If you haven’t read Elements of Photographic Exposure it’s a good time to do so now, before moving on! In this tutorial we are going to talk about how you apply this knowledge in practice.
Every DSLR has several exposure modes, which control the way the camera makes exposure decisions (the combination of aperture, shutter speed and ISO). Many consumer DSLRs have a number of auto exposure modes, eg. Auto, Portrait, Landscape, Night Landscape, Sport, Beach, etc). These modes contain settings loaded in the factory and they promise to make things just work, even if the user doesn’t understand basic photographic concepts (that’s why they are also included in point-and-shoot cameras). So what are the disadvantages of these modes?
- They are automatic modes, so they don’t allow the user to take exposure (and thus creative) control (e.g. in Auto mode, if the camera perceives that the light of the scene is too low, it will pop-up the build-in flash in order to illuminate the scene. It’s ok if this is what you want, but it’s a big problem if this is not what you want).
- They are programmed according to average situations, but not all situations (scenes) you are photographing are average (not all portraits are the same, not all landscapes are the same, etc).
- The settings being applied by these modes are quite hidden and the user doesn’t know exactly what the camera is doing, thus it’s difficult to master these modes.
Pro DSLRs have only 4 exposure modes that give the photographer total control over the exposure:
- P (Program Priority)
- A (Aperture Priority)
- S (Shutter Priority)
- M (Manual)
P (Program Priority): Camera sets aperture and shutter speed. You control ISO, focus point and flash, but you can also alter camera’s decisions and set aperture or shutter speed (this mode is like Auto, but allows you greater control).
A (Aperture Priority): This is the most famous exposure mode; the one that serious amateurs and pros use most of the time. It allows you to set aperture and camera sets shutter speed accordingly (based on the aperture and ISO set). It’s the mode to use when depth of field is important.
S (Shutter Priority): You set the shutter speed and camera sets aperture accordingly (based on the shutter speed and ISO set). It’s the mode to use when shutter speed is important (if you want to freeze motion you set high shutter speeds, if you want to blur motion you set slow shutter speeds).
M (Manual): This is the mode that gives you full control over exposure. You set both aperture and shutter speed, but manual mode doesn’t throw you in the middle of the ocean and tells you “swim to get out”! It gives you “clues” on which you can rely to set the appropriate exposure (when Manual mode is selected, the viewfinder displays a bar that looks like this:
The middle line represents 18% middle gray reflectance. Everything above or beyond are perceived by the camera’s meter as over or under exposed. This is the true power of Manual mode; it allows you to set exposure in the way you wish, not the camera!
Strictly speaking, all exposure modes, except Manual, are automatic modes, in a sense that the camera takes control over exposure. e.g. when using Aperture Priority, you set the lens aperture in order to control depth of field, but the camera sets shutter speed assuming that the scene has an average gray reflectance. Of course you can alter the shutter speed set by the camera, by using exposure compensation.
Putting them to work in practice!
In practice things are very simple!
1. You are photographing a scene where depth of field is important. Set you are ISO according to available light (start when the lowest possible value for best image quality). Set Aperture Priority and specify an aperture (if photographing a portrait use a wide aperture, e.g. f4, or even 2,8 or 1,4, in order to isolate your subject from the background. If shooting a landscape, use a smaller depth of field, e.g. f11 or f16, In order to get everything in focus). Check the shutter speed set by the camera. If you are not on a steady tripod and the shutter speed is not fast enough to get a sharp image by handholding the camera, increase the ISO until you get a fast enough shutter speed. Note: if you are photographing a black or white subject, the exposure most probably is going to be wrong. Use exposure compensation to override the camera’s meter; -1,5 or -2 for black subjects, +1,5 or +2 for white subjects).
2. You are photographing a scene where motion is important. Set you are ISO according to available light (start when the lowest possible value for best image quality). Set Shutter Priority and specify a shutter speed (if you want to freeze motion, set a high shutter speed, if you want to blur motion, set a slow shutter speed. How much is high and how much is slow depends on the moving speed of your subject. On average, 1/60 blurs rain, 1/8 blurs people walking, 1/250 freezes sports, 1/1000 freezes a bullet). Check the aperture set by the camera. If the camera needs a wider opening that the lens’ widest aperture, in order to expose the scene correctly, it will display Low; in that case set a higher ISO. If the camera uses the smaller available aperture and still the quantity of light coming in the sensor is high, it will display High; In that case you have to lower ISO or/and use a faster shutter speed. Note: if you are photographing a black or white subject, the exposure most probably is going to be wrong. Use exposure compensation to override the camera’s meter; -1,5 or -2 for black subjects, +1,5 or +2 for white subjects.
3. You don’t have the time to make exposure decisions (e.g. street or wedding photography). Set your ISO according to available light (start when the lowest possible value for best image quality). Set Program Priority and start shooting. You can bypass camera’s decisions (choose a different aperture or/and shutter speed) by rotating the camera’s front and rear command dials. Note: if you are photographing a black or white subject, the exposure most probably is going to be wrong. Use exposure compensation to override the camera’s meter; -1,5 or -2 for black subjects, +1,5 or +2 for white subjects.
4. You want best exposure control and you have the time to do so (you don’t need much time, trust me!) Set you are ISO according to available light (start when the lowest possible value for best image quality). Set Manual mode and adjust aperture and shutter speed according to your appetite and by taking notice of the exposure bar in the viewfinder display. If the subject you are shooting is black, set the exposure to -1,5 or -2 on the bar scale. If the subject is white, set the exposure to +1,5 or +2.
Practice
Once you apply exposure modes in practice, you will soon realize how easy is to master them! If you used to shoot in Auto mode, start shooting with Program mode. It has much more fun to select the focus point you wish and not to have the build-in flash pop in the way.
As soon as you feel comfortable, move to aperture priority. It takes some practice, but in a few days time will start shooting like a pro! (just watch out of your shutter speed).
Once you get yourself familiar with Aperture Priority, move on and have some fun with Shutter Priority. You have unlimited creative choices when experimenting with motion.
For ultimate control, move on and start practicing in Manual mode. There is only one boss here and that is you!
There is no right or wrong exposure; only creative exposure choices. Explore your passion and yourself. One of the main things that distinguish amateurs from pros is exposure handling. Don’t make average images; make stunning images!
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