Pure black background

[jpanganiban]

Sorry if there are threads about this already, couldn't really find what i was lookin for.

Anyways, I need some help in achieving a pure black background for portrait photography. I have very limited space and somehwat of a limited budget. Right I have a rebel xti with a 50mm 1.8 and 18-55mm IS. From what i've read a few light sources and a perhaps a black velvet backdrop will do the trick. Now I just need some more detail in what equipment i need and how to set it up. any help appreciated.. thank you

[widowmaker]

Check out strobist.com, for advice and tutorials on using flashes. But basically, you want to eliminate most of the ambient light, (to darken the backroung), and then light your subject using flash. Set your camera to its highest sync speed (most likely 1/250th of a sec), and then the camera to f/5.6 for starters. Your f stop will control your exposure, while your shutter speed controls the amount of ambient light in the picture.
Also, do a search in the flash section, on off camera set up. There's also lots to learn in the sticky's.

[and.duncan]

widowmaker has it :) Viva la Strobist!

What you're doing is underexposing the background so much that it's black and you can't make out anything in it. So you have to light the hell out of your subject while making sure that there isn't any light spilling over to your background.

The use of a black background etc. will mean you don't need to light the subject as brightly to achieve the same effect, it's not essential to what you want to do though. In all cases you will want a decent distance from your subject to your background to help avoid problems with light spill.

edit:
Actually, bit of an exaggeration, but this was taken without any background. It's just in my loungeroom. Though I think I may have ended up blotting it out rather coarsely in Photoshop just to make it completely black.

http://farm3.static.flickr.com/2204/2480860478_c64cc7f4ff.jpg (http://www.flickr.com/photos/26446205@N03/2480860478/)

[Derbyshire Weddings]

Ratio wise, your background should read 3 stops less than the reading from your subject's face. This should achieve complete black. It's the inverse square law etc.
Eg; if the reading on your subject face is f11 then your background should be reading f4 or less. Very dependant on how far you can get the subject from the background, whether you can achieve relevant distance. That's the technical way, but you can (if you can't achieve these factors) adjust the background in Photoshop by various methods.

Hope this helps. This is based on using a meter in incident mode, with invercone on, to read light.

Lee

[SkipD]

In order to keep the lights that are illuminating the subject from over-illuminating the black background, move the background further behind the subject. Also, make sure that your lights don't bounce off walls and ceiling and thus illuminate the background.