18% gray, 2.5 stops... that type of thing.

[wingflapp]

So, I've confused myself again. Here goes.

I made a DIY light tent. Took a couple of pics in it, for fun and testing. The white background came out all gray. So I went back to my book and re-read on 18% gray. I eventually re-read that if I want a white background to come out white, I need to up the exposure 2.5 stops. Or somewhere in there.

That's great and all, but..... What about the subject in the light tent. Now it will be overexposed. I don't want to correct in Photoshop. I'd rather learn what it is I'm missing. I can only imagine adjusting the distance of the light from the subject, but can't imagine how that would work in a light tent, seeing as the tent itself is the light source.

What's more, that .5 of a stop is confusing. I may need to study more on my camera, because the way I understood things yesterday = every change in setting was equivalent to one stop..

Any reading info would be helpful.

Thanks in advance.

[OsmosisStudios]

First off: depending on how the camera is set, you can have it set for full-stops, half-stops, or third-stops. At least on my Nikons. I leave mine in thirds (gives me just that bit more control).

As for exposure issues: what the book isnt saying is that it should only be your BACKGROUND that is +2.5 stops. THe light that falls on your subject is whatever is needed. This is why you always light your background independently of your subject.

[John Hendry]

Originally Posted by OsmosisStudios

First off: depending on how the camera is set, you can have it set for full-stops, half-stops, or third-stops. At least on my Nikons. I leave mine in thirds (gives me just that bit more control).

As for exposure issues: what the book isnt saying is that it should only be your BACKGROUND that is +2.5 stops. THe light that falls on your subject is whatever is needed. This is why you always light your background independently of your subject.

Yip well said.

[metallion58]

Let's see...

• Tent lighted up.....check
• White balance adjusted.....check
• Exposure adjusted for background....check

Seems to me you only have to add a little fill light on your subject to bring it to the right level and you're all set.

[wingflapp]

Originally Posted by OsmosisStudios

First off: depending on how the camera is set, you can have it set for full-stops, half-stops, or third-stops. At least on my Nikons. I leave mine in thirds (gives me just that bit more control).

As for exposure issues: what the book isnt saying is that it should only be your BACKGROUND that is +2.5 stops. THe light that falls on your subject is whatever is needed. This is why you always light your background independently of your subject.

I understand what you are saying, but I don't think this falls into that category... It's a light tent. The tent diffuses outside light and bounces it all around itself. Basically one light lights the whole shebang (possibly 2 lights). It's also very small. Can't really separate the subject from the background in order to light them separately.

Maybe there isn't enough 'subject' filling the frame to render the whites as whites. I wonder if that's it....

I'll keep trying.

[OsmosisStudios]

Nope: to get a flat bright white light, you need to light the background and subject separately, even in a light tent. Use flags and gobos.

[wingflapp]

Originally Posted by OsmosisStudios

Nope: to get a flat bright white light, you need to light the background and subject separately, even in a light tent. Use flags and gobos.

Thanks much, Osmosis. I'll work out a way to get the background light going. (hopefully).

I dunno, but I guess I misunderstood the whole tent concept.

[NathanFranke]

Originally Posted by wingflapp

Thanks much, Osmosis. I'll work out a way to get the background light going. (hopefully).

I dunno, but I guess I misunderstood the whole tent concept.

I'm not sure about that...

My understanding that with a light tent, you do really only need one light--the point of a light tent is even, shadowless, floating-in-space images.

In a quick (minute and a half) google search, I found lots of tutorials about how to make light tents, but few useful ones on how to use one. None of them mentioned what kind of light setup--the few with pictures showed only one light, outside the tent.

As for overexposing the white background, that's kind of the idea. Think of the Zone System--if it's a white background, you'll want that in zone 7 or 8. Spot meter off the background, then mark that at zone 7 or 8 (<-3 | | -2 | | -1 | | 0 | | 1 | | 2 | | 3>) {arrow somewhere in the bold portion}

Tell the meter what zone 7 (or 8) is, and your subject should expose correctly, regardless. If it's still too bright, you have too much light. Back it off a bit, either with distance or power.

[Tito87]

Originally Posted by NathanFranke

I'm not sure about that...

My understanding that with a light tent, you do really only need one light--the point of a light tent is even, shadowless, floating-in-space images.

In a quick (minute and a half) google search, I found lots of tutorials about how to make light tents, but few useful ones on how to use one. None of them mentioned what kind of light setup--the few with pictures showed only one light, outside the tent.

You can use more than one light: you can light it from above, from the sides, and if you want to brighten up the background--you can light it from behind.

[metallion58]

Perhaps this link will be of help.
And there's plenty more information in this series.