Achieving dark matte background in studio

Question

I've been trying to achieve a dark matte background (maybe with some texture on it) in a studio, but i have a limited experience with backdrops and so far i haven't been able to produce satisfying results. Here's what i do:

• i hang a black seamless paper backdrop
• i put a very dim strobe on it (just for a little gradient)
• i put my model a few meters from the background

In this situation the results are pretty good, but only for headshots. And since i have limited space, i can't shoot full-length portraits with the model so far away from the background.

So ... as soon as i get the model closer to the background and as soon as more light starts hitting it ... the results are terrible: the background looks very uneven, and obviously, there's this terrible line of light where the background curves near the ground. It takes huge amounts of post-processing to fix it and even then it looks horrible.

So my question is ... how do i get a matte look even when a model is close to the background? Below is an example of what i'm talking about (WARNING: slightly NSFW). It looks to me as if the background in the sample image was simply done in post, but i believe there are some backdrop materials that could achieve a decent result as well. What are your thoughts on this?

Sample image (slightly NSFW): https://500px.com/photo/83383151/catia-by-paulo-latães (as you can see, instead of a white highlighted horizontal area we have a beautiful dark shadow where the background curves on the ground)

Thanks for your input

Answer 1

Black seamless is not what you want to be using to get a midnight grey background in a small space; it takes quite a bit of light to lift the values, and there's no way to sneak enough light in without making the paper seem glossy in spots. (With a lot more room, you can control the angles to avoid shine or use softer light without worrying about spill.) Seamless is pretty heavily sized and calandered as matte papers go; it's glossier than most people think it is. A more truly matte paper, like a good pastel paper with a lot of "tooth", would need to be much heavier to avoid easy tearing in sheets/rolls that size.

You'll probably find that a charcoal grey or "black tie-dye" fabric (muslin) will give you fewer problems, provided that you steam or press it and hang it carefully. Canvas would be better, except that the fabric will be coarse enough to show texture with your subject so close to the background. That may or may not be a problem, depending on your tastes. A good muslin isn't especially cheap, but you can test the concept using a small remnant (about a linear metre) from a fabric store. You want something dark enough that it's easy to let it fall to black when unlit (or not well-lit), but that will be near enough your desired grey value when lit as the model is lit.

Answer 2

Bring the model as far forward as you can to open up as much distance as possible between the model and the backdrop and to bring the light(s) in as close to the model as possible without getting it in shot. You then drop the level of the lighting to suit the closer positioning

As light falls off in accordance with the inverse square law, you have the same light level (ie exposure) on the model, but the light on the background reduces significantly.

Answer 3

You can make the post processing a lot easier by taking pictures in a big room without the background you want, where the walls are quite far removed from the model. You can even take the pictures outside. There you take two pictures, with and without the model using a tripod. The post processing to get the desired background then works as follows. In a linear color space, you subtract the two pictures (make sure they are aligned, and you need to scale the background picture so that it becomes equally bright as the background in the picture with the model), pixel values close to zero correspond to the background, they must be set to zero while pixel values above some small tolerance will be set equal to 1.

You may need to do some minor editing to get rid of accidental zero values for pixels corresponding to the model, and outlier values of pixels in the background can cause a value of 1 there. Also shadows cast by the model will become 1 while they should be zet equal to 0. This will require the most editing work, so one should keep that in mind when taking the picture of the model.

You then use this mask to make the background of the picture of the model black. The next step is to make a picture of the desired background, and then using the mask you add that to the picture of the model with the black background.