Digital Camera Users - Interesting in Lighting 101? (Full Version)

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TMeeks -> Digital Camera Users - Interesting in Lighting 101? (7/9/2008 2:08:15 PM)

The purpose of a camera is simply to capture light... which is the same purpose for which our eyes where created. The difference between our eyes and a camera's sensor is that God also provided us with a brain that instantly processes the information from the eye, integrates it and then composes a final light-balanced image almost instantly. We digital camera users have to 'post-process' our images if we want to have the best rendition of the light that our eyes saw at the moment the picture was snapped.

It doesn't matter whether you have a point & shoot that costs less than $100 or a professional SLR that costs $2oK+. Knowing about light can made a huge difference in what you get out of your camera and how hard you have to work at post-processing your camera's original images.

Is anyone interested in learning more about light with regards to getting better results from your photography? If so, I'd love to chat about it in this thread. Let's start with this question.

Why do cameras have different settings for indoors, outdoors on a cloudy day and outdoors in bright sunlight?

The 'COLOR' of Light

Light is really the same thing as heat. If you heat up a piece of iron, it begins to glow. At first it glows orange or reddish and as you heat it to various temperatures it turns bluish and whiter. The color it will be is predictable based on the temperature it is heated. This range is mesaured in Kelvin Degrees. A regular light bulb is heated to 3200 degrees kelvin and produces a lightly red light with very little blue. The flash in your camera is the same color as a piece of iron heated to between 5500 and 6500 degrees. It has a blue tint to it.

Since both our eyes and a camera's sensor see color as a combination of three different colors... red, green and blue, we can represent any light source with these values in a bar graph. I'll uses 'X's for the graph.

A household incandescent bulb looks like this:

R: XXXXXXXXXXXXXXXXXXXX
G: XXXX
B: XX

Bright Sunlight or 'Full-Spectrum' bulbs look like this:

R: XXXXXXXXXXXXXXXXXXX
G: XXXXXXXXXXXXXXXXXXXX
B: XXXXXXXXXXXXXXXXXXXX

The color mix of 'Cool White' Flourescent Bulbs might look like this:

R: XXXXX
G: XXXXXXXXXXXXXXXXXXXX
B: XXX

White in a photograph needs to be:

R: XXXXXXXXXXXXXXXXXXXX
G: XXXXXXXXXXXXXXXXXXXX
B: XXXXXXXXXXXXXXXXXXXX

When we talk about a photo having a 'color cast' it simply means that the lighting was such that the photo took on the tint of the most prominent light source. Those taken under incandescent lighting will have an orange color cast and those taken under 'Cool White' will have a green color cast.

So, when we 'COLOR CORRECT' our photos we simply boost the primary colors that are low so that they match the highest primary color value. A photo taken under incandescent light must have the blue and gree boosted to get a true white. And, a photo taken under 'Cool White' flourescent must have the red and blue channels boosted to create a true white.



David_D -> RE: Digital Camera Users - Interesting in Lighting 101? (7/9/2008 2:16:05 PM)

Sure, Teach! Lay it on me. [:)]



TMeeks -> RE: Digital Camera Users - Interesting in Lighting 101? (7/9/2008 2:47:05 PM)

Not so much "teaching" as discussing the many things we can do to harness light sources to our advantage. I'm sure plenty of others here can be very helpful in this regard. You posted wile I was editing the original so I'd like to get some feedback on that additonal information. Was it at all helpful?

quote:

ORIGINAL: David_D

Sure, Teach! Lay it on me. [:)]



bluestone -> RE: Digital Camera Users - Interesting in Lighting 101? (7/9/2008 2:50:13 PM)

Well, a lightbulb just went off in my head!

That small bit of information will help me a lot in post processing, when raising or lowering the color values. I have been guessing and doing trial and error up until now. Knowing the cause of each will cut down on correction time.



David_D -> RE: Digital Camera Users - Interesting in Lighting 101? (7/9/2008 3:26:05 PM)

quote:

ORIGINAL: TMeeks
You posted wile I was editing the original so I'd like to get some feedback on that additonal information. Was it at all helpful?



Sure was! This is what we're using the white balance settings on our cameras to correct for, is that right?



TMeeks -> RE: Digital Camera Users - Interesting in Lighting 101? (7/9/2008 6:04:10 PM)

That's exactly right.

Lets say that you have something in your photo that you know, for sure, that is white or grey. You want an editing program that gives you the RGB values for any pixel that you hover over. If you hover over the area that you know should be white or grey (We call them neutral colors) then each of the values should be very close, like 247,245,248. But, if you see 247,125,167 then you know you have to boost the Green and Blue values until they are close to 247.

But, you can also buy some programs that are completely dedicated to color correction with a single mouse click. I use iCorrect EditLab ProApp ($149.00). But, they have a scalled down version that does a great job of snapping photos into the correct color called CorrectPhoto that is just $39.95.

www.pictocolor.com

By clicking on a known white or grey area it knows what percentage to adjust to bring all the values up to an even level. I'll try to make a short video to demostrate the process manually and with tools.

quote:

ORIGINAL: bluestone

Well, a lightbulb just went off in my head!

That small bit of information will help me a lot in post processing, when raising or lowering the color values. I have been guessing and doing trial and error up until now. Knowing the cause of each will cut down on correction time.



TMeeks -> RE: Digital Camera Users - Interesting in Lighting 101? (7/9/2008 6:14:40 PM)

That's exactly what the white balance in your camera does.

Manual WB Mode

Step #1: Capture Image
Step #2: Convert Image to JPEG using the known properties of the WB Setting in the camera.

The camera knows that incandescent lights have a certain well-defined percentage of red, green and blue and boosts blue and green using those percentages.

Custom WB

On those cameras that permit you to create a custom white balance setting by first shooting a grey or white card, it uses the percentages of Red, Green and blue that it sees in the image to make the adjustments in subsequent pictures.

Auto White Balance

Here's where it can get tricky for the camera. It can't really SEE colors. All it can see is that the CCD element having a red filter over it is one value, and the adjacent ones next to that having either green or blue filters over them have other values. It then has to guess at the light source type. Sometimes it gets it right and sometimes it gets it wrong. Most of the time it assumes that you are shooting outdoors or knows that you are using flash and balances it closer to daylight conditions.

Some years ago, I wrote the following article on a blog that shows the Spectral Power Distribution Curve of various light sources.

quote:

ORIGINAL: David_D

quote:

ORIGINAL: TMeeks
You posted wile I was editing the original so I'd like to get some feedback on that additonal information. Was it at all helpful?



Sure was! This is what we're using the white balance settings on our cameras to correct for, is that right?



bluestone -> RE: Digital Camera Users - Interesting in Lighting 101? (7/10/2008 8:57:57 AM)

So what about night photography? I usually set the camera for "shade", is this correct? I have been photographing phases of the moon, and have done well, but would like to improve if possible.

I normally shoot manual or shutter priority, spot metering, ISO 200 or 400, no flash of course.



TMeeks -> RE: Digital Camera Users - Interesting in Lighting 101? (7/10/2008 11:26:42 AM)

quote:

ORIGINAL: bluestone

So what about night photography? I usually set the camera for "shade", is this correct? I have been photographing phases of the moon, and have done well, but would like to improve if possible.

I normally shoot manual or shutter priority, spot metering, ISO 200 or 400, no flash of course.

That's a good question. The only light you care about is reflected sun light or star light. I think I would use shade or daylight. But, I've never really tried it.

I'm assuming that you are using a tripod. In this case, you might try aperture priority and let the shutter stay open a little longer. Set the lens about 3 or 4 stops higher than the lowest your lens can do and you might find that the images are sharper.

If you want to invest in a great noise reduction software, either Noise Ninja or my favorite, Noiseware, then you can boost your ISO up even further. Both of these programs are amazing.

In the meantime, I have created a short video to demonstrate color correction. I've also include the Purposely Pitiful image that I used in the video for people to use for trying their own color correction. I plan to also make a video showing how to do this in PhotoShop Elements, since that is one of the programs most people probably have.

Color Correction Video

Purposely Pitiful Image used in the video for practicing

Let me know if it's helpful



ezri -> RE: Digital Camera Users - Interesting in Lighting 101? (7/10/2008 12:01:23 PM)

I am reading along too- the vid was informative. I am just now, meaning in the last 2 months, starting to let go of the in camera pre-set white balance settings. I have a digital calibration target that has black, white, and grey on it that I can shoot prior to actually snapping and set a custom white balance. it works wonders and in only one snap and 2 clicks!

..... if some ditz doesn't decide 5 minutes into the graduation ceremony that it would look better, you know- set the mood if they turn off the already marginal overhead lighting. [:'(] the lighting in the building was miserable to begin with. Them cutting off the overhead made it MUCH MUCH worse. I had to extensively color correct every image.

Sure, I had to touch them all after anyway, but there would have been less touching if they had not of messed with my lights- *growl* I know why Photographers usually have those assistants. IF I had of had my 16yo with me at the front I would have sent her back to insist they TURN THE LIGHTS BACK ON! [&o] as it was I wanted to stand up and shout "WHO TURNED OFF THE LIGHTS!?!? WE ARE TRYING TO TAKE PHOTOS HERE!!!

~e



TMeeks -> RE: Digital Camera Users - Interesting in Lighting 101? (7/10/2008 12:34:46 PM)

Been there, done that!!! [:D][:D][:D]

I had to laugh when I read your post because it reminded me of my video production days. You arrive early, get all set up and 3 seconds before the event everything changes. [sm=shocked.gif]

One of the reasons why I switched from doing color correction in Photoshop was the number of pictures I take made it such a laborious task. So, I tried the iCorrect and now I can whip through even the toughest set of photos. Right now I'm processing over 3000 slides that I had previously scanned in and every one of them needs some color correction and, even more desparately, noise reduction. If I had to process these in PaintShop, it would be a massive task. I'm going to be talking about ISO and noise reduction in a bit.

In a pinch, just a sheet of white paper is helpful in setting a correct custom color balance. In years past, that's all we used. It was only in the last few years, digitial still photography came along that a grey card was perferred. I think that's because the digital still camera not only uses the grey for color correction; but, also for automatic ISO settings.



quote:

ORIGINAL: ezri

I am reading along too- the vid was informative. I am just now, meaning in the last 2 months, starting to let go of the in camera pre-set white balance settings. I have a digital calibration target that has black, white, and grey on it that I can shoot prior to actually snapping and set a custom white balance. it works wonders and in only one snap and 2 clicks!

..... if some ditz doesn't decide 5 minutes into the graduation ceremony that it would look better, you know- set the mood if they turn off the already marginal overhead lighting. [:'(] the lighting in the building was miserable to begin with. Them cutting off the overhead made it MUCH MUCH worse. I had to extensively color correct every image.

Sure, I had to touch them all after anyway, but there would have been less touching if they had not of messed with my lights- *growl* I know why Photographers usually have those assistants. IF I had of had my 16yo with me at the front I would have sent her back to insist they TURN THE LIGHTS BACK ON! [&o] as it was I wanted to stand up and shout "WHO TURNED OFF THE LIGHTS!?!? WE ARE TRYING TO TAKE PHOTOS HERE!!!

~e



David_D -> RE: Digital Camera Users - Interesting in Lighting 101? (7/10/2008 6:52:09 PM)

Could you explain metering? What it is and how it's done?



TMeeks -> RE: Digital Camera Users - Interesting in Lighting 101? (7/10/2008 9:23:42 PM)

I'll try. It's a bit different with each camera and it's different between having a flash and not having a flash.

In general, there is usually some type of 'Matrix' metering that breaks the screen down into areas and the camera takes all the exposures into account to set what it can to achieve the best picture. Then there is usually a 'center weighted' metering which looks at a circle in the center of the image and gives that a heavier weight in calculating the exposure. Some cameras have 'Spot' metering that looks at a specific spot and meters just that spot. The XSi goes further and allows the user to chose a spot anywhere in its exposure matrix.

The more expensive the camera the more metering spots in its matrix.

The most important point in using the in-camera metering is to understand that the camera is trying to find gray in the image. Usually, the cameras don't care what colors are in the picture. The Nikon D40 might be the exception since it seems to use an RGB sensor. In any case, it's looking for the average in the picture and not the brightest or darkest spot.

Of course, this means that the camera can be easily fooled. For this reason, I tend to use spot metering and try to think in grayscale when picking a point to meter. Here is a sample image and where I would use Spot Metering and AE Lock (Auto Exposure Lock).

This is the original image in color.

Image #1 - The Original in Color

But, to really take advantage of our metering system we really need to 'see' the image in terms of the luminance or gray scale behind it.

Image #2 - Think in Gray

The best way to learn to do this is to practice looking for the darkest or blackest area in the image. In the case of our squirrel it is the eyes.

Image #3 - Locate the Blackest Point (Avoid)

Then look for the whitest area in the image. In this case the seeds are the brightest.

Image #4 - Locate the Whitest Point (Avoid)

Knowing the darkest and lightest give us the range of luminance that we have and now all we have to do is to find the most consistent medium between the lightest and darkest areas. The squirrel's body would do if it weren't so mottled. Some hair is lighter and some darker. It could be used; but, might give uneven results.

Image #5 - A Gray Candidate

In this image, it is the wood that has the most consistent gray surface. This is what I would use as my Spot Metering choice. It should result in a relatively even Histogram with neither blacks nor whites being clipped.

Image #6 - The Best Gray Candidate

While I discussed Spot Metering, this particular image is one that should work with both Full Matrix and Center Weighted metering. That's because there aren't any large light or large dark areas. The framed area has a nice average to it.

AE-L

The problem in this image is that the point I selected for using Spot Metering isn't in the center of the frame. So, I needed to take the image in two steps. I first used the AE-L function on my camera to lock the exposure and then I moved the camera to actually take the image. This requires me to set up my camera for AE-L using a special button on my camera. Most SLRs and many Point & Shoot have this capability. It is the single most effective thing you can learn to use on an SLR.

Here is an image from the DPReview web site that shows the AEL Lock button on the XSi. It's the button under the Asterisk symbol. On the Nikon D50 it's marked AE-L/AF-L. Each can be programmed to behave as AE Lock or AE Lock and Hold.

Canon XSi AE-Lock button

Nikon AE-Lock Button

Has this been helpful at all? If so, I can move to what the camera does with this information.

quote:

ORIGINAL: David_D

Could you explain metering? What it is and how it's done?



David_D -> RE: Digital Camera Users - Interesting in Lighting 101? (7/10/2008 9:41:12 PM)

quote:

ORIGINAL: TMeeks

Has this been helpful at all? If so, I can move to what the camera does with this information.

quote:

ORIGINAL: David_D

Could you explain metering? What it is and how it's done?



Extremely helpful! I have noticed that button on my D40 but I had no good idea what it did. Please, go on.



TMeeks -> RE: Digital Camera Users - Interesting in Lighting 101? (7/10/2008 10:23:20 PM)

Look on page 77 of your manual. It's also discussed on page 46. I have to admit, the way they explain it is not all that clear.

Go to the menu (Custom Settings) and set AE-L/AF-L to AE Lock Hold and set AE Lock to OFF. The first setting defines the button behaviour and the latter setting defines the behaviour of the half-press of the shutter button.

Then look in the viewfinder to the 3rd item from the left. If AE-Lock is active you should see EL at that position

Give it a try. [:)]


quote:

ORIGINAL: David_D

quote:

ORIGINAL: TMeeks

Has this been helpful at all? If so, I can move to what the camera does with this information.

quote:

ORIGINAL: David_D

Could you explain metering? What it is and how it's done?



Extremely helpful! I have noticed that button on my D40 but I had no good idea what it did. Please, go on.



TMeeks -> Point & Shoot lighting tips (7/15/2008 8:45:54 PM)

Most focus, when it comes to lighting, is on SLRs. But, lighting is important to all photographers, including those who are using point & shoot cameras.

The best thing one can do to make their indoor pictures better is to do something to make their flash bigger. The bigger the flash, the softer the lighting. Most point and shoot cameras have very tiny flashes that give off little output. But, that isn't the biggest problem with the incamera flash. It's the SIZE of the light source that is the real issue.

So, how can you make your flash BIGGER in covering your subject.

If you have certain camera models, you can actually buy a diffuser that fits over your lens and in front of your flash.

But, here is a very simple way to diffuse that flash for just pennies. Try taping over it. You can also try draping tissue paper over the flash.

You can also buy very inexpensive Slave Flash units that fire when your flash fires. Setting these to the side of your camera will help get rid of harsh shadows. If you can turn off the pre-flash in your camera you can use this one. Nut, if not, then you will need this one. These are especially useful if you are using your camera to take pictures of objects for sale on the web.

Finally, you can use white posterboard or foamcore off to the side of your subject and at an angle so that the light from the flash bounces off the white surface and on the subject from the side.

All of these tips can help you get better lighting with your point & shoot camera.



ezri -> RE: Point & Shoot lighting tips (7/16/2008 1:00:20 PM)

I have a Lightsphere and a Lumiquest mini softbox

I find myself using the lumiquest mini softbox more often than the lightsphere. It is just as easy to put on and take off when coupled with the Cinch Strap and it takes up so much less room in the camera bag and gets fewer "WHAT IS THAT THING" questions than the lightsphere when in use.

AND I get just as good results with it as with the light sphere- and better results with both of them than with the simple white index card and rubberband.

My Flash the user manual for the flash is bigger than the one for the camera folks- I seriously get lost in there trying to figure it all out.

~e



TMeeks -> RE: Point & Shoot lighting tips (7/16/2008 3:12:43 PM)

The first bouncer that I had, with my Olympus E-10, was Lumiquest and it worked quite well. I also have the Photoflex softbox for flash, which is very unwieldy on camera; but, useful on a stand with a slave. It was like the Pro-Maqx system but didn't attach with a strap. It used Velcro, which is why I didn't bring if forward with my canon cameras.

Where the Lightsphere comes in handy, for me, is (1) when I need to match the 3200 Kelvin lights in the room with my flash. The Amberdome does a great job at doing this. And, (2) when you are in a smaller room with white walls that can help by bouncing the light. The 360 degree diffusion in a small space (with wight walls) is very beneficial.

By the way, the Lumiquest 'SoftScreen for Pop-Up Flash Units' looks interesting. I think I'll pick one up to see how well it works. I'm always looking for low-cost alternatives for artists wanting to shoot their own work.

Timing is everything. I bought my 580 EX before the II mondel was introduced and the one you have appears to be a significant upgrade in ease and robustness.

quote:

ORIGINAL: ezri

I have a Lightsphere and a Lumiquest mini softbox

I find myself using the lumiquest mini softbox more often than the lightsphere. It is just as easy to put on and take off when coupled with the Cinch Strap and it takes up so much less room in the camera bag and gets fewer "WHAT IS THAT THING" questions than the lightsphere when in use.

AND I get just as good results with it as with the light sphere- and better results with both of them than with the simple white index card and rubberband.

My Flash the user manual for the flash is bigger than the one for the camera folks- I seriously get lost in there trying to figure it all out.

~e



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