ll stop now, and get back to the automatic approach next time. I have already written too way too much, despite the fact that in my previous post I complain about myself too often writing too long texts. So thank you for staying to the end.