Last day of Intro to Photo! Last time we talked about how to set up your exposure. Today, we are going to discussing the ins and outs of lenses. Here comes the easy stuff!
Lenses
Lenses can be either zoom or prime. Zoom lenses allow you to vary focal lengths (based on what is built into the lens) and – as the name says – zoom in and out of the frame. Prime lenses are fixed. This means that it has one focal length. In order to “zoom in or out” with a prime lens, you must physically move closer or farther from the subject. Prime lenses typically have a larger maximum aperture, making them “faster” than zoom lenses.
Lenses that have larger apertures are described as fast lenses because they have the ability to collect light faster. However, lenses with smaller apertures have a greater depth of field.
Lenses fall into a few different categories:
A wide-angle lens widens the angle of view thus bringing more into focus. A wide angle can also have a flattening effect.
– Super wide angle lenses are typically anything under 20mm
– Wide-angle lenses are from 21-35mm
A “normal” is a lens that most accurately portrays what a human eye will see. With a 35mm camera, this is typically a 50mm lens. Normal lenses fall into the category of standard lenses.
– Standard lenses range from 35-70mm
A telephoto lens reduces the distance between objects in the photo, bringing the subject “closer” to the photographer.
– Medium telephoto lenses are considered portrait lenses. These range around 80-135mm
– Telephoto lenses are between 135-300mm
– Super telephoto lenses are anything over 300mm
Focal length is the distance in millimeters between the lens and the sensor when the camera is focused on a subject at infinity. Lenses that are classified as “long” lenses have a larger focal length- these are telephoto lenses.
Each lens has its place. Standard lenses are great all around lenses but excel when used for documentary and street work. Wide angle lenses are great for landscape and architecture whereas telephoto lenses work well with portraiture, sports and wildlife photography.
Be careful when selecting a portrait lens. Different focal lengths can distort the face in different ways. Wide angles tend to flatten out the face in an unattractive manner. The optimal portrait lens depends on what camera you’re using (and if there is a crop factor) but you’re typically safe using a lens between 85-135mm long. 135mm lenses (or about that) are optimal when shooting head shots.
How focal length distorts the face
Megapixels
People are far too concerned with megapixels when it comes to buying a new camera. Let me put this very clearly… MEGAPIXEL COUNT DOESN’T ALWAYS MATTER! The only time megapixel count really matters is when you’re going to be shooting something which has to be blown up large scale, such as a billboard.
Don’t drive yourself crazy over it! In the end, it really doesn’t matter that much.
Crop Factor
Most digital camera sensors are smaller than film. An image created with a 35mm body but smaller sensor will end up cropping a bit of the image out, as compared to what would have been captured with a full sized 35mm film frame. Hence the term “crop factor.” This determines how much of the image is cropped out as compared to a “full frame” sensor (a digital sensor the same size as 35mm film).
Be conscious of your gear. If your camera has a crop factor, it effects how you view the world through your lens. Because the focal length is effected, a crop sensor zooms in a bit with every lens. A 50mm lens is closer to a 70mm or 85mm lens. Each camera model has a different crop factor. Be sure to look if your camera has a crop factor and what it is.
To determine actual focal length, take the crop factor and multiply it by your lens’ focal length to determine the focal length you’re actually viewing. (I.e. – If you’re using a 50mm lens on a camera with a crop factor of x1.6, you’re actually shooting at a focal length of 80mm.)
Taken with a full-frame sensor
Taken with a camera that has a x1.6 crop factor
Last but not least, just a few tips:
– Don’t trust LCD backs for exposure! Always meter when possible. LCD’s don’t accurately depict the information recorded by your camera’s sensor. Something that looks perfectly exposed according to your LCD can actually be an entire stop under or over exposed. The only way to trust what you see on the back of your camera is to learn how to read histograms.
– Check out this article on how to read histograms: How to Use Histograms by Ken Rockwell
– It helps to turn on the “over exposure indicator.” This feature will cause the whites on your LCD screen to blink when they’re blown out. (When they contain no detail and are essentially just blobs of pure white.)
– And last but not least.. As boring and nerdy and tedious as it is.. READ YOUR CAMERA MANUAL!
If you’re just tuning in to today, be sure to check out Part 1 – Cameras and Part 2 – Exposure.
I know there was a lot thrown out over the past few days – hopefully you made it through okay! If you have any questions, feel free to shoot me an email at alana@alanatylerslutsky.com.
Happy shooting!
Alana
PHOTO SOURCE:
Feature Image & Photo 1: www.timeslive.co.za
Photo 2, 3, 4, 5: Alana Tyler Slutsky
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