One of the main advantages of using a well equipped photographic studio to have your photos taken is that the resultant images will be 'properly' lit, but of course a well equipped studio can produce a wide range of lighting styles.
Here we take a look at some fairly standard portrait lighting setups and look at how varying the lighting used to light a subject can make a difference to the final image.
Using 'Bert' our stand in 'model', here are a series of images with differing lighting setups.
Firstly, an image with no studio lighting, just the room lights in the studio space.
On the face of it this looks reasonable, it is certainly useable, but in order to get a well lit image, we are having to shoot at a lower (wider) aperture which reduces the depth of field (which may be wanted for some images, but not for others) and we have also had to increase the ISO settings, which isn't too much of a problem with good quality modern cameras, but there is limited flexibility with 'room lighting' alone and the background is a bit murky with uneven shadowing. In this instance the camera settings were f1.4 at ISO 400.
Next, we have a single studio light, a 'key' light or 'main' light. This is placed to the upper left of the 'model' (as we look at the image) with a large octagonal soft box to soften the shadows. This has the effect of 'wrapping' the light around the subject to a degree but you can see that the right hand side of Bert is darker than the left. This can be useful where 'contouring' is desirable. But on other occasions you will want more uniform lighting. Camera at f8 at ISO 100.
Next we add in a 'fill' light to the models right hand side (as we look at the image) the 'fill' light is set to the same power and at the same distance as the 'key' light. You can see that this removes the area of shadows on the right hand side resulting in a more uniformly lit image. Camera still at f8 ISO100.
This is now somewhere between the previous two images. We still have both a key and a fill light but we have reduced the power of the 'fill' light to a setting of f5.6. This darkens slightly the right hand side of the subject, maintaining a reasonable uniformity but with a little more 'interest' or 'shaping'. This can serve to 'soften' an image slightly and looks a little more natural than a completely uniformly lit image.
Now we add a third light, this one above and to the rear, left hand side as we look at the image, this light is fitted with a 'grid' which causes the light to behave as a spot light, with much less 'spread' than a soft box. This is used as a 'rim' or highlight to separate the subject from the background. We have changed the camera settings to f9 ISO 100 which serves to darken the background slightly, but with the rim light the subject still stands out, though the subject is also a little darker due to the narrower aperture on the camera.
Closing the aperture on the camera a little further to f11, further darkening both the background and the subject (all lights as they were)
And a bit more, with the camera now at f13 (otherwise everything as before) - the subject is beginning to look a little less 'distinct' against the background and we are losing some colour saturation.
Keeping everything as for the previous image, but adding a fourth light, a strip box to the rear right hand side of the subject (as we look at the image) - you can see this provides some 'rim' lighting on the right hand side now as well as the left. This serves to further 'pick out' the subject from the background.
Now we take away the 'key' or main light, so this is lit only with the 'fill' light to the front and right (as we look at the image) the the two 'rim' lights from either side at the rear. This reduces the light on the subject but also on the background, as we have the rim lights lighting the rear/sides of the subject this serves to increase the contrast between the subject and the background.
The image previously was a little too dark overall (when looking at the image histogram which records the total range of light and dark tones of the image) so we have widened the aperture to f9 but the light setup is as previously, so camera now at f9 ISO 100.
This adds a red 'gel' to the gridded rim light (to the rear and left of the subject as we look at the image), this produces a strong red tint to one side of the subject.
If we now point the red light to the backdrop instead of the subject, we get a red 'hotspot' on the backdrop with a gradual fall off to grey then black.
Further opening up the camera aperture to f8
If we were to turn the 'key' or main light back on, this adds 'white' light to the subject and backdrop, completely changing the 'mood' of the image once again.
With the main light back on the subject was a little too brightly lit again, so we have reduced the camera aperture back to f11. So this image is lit with a key or main light, a fill light at a lower power, and a strip box rim light to the rear and right hand side. The backdrop is lit with a red gel.
I should note that all of these images are 'straight' from camera, they haven't been edited at all. If you shoot in 'RAW' as we do, there is a lot of latitude to 'process' the images shot, in effect 'developing' a digital negative Just as in developing a film negative, alterations can be made to the brightness, contrast and colour saturation of the image. Any of these images here would provide a sufficiently good start point to be able to end up with a good, well exposed image so the lighting and camera settings chosen will come down to the style and mood required for the final image. Of course there are many, many more lighting options that could be used with a 4 light setup, the position of the lights can be moved, the modifiers used can be changed to change the 'shape' of the light or the colour where gels are used. The area that the lights are aimed can be changed etc.
This final image does not use the main or key light, so consists of a 'fill' light to the front and right hand side of the subject (as we look at the image), a strip box 'rim' light to the right hand side and rear of the subject and a red gel light shining on the backdrop. The camera is at f9 ISO 100. The image has been edited to boost contrast and balance the exposure.