Syllabus | Notes Index

Lesson 5

Printer and how to use it.

Go over printing method - print as much as possible using:

Color-Managed-Workflow.pdf

Exposure:

When you point your camera at a subject whether it is a snowy field or a black dog. The meter in your camera will assume that every tone in the image should average out to be 18% grey. This works well with most images that are "normal"... however if we start photographing things that should be black or white, we can run into trouble... so if I photograph a piece of paper that is black, the camera will make it 18% grey, if I photograph a piece of white paper the camera will make it 18% grey.

Types of light meters--two:
1. Built into the camera: reflective.
2. Hand held: can usually be set up to measure the light as either incident or reflective

Incident is light falling onto the subject---these are used mainly for studio situations when a flash is being used
Reflective is light reflected off of the subject

Digital Cameras often offer a choice of metering modes: Matrix, Center-weighted, and spot

Matrix (multisegment, pattern, or evaluative):
Measures the image in several different "zones" and then the zone that has the most information will set the exposure.

Center Weighted: This mode meters the entire frame but gives more emphasis to the center. If you have no choice for metering modes in your camera this is probably the one that it offers. Discuss problems with

Spot or Partial metering: Designed to measure only a part of the image and make that correctly exposed. Useful when you want your photo to be measured on the luminance of a particular object and then have the exposure of the rest of the image be based on that.

The light meter can affect the final outcome of your image more than anything else.

What to meter: We first have to practice seeing the world just in tonal values (as opposed to color). Imagine a scene in black and white.
We also want to take into consideration if there is a lot of contrast between the main subject and what is in the background (a woman in a white dress standing in front of a dark background--useful for all of those wedding photographers)---here we may need exposure compensation

1. in the instance of the woman with the white dress on a dark background we would need to underexpose our image a bit to pull out the details in the white dress

2. If we were to photograph black satin and we are filling the frame with that---the camera is going to make the subject look like 18 grey---so in this instance we would have to underexpose too (I know that this is counter-intuitive)

3. White lace?

What do we do if the average tonal value of a scene is not around 18% grey?
1. Find an area of the scene that WOULD be the equivalent of 18% grey and meter that area (this is why photographers will sometimes hold up an 18% grey card) (a pair of jeans, a sidewalk... what else?)---this object is know as the "metering target"

2. Hold the shutter button half way down the activate the light meter. Keep the button half way held, this will lock the exposure settings

3. Now frame the scene like you want and take the picture.

Where you may run into a problem is that with many cameras holding the button half way down also locks the auto focus (so if the actual image that you want to shoot is a different distance...so for this technique to work you really need to have an exposure-lock function on your camera)

Overriding Exposure:

Backlight: What is the simplest way around this?
Flash.
How would we overide the meter?

Snow and Beach scenes (or Desert Scenes)

Nightime:
Flash. Built in flashes are often limited to 8 to 12 feet---if you want to keep the feel of the light, the first thing you need to do is to turn off the flash. The camera will try and compensate and make everything 18% grey, this will lead to the bright areas being overexposed and the dark areas being underexposed. Give the shot less exposure than the meter recomends (you can do this by manually using a short exposure time---unless you are photographing lightning at night---we are talking more about twilight here.).

Exposure Compensation: not all cameras have it. Some cameras you will have to go into the menu, others have a dial or a button for this.

The most important aspect to getting a good exposure is to know your camera's light meter inside and out... then you will be able to tell when you might need exposure compensation (or if your camera doesn't offer this---when you will need to adjust the shutter speed or aperture).

Start by comparing brightness levels of the main subject compared to the background. If the background is substantially darker than your main subject, underexpose just a bit and if it is significantly lighter, overexpose just a bit. Also a good rule of thumb is that if the scene is kbright, you should add an exposure of 1/2 to 2 stops so that the meter won't expose it as middle grey. If the scene is dark, you should subtract exposure of 1/2 to 2 stops.

Evaluating Exposure using the Histogram: Some cameras allow us to check before we take the picture.
Show the histogram of an image in PS.
The histogram shows how the tonal values in an image are distributed along the camera's greyscale tonal range. It is essentially just a bar graph with the horizontal Axis representing tones from black on the left to white on the right. The vertical axis indicates the number of pixels at a given location on the tonal scale---with underexposed images the pixels will bunch up on the left hand side, with overexposed on the right.

Adjust the photo in PS and see how the histogram changes.

Darker images: it is normal for there to be more info on the left and vice verse. If an image has a lot of contrast (discuss what contrast is)... the histogram will be divided

Homework: Take a series of photos in different lighting situations (backlight, nightime, snow and beach scenes (we are not going to get either of these here, so use your imagination), sunsets using each (if more than one is offered) mode. Figure out if your camera offers exposure compensation). Does your camera have an exposure-lock function?