lit object with black background

[confucious]

HI all...you will perhaps of had this question before so please bear with me as I don't even know the name of what I am trying to do.

The goal: To create a shot in which the model/object is isolated in blackness, ie: object is lit and background, sides are deeply black.

I have some ideas...first off I imagine I need a completely dark room and must work with decent lighting and reflective material. I have two lights with stands and bright "day" bulbs, how would I place these?

As to f/stop...I am thinking I would need/want to shoot it with it wide open for blurred black background, and closed for plain black (if there is such a thing as a blurred black anyways. Does this sound right?

And lastly, is there some method I need to employ wherby the subject is 3 or so f/stops from the background??

I would be using a Canon Rebel XTI with a kit 18-55 mm and a Sigma 70-300 APO DG Macro lens.
Any and all suggestions would be greatly appreciated...THanks in advance!!!

 

[Sw1tchFX]

You need black velvet, and place your subject far from the background. Light from the side and you might want to use kickers for separation.

I've done this before for product shots, but it's on 4x5 film and I don't have a scanner here, so I can't show you, but that's how you do it.

 

[Mike_E]

It's called 'low key' and the background doesn't have to be totaly black as long as the face is the lightest thing in the photo. The thing is that as long as the background is 3 stops or more below your meter reading on your subject the background will appear black (the opposite works with 'high key') so you don't have to shell out for 10 yards of black velvet exactly.

Switchfx is right about the kickers and side lighting.

For more info, Google low key portraits.

 

[Big Mike]

Technically, I suppose you could get this effect with a white background...you just need to have more light on the subject than on the background. As Mike E said, with a dark(ish) background, all you need it three stops less light reflecting off of the background than the subject.

Keep in mind that light fall off is an inverse square. As you move your lights farther from the background, the amount of light falls off exponentially. So the trick to getting a good 'black' background to your shots, is to move your lights (and by necessity, your subject) far away from your background.

Of course, space may be a limitation. You can also move your lights as close to your subject as possible (making the distance from subject to lights, much smaller than the distance from the lights to the background.

Also, it helps if you have things like softboxes or something that directs the light at the subject but not toward the background.

Finally, there is Photoshop. I've done plenty of portraits with a black bed sheet, where it didn't come out as black as I wanted. So I just isolated the background from the subject and darkened it.

*edit*
Of course, as you can see from this photo. With a dark backdrop, anything dark on your subject may tend to blend into the background. The solution for this is a kicker light or hair light. It's a light that is behind your subject, pointed at them. It helps to give them separation from the background.

 

[Jon, The Elder]

Nice one Mike. It will still be nice 20 years from now.

 

[Big Mike]

Thanks Jon.

 

[gizmo2071]

As Mike stated, a kicker or hair light is usually ideal to seperate the subject from the background.

This was shot with a softbox infront and a light with a spill kill aiming up from behind as a backlight.
This gave a very strong seperation, I could have turned the power down on the backlight.

This was shot in a similar scenario, but using a hair light. This light was shot down from behind the backdrop through a shoot through umberella and the main light was about 45 degrees in front with a softbox. The front light could have been positioned better, but thats another story

This is a great tip for making your background Black, if it isn't quite there and most people seem to over look the simplicity.
This guide was showing how to make a grey'ish back ground white, but same is used for making a darker background black, just set the black point instead of the white point.

​

 

[Big Mike]

Great examples of kicker & hair lights :thumbup:

 

[confucious]

Thanks all - your replies are extremely helpful (especially as I now know it is called "low key").

A couple of questions then...

1. I understand I need to make the background 3 stops different from the foreground (or object), how do I do this exactly, or at least how do I know that I have? I do not have a meter, and my Rebel XTI has only evaluative, center and partial metering. Can I use these to "measure" the object and then the background?? Is it just a matter of difracting the light AWAY from the background (ie: trying to "spot" the light more streamlined onto the object so the light doesn't spread) and if my shot comes out with black background I've suceeded and if not I need to move the object further from the wall or lessen the light hitting the background?
2. Are there any suggestions on how I may fashion a cylinder with filter to attach to my light cone in order to direct the light more accurately?? (fyi - my lights and "shade" get intensely hot...)

Look forward to hearing people's ideas....this forum is a godsend!!

 

[Big Mike]

I understand I need to make the background 3 stops different from the foreground (or object), how do I do this exactly, or at least how do I know that I have? I do not have a meter, and my Rebel XTI has only evaluative, center and partial metering. Can I use these to "measure" the object and then the background?? Is it just a matter of difracting the light AWAY from the background (ie: trying to "spot" the light more streamlined onto the object so the light doesn't spread) and if my shot comes out with black background I've suceeded and if not I need to move the object further from the wall or lessen the light hitting the background?

You can use your camera's meter, it doesn't really matter the metering mode but centre would be best for getting a good reading of your subject. Point the camera at your subject (maybe close up of the face) and half press the button. Record or remember those settings. Now do the same thing to your background. You will want to have a three stop difference between them.
To make it easy, I'd suggest you try it in Av mode. Set the aperture to F8 and record the different shutter speeds. Each time the shutter speed is doubled or halved...that is one stop. So from 1/15 to 1/120 (125) would be three stops.
Of course, it's digital and it should be easy to check. Also, make sure that you meter off of your subject (again, centre metering mode) and use those settings for the shot. If you use evaluative metering, you will likely end up with a muddy background and a washed out subject. It might even be a good idea to put the camera into manual mode and adjust the settings to get the exposure of your subject just right. Then the dark background is not affecting the metering of the actual shot.