Using Variable Focal Length Lens for Your Camera
First of all, what is focal length? The textbook definition is "Focal length is measured in millimeters (mm) and it represents the distance from the optical center of a lens to the digital camera sensor when the subject of the photo is in focus.
" In plain language, this means that with a shorter focal length lens, to be able to capture a close up of your subject, you have to be closer.
Conversely, with a longer focal length lens, you can be further away to get that same close up shot.
Lens can be fixed i.
e.
a prime lens, or variable such as a zoom lens.
I f you look at any of your lens, you will see for example a range of 18-55mm or just 50mm.
The first is a variable focal length lens and the second is a prime lens.
So how do you determine what lens you will need? First work out what you want to photograph.
If you want to photograph landscapes, buildings, and interiors, you will want to use a wide-angle lens.
If you are interested in shooting portraits or nature scenes, then you will need a telephoto lens.
Somewhere in the middle, i.
e.
neither wide angle nor telephoto lens would be a normal or standard lens setting.
Here is a list of lens to you choose the right for the right situation:
However, the telephoto lens will have the effect of pulling everything in your shot close to you, making them to appear bigger.
Do you experience difficulty with blurry or out of focus pictures? One of the main reasons for this is camera shake.
The longer the shutter speed, the more chance your shots will suffer from camera shake.
Most of can't take a shot without camera shake below a shutter speed of 1/60s.
You also have to use the correct shutter speed for the focal length that you want to get really sharp in-focus photos.
This is because when you magnify an image using a telephoto lens, it is also magnifying camera shake.
To overcome this, set the shutter speed slightly higher than the focal length.
For example, a 1/40 of a second shutter speed is good for a 30 mm lens, 1/60 of a second for a normal or 50 mm, 1/125 of a second for a zoom of about 100 mm, and 1/250 second for a zoom of 200 mm.
Have you ever notice photographs which have the subject in sharp focus but the background is out of focus? Have you noticed other photographs where everything is in focus? This is called depth of field (DOF).
Choose a shorter focal length to give you more depth of field.
A 50mm lens will have more depth of field than a 200mm will have more than a 500mm lens.
When you increase your focal length to zoom in on a subject this decreases the amount of light entering the lens.
To compensate for this, you need to increase the aperture, or decrease the shutter speed, or increase the ISO.
Focal length, ISO, shutter speed and aperture all play a role in capturing an image.
Focal length controls the amount of light coming into the lens.
ISO controls the sensitivity of the image sensor.
Shutter speed controls how long the image sensor captures the light.
Aperture controls how much light the image sensor sees.
" In plain language, this means that with a shorter focal length lens, to be able to capture a close up of your subject, you have to be closer.
Conversely, with a longer focal length lens, you can be further away to get that same close up shot.
Lens can be fixed i.
e.
a prime lens, or variable such as a zoom lens.
I f you look at any of your lens, you will see for example a range of 18-55mm or just 50mm.
The first is a variable focal length lens and the second is a prime lens.
So how do you determine what lens you will need? First work out what you want to photograph.
If you want to photograph landscapes, buildings, and interiors, you will want to use a wide-angle lens.
If you are interested in shooting portraits or nature scenes, then you will need a telephoto lens.
Somewhere in the middle, i.
e.
neither wide angle nor telephoto lens would be a normal or standard lens setting.
Here is a list of lens to you choose the right for the right situation:
- Less than 21mm: super wide-angle lens
- 21-35mm: wide-angle lens
- 35-70mm: standard or normal lens
- 70-135mm: standard telephoto
- 135-300mm (or more): telephoto
- 600mm or more: super telephoto
However, the telephoto lens will have the effect of pulling everything in your shot close to you, making them to appear bigger.
Do you experience difficulty with blurry or out of focus pictures? One of the main reasons for this is camera shake.
The longer the shutter speed, the more chance your shots will suffer from camera shake.
Most of can't take a shot without camera shake below a shutter speed of 1/60s.
You also have to use the correct shutter speed for the focal length that you want to get really sharp in-focus photos.
This is because when you magnify an image using a telephoto lens, it is also magnifying camera shake.
To overcome this, set the shutter speed slightly higher than the focal length.
For example, a 1/40 of a second shutter speed is good for a 30 mm lens, 1/60 of a second for a normal or 50 mm, 1/125 of a second for a zoom of about 100 mm, and 1/250 second for a zoom of 200 mm.
Have you ever notice photographs which have the subject in sharp focus but the background is out of focus? Have you noticed other photographs where everything is in focus? This is called depth of field (DOF).
Choose a shorter focal length to give you more depth of field.
A 50mm lens will have more depth of field than a 200mm will have more than a 500mm lens.
When you increase your focal length to zoom in on a subject this decreases the amount of light entering the lens.
To compensate for this, you need to increase the aperture, or decrease the shutter speed, or increase the ISO.
Focal length, ISO, shutter speed and aperture all play a role in capturing an image.
Focal length controls the amount of light coming into the lens.
ISO controls the sensitivity of the image sensor.
Shutter speed controls how long the image sensor captures the light.
Aperture controls how much light the image sensor sees.