acrylkic black background changes color

[macobee]

when i use flash my black acrylic background becomes almost white in my pictures.......how can i keep it pitch-black whilst illuminating my subjects on it correctly?

[Deckham]

Make sure there is no reflecting light hitting it?

ie - side lighting/soft front/distance from model to backdrop.

[macobee]

http://farm3.static.flickr.com/2297/2524006124_d825fbd1c9.jpgi hear what you are saying, however my subject (a tomato) stands straight on top of the acrylic, and i need to use lighting to illuminate the tomato.

would a soft box help, or a light tent? i think that should also reflect.

[FeXL]

Have you tried using a circular polarizer?

[Deckham]

Ahhh!!!!!!!
You use it as a platform!

Ok, disregard what I said then.
Get some nice matte black cloth, and throw it over your pedestal!

[macobee]

yes as a platform, sorry for being confusing.

matte black cloth, you mean hang it above the tomatoes, with the lights still under it?

[Deckham]

yes as a platform, sorry for being confusing.

matte black cloth, you mean hang it above the tomatoes, with the lights still under it?

Ahm, no, not exactly.
It isn't turning white, so to speak, it is reflecting. So you need to eliminate the reflections. You can do this by either using a non-reflective surface as your platform, positioning your lighting to minimize reflection, using a circular polarizer - or combinations of those options.

[Wilt]

The black plexi is bouncing light to the surroundings, which are then appearing in the photograph. (Imagine what you would see if a mirror replaced the plexi!) Eliminate the surfaces behind (black felt or background paper) and the plexi will be much better.

[macobee]

right ok so i need to loose the nice feeling of floating and get me a non reflective black background........i am happy today i just did a test shoot!

i will also try in a bit with my cpl see if it can help enough.

cheers

[tehdrok]

.. Or paint all the walls and the ceiling black :lol: :lol:



But the cloth thing, that's probably easier.

[tehdrok]

Seriously, though, you could still get the effect you're going for.. Get a piece of clear plexi (not black) and put it on top of something matt black (ie: card, material, whatever..).. You'd get a little reflection, but not as much as you're seeing at the moment AND you'd get the 'floating' feeling that you're looking for (but not as pronounced).

[Mark1]

What you are seeing is a reflection of a white background on a black surface. You need to change the background as well, to black. Leave everything not seen in the frame as white. The "float" will still be there, just in black not white.

Notice the reflection on part of the black acrylic here....
http://www.tabletopstudio.com/images/jewelryphotography/seahorse_setup200h.jpg

THis is what you are getting, when you change the background yo will get what is on the right side.( no reflection)

Final image...
http://www.tabletopstudio.com/images/jewelryphotography/goldseahorse_200.jpg

The black background will also help with the burnt out spots on top of the tomatoes. A light tent will help tremendously. A cheep sheet and a support of some kind is all you need. Dont buy the $100 tents Unless you plan on doing a lot of stuff. Check this link on how to build one... http://www.pbase.com/wlhuber/light_box_light_tent Also dont trust your light meter in times like this. Too much black or white will throw it off. Use it to get a base then open or close down by hand till you get whar you need.

[macobee]

hey mark, thanks, interesting......so lets say if i'd take black acrylic platform and on 2 sides cornering each other put black backgrounds, then i would be halfway there.

I want to achieve exactly as what you pictured here but im still lost, where do i put my lights then? do i have to use a snoot to beam the light in from far away so theres no softbox which will reflect again maybe?

[Mark1]

Lights are on the sides and top. Black acrylic on bottom, flat black background. Got to go for a few hours.... I can help more tonight. Reed the DIY light box thread here........ http://photography-on-the.net/forum/showthread.php?t=281524

[Wilt]

hey mark, thanks, interesting......so lets say if i'd take black acrylic platform and on 2 sides cornering each other put black backgrounds, then i would be halfway there.

that's exactly what I was posting about in message #8 !

[breal101]

Angle of incidence is equal to the angle of reflection, putting black behind the subject will reflect black onto the surface. Try it with the light from the top, it is also important to control the spill of the light from hitting the black reflector. A cpl won't help unless the light source is polarized, i.e. the sun or a filtered artificial light.

[macobee]

now i understand, thank you ;)

[Mark1]

that's exactly what I was posting about in message #8 !

Not really... the black is reflecting FROM the surroundings. It is a reflection of a white background. It is not bouncing the light to the surroundings.

[Mark1]

YOU can get the 'float' useing all flat black as well. the floor does not have to be reflective.

[Wilt]

Not really... the black is reflecting FROM the surroundings. It is a reflection of a white background. It is not bouncing the light to the surroundings.

I also mentioned the fact that the black plexi, if you had replaced it with a mirror, served to see the surroundings which had light cast upon them! Two different concepts mentioned in my earlier message, but I can understand how someone might not realize there were two different points made.

[Mark1]

You don't need a mirror when the plexi is already reflective. I guess that is where you gave mixed signals.

[Wilt]

You don't need a mirror when the plexi is already reflective. I guess that is where you gave mixed signals.

I had mentioned about imagining the use of a mirror (instead of plexi), and you would then easily see the reflections of the surroundings that are going to be seen in the reflections on the plexi.

[Mark1]

OK I got you I think. I was thinking you meant use a mirror and a black background for the shot. I dont know where I went off track!