DSLR & Photography 101
The digital single lens reflex ( dSLR ) and Photography 101 course is a great step upward for anyone who wants to expend their creative horizons, or simply just get better pictures. Whether you want to become a serious photo hobbyist, have a hankering to turn pro. This is the perfect opportunity to build a strong foundation and understanding of DSLR & Basic Photography.
This week's class we will learn all about exposure and how to use resources given to you to create perfect, balanced and exposed images!
Lesson 5- Exposure
What is the right exposure? Not to make this complicated, but exposure is a choice you have to make. The exposure you choose determines how the image looks. But, we’ll start with a basic understanding and work up from there. Getting the right exposure is fundamental in photography. It’s like getting your balance in riding a bike, you’re never going to win a competition unless you have the awareness of your balance from the get-go. Three settings will factor into your exposure: Aperture, Shutter Speed and ISO.
Exposure consists of four factors:
For the moment, we’ll set an average exposure on an average scene.
If your camera does not have a built in meter – it's really old. But, that’s okay. You’ll just have to buy a hand held meter. If you have an SLR or advanced point and shoot digital camera, spend some time with the manual to find out how to bring up the “Histogram” which graphically shows the amount of light in an exposure.
Exercise – set your ISO to 100, set your camera to ƒ16 and the shutter to 1/125th of a second. (Some digital cameras are limited to ISO 200 – which means you have to cut your exposure by one stop, i.e. use 1/250th instead of 1/125th of a second) With this setting, take your camera out during a sunny day, put the sun behind you and shoot anything – you’ll have a well exposed image. This is called the “Sunny 16″ rule.
To make life interesting, and your photography more creative, you can change the setting and still have the same exposure. These are equivalent exposures: Try going to ƒ11 at 1/250th of a second. Push it a little further at ƒ8 at 1/500th of a second. These are all the same exposure because the same total amount of light is hitting the film.
Of course, you’re not always going to shoot with the sun behind you on a sunny day. For other situations you need to be able to find out your exposure with a meter. This can be in your camera or hand held.
Looking at any scene, your meter will give you a suggestion as to what exposure to use. Most of the time this is fairly accurate.
Using your meter, take a reading off of something with mixed tones in shade on a sunny day – you’ll find the exposure is two or three stops slower than the “Sunny 16.”
A final note – A meter is very handy for getting your exposure, but it does have a limitation. As said earlier, the meter thinks the world is 18 per cent grey. Most of the world is kind of like 18 per cent grey, but not all of it.
Look at what you’re shooting. If its black (or very dark), your meter will try to make it grey – and make the exposure too light. Conversely, if you’re subject is white, the meter will try to make it darker – or 18 per cent grey.
There are two more lessons on high key and low key photos which will help you handle more extreme situations.
Note: Be aware that some digital cameras have exposure compensation built in to prevent overexposure. If exposure is too bright the highlights could be “blown out” and detail lost in the brightest parts of the image. By artificially “darkening” the image, the camera makers try to make sure the exposures aren’t too bright. This doesn’t affect all cameras but it does seem to be the case for some. That means that the exposure needed in lessons 2, 3 and 4 may be slightly higher than suggested in the lessons. You might use the “expose to the right” method.
As a point of reference, these are the typical “whole stops” for exposure;
Many cameras have more stops at either end of these scales, but these are typical. As well, most modern cameras have half stops or third stops. These make learning a little more difficult, but keep the above numbers in mind to do proper exposures.
So the question then becomes “How do we achieve correct exposure?”
Study this and learn it, then you will KNOW how to control exposure.
(Exposure-settings-lens-subject image sample)
Okay, remember how the lens bends the light rays into the camera and onto the film plane? Good. Between the lens and the film plane are TWO devices we use to for exposure control, to control the exact amount of light hitting the film. THAT’S RIGHT, THERE ARE TWO DEVICES TO CONTROL EXPOSURE….We learned about these last week. Can you guess what they are?
THE SHUTTER, is usually a curtain-like device just in front of the film. Think of a shade pulled down on a window, and then quickly open it and close it. FOR AN INSTANT THE ROOM WAS FILLED WITH LIGHT and the length of time that burst of light filled the room is shutter speed! That is basically how a shutter controls the amount of light getting to the film.
The time the shade was open determined – to some extent – how much light came into the room – but so did the SIZE of the window! That window opening acted as…
THE APERTURE, which is built inside each lens and controls how much light enters the lens. “Stopped down” f16 or f22
(F16 image sample)
Now for some clarification on shutter speeds. Looking at the photo below, you will see the numbers that are changing are the shutter speeds in fractions of a second (i.e. 30 = 1/30, 60 = 1/60). This is the time taken from when the shutter opens to when the shutter closes, after you press the shutter release.
Moving from one speed to the next one halves the amount of light that enters the camera. Moving the other way, to a slower shutter speed, doubles the amount of light that enters the camera. This change from one speed to another is called moving a stop. For instance, moving from a speed of 1/30th to 1/60th of a second is going 1 stop faster, and from 1/60th of a second to 1/250th of a second is moving 2 stops.
HERE IS A RULE OF THUMB FOR PROPER EXPOSURE OUTDOORS:
First, take the film speed number as your shutter speed (100 ISO = 1/125th of a second or, if your film speed is 400 then the shutter speed would be 1/500th of a second for instance), your aperture setting is:
For bright sunny days and the sun is on the subject. f16.
For overcast, cloudy. f8.
Sunsets and sunrises, low light. wide open @ 1/30th (only if you can use a tripod. If not use lowest comfortable shutter and adjust the other settings accordingly)
These are basic starting points that usually work. The film package also has some excellent, basic exposure suggestions.
So, you have two methods of controlling exactly how many light rays get on the film and if you understand the above, you then understand how to control exposure for different types of film or different ISO. Re-read it until you understand it, because this is the crux of exposure for daylight photographs.
In order to become more sophisticated with exposure control you need to learn how to use a light meter. This can get very complicated because there are so many light metering systems out there, and so many ways of using those meters. I learned through the years, trials and errors that the only true metering system you NEED to master is the light metering system offered in any good SLR camera. Learn that, find your sweet spot and shoot away!
(dSLRs exposure meter image sample)
The light meter reads the light coming off the subject matter, through the lens you are using, and is controlled by the film speed you have already set that meter to. It simply is the most sensible, accurate way to meter those light rays. SLR meters are getting more advanced all the time offering “spot” metering (you can zero in on one particular spot on the subject, get the right exposure, and lock in that setting and make your photo) … overall metering, reflected metering, incident metering, ……and on and on. It is no longer necessary to “bracket” your exposure ( shoot one frame over by one stop, one frame at the indicated exposure, and one stop under the recommended exposure). I quit bracketing twenty years ago and have not exposed a frame improperly.
Therefore, I will not get into other methods of metering. All of the recommended exposures from now on will be based on through-the-lens metering with an SLR camera.
What do I mean with bracket your exposure?
(BKT image sample)
When it’s difficult to set exposures or check them to make adjustments, the bracketing feature permits a group of images, each with a different exposure. (Note: You’ll first have to set up the camera with the numbers of images to shoot as well as the steps between exposures.) The results are well worth the time and effort it takes to learn bracketing.
Exposure bracketing: The camera varies exposure compensation with each frame. Use this when there’s tricky lighting situation but you have to get it right. This is also the set up you’ll use when you’re shooting HDR (high dynamic range) sets.
You also may hear about: Flash bracketing: The flash level is varied with each shot. White balance bracketing: The camera creates multiple images each time the shutter is released. This is content on more advance photography in which is covered on fallow on courses.