Photographer's guide to "real" lights?

[KrazyPete]

Does anyone know of a web site for photographer that describes different kinds of room lighting? I need a field guide to electric lights. I'd like to be able to walk into a room, look up and go, "yeah, those are mercury vapor lights." If this guide has the average color temperature for the lights so I could set my white balance that would be awesome.

 

[AbbysFamily]

That really depends how close you want to be.. For example mecury vapor lights can range from 3500K to 6000K (according to a bit of quick research).

If you are caring enough to set your white balance by looking at the lights (as we SHOULD try, but not all of us are great at it) then you're better off getting good at setting a white balance by hand.

Doing a quick search, here is a page I found that at first glance reads quite well... (I just bookmarked it for further reading - it looks like a nice writeup).
http://www.kenrockwell.com/tech/whitebalance.htm

 

[mabas9395]

Shoot RAW and fix it in post.

 

[MarkBarbieri]

I think you're better off with a grey card or expodisc. Many lights vary in color temperature as you dim them or as they warm up.

 

[boBQuincy]

Fluorescents are even worse, they may have a color temperature marked on them but their spectrums can be different even with the same color temperature.
The good fluorescent bulbs are rated by their CRI (color rendering index), where anything over about 92 is considered close to daylight.

 

[MICKEY88]

I think you're better off with a grey card or expodisc. Many lights vary in color temperature as you dim them or as they warm up.

I'm pretty sure that rather than a grey card you want a piece of white paper, you do your WB reading off of the paper and it should be right on...


Manual White Balance

This is where the concept of "White Balance" comes in. If we can tell the camera which object in the room is white and supposed to come out white in the picture, the camera can calculate the difference between the current colour temperature of that object and the correct colour temperature of a white object. And then shift all colours by that difference.

Most advanced digital cameras therefore provide the feature to manually set the white balance.

By pointing the camera at a white or gray card (angled so that it is reflecting light from the room) as a neutral reference, filling the screen completely with it, then pressing the White Balance button (or set it in the menu), the camera does its WB calculation.

From then on, any picture taken will have its colour temperature shifted appropriately. It's quite simple, really, and you should not be afraid to try it out and see your indoors pictures improve considerably (assuming there is enough light for correct exposure).

[A "neutral" gray is 18% gray and will reflect all colors equally.]

Caution:

- Ensure the card is not in shadows, but illuminated by the artificial light in the room
- If you are bouncing light off the walls, ensure the card is reflecting the bounced light
- Beware of mixing artificial lights -- in this case, you might want to use RAW and adjust in post processing for each light
- Beware of fluorescent light: since fluorescent light does not contain all the spectrum of light, you may obtain unexpected results

 

[KrazyPete]

I do use a gray card sometimes. It's been the most accurate method of setting the white balance for me. My understanding was that white paper was good but any color can go to white if it is over exposed and paper isn't always "white." So a professional neutral gray card is better.

Honestly, I've never tried the paper method. I may give it a shot.

My hope with the lighting reference was that I could get in the ballbark by looking at the lights in the room and setting the color temperature (kelvin) on the camera. Then, chimp a couple of shots to dial it in. It sounds like there is so much variation in color temperature (even among similar lights) that it's not practical to try to do it that way.

 

[MarkBarbieri]

I'm pretty sure that rather than a grey card you want a piece of white paper, you do your WB reading off of the paper and it should be right on...

grey, white, or black...it doesn't really matter as long as it is neutral colored. What you are trying to do is photograph something that is truly neutral in color. Then, the software can compare how the camera saw it to see what color bias the lighting has added.

A grey card is handy because it can be used for both white balancing (because it is neutral grey) and setting exposure (because it matches the brightness that your camera assumes everything intrinsically is).

A white piece of paper will also work, but with two caveats. First, it must truly be white. A lot of paper has it's only slight color cast. For normal use, it's probably not an issue. If you are doing a product shoot or something that requires spot on color accuracy, you really want something exact.

The other caveat is that you have to be careful not to overexpose it. To understand why, assume that the light in the room is slightly warm, giving a yellow cast. Your white piece of paper should appear slightly yellow before white balance corrections have been applied. However, if it is over exposed, all three color channels may be maxed out and it will appear absolutely white, which your color corrector will see as neutral and not apply the appropriate adjustment. With a grey card, it's much harder to miss on your exposure.

I talked to a professional high school sports shooter (amazingly, you can make a living doing that) and he had an interesting trick. Because of the odd mixture of lights, flash, and sunlight coming into the gyms in which he shot, he had a terrible time getting consistent colors. His solution was to discretely tape grey cards in various places around the gym. When he shot, he often had a grey card somewhere in the picture and could use that for white balance. When he didn't he could still work it out with another trick.

The other trick was through color matching. He would find a relatively neutral part of a uniform. He would then find a shot with a grey card that had that same part of a uniform. He would adjust the white balance via the grey card. He would then adjust the exposure so that the uniform patch matched for both pictures. He would then look at the RGB values for the patches and adjust the white balanace of the first picture until he got the RGB values to match.

As for me, I just adjust the white balance until I think the picture looks good. I really don't care what the correct white balance was. If something wrong is more appealing to me, I'll take it. The only thing I've had to change over time is to be careful to make the white balance match for a series of photos all in the same lighting. It looks really goofy if you have a few shots taken all together and the white balance changes between them.

 

[MICKEY88]

grey, white, or black...it doesn't really matter as long as it is neutral colored. What you are trying to do is photograph something that is truly neutral in color. Then, the software can compare how the camera saw it to see what color bias the lighting has added.

A grey card is handy because it can be used for both white balancing (because it is neutral grey) and setting exposure (because it matches the brightness that your camera assumes everything intrinsically is).

A white piece of paper will also work, but with two caveats. First, it must truly be white. A lot of paper has it's only slight color cast. For normal use, it's probably not an issue. If you are doing a product shoot or something that requires spot on color accuracy, you really want something exact.

The other caveat is that you have to be careful not to overexpose it. To understand why, assume that the light in the room is slightly warm, giving a yellow cast. Your white piece of paper should appear slightly yellow before white balance corrections have been applied. However, if it is over exposed, all three color channels may be maxed out and it will appear absolutely white, which your color corrector will see as neutral and not apply the appropriate adjustment. With a grey card, it's much harder to miss on your exposure.

I talked to a professional high school sports shooter (amazingly, you can make a living doing that) and he had an interesting trick. Because of the odd mixture of lights, flash, and sunlight coming into the gyms in which he shot, he had a terrible time getting consistent colors. His solution was to discretely tape grey cards in various places around the gym. When he shot, he often had a grey card somewhere in the picture and could use that for white balance. When he didn't he could still work it out with another trick.

The other trick was through color matching. He would find a relatively neutral part of a uniform. He would then find a shot with a grey card that had that same part of a uniform. He would adjust the white balance via the grey card. He would then adjust the exposure so that the uniform patch matched for both pictures. He would then look at the RGB values for the patches and adjust the white balanace of the first picture until he got the RGB values to match.

As for me, I just adjust the white balance until I think the picture looks good. I really don't care what the correct white balance was. If something wrong is more appealing to me, I'll take it. The only thing I've had to change over time is to be careful to make the white balance match for a series of photos all in the same lighting. It looks really goofy if you have a few shots taken all together and the white balance changes between them.

OK it appears we are talking 2 different things, you are photographing somethng to do your white balance after the fact, I was talking about setting custom whote balance in camera before shooting.

that negates the issue of overexposing the white card, you simply get something that is a good white, I generally keep a pack of unlined index cards for this, you simply go thru your cameras custom white balance procedure while aiming the camera at the white card, making sure the card is reflecting whatever type lighting is in the room.... once your white balance has been set for that room, your pics should all be fairly accurate as far as white balance goes...


wow your sports photographers method seems way more complicated than neccessary, my experience has been that almost all HS uniforms have white on them somewhere, the odds of both teams not having white are rather high....

I always did the custom white balance before shooting, if I forgot I simply looked for the white in the pic and balanced from there...

 

[MarkBarbieri]

I think the same issues are present whether you are setting a custom white balance in the camera or doing it in post production. In both cases, the algorithms are the same. In either case, trying to white balance off of a blown out white card will result in problems.

I agree that white balancing before shooting is ideal, but it only works when the light doesn't change. Some lights change color temperature frequently, so it doesn't work for them.

As for white balancing against whites found in your picutre, it's a "good enough" technique. Again, you need to make sure that the white you are using isn't blown out. You also need to be aware that most "white" things aren't precisely neutral, so you probably won't be dead on. It'll be good enough for almost anything that doesn't require precision white balance. Assuming that you use the same "white" in each shot, it'll also have the benefit of consistency across pictures.

If you didn't do a custom WB before shooting and you have a lot of shots in the same lighting, you can usually work out the white balance for one shot and then copy the same setting to all of your other shots.

If you really find the subject fascinating, Photoshop Color Correction is an old but good book on the subject.

 

[MICKEY88]

I think the same issues are present whether you are setting a custom white balance in the camera or doing it in post production. In both cases, the algorithms are the same. In either case, trying to white balance off of a blown out white card will result in problems.

I agree that white balancing before shooting is ideal, but it only works when the light doesn't change. Some lights change color temperature frequently, so it doesn't work for them.

As for white balancing against whites found in your picutre, it's a "good enough" technique. Again, you need to make sure that the white you are using isn't blown out. You also need to be aware that most "white" things aren't precisely neutral, so you probably won't be dead on. It'll be good enough for almost anything that doesn't require precision white balance. Assuming that you use the same "white" in each shot, it'll also have the benefit of consistency across pictures.

If you didn't do a custom WB before shooting and you have a lot of shots in the same lighting, you can usually work out the white balance for one shot and then copy the same setting to all of your other shots.

If you really find the subject fascinating, Photoshop Color Correction is an old but good book on the subject.

how would you blow out the white card when doing a custom balance, you're not taking a picture of it so thwere is no exposure.... you camera is just reading the white card