How to operate with continuous and strobe light in the studio

May 19, 2016   5480 views

Continuous and strobe light in studio lighting, aperture and shutter speed

Part 1 and part 2 of this article

At the beginning I would like to give a definition of a theme I will explain in this article. Mixed lighting is a technology where we simultaneously use two types of lighting sources: strobe and continuous lights. Achieving the same color temperature for both types of lighting sources by using conversion gels, then correctly exposing the picture with using the appropriate shutter speed and aperture we can blur some part of the picture by continuous light with movement of camera or object or our picture leaving another part sharp by strobe light and thus achieve many amazing effects.

I'll break the entire article into four parts:

The first will focus on the relevance, aesthetics, originality and importance.

The second part will describe the theory of strobe and continuos light and working with these types of light.

The third part will be dedicated to the process of converting the color temperature. And to process of moving camera when getting pictures with mixed lighting.

In the fourth part I will show examples of my photos which illustrate this technology.


Part 1. Relevance, aesthetics, importance of mixed lighting

At the beginning I would like to find out why I use this so complex technique in my practice. Why is it so important to me?

Firstly I am a commercial photographer and all the time I must make new, interesting, vibrant works, which should attract the attention of my customers, agents, editors, gallery owners etc.

Secondly I am an artist, I have to create and have fun from what I do. Developing as a commercial photographer, I remain a creative person. Sometimes I don't imagine myself as a photographer, I imagine myself as a painter. And this is a technology that allows me to enjoy all the feeling of escape from the usual frame of dry commercial works and bring something new in photography that I am doing.

Thirdly I am a practicing photographer, I have to continuously train my skills and work of my team. Every photographer should practice every day. For me, this kind of shooting is kind of working out for my shooting skills. Sometimes, it is really hard to solve a task of right exposure, aperture, shutter speed etc. And this type of shooting gives me real practice in that. In the ability to hold the camera, work with it, it's the same skills as skills in dance, skills of athletes who have to work out day-to-day with their equipment.

Finally I am an advanced photographer and must develop new technologies.
Sometimes thinking about new ideas (and technologies creating them) I make new discoveries, new development of my shooting style. Complex imaging technology distinguishes us from the rest. However, it is impossible to develop new technologies, to reveal secrets sitting in one place and from year to year doing the same thing. Only moving forward, inventing ideas is a way to discover new horizons.


Part 2. Continuous and strobe light

When shooting in the studio we usually have two different sources of light: strobe and continuous lights. All studio strobe lighting sources are equipped with continuous lamps, so buying strobe lighting unit you get a source of continuous light. Of course, manufacturers of strobe units equip each unit not with high power continuous lamps but having the values of 200-300 Watt (such lamps are included in the majority of sources). We can safely and confidently use them as powerful continuous lighting sources. There are also sources with only continuous light. Usually they have 500, 1000 and more and more Watt.

There are also "exotic" sources of continuous light. HMI sources with “white light”, fluorescent lamps having green cast, daylight lamps, many others. And their presence in the studio, sometimes in the form of everyday lighting, can be used by photographers, enriching the list of effects that can make in his studio. But the most useful type of continuous light is still halogen or tungsten.

Now let's look at how they work. How their light looks like. For test shoot I used two identical lighting sources equipped with both strobe and halogen lamps. The left lighting source uses only modeling light, it does not respond to trigger on my camera. So this part of the picture is made with only continuous light. The right source responds to trigger but its modeling light is off and this part of the image is formed only by flash of strobe lamp. See how they differ from each other. I used 1/200 shutter speed, f4.0 aperture and ISO 100.

Continuous and strobe light in studio mixed lighting technology The color temperature in RAW-conerter is set to 5300K (the color temperature of strobe light) and you can see that the right spot is neutral (has no any colors), while the left one we could call orange and warm. We will talk about the color temperature and change it in the next part of this article but now let's talk about basic pricnciples of working with continuous and strope lights.

If we take pictures in the studio where there is no ambient light and if we use strobe light (and we do not need effects of mixed lighting), we always set the shortest shutter speed at which your camera allows to take pictures with strobe light. For different cameras, this value can vary from 1/ 200 - 1/250 seconds (for 35mm cameras) up to 1/800, 1/1600 seconds of medium-format cameras depending on the manufacturer (the presence of a central shutter allows the use of such short exposure with medium format cameras). However understanding that the majority of photographers use 35mm technique I will not use shutter speed shorter then 1/200 second in this test.

So, let’s set the shutter speed to 1/200 sec and ISO to 100. Most often photographers use this setup in the studio to eliminate the presence of continuous light. It often happens that the photographer has to make sure that the ambient or modeling light does not "come" into the image, especially when using the open aperture. For that he has to turn off the trigger and look whether there is some kind of an image on the screen. If it is presented it means you see the presence of the image exposed by the continuous light (modeling or ambient). An experienced photographer tries to reduce the power of modeling lamp to the level when he can focus without any difficulties or closes aperture to the level when continuous light is totally eliminated.

For most photographers who shoot advertising, classic portraits etc the continuous light in the image is an unfavorable factor. It brings additional blurred parts, changes color temperature, gives color to image.

But in this case, when we want to use continuous light as a source of a variety of effects, continuous light is necessary to us. We will be able to effectively use its properties, But only under our full control. Now let's try to operate with these lighting sources. Before taking pictures wih mixed lighting technology we have to totally understand how aperture and shutter speed work with continuous and strobe light.

As it is known the exposure with strobe light is regulated by aperture of the camera. Shutter speed doesn’t work here. Actuallywe can say that the strobe lighting unit works as a shutter itself. Flashing only a thousandth (and sometimes ten-thousandth, depending on the class of equipment) of a second. Exposure happens only at this moment and if you shoot in a completely dark room (with no ambient or continuous sources of light) you can indefinitely extend the camera's shutter speed to any value, each time getting all the same exposure. The amount of light that falls on the sensor is the same and in this case is formed only by a strobe light.

Continuous light can be exposed with both the aperture and the shutter speed. By adjusting these two values we will change amount of light that falls on the sensor and eventually capture a picture in your camera.

So back to our picture.

Continuous and strobe light in studio mixed lighting technology I made the strobe light (on there right side) for 3 stops brighter, set the aperture in my camera to f11 and took the shot. You see that the right part of the picture is exposed correctly, but the left side (where there's only a continuous light with halogen lamp) could be hardly seen.

Now I’ll take several pictures extending the shutter speed each time by one stop.

Continuous and strobe light, mized light I used 1/100 sec shutter speed on the second image and you see that the left side of the picture became lighter comparing with initial level.But the right has the same exposure.

Continuous and strobe lights in studio mixed lighting technology, aperture and shutter speed The next picture was taken with 1/50 sec shutter speed. The left part became more bright.

Continuous and strobe light in studio mixed lighting technology For the next I made shutter speed slower to 1/25 second. Now the amount of light capturing on the left part of the image is the same comparing to the right part. I achieved the same exposure on both sides of the picture but you understand that I got it with totally different types of lighting sources. I will consider this picture as a basic image and compare all changes to this.

By the way here you can see the differences in the geometry of the different types of light: continuous light a little sharper, it has a small focus, concentration of light in the center of lighting spot, edge of the spot is more clear, harsh, while the strobe light makes more soft image with feathered edge. This happens because of the differences of the shapes of the lamps. The halogen lamp is usually smaller, while the strobe lamp larger. And we see that the geometry of these two sources of light is different, although both lighting modifier are exactly the same with the same distance to the wall. You should remember that and understand that a picture made with the modeling lamp is only preliminary and the lighting spot of the strobe light will have slightly different shape. But let’s continue.

Continuous and strobe light in studio mixed lighting technology I made the shutter speed for one stop longer to 1/12.5 seconds and you see that the left part formed by continuous light becomes brighter.

Continuous and strobe light in studio mixed lighting technology, aperture and shutter speed 1/6 sec - other stronger brightness of continuous light.

Continuous and strobe light in studio lighting At a value of 1/3 seconds I got a clear overexposure. The amount of light on the left part of the image brighter than on the right for 3 stops (extending the shutter speed for 3 times I got an increasing of exposure for 3 stops).

Continuous and strobe light in mixed lighting, aperture and shutter speed Now I went back to the basic value of exposure I got in with 1/25 sec shutter speed and f11 aperture. But then I opened the aperture to f8 value (i.e. opened by 1 stop). You see that both lighting spots became brighter. So you see that the aperture affected both the light source.

Continuous and strobe light in mixed lighting If I set the aperture to f16 both sources will be darker by 1 stop.

Continuous and strobe light studio mixed lighting technology Or even by 2 stops darker if I set the aperture to f22.

Continuous and strobe light, aperture and shutter speed Now I set the shutter speed to 1/6 sec. Extending the shutter speed from 1/25 to 1/6 sec I increased the exposure of continuous light by 2 stops, returning it to its “basic” value of brightness. But you see this change didn’t affect the right side with strobe lighting sources which remains on the same level of brightness (2 stops darker comparing to "basic" picture).

Continuous and strobe light in studio mixed lighting technology If I want to keep the continuous light on the basic level, but on the contrary to switch the right lighting sources by 2 stops brighter I have to set the aperture to 5.6 (open at 2 steps from the original 11) and shutter speed to 1/100 second ( 2 stops darker than the initial 1/25 seconds)

Here is a simple arithmetic. If someone hasn’t understood yet, read again, try to do these exercises in the studio. Modern professional photographer is a specialist who instantly solves dozens of complex tasks. And you should make this calculation automatically understanding everything what happens. And this is only a way to take step to the next level of your professionalism.

But now let’s take a break before we start to convert the color temperature of both sources and to move camera getting amazing effects. 

To be continued...

Part 1 and part 2 of this article