thanks for the info.
Just looking at these setups i have a question. Doesn't having the flash mounted at the front (subject side) of the umbrella create small shadows? or isn't it noticed?
Thanks
When your light is directly on the camera the subject is evenly lit, which means you don't see any highlights and shadows on the subject. This deer in the headlights lighting is possibly the worst possible lighting for portraits and produces a flat image that looks flat.
To give a subject in a flat image a 3D appearance you want highlights and shadows. You get these by using the light off to the side, up, and at certain distances.
It is easy to understand why moving the flash away from the camera to the side and up causes highlights and shadows. Understanding how to control how soft the light is and what the ratio of the highlights to shadows is a bit more difficult.
Basically the larger a diffuse source of light is with respect to the subject the softer it is. If you have a diffuse light source the closer it is to the subject the larger it will be with respect to the subject so the softer the light.
Control of the ratio between highlights and shadows depends on two things.
The first is the distance of the light from the subject. The amount the brightness of the light on the side of the subject closest to the light vs the far side of the subject is controlled by the inverse square law.
Four Flash Photography Basics we must know - Inverse Square Law
Frank Doorhof - Inverse Square Law - YouTube
The closer the main light is to the subject the greater the amount of light fall off across the subject, thus the greater the ratio between the highlights and shadows. Get too close and if you expose for the brightest diffuse highlight (which is what you should do) then the light fall off is so great that the shadows will go pure featureless black.
Conversely the further the main light is from the subject the less fall off across the subject. The near and far sides of the subject receive almost the same amount of light since the relative distance across the subject is small with respect to the distance from the light source. The light becomes flat and boring.
The second method of controlling the highlight to shadow ratios is the use of secondary "fill" light.
You normally use a diffuser that is as large as or larger than the subject at subject to diffuser distances between 1 and 2 times the diameter or diagonal of the diffuser. At these distances you get the best combination of softness and light fall off across the subject.
At these distances any blocking of the light from a reflection umbrella by the flash or strobe head is unnoticeable because the light has been diffused so much.