Stupid question - Black BG

I had a shoot two weeks ago and I had a Black BG - Once I started shooting I saw that it became grey - I'm assuming the two lights I had lighting the models where spilling to the back and making it bright ..

My question is was that the case? Or was it because the room was not dark but rather had ambient light?

What's the best way to keep a background black the way I want it and the model properly light?

Thanks ...

Here's a question for you - if the BG was properly lit, what color would it be?

Tips to getting a black background using flash.

1. The subjects should be six to eight feet in front of the background so the fill light will not add to the background illumination.

2. Feather the main light in front of the subjects not behind them.

3. Don't use any background light and use a black cloth background (duh!) Flat black cloth will absorb tons of light. Shiny black cloth may reflect light.

4. Use a fast shutter speed (but not faster than flash synch.)

Benji

RiKaN HaVoK wrote in post #8565598
I had a shoot two weeks ago and I had a Black BG - Once I started shooting I saw that it became grey - I'm assuming the two lights I had lighting the models where spilling to the back and making it bright ..

My question is was that the case? Or was it because the room was not dark but rather had ambient light?

What's the best way to keep a background black the way I want it and the model properly light?

Thanks ...

It can be one of both of these things.

1. Spill from your subject area strobes.
2. The ratio between subject area and background exposure is not great enough.

Do your best to make sure there isn't significant ambient contribution. If there isn't ambient contribution then shutter speed isn't going to affect it.

The is demonstrated in 2 of my recent post here:

https://photography-on-the.net …hp?p=8550895&po​stcount=22

https://photography-on-the.net …hp?p=8556632&po​stcount=33

increase your SS and pull your model a little bit away from the bg.

In almost all cases of black backgrounds showing as gray it's because of spill from the subject area and not ambient contribution, so shutter speed is not going to make a difference.

Distance between subject area and background and controlling the spill from the main and fill light sources will be the contributing factors.

TMR Design wrote in post #8566152
In almost all cases of black backgrounds showing as gray it's because of spill from the subject area and not ambient contribution, so shutter speed is not going to make a difference.

Distance between subject area and background and controlling the spill from the main and fill light sources will be the contributing factors.

I think the fact that the model was not 6 - 8 feet away from the seemless paper and that the light was at eye level in front might of have contribute to the grey ....

thanks for the clarification guys ...

So if I move the model to about 6 - 8 feet from the background and I place the lights a a 45 degree down to the model or to the sides and fether to the side (front) so no spill is going to the background - this should fix the problem?

thanks ....

Correct, and this is where grids come in handy. Grids will give you more directional light and much more control over spill. Work your lights close to the subject and pull the subject as far from the background as possible.

If you don't have reason to shoot at a shallow depth of field then shoot something like f/11 and that will also ensure that the difference between subject and background exposure is great enough to render the background black.

Thanks for the class TMR ..

I have the set of 4 grids from AB and they'll probably be use this Thursday ...

I also bought barn doors so I might use that for hair from the back .. I started noticing spill on my last shoot ..

Thank you guys .. this truly was a big help ...

P.S. I like to shoot at around f/8 with the 85MM I think it gives me the sharpest picture

Grids and barn doors are your friend

Not just honeycomb grids for reflectors and beauty dishes, but also fabric grids for softboxes and octas. They give you a tremendous amount of control and really come in handy when working in small spaces.

Check the camera metering mode. Try spot metering on the subject or a grey card

LGB wrote in post #8566409
Check the camera metering mode. Try spot metering on the subject or a grey card

I don't see how this is going to help the OP at all. Why would he try that? He's using flash and needs to control subject exposure relative to background exposure.

TMR Design wrote in post #8566334
Grids and barn doors are your friend

Not just honeycomb grids for reflectors and beauty dishes, but also fabric grids for softboxes and octas. They give you a tremendous amount of control and really come in handy when working in small spaces.

Totally agree with Robert. It took me awhile to figure it out. I've been shooting with a black background for a year and you can see how much darker the background gets as you get to my newer photos, hehe. Light control is very important to begin with.

If b/g is black to begin with, you can consider it to be -2EV in brightness relative to a gray card at subject position. THEN use the Inverse Square Law, think of distances like f/stops:

If your light to subject is 4' away, then you want the black background another 4' farther back to get the -4EV which Robert suggested. f/4...f/5.6...f/8 is -2EV (-2EV brackground + -2EV less light = -4EV compared to subject)

If your light to subject is 5.6' away, then you want the black background another 5.6' back to get the -4EV which Robert suggested. f/5.6...f/8...f/11 is -2EV (-2EV background + -2EV less light = -4EV compared to subject)

TMR Design wrote in post #8566036
It can be one of both of these things.

1. Spill from your subject area strobes.
2. The ratio between subject area and background exposure is not great enough.

Do your best to make sure there isn't significant ambient contribution. If there isn't ambient contribution then shutter speed isn't going to affect it.

The is demonstrated in 2 of my recent post here:

https://photography-on-the.net …hp?p=8550895&po​stcount=22

https://photography-on-the.net …hp?p=8556632&po​stcount=33

I have another related stupid question. I remember that there was a time I needed to get yellow color on the black muslin. I put yellow gel on the flashes. In the first time the yellow was not rich enough and it looked greenish. But the flashes were set at full power already (and they were in manual mode). So, without much thought, I decreased the shutter speed as in the case of ambient light and it seemed that I can get a more yellowish and brighter background. This experience seems incompatible with Robert's claim, which actually I understand and believe. So, I'm a bit confused now.