Syllabus | Notes Index

Lesson 3

Read: http://www.shortcourses.com/using/cameracontrols/chapter1.htm#Choosing%20Exposure%20Modes

and your camera's manual!

Setting up your digital camera:
The most important factors in determining final image quality when you shoot with your camera is:

1. Image size and compression (or format)
2. ISO (Sensitivity to low light)
3. Shutter speed (If slow shutter, then solid technique when hand-holding, or put on a tripod)
4. Depth of field (Aperure setting)

RAW files are captured at the largest size without compression. We will get more into this a bit later.

Image Size: many cameras offer different size variations on their menu systems. Some offer this as Large, Medium, or Small or some specify the exact pixel size, such as "5M 2592x1944
If you are shooting in RAW, you won't have a choice of image size. It is always recorded at the largest size that a camera can produce.

Which size do we use? web, print, etc.

JPEG format:
You can decide how much compression to apply. Show saving a file as a jpeg in photoshop.
How Jpeg compression actually works: It analyzes the pixels in 8 by 8 pixel blocks (64 px). It compares the color in this area and identifies an average color. It then looks at pixels individually and sees how close they are to the average color---if it's close, then it will switch it to the generic color.

If your camera only shoots jpegs, then use the lowest compression setting (or highest quality) available.

Why you don't shoot jpeg if you have another option---no turning back.

Tiff Format: no compression

RAW: http://www.cambridgeincolour.com/tutorials/RAW-file-format.htm
It isn't really a format. It is just RAW information that has been captured by the sensor and not converted into a file format yet. Can compensate for deficiencies when the photos were shot (even more so than if you shot with film).
Can't simply open the file in Photoshop - add Camera RAW plug-in.

ISO (International Organization for Standardization): Most cameras are between 100 and 400---high ends can go up to 3200. The higher the ISO, the more grain you will get. The ISO used to be the equivalent of film speed for analog cameras. Now ISO can be changes without changing film (obviously)---the ISO determines the sensitivity of the sensor in the camera (more next week).----If you want to shoot a shot at night and not have it be grainy, the best thing to do is to shoot at a low ISO and with a wide aperture (low number) or slow shutter speed (you will need a tripod)---show the tripods in the cabinet. You may be able to reduce the noise in a photo afterwards in photoshop using a filter---but the effect is not as good as it would be if shot right to begin with (it actually just blurs it a bit).

Color Temperature: Describes the color of light (it doesn't refer to heat)---it's measured in Kelvins.
The chart on page 211 shows the Kelvin measurement of different light sources. The capacity of the human eye----
The only way you can really see change in color that is extremely noticeable (and this is just through experience) is if you have a pair of green sunglasses on for a while and then you take them off you will see red. But an instance of moving from Flourescent light to the outdoors doesn't have this extreme an effect.
If you try taking a photo inside under typical lights in your house (not fluorescent), without a flash, you will get a yellow cast on your photo. (a good example is on page 212 of your book)

With film cameras, we can shoot with two kinds of film, Tungsten and then outdoor film, if we are shooting in other kinds of light, we can use a filter to give the images a more balanced color.

With digital, we do this by choosing a "White Balance" setting: Most cameras have AWB. What happens with Auto White Balance, is that the camera looks for the brightest spot in the scene that you are shooting and presumes that that should be white (we can see something similar to this if we go into Levels in Photoshop---show).

Note: If we are looking at our LCD screens is sunlight, it is quite hard to see if the camera is doing a good job in regards to picking a good white point.

White Balance Presets: For extra credit, see if your camera offers these for next weeks exercise. Shoot the same scene with all of the options.

Custom White Balance: Does anyone have this on their camera, and can they talk about it if they've used it?
Some cameras allow you to set a custom color temperature as well. The temperature of a photo can be fixed relatively easily in photoshop as well (show).

Color Space Settings: RGB (everybody understand)?
There is a wide spectrum in RGB that we can see., within this spectrum are different "color spaces" which have different (larger or smaller gamut sizes---meaning how many colors). Adobe RGB is the largest gamut and is the best for reproducing what we see more closely than sRGB.
http://www.chromix.com/ColorSmarts/index.cxsa?-session=tx:44232DD51625124F2CTjX42CDC01 (try and download a demo)

Exposure and Aperture: any questions on These. How is everybody doing with homework?