How big should backdrop be?

I am looking to buy some black fabric as an inexpensive backdrop. 2 questions.(1) How big should it be for 1 or 2 people, and (2) is one type of fabric better than another? The fabric had a polyester fabric on sale which was 60 inches wide. They also had muslin which was 120 inches wide, but 3 times the price. I'm thinking one is too wide and the other not wide enough. A little help, please.

How much of these two human beings do you want in the frame?

If you want the entire humans, then the 120 inch stuff is the way to go.

And, 120 inches is not "too wide". I use several 120 inch backdrops for images of human beings and at times I wish it were a couple of feet wider.

PS - Make it at least 20 feet long, but I much prefer something near 25 feet.

Enjoy! Lon

Yes...you need 10 feet, and likewise, even so I sometimes overshoot the backdrop, working with just a single model. Being a low budget guy, I have used painter's fabric backdrops; and also material made for sewing. This is available cheaply at Wal-Mart and other discount stores. However, to get the width, I have had a local seamstress sew 2 or 3 pieces together. 10 feet (wide) by 15 feet is ideal for me. Even after paying for the stitching, it comes in at under $75 US. The painter's drop cloth is tough as nails and has lasted me years. I travel with it, so there's a lot of folding, dragging, and walking upon it.

i got a 10x20 a while back and thought 20' long was way too long and 10' wide was enough. however when recently put it to use with a friends family of 6, it almost became too narrow! but the 20' length was good. you don't want to have your subjects right on top of your bg. i found that i kept moving them out, 6-10ft away. EDIT: even with a two person shot i found these comments to hold true.

I recently won a couple of eBay auctions for backdrops here: http://stores.ebay.com​/amvona-com

They came in at about $60 each after shipping. One is 10x12 for head shots and the other is 10x20. Both have a rod pocket on one side and grommets on the other for hanging.

Tim, make note of what focal length you want to use when shooting, and made note of how much distance between your subject(s) and background, which permits you the degree of independence in the background lighting as you want. Both of those things are very important to 'how wide do I need' for the backdrop!

For example, if you find that you want to be 8' away from your subject using a 50mm focal length, then with a program like f/calc (available on the web) it is easy to determine that where your subject is, you will photograph an area (in portrait orientation) of 2.4' wide, and if the backdrop is 6 more feet away, you will photograph an area 4.1' wide at that distance. So, with cropping you could get away with a 4' roll of seamless.

Figure out how big your subject is
Figure out how wide your lens is
And then how far away the subject if from the background

Then draw a little diagram and it all becomes clear.