Digital Photography Week Three
Flash, Email Files and Color
Exposure Compensation
Exposure compensation forces camera to give more or less exposure than the camera thinks it needs. Use positive compensation if background is significantly brighter than your subject or if large areas of background are white (snow). Negative compensation is less used. Needed if large areas of background are dark/black or if subject is significantly brighter than background.
Flash
- In camera flash. Flash dissipates very quickly over distance. Double the distance from camera to subject and you get ¼ the flash power (not ½). Built in f lash units on typical consumer cameras are useful only if the subject is 4 feet to 12 feet away from camera.
- On camera flash. Many (not all) digital cameras will allow you to purchase and use a more powerful flash. These are typically attached to a “hot shoe” on the camera. Typically 8 times more powerful than an in camera flash, allowing use from 4 feet to 60 feet.
- TTL automatic versus manual flash on camera flash. TTL flash must be “compatible” with your camera and then it allows the camera to set correct exposure.
- Your camera’s sync speeds. One place where the inexpensive cameras often outperform the expensive cameras! Synch speed is the fastest shutter speed you can use when a flash is being used. On many simple consumer digital cameras there is no limit (use any shutter speed you want). Some prosumer digitals cameras are limited to 1/500 (use 1/500 or any speed slower). Top end professional DSLR cameras are typically limited to 1/180 (use 1/180 or any speed slower).
- Daylight fill flash. Most people think of flash only for night or dark indoor images. An overlooked flash use is to “fill” in shadows in an outdoor daylight image. Just turn on your automatic (in camera or TTL on camera) flash and shadows on “near to camera” subjects will be significantly reduced.
Camera White Balance
Color of Light. Perhaps you’ve seen a lighting display at a hardware or interior design store showing that different light bulbs have different colors. Sunlight is actually blue light, regular light bulbs (incandescent) are rather orange and most fluorescent tubes are green. In the real 3D world or brains “fix” this for us, we don’t “see” these colors. In a 2D photograph we do!
White Balance in camera. Digital cameras can be set any of three ways to fix this problem. Auto white balance tries to read the color of light and adjust the camera without your input. It works reasonably well, but can be fooled in odd situations (a room with bright colored walls, snow, a room with strongly colored lights such as a stage production). Manual white balance is used when you want to tell the camera what color light exists. If color on a ski slope fools your auto white balance, you would switch to manual white balance and select sunlight. Custom white balance (may not be available on simpler cameras) lets you make and use your own personal versions of manual settings. Very useful in situations where you have 2 or more light sources mixed together (blue sunlight coming in a window mixing with green florescent lights in the room).
White Balance in image editing software. It is possible to “fix” an imperfect white balance in software after the image is taken. See below for image editing software part (3 color correction). Because this is time consuming and often confusing, it is best to get color as close as possible in the camera first, rather then try and “fix it” later in software.
Image Editing Software Part 3 (email and color correction)
Email sizing and compression. Images for web or email VIEWING should always be sRGB color space and 96dpi at a maximum of 1000 pixels on the longest side (600 pixels is probably safer). A direct from camera file may be as large as 3Meg, this can take a few minutes per image for a phone modem user to download. Using these instructions will reduce your file to about 1/60th that size. Photoshop Elements instructions:
- Launch Photoshop Elements, if needed.
- Close “Welcome” screen (Mac) or select “Edit and Enhance” (PC), if needed.
- Open image (File > Open). You will see image on your screen.
- Make sure you are “Standard Edit” rather then “Quick Fix” mode (Elements specific command, in upper right of screen). Make sure you are in the “Cascade Windows” view mode (two overlapping squares symbol in upper right).
- Resize (Image > Resize > ImageSize). Make sure both “Constrain Proportions” and “Resample Image Bicubic” are checked.
- Enter 96 into the resolution box.
- Select Pixels in the width drop down menu.
- Enter the number of pixels you want on the longest side (height or width).
- Click OK.
- Save your new smaller file as a new file/name (File > Save As) to a location on your hard drive (not your camera’s memory card). Chose file type as JPEG. In the next window chose Quality “6.”. Without this step you would “over-write” your existing file, which would permanently reduce your resolution.
- Using your email program, attach this new (smaller) file to your message.
Manual Color Correction (best method)
- Launch Photoshop Elements, if needed.
- Close “Welcome” screen (Mac) or select “Edit and Enhance” (PC), if needed.
- Open image (File > Open). You will see image on your screen.
- Make sure you are “Standard Edit” rather then “Quick Fix” mode (Elements specific command, in upper right of screen).Make sure you are in the “Cascade Windows” view mode (two overlapping squares symbol in upper right).
- Select Enhance > Adjust Color > Color Variations.
- For most images, select midtones and set the amount to 1/4 or 1/2.
- Look at the small thumbnails and chose the one that looks best. This step can be repeated.
- Save your new corrected file as a new file/name (File>Save As) to a location on your hard drive (not your camera’s memory card).
Auto Color Correction (quick and easy, but very little control)
- Launch Photoshop Elements, if needed.
- Close “Welcome” screen (Mac) or select “Edit and Enhance” (PC), if needed.
- Open image (File > Open). You will see image on your screen.
- Make sure you are “Quick Fix” rather then “Standard Edit” mode (Elements specific command, in upper right of screen). Make sure you are in the “Cascade Windows” view mode (two overlapping squares symbol in upper right).
- Click the “Auto” button on the color pallet.
- You can “fine tune” the adjustment using the 4 sliders under the “Auto” button.
- Save your new corrected file as a new file/name (File > Save As) to a location on your hard drive (not your camera’s memory card).
Computer and Screen Color Management
Computers use color spaces and tags to describe the color field and its limits. sRGB is most common space used in consumer gear. sRGB is always used for email or web viewing. AdobeRGB is an example of a larger color space. Larger color spaces contain more extreme colors. Your camera gear most offer a larger space for it to be useful. Windows XP lacks a color management panel (Macs include colorsync), consider this add on.
Calibrating a Computer Screen, at the very least:
- Set the correct monitor profile in Start > Control Panel > Display > Settings > Advanced > Color Management (Windows XP) or System Preferences > Displays > Color (Mac). Select the profile with your monitor’s name on it.
- Set your monitor to 6500K and Gamma 2.2. These setting often found on your monitor’s (not your computer’s) menu.
- Use the brightness and contrast calibrations strip shown below:
- Steps 1 and 2, as well as steps 12 and 13, can be similar. But a close examination should show some difference. Adjust your monitor's brightness and contrast controls if needed.
Calibrating a Computer Screen, the better and more expensive way. Use a hardware “spider” that measures your monitor and creates a custom profile.
- Read typical instructions for using a calibration spider.
- Read reviews for available hardware.
- Buy and use a calibration “spider”.
HOMEWORK (in four parts, 5 prints):
- Part #1: Know where your camera settings are (read manual).
- Part #2: Shot a backlit object or person with and without a plus two stop exposure compensation.
- Part #3: Shot one indoor or night scene including a close subject and distant background. Use an on camera flash as the primary light source and your camera’s highest sync speed.
- Part #4: Shot a "harsh light" daylight scene two ways, with daylight flash fill and without.
- Bring you favorite of each assignment to the next class (5 prints)
Class Index | Class 1 | Class 2 | Class 3 | Class 4
