strobe defuser

this may sound like a stupid question but when do you use a defuser, i am just about to invest in a strobe for my sony P12 and havent got a clue.

Most airlines these days sensibly require that you remove all fuses from your strobes before flying. Just kidding.

The purpose of a diffuser is simply to diffuse the light. Without a diffuser, your strobe acts like a point-sized source of light. A single point-source creates clear hard-edged shadows, which can be good for revealing surface texture and detail, but can also look harsh.

A diffuser or softbox spreads the apparent source of light across its surface, softening the edges of shadows. It's like the difference between taking photographs on a clear, sunny day and a bright but cloudy day. A cloudy sky is the ultimate diffuser/soft box.

It also broadens and smoothes the edges of the beam, which can be useful when shooting wide-angle with strobe whose angle of coverage is not wide enough to illuminate a large main subject evenly. Last but not least, the diffuser reduces the intensity (power) of the beam by varying amounts, usually equivalent to something between 0.5 and 1.5 stops.

To make things more confusing, using multiple strobes also softens or even completely removes shadows, but the effect is very different than that obtained by using a diffuser on a single strobe. There is also the more subtle but important difference in visual effect between using diffusers on multiple strobes, or not, which depend in part on strobe placement.

Diffusers fit over the outside of the strobe, so they can be removed and replaced underwater. You will need a suitable pocket, or else attach lanyards. Try shooting the same subjects (both w/a and macro) with and without the diffuser. You will quickly get a feel for the effect and develop a sense of when you will want to use diffusers and when not.

The only time you absolutely must use a diffuser is when taking topside portrait using flash of your wife/girlfriend/significant other. * Trust me on this!

Frogfish

* Professional portrait photographers use soft-focus medium telephoto lenses with designed-in (and controllable) spherical aberration to conceal blemishes and create a magical soft glow around the subject's face, but one can do a lot with carefully applied softening in Photoshop. First, make a duplicate layer, then sharpen the bottom layer. Now apply some gaussian blur or smart blur to the top layer. Erase those parts of the top layer (eyes, lips, etc.) with details that you want to keep maximally sharp. Finally, adjust the opacity of the top layer to moderate the balance between the sharpened lower level and the softening effect on skin tones on the top layer. A few flattering portraits will go a long way to build a more sympathetic understanding of your need to invest in more photo gear.

cheers frogfish, you have made it very clear.

Additionally, you can make a diffuser out of an old plastic milk jug, the translucent types, when you lose the one you paid good money for. In general, a diffuser reduces light output by about one-stop (at least the ones I make do). Use velcro to attach it to the strobe (gaffer tape works as well).

rinjani