What is more usefull to have, a shoot through or reflective umbrella , what are the plus's and minus's of each system
Shoot-throughs can deliver very soft light. Because you can use them close, so the light source becomes relatively larger compared to the subject, and the larger the light source, the softer the shadows.
In addition, half the light is reflected straight out of the back and in a typical domestic room this bounces off the ceiling/walls and all around the room back to the subject and this adds even further fill-in softening. Watch out that this light doesn't pick up too much colour from walls and furniture, though there's often not much you can do about it - the downside of shoot-throughs is lack of control.
White brollies are also very soft, similar to a softbox of the same size.
Silver brollies give a more punchy light, not unlike a beauty dish, with a harder core delivered from the centre with a softer component from around the edges. It's a nice combination, and silver is also more efficient, making the flash head appear more powerful.
Brollies seem to be a bit underrated and these days, compared to softboxes. Other upsides of brollies are that they're very cheap, take seconds to put up/down, pack away very small, and because of the way they mount, they usually take up less working room if you're tight on space.