Monday, November 12, 2007

A Beginner's Guide to Manual Mode


Something that I hear a lot from new users is that they’re going to stick to the green box mode until they learn enough to operate the manual settings. This is something I disagree with and think that all new users should experiment with their DLSRs manual settings as most shutters are rated by manufactures to last at least 50,000 actuations and you can always chimp and erase; there’s no worries about wasting film and you can see the results immediately.

What should I know about the big M?

There are several very important things that a photographer must know about. I won’t cover this in depth in this tutorial as the discussion and arguments that can arise from the topics can be rather lengthy. Since this is the case, I’m only going to touch on them separately before attempting to explain how they relate to each other when controlling each parameter individually.

Exposure
In photography, exposure is the total amount of light allowed to fall on the photographic medium (photographic film or image sensor) during the process of taking a photograph
-Wikipedia

The exposure is what controls how light or dark a photograph is. The longer the exposure to light, the brighter the photograph; the lesser the medium is exposed (in this case the camera’s sensor), the darker the photograph.

ISO
The first one is ISO. It directly affects the pictures you take and the exposures that crop up from the rest of the settings. ISO stands for International Organization for Standardization ( http://photonotes.org/cgi-bin/search.pl?input=iso&which=d ). The ISO was originally for film speed and dictated the sensitivity to light that a film had, with the lower the number being the slowest and the higher being the fastest. The lower ISO rated film also contained less grain and would yield better quality pictures.

Most entry level DSLRs have an ISO setting that ranges from 100-1600, with higher end models going as high as 6400 ISO. Several different models contain auto ISO settings and can adjust this on the fly. I prefer to do it myself. The ISO setting works like the film ratings, but can be changed in camera. The lower the ISO setting, the faster your shutter speed will have to be to compensate for the slow film like effect. Also, the lower the ISO setting is at, the lesser the amount of grain that will be evident in the photos, yielding a better quality picture. On the other hand, a higher ISO setting emulates faster film allowing you to get brighter exposures with a slower shutter speed. Using a faster ISO setting will create grain in the photo though, with sometimes extreme amounts at higher ISO. The grain will be more noticeable in areas of the photo that are black and underexposed.

So when setting your ISO, you’ll want to use higher settings for darker atmospheres where you can’t use a faster shutter speed, but balance it out so that your photos don’t turn out too grainy. In doors and around low ambient light, I usually try and go no higher than ISO 800 unless I have to.

Shutter Speed
Shutter speed’s basic definition is pretty straight forward. It’s the duration of time in which the shutter remains open. Having a slower shutter speed will allow more light in for a brighter exposure; having a faster shutter speed will let less light in and will create a darker exposure. The duration of a shutter speed will also affect blur from camera shake and the motion of a subject. If you’re photographing a moving subject and have a slow enough shutter speed, you will get a photo of the subject from the point when the shutter first opens to the point when it closes. This can create some neat effects, but is usually not the desired result of taking a photo. Also, a slower shutter speed while hand holding a camera can cause everything to appear blurry from the inability of a human hand to hold the camera perfectly still.

Usually the guideline for the slowest shutter speed allowed when hand holding a camera is 1/focal length. So if you’re using a 50mm lens, 1/50 is generally accepted as the slowest shutter speed possible before camera shake starts to become an issue.

Aperture
Aperture is the hole or opening through which light is admitted. In our lenses, it’s the set of blades that can be adjusted to allow light through. Aperture does many things, like controlling the DOF (Depth Of Field) as well as the exposure. The number of blades can also shape the way the out of focus area looks when using a shallow DOF. Apertures can range from 1.0 to 32. They are designated by a f/(aperture number). The lower the aperture equals the wider it can open and let light in. This also causes a shallow DOF as it uses the whole lens as opposed to just a portion of the center. Generally lenses with a larger maximum aperture (lower number) cost quite a bit more than those with smaller maximum apertures.

The Light Meter
All new DSLRs should have a light meter. It should be viewable in the bottom part of the viewfinder. When pressing half way down on the shutter button to focus, the meter should come up with a tick above it, indicating the exposure that the camera is reading. Most entry level cameras will just take a general reading where the higher level models will let you set which part of the view finder you wish to meter off of. The meter should have three numbers, a 0, a 1, and a 2. Those usually have two ticks between them. Each number is a full stop of exposure. There will be a -1 and a +1 as well as a -2 and a +2. This means that if the tick telling the exposure is hovering above the -1, that the photograph will be underexposed by one stop; +1 means that the photograph will be overexposed by one stop.

Using This All Together
Now with the little bit of information provided, you should be ready to start experimenting with the manual control on your camera.

With your ISO set at an appropriate range (outdoors should be ISO 100 and indoors about ISO 640) you want to set you aperture. Generally speaking, 5.6 is a good aperture that will allow you to take a photo of a subject without having too shallow of a DOF and will let you have the majority of it in focus. While having your camera pointed at the subject, press the shutter button half way down. The light meter should appear with the tick telling you what the exposure should be hovering somewhere above. If it’s to the left, over the negative numbers, it means that the current reading shows as under exposed and the shutter speed needs to be lowered to compensate. Conversely, if it’s hanging over the positive numbers, the reading is that the photograph will be overexposed and the shutter speed needs to be faster to compensate.

When the shutter speed is set correctly, the tick on the meter should hover over the center, which should a zero. This meter reading is showing that if you take the current picture, it will be properly exposed for the ISO and aperture settings you use.

If you’re indoors and your shutter speed drops below the generally accepted minimum, you can either raise the ISO or widen the aperture. Keep in mind that some cameras will produce considerable amounts of grain at higher ISO’s and too wide of an aperture can cause a very shallow DOF, which can be a cool effect, but can also provide the undesired characteristic of having focus placed on the wrong area of the photograph.

In conclusion, this little bit of information should be enough to get most beginners on their way to using the manual mode of their camera. The manual mode offers greater control over your photos and unlike the Green Box mode on many cameras, will allow the user to start delving into the world of the RAW file format. That, is a whole ‘nother ballgame there and will be covered in a future tutorial. Until then, don’t be afraid to experiment with your camera’s manual mode and have fun doing it.

1 comment:

Anonymous said...

Great guide! I've been taking photos for awhile now, but this was extremely useful getting reacquainted with the basics.