Definition - a soft box is a much more elaborate diffuser for an external Flash, we have seen these at many of the weddings where photographers have a huge light source attached on a tripod, which seems to have a cloth like finish.
here is a pic Function - it works very similar to a diffuser, briefly said brings a balanced exposure on the subject when you use a flash, thus there are no hotspots or underexposed sections in a photograph of the subject. this is done by adding a white or colored translucent material over the flash that absorbs the light to a very small extent and the rest is passed on.
the smaller diffusers such as the one showed below are good for very small subjects such as a flower or for impromptu photography, but when it comes to photographing tanks or people portraits a diffuser would be inadequate and thats where a softbox comes into play
here is the diffuser i use for smaller fish, that i photograph, yes i do have one for larger fish also one for photographing tanks
and each one of them was made out of discarded materials lying around
i will illustrate the smaller softbox and if required will also put up the larger ones
so here it is
Things required
1 - a small box, which has one open face, the box i used was a washing powder box( surf excel i guess )
2 - some aluminium foil, it should be enough to cover the inside of the box you have chosen
3 - a good pen knife
4 - insulation tape
5 - a white colored 40 micron polythene bag
a pen knife and insulation tape
First step would be to mark an area on the base of the box you have selected, the marking should be such that the light emitting end of the flash would fit tightly in it. the face of the box that is selected should be exactly opposite to the open end of the box
once the marking is done it is time to cut out that part.
sorry don't have all the pics
the flash was a perfect fit
once the hole is done it is time to cover the insides of the box with aluminium foil, i used insulation tape to hold the pieces of foil that i placed inside of the box.
then the open end of the box is to be covered using the 40 micron polythene, if you don't find a thick polythene bag then you could use double ply. cut the bag in such a way that you have a sheet to cover the open end of the box.
i used insulation tape to hold the polythene sheet in place.
once that is done here is how my really shabby softbox looks like, i am sure a lot of people with better DIY skills than mine would come up with a much more appealing softboxes.
here is a pic of it in action
do you notice how even the lighting is on the fish
there can be many variations done, you could go for black garbage bags instead of white polythene, that gives a niice black water effect
happy photography
lemme know if any thing i've posted is not comprehensible
