Blacking Out The Background

Bilko

Bilko

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Robert
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I'm trying to take some shots with a black background.

What sort of distance do I need between the subject and the background?

Do I have to do this with an umbrella to get the blackened background?

Some pics are getting close but I'm sort of stuck for space.

This is all new to me, so any help appreciated.
 
its more about the environment, i.e. not having white walls and ceilings bouncing around light all over the place

It is then about flagging and screening your lighting to make sure none of it hits your background

In a darkish room, with the right settings, and well controlled light, you can use a white background, and make it "black" by simply not illuminating it, and only illuminating your subject

Umbrellas have nothing to do with this
 
Bilko said:
Thanks Richard.

I think this means I need experience, lots.
Click to expand...

just use your eyes and common sense, it will get you 85% of the way there

If in a darkened room, you have a white wall, what colour is it as you look at it... Black

If you shine a torch at it what colour is it - white

If you shine a torch at a side wall, what colour is back wall - barley grey

If you spotlight your torch on a bunch of flowers in the middle of the room, and make sure none of the light is reflected about, by using sheets of black material, the flowers will look like flowers, and the back wall will be black

Yes its easier if you start off in a totally black room, with no light, but if you don't, you just need to make sure no light (or very little) hits the background

The next trick is about getting the exposure right. If you add "lots" of light to your subject, and then alter your cameras exposure accordingly, the background will appear to get darker and darker, as you increase the light levels, and adjust out on camera
 
softboxes with grids on will help a lot.
You will have problems with an umbrella


edit - unless you close the back of the umbrella and dont shoot through it as that might work if you have it close
 
In this situation, the inverse square law is your friend. Your bestest buddy, in fact.

Get your light source close to your subject and have it fairly bright. THEN metering towards the lightsource, make sure you're at a small aperture and shutter pretty fast (as fast as you can sync, perhaps?)

Small aperture and fast shutter lets in less light than big aperture and slow shutter - back to basics there, and an apology to you if I sound to be patronising.

The inverse square law being your buddy kicks in right here.

Consider this hypothetical situation and then apply to the space you have for shootng in:
Subject to background distance is 4 meters.
Light to subject distance is 4 meters and the light is directly in front (you're butterfly lighting).
Background is therefore double the distance the subject is, so that gives us (from inverse square law) 1/4 the power. Or, in practical terms, 2 stops lower. Normally, if we have something white only 2 stops lower lit than the subject, we can see it easily.
How about now having your light at 2 meters from your subject. Light to background distance in is now 3 times the light to subject giving us 1/9 the power.
Move your light to only 1 meter from the subject and you now have a light to background of 4 times the distance which is 1/16 the power hitting the background relative to what hits the subject. Now increase your subject to background distance to 6 meters and keep your light 1 meter from the subject. What do you get? A light to background distance of 6 times the light to subject and squaring that up gives you 1/36 the power hits the background compared to the power which hits your subject. The further you can move your subject away from the background, the darker you can make it.

Simple!

Try it out and see what you get - and yes, you can point your light directly at the background for this experiment
 
rgrebby said:
softboxes with grids on will help a lot.
You will have problems with an umbrella


edit - unless you close the back of the umbrella and dont shoot through it as that might work if you have it close
Click to expand...
So true, especially shoot-through umbrellas will spill over the whole room.

As Richard mentioned, the less bright your walls, the higher the ceiling and the farther away your background, the easier it will be.
 
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