I would definitely play around with it. Your not going to want to go too wide with 4 because odds are they will move around a bit and you’ll end up with some soft faces. Some key things to remember would be try to keep their faces all on the same plane of focus, that will allow you to shoot a little wider. Generally with 4 kids I would aim to shoot around f/4 but certainly play around. At that aperture you may want to consider moving them further away from the background. Keep in mind the closer you are to them and the further away from the background they are the more bokeh you will get! What this tells us is that the further away the light source is from the subject and backdrop, the more likely we are to get an equal exposure from one to the other. The quality of the light source can also change with distance. You will notice that as the light gets further away it becomes a harder light with less transitional values. Also, if the subject appears to be further away from the backdrop in the last image, it's due to me needing to use a shorter focal length (zoom out) to avoid getting the softbox in the shot. The shorter focal length exaggerates perspective.
A traditional backdrop support system is the most common mounting solution for photography studios. The backdrop support system consists of a 3-section cross bar and two light stands. By utilizing two of the included cross bars, the backdrop support system can mount backdrops up to 7-feet wide. By utilizing all three cross bars, this system can mount backdrops up to 10.5-feet wide. The included stands can extend up to 12-feet high for photographing tall people, high movement, or products.
With a 20 or 24-foot long backdrop you’ll be able to cover just about every style of portraiture and product photography. These backdrops are great if you want to photograph a larger family full-length, or have a video shoot that requires movement. These long backdrops are great for when you want to pull your subjects far from your backdrop as well.
Create the ideal setting for your photo shoots with photo backdrops and backdrop equipment. To accommodate a variety of client needs, consider stocking up on a selection of solid color and printed photo backdrops. Whether you own a collection of seamless background paper or you're just starting out in the business, you can choose from numerous designs and accessories suitable for headshots, family portraits, and product photography.