You must have an external flash unit in order to attach a soft box to your camera.
Camera-mounted soft boxes attach to the flash unit only. Soft boxes are designed for large external flash units that attach directly to the hot shoe of your camera. Attaching a soft box to the built-in pop-up flash is difficult since most soft box products are not made to mount a pop-up flash. However, there are some flash diffusers available for pop-up flash units. However, these diffusers are usually screens and not full-encompassing soft boxes.
Instructions
1. Attach the external flash unit to the hot shoe of your camera. Most soft box diffusers are built to attach to most external flash units, including those made by Canon, Nikon, Olympus, Pentax, Sony and Sigma.
2. Place the flexible soft box over the bulb strip at the tip of the flash unit. Pull the adjusting strap of the soft box until it fits snugly around the flash. Secure the Velcro to the strap.
3. Snap a hard box flash diffuser directly onto the bulb end of the external flash unit. Plastic soft boxes for external flash units are known as flash caps and although they are not "soft" in texture, they perform the same light-softening effect as flexible soft boxes. Diffusing flash caps are built for specific flash unit models, such as a Canon flash cap for a Canon flash unit and a Nikon flash cap for a Nikon flash unit. The flash cap will only snap on and lock to the correct model.
4. Pop open the built-in flash on your camera. Hook the front end of your pop-up flash diffuser (which looks like a white opaque flexible card case) into the dip in the front of the camera where the tip of the flash tucks into. Hook the flat edge with the small foot onto the back of the popped-up flash. If the diffuser is a wrap-around diffuser, known as a "puffer," slide the attachment into the hot shoe of the camera.
Tags: flash unit, external flash, flash units, pop-up flash, soft boxes, your camera