Registered: Nov 18, 2002
Total Posts: 8543
Country: United States
Conventional wisdom says bigger is better with modifiers, but it is not necessary to use huge modifiers to obtain perceptually "soft" lighting if you know how to control key and fill lighting with two separate flashes effectively.
"Soft" lighting is a complex perceptual illusion created by a number of factors and how fuzzy the edges of the shadows are plays a minor role. The more important factors are: 1) precise placement of shadows so they naturally model the the shape of the nose, cheeks and other facial features, and 2) how light the core area of the shadows are. So its possible to create soft looking lighting with two direct flashes if key and fill are used in cooperation with each other effectively: key light to model the shape of the face via its position relative the nose, and fill to lift the shadows the key light creates up into the range where the short range of the digital sensor can record detail. That's especially true outdoors when the sun is used as backlight. This test was done to illustrate that fact:
It was taken with two direct flashes. One on a bracket above the lens and the other about 6 feet away to the right. The lighting on the front of the face looks soft with smooth transitions because outdoors with back the the sun the face of the subject is oriented towards God's own softbox, the Northern sky. The only problem is the technical limitation of the camera to record all that soft lighting with the short range of the sensor pushes into the shadows. So outdoors all the flash really needs to do is give the fill from the sky a boost. Because the sky wraps around the subject 360 degrees that same softening effect is also added to the direct off camera flash. So you really don't need huge diffusers outdoors to create soft looking lighting. The only place the shadow are harsh in the example above are under the chin where little fill from sky or flash reached, but that's an area where shadows naturally occur so the brain will tend to tune them out anyway when focusing on the highlights on the front of the face.
Indoors the most effective fill mimics that same sky effect. In the 1960s it was common practice for studio shooters to bounce their fill flash towards the back wall of the studio which was painted white on all three walls near the back to create the same wrap effect. With a single flash that same neutral fill effect can be obtained by simply putting the flash above the camera lens.
Diffusion is required to soften shadow edges created by an off camera light source, but with flash placed over the camera for fill there are few shadows visible to the camera. So do you really need to diffuse shadows you can't see with a huge diffuser on the fill? No. Actually a bare bulb flash can be a very effective fill source if it is kept near the camera axis here it will not create shadows which might overlap the shadows created by the key light (i.e., crossed-shadow lighting). You want to avoid crossed-shadow lighting because wherever the key and fill shadows cross you'll get a dark dead void because neither light reaches there.
Indoors a simple neutral fill based lighting strategy results in soft looking lighting with smooth transitions because the key and fill work together cooperatively to create modeling and apparent softness via how light or dark the shadows are. Softer looking light is most a matter of adding more fill, which is why low ratio lighting is more flattering for babies, young kids and women of all ages. When you increase the ratio and make the shadows darker the perception is that the lighting is harder and more "rugged" which makes it effective perceptually for portraying men and boys you want to look mature, or women you want to look tough, determined, etc.
Thus lighting portraits effectively is actually more reliant on understanding how lighting ratio affects perception of cultural / societal conventions and stereotypes that how big of a soft box you use. Don't fall into the trap of making the lighting solution fit the tools. Instead understand the goals for the lighting -- the emotional reaction you want it to evoke in the mind of the viewer -- and let that understanding guide your choice of tools.
Consider that hot shoe flash isn't designed as a substitute for studio lighting. Its best used as a tool for "studio style" lighting with 3D modeling in candid, dynamic situations like wedding receptions. If portrait lighting is your goal you'd be better served by investing in studio lights with a battery inverter than trying to make the hot shoe flash into a studio lighting rig. The Nikon system, like Canon, relies on coded optical control pre-flashes for setting the slaves and their performance can be compromised by using large modifiers which cover up the sensors on the slaves.
All lighting solutions tend to become compromises between results and convenience. While you would certainly get better results with studio style modifiers on hot shoe flash vs direct flash, you can also get very flattering results with smaller modifiers used with two hot shoe flashes in a key / neutral fill configuration:
Common sense argues to try the simplest and least expensive approaches first and nothing is cheaper than building stuff yourself:
I used the manual flash approach for many years and also have a set of studio lights to use when I want more sophisticated results and control. But for location shooting I just grab my shoulder bag with its two speedlights, folding diffuers, bracket and a single stand and go because I understand how to use lighting effectively and its the best balance of convenience and results I've found after trying just about everything else. It also doesn't preclude using other techniques such as various forms of bounce for key and fill, a larger modifier like an umbrella on the off camera flash (which is mounted on an umbrella bracket, or adding a reflector or two to nuance the fill from over the camera. Its similar to a Swiss Army knife in that it is is a single tool which can perform all the tasks most other modifier strategies do with similar results, more conveniently. See this thread: http://www.fredmiranda.com/forum/topic/712161/0#6427656 for more detail on this approach.
Also read these tutorials before spending your discretionary income:
How diffusion actually works
How to create a DIY diffuser
I use Canon, but the principles of use are the same regardless of brand:
Using multiple Canon flashes
Chuck
