The nice thing about a light with an integral Fresnel is that you don't need an external modifier to change the focus of the light. They're fairly compact and light, as well. Other manufacturers also offer Fresnel strobe options, including the Hensel Starspot and Maxi-Spot lines, while still others, such as Bowens, offer detachable Fresnel attachments for use with a number of strobes. The Bowens Fresnel 200 attachment also includes a built-in iris for adjusting the diameter of the beam of light produced by the Fresnel.
However you utilize Fresnels for spot lighting, they're an ideal way to light several parts of an architectural interior or tabletop setup without spilling light broadly across the scene. And they're handy for portraiture in much the same way as grids and snoots—when keeping light separate is paramount.
Barn DoorsBarn doors are one of the most common modifiers, and you should be well versed in them. The barn door is like a set of metal flags that affixes to a light fixture, and can be adjusted to cut and shape the pattern of light. Fresnel lights often include a bracket for attaching modifiers like scrims and barn doors, and many strobe manufacturers also offer barn doors that easily mount to the front of dish reflectors.
At their simplest, barn doors are a great way to flag light at the source and contain spill or prevent illumination from hitting a background without changing the quality of light. But barn doors are much more than flags. While barn doors don't optically focus light in the same way as a Fresnel or optical snoot, the effect of cutting light at the source makes barn doors especially versatile. In some cases, barn doors allow you to physically shape the beam of light more precisely than would be possible with snoots and grids. For instance, to add an eye light to a portrait subject, a round modifier like a snoot or grid would create a round beam of light, but with barn doors, the light can be shaped into an oblong or a rectangular shape to precisely add sparkle to a subject's eyes.
Want to put a precise square of light on the background, or maybe fit a thin shaft of light between two scene elements in order to deliberately light a third? Barn doors are the perfect modifier to offer this fine control in delivering light exactly where you want it.