Unit 1.3 Lenses and Filters
What are threaded filters?
circular filters that screw onto the front of your lens.
If you do need a filter to protect your lens, NYIP recommends you look around for a ______________ filter.
clear glass
Perspective Distortion: The __________ the object, the stronger the effect of perspective.
closer
In black-and-white photography, you can choose a _________ filter to either lighten or darken the gray tones that a color produces in the negative and print.
color
All neutral density filters are designed to be __________ neutral.
color o That is, they hold back equal amounts of all colors, so they don't shift the color mix of the light entering the camera.
A fisheye is a special-effect lens; _____________ is tremendous, with perspective lines ____________ ____________ from the center in all directions.
distortion curving out
What are skylight filters?
A skylight filter is a very pale magenta filter designed to warm the color of the subject a tiny bit. o You don't want that impacting your image capture.
What is a zoom lens?
Zoom lenses have variable focal lengths, and you can change focal lengths with a touch of your finger.
What is a crop sensor camera?
a camera with an image sensor that is much smaller than a frame of 35mm film.
What is flare?
a known imperfection (or aberration) in any lens.
What is a fast lens?
a lens that can transmit a lot of light "Lets in light fast"
What is a slow lens?
a lens that transmits considerably less light when opened fully. "Lets in light slowly."
What is a catadioptric (Cat) Lens?
a long focal-length telephoto lens that employs a curved mirror to increase the size of the image. o There are some specialized cat lenses used for low-light surveillance work and astrophotography.
Film can be properly exposed with light that strikes it at any angle. An image sensor, on the other hand, consists of ____________________________________________________________ and works better when light falls on it at a right angle.
a matrix of light-gathering photo sites set in "wells"
What is the one advantage to a Cat Lens?
a very long focal length can be contained in a relatively short barrel. o A typical 500mm cat can be under four inches long. This is significantly shorter than the regular 500mm telephoto lens, which can measure a foot or more in length.
In photography, we're not just interested in how much light enters the camera. What really interests us is how much light ...
actually reaches the digital sensor or film.
Perspective distortion gets ________ and ________ as the subject gets farther and farther away.
less and less Things begin to flatten out. Objects that are far away appear to be one on top of the other.
the farther the lens is from the sensor or film, the ...
less intense the light reaching it will be.
The ___________ the focal length of your lens, the larger the image of the subject will be.
longer
The ____ the focal length, the longer depth of field. (meaning more is in focus from near to far)
lower
The ___ the focal length - the wider the view
lower 35mm will be wider than an 85mm lens
lenses made for 35mm film cameras _____ _____ give the best results on digital models.
may not
Perhaps the most useful filter you can have in your bag is the ______________________ filter.
neutral density
The slotted holder system is ideal for what type of filters?
neutral density filters
The focal length of a lens determines ...
the size of the image of your subject that the lens forms on the camera's sensor
the speed of a given lens is designated by
the ƒ-number of its widest aperture.
ƒ/4 admits _______________ the light of ƒ/5.6; ƒ/5.6 admits ______________ the light of ƒ/8; ƒ/8 admits _____________ the light of ƒ/11.
twice twice twice
When talking about a zoom lens, what does it mean to talk about it's "widest view"?
when it is zoomed out as much as possible.
Regardless of the size of the sensor or film, the shorter the focal length of a lens, the _________ is its field of view. The longer the focal length, the _________ its field of view.
wider narrower
What are 3 types of mounting systems for filters?
1. Threaded Filters 2. Slotted Holders 3. Gelatin Holders
Name 1 advantage and disadvantage to gelatin holders.
Advantage: These filters are less expensive than glass and plastic filters Disadvantage: They're delicate and need more careful handling.
What is 1 advantage and 1 disadvantage to using a slotted holder system?
Advantage: You can use the same filter with different lenses as long as you can attach the holder to the lens. Disadvantage: You may need several different holders to fit your various lenses.
Filter Manufacturers: o Tiffen is the largest American glass filter manufacturer and their designers have won Academy Awards for Technical Achievement for some of their innovative filters, including the warm polarizer.
As a digression, it's worth noting that filters are used extensively in film and television where a very expensive cast and crew can't wait around on shooting days for the light to be "just right." Many of their special effects filters for motion pictures and television are available to photographers in their filter line.
Filter Manufacturers: o The U.S. arm of a German optics company founded in 1913, Schneider also makes black-and-white filters noted for water-, dirt-, and scratch-resistant multi-layer coatings.
Like Tiffen, they've won Technical Achievement Awards from the Academy of Motion Picture Arts and Sciences (four times, in fact).
Filter Manufacturers: o Cokin is the French company started by pro photographer Jean Coquin, who came up with the concept of creative filter photography in 1978 consisting of an innovative system of square filters to allow use on a variety of lenses of different diameters.
They make the most comprehensive collection of plastic filters for use with their filter holders. They also make a respectable collection of glass filters, but the plastic special-effects filters are worth a close look.
A lens that admits more light than another is said to be
"faster."
What is the purpose of a lens? (2)
1. To focus light rays to produce a sharp image on the sensor. 2. Admit larger amounts of light, permitting proper exposures in a small fraction of a second
What are 3 fast lens alternatives?
1. You could reset the sensor ISO to a higher setting. 2. You could put your camera on a tripod and set the shutter speed to allow light to hit the sensor for a longer period of time. 3. You could add artificial light to the scene with floodlights or an electronic flash.
What are 2 disadvantages to in-camera ND filters?
1. You don't have the ability to change the strength of the filter. If the camera manufacturer has decided on a three-stop ND, then that's the only option you have to work with. 2. You can't adjust the actual placement of the filter.
List 2 ways to vary the amount of light that reaches the sensor
1. shorten the focal length 2. widen the aperture
What are the most common conversion factors?
1.3, 1.5, 1.6
ND filters usually have a numbering system to describe how many stops of light they hold back. _______= 1 stop _______= 2 stops _______= 3 stops _______= 4 stops
0.3 = 1 stop 0.6 = 2 stops 0.9 = 3 stops 1.2 = 4 stops Example: If you're making a photograph in daylight and your exposure at ISO 200 would be 1⁄250 sec at ƒ/16, you could close down your aperture to ƒ/22 and use a shutter speed of 1⁄125 sec. That's probably the smallest aperture on your lens. Pop a 0.9 ND filter onto your lens and you can take your shutter speed down three additional stops to 1⁄15 sec.
Name and describe the 2 types of graduated ND filters.
1. A hard edge has a definitive line where the effect stops. Hard edge filters can be a bit difficult to work with, since the effect isn't gradually blended. The hard edge works well for ocean seascapes or flat landscapes. 2. However, for mountainous landscapes that require a gradual shift in the effect, the soft edge ND is the better option. These are useful in a wide variety of situations, and it will allow you to start making your landscapes more dramatic right away.
What are 3 ways to avoid linear distortion?
1. Keep the back of your camera parallel to the face of the structure you're photographing. If you can't get the entire structure in view, then either use a wider-angle lens or move back. 2. Use a view camera With a view camera you can move the lens up or down or side to side while keeping the face parallel to what you're photographing and the sensor or film in a fixed position. 3. Use a tilt shift lens (or PC lens)
List 3 disadvantages to a zoom lens.
1. Larger and heavier than prime lenses 2. Some may not be as sharp at any given focal length as the best prime lenses of that specific focal length. 3. They're slow. Most zoom lenses have relatively small maximum apertures.
Name the 2 types of polarizing filters.
1. Linear Polarizer: most autofocus and auto-exposure cameras are confused by the linear polarizer. 2. Circular Polarizer: is more commonly used and works better with most cameras.
What are the 3 Filter categories?
1. Physical filters that can be used with DSLRs and film SLRs. 2. Special color-correcting filters (also made of glass or plastic) that are best used with film SLRs. 3. Digital darkroom filters and effects that are applied to digital photo files in post production.
What are 3 things you can do to try to eliminate flare in a picture?
1. Place a lens hood on your lens This won't help if the bright light is directly in front of you. 2. Try aiming the lens in a direction that eliminates the flare. If you start turning slightly away from the light source, the flare will disappear at some point. 3. You can also try to block the light source by holding your hand (or a hat or piece of cardboard) above and in front of the lens. In effect, you're creating an extended lens shade.
What are 2 advantages to using a teleconverter?
1. Small 2. Reasonably priced (compared to a comparable telephoto lens)
When taking a portrait, you want to fill most of the frame with the subject's face. What are 2 problems you want to avoid when choosing what lens to use?
1. The "enlarged nose" problem that will occur if you get in too close with your lens. (wide-angle lens) 2. the "flattened face" problem that will occur if you shoot from too far away. (telephoto lens)
What are 2 disadvantages to using a teleconverter?
1. The image may not be as sharp as that obtainable with an equal-quality telephoto lens. 2. It reduces the amount of light entering the camera, and this may be a problem in some lighting situations. A 2x teleconverter reduces the light entering the camera by two stops. However, if you are using through the lens metering, your camera will automatically compensate.
Describe 2 instances where a polarizing filter will not work.
1. There are times when a polarizer won't be able to darken the sky. When you're shooting under an overcast sky or in a mist or fog, the polarizer is of no value because the light in these situations isn't polarized. 2. When using a wide-angle lens, the polarizer may darken one part of the sky and not the other because the lens covers such a wide area.
Name 3 disadvantages to a PC lens.
1. They're expensive 2. They offer you only a limited range of adjustment 3. They're time consuming to adjust
ƒ/2.8 allows ______ the amount of light of ƒ/11
16x • From ƒ/11 to ƒ/8 is double (2x) the amount of light. • From ƒ/8 to ƒ/5.6 is double again (2 x 2 = 4), so ƒ/5.6 allows 4 times the amount of light of ƒ/11. • From ƒ/5.6 to ƒ/4 is double again (4 x 2 = 8), so ƒ/4 allows 8 times the amount of light of ƒ/11. • And from ƒ/4 to ƒ/2.8 is double yet again (8 x 2 =16), so ƒ/2.8 allows 16x the amount of light of ƒ/11.
ƒ/2.8 to ƒ/11 you get ______ of the light.
1⁄16 • From ƒ/2.8 to ƒ/4 cuts out half the light (1⁄2). • From ƒ/4 to ƒ/5.6 cuts out half the light again (1⁄2 x 1⁄2 = 1⁄4). So from ƒ/2.8 to ƒ/5.6 you get 1⁄4 of the light. • From ƒ/5.6 to ƒ/8 cuts out half the light again (1⁄2 x 1⁄4 = 1⁄8). So from ƒ/2.8 to ƒ/8 you get 1⁄8 of the light. • And from ƒ/8 to ƒ/11 cuts out half the light again (1⁄2 x 1⁄8 = 1⁄16). So from ƒ/2.8 to ƒ/11 you get 1⁄16 of the light.
There are approximately ___ to the inch
25mm , so a 50mm lens is about the same as a 2in lens. A 100mm lens is about the same as a 4in lens.
You'll see that the polarizer is most effective when it faces the reflecting surface at between _______ and _______ degrees.
30 and 40 o So if you face the subject head on, you won't see much of an effect. But stand a bit to the side and the polarizer will do its magic.
Which lens will have a longer depth of field, 35mm or 85mm? (meaning more is in focus from near to far)
35mm
What is considered a "normal" lens? and why?
50mm (on a full frame, 35mm sized sensor) o This focal length captures the scene in front of your camera with a perspective that appears normal to our eye. (50mm focal length)
The diagonal of a 35mm frame is approximately ______________.
50mm long. Hence, the normal lens for this film size is approximately 50mm. So, too, for the other film sizes.
Which lens is better for portrait photography, 35mm or 85mm?
85mm
Which lens will drop the background off better, 35mm or 85mm? (meaning shorter depth of field)
85mm
Any lens that produces a flattering portrait is a good portrait lens. Lenses between _____mm and _____mm are most desirable for portraits.
85mm and 135mm
What is an Autofocus Camera?
A camera that automatically focuses on the subject by using a computer microchip that activates a tiny motor in the lens. * Usually this is done by pressing the shutter release button part-way down until the image is focused.
What is a Focus-Free Camera?
A camera where the lens's focus is preset at a medium distance to give reasonable sharp results with any subject about four feet away or beyond. Ex: a simple point-and-shoot camera and all single-use cameras.
What is an Interchangeable-Lens Camera?
A camera with a lens that can be removed from the camera body and replaces with other lenses. * With these cameras, you have the greatest freedom of creative control since you can select the precisely right lens for each situation.
What is an Adjustable-Focus Camera?
A camera with a lens that can focus over a range of distances. All lenses have a minimum focusing distance.
What is a Fixed-Lens Camera?
A camera with a lens that cannot be removed.
A colored filter __________ light of its own color, and ___________ light of other colors.
A colored filter transmits light of its own color, and holds back light of other colors.
What is a slotted holder filter system?
A filter system that uses a holder you attach to the lens. The filters are usually square, although they may also be round. In either case, the filters slip into slots in the holder that you've attached to your lens. You can insert a square filter all the way or partially to create a variety of different effects.
What is a a long lens (or long focal-length lens)?
A lens that is as long as its focal length
What is a fisheye lens?
A lens with such an extremely short focal length that its angle of view is close to or equal to 180°.
What is a macro lens?
A macro lens is one that can be focused so close to an object that the image it forms on the sensor or film is the same size as the real-life object itself.
What does a polarizing filter do?
A polarizing filter can prevent scattered light from entering your camera.
__________________________ serve the same purpose as filters used on a camera.
Adobe Photoshop filters o Rather than attaching a filter to your camera or inserting a gel over your lights, as in traditional photography, the computer applies a filter to the digital file containing your image.
What is the ideal focal length for portraits?
Any lens between 85-135mm. It's up to your personal preference. • 85-135mm will permit you to be close enough to maintain good psychological contact, yet to be far enough away not to be breathing down the subject's throat.
Name 1 disadvantage to using a polarizing filter.
At maximum polarization, the filter can reduce the amount of light getting into the camera by 1.5 to 2 stops, which is not desirable in many circumstances. While a polarizing filter is a wonderful tool, it isn't meant to stay on the camera at all times.
Why is a wide-angle lens usually the culprit in creating a distorted perspective, such as our example of the huge dog nose?
Because when you're shooting with a wide-angle lens, you tend to shoot from a position close to the subject, in order to fill the frame. The closer you are, the stronger the perspective effect.
Why is "reverse distortion" commonly seen in pictures shot with telephoto lenses?
Because most long-distance shots are taken with telephoto lenses. o In truth, the distortion would be identical with any lens at the same distance.
Most digital cameras have sensors that are smaller than a 35mm piece of film, so we've got to apply a __________ ____________.
CONVERSION FACTOR. This means that a "normal" perspective for those cameras would be more in the 35-40mm range.
What is the advantage to using physical filters instead of a digital filter (Photoshop)?
Camera-mounted filters help you get the picture right, the first time, straight out of the camera. o This will save you time sitting at the computer trying to fix an image. o Plus, images that require heavy alteration tend to appear overworked, and they may not hold up as well once they're enlarged.
___ tells us how much is in focus from near to far
Depth of field
The f-number system calculates your exposure by relating 2 variables -- ________ & ________ -- into one simple number
Focal Length & Aperture
If focal length is the distance to the image sensor from the center of the lens, that would mean that the lens barrel would have to be about the same length as the _________________________.
Focal Length. that is, a 100mm lens would have to be about 100mm (about 4 inches) long and a 400mm lens about 400mm (16 inches) long.
In order to hand hold your camera and be confident...your shutter speed should at least be the reciprocal of the ___ focal length of the lens.
HIGHEST Ex: at 70mm, the shutter speed should at least be 1/70th of a second. (The shutter speed that is above 1/70th is 1/90th.)
What are color-correcting filters and what type of camera using them?
Gelatin Filters that are used in film-making and FILM cameras.
There are an ever-changing number of filters included with Photoshop.
Glowing edges filter applied in Photoshop
What are Graduated ND Filters?
Graduated neutral density filters are designed to reduce the difference in brightness between the foreground and the sky.
What color filter will make red lipstick look darker in a black and white portrait?
Green
Explain how to use a polarizing filter.
How to use a polarizing filter: o Regard the filter as though it were the hands of a clock. o Let's say that at 12:00 all polarized light can get through. As you rotate the filter to 1:00, less polarized light can get through. Even less at 2:00. And the least possible at 3:00. If you continue turning the filter to 4:00, more polarized light will start to be transmitted. Even more at 5:00. At 6:00 all the polarized light will again be transmitted. o So the trick is to turn the filter the right amount to cut out the greatest amount of polarized light.
What kind of lens would be an alternative to the long lens?
Image Stabilization Lens (or vibration-reduction lens)
What does a 2x teleconverter do?
It doubles the size of the image, effectively doubling the focal length of the lens it's attached to. If you attach it to a 50mm lens, the image it produces is the size that would have been produced by a 100mm lens.
The image a lens transmits is determined by 2 characteristics that are built into the lens itself:
Lens speed and focal length
What focal length is considered a fisheye lens?
Lenses of 16mm or less (on a 35mm film camera) are generally classified as fisheyes.
What is another name for distortion that results when you try to photograph tall, straight structures from close up—for example, buildings or trees?
Linear Distortion
Define Linear Distortion
Lines that are actually parallel do not appear to be parallel.
Appropriate terminology for macro lenses: o ____________________—a lens with a reproduction ratio around 1:1. o ________________________—a lens with a reproduction ratio between 1:1.2 and 1:2. o ______________________—a lens with a reproduction ratio between 1:2 and 1:4.
Macro Lens Macro-focusing lens Close-focusing lens
Neutral Density filters are also referred to as ________________________.
ND Filters
Are wide angle lenses the only lenses that create linear distortion?
NO Any lens will create linear distortion of a tall structure if shot from a tilted camera angle, and it can happen when you point the camera down as well as up. o The problem is more pronounced with a wide-angle lens because of the more rapid fall off in size
Are skylight filters necessary?
NO o Some photographers use a skylight filter to protect the front surface of the lens. o Unless you are working in situations where you'll encounter a lot of dust, sand, and dirt—or you photograph babies with dirty hands and a tendency to sneeze!
Is a 50mm lens the normal lens for all cameras?
NO. The normal lens for a camera depends upon the size of the CCD chip or the film used in the camera. The larger the chip or negative, the longer the focal length required to create an image covering the "normal" field of view.
Name 1 very common application for graduated ND filters.
One very common application for these filters is for photographing sunsets and landscapes. o These will help to balance a bright sky and shadowy foreground.
What are PC Lenses(or tilt shift/TS lenses)?
Perspective control lenses • These lenses look like ordinary lenses except that they have a handle attached. When you turn this handle, the face of the lens screws upward, downward, or sideways. As you peer through your viewfinder, you can see the image changing with the position of the lens. You keep changing the lens position until you see the image you want. Then shoot.
A blue filter transmits light of blue objects and holds back light of other-colored objects. A green filter transmits light of green objects and holds back light of other-colored objects. A red filter transmits light of red objects and holds back light of other-colored objects.
Photo Examples: o Picture 1 shows the subject photographed in color without a filter, o Picture 2 is in black and white without a filter. o Picture 3 was photographed through a red filter. o Picture 4 was shot through a green filter. Notice the effect that red and green filters have on the lipstick and nail polish. The red filter (Picture 3) darkens the blue polish and lightens the red lipstick, while the green filter (Picture 4) does the opposite.
Today, all of the subtle corrections from CC Filters are made using ______________________________.
Photoshop or other image-editing software
What color filter will make a blue sky appear as a darker shade of gray than if you took the photo without a filter?
Red
What are gelatin holder filter systems?
Similar to the slotted holders for glass and plastic filters, there are also gelatin filter holders which are designed to hold very thin acetate filters (gelatin filters) in front of the lens.
What is an image stabilization lens?
The image-stabilized lens does some optical magic, enabling you to get a sharp image even when shooting at slower shutter speeds.
How do you know the diameter of a lens?
The lens is usually marked somewhere on it with the symbol Ø
How do you determine the speed of your lens?
The maximum aperture of your lens (that is, its lowest ƒ-number)
What is a reproduction ratio when talking about macro lenses?
The relationship of the size of the image on the sensor to the size of the actual object.
How do filters on point-and-shoot cameras work?
There are magnetic filter systems with a metal ring that fits around the camera lens, keeping a filter holder in place. They also have a shoe holder that affixes to the tripod mount screw-thread socket found on the bottom of most cameras. The filter may not fit right against the lens, raising the danger of glare in some circumstances
What are step-up rings?
These are adapter rings that will let you attach a filter that's designed for a lens with a larger diameter to a lens with a smaller diameter. For example, if you have a filter for a 72mm diameter lens and you want to use it on a 67mm diameter lens, the adapter ring will screw into the 67mm lens and hold the 72mm filter.
What do Equal Density ND Filters do?
These filters are used to reduce the overall light entering the camera. o This can be helpful if you want to make a very long time exposure that exceeds the exposure time required if you set your lens to its smallest aperture.
What are enhancing filters?
These filters contain certain rare earth elements that remove a portion of orange-colored light, which makes some red objects appear to have a higher color saturation by eliminating some mid-tones. o One of the most common uses of these filters is to get greater saturation of red leaves in fall foliage photographs.
What is a teleconverter?
They are optical adapters that attach between a lens and the camera body. • Also called tele-extenders. • Offer varying amounts of magnification
Filter Manufacturers: o HOYA is a large Japanese manufacturer that makes glass for optical disks and eyeglasses, as well as filters.
They have a wide range of glass filters for photographers.
What is Vignetting?
Vignetting is the result of putting something on the front of a lens that blocks some of the light around the edge.
An f/2 lens is faster than an f/4 when wide open, however, would both admit the same amount of light at f/8?
YES
Besides the 3 ways to avoid linear distortion, are there alternative ways to correct an image?
YES You can use software like Adobe Photoshop to greatly reduce the distortion. While it's quite effective, this method presents its own complications, such as the need to crop the image after applying the correction. However, if you're specializing in exterior, or architectural photography, then you may want to consider a perspective correction (PC) lens.
Are there filters available for strobes, lights and windows?
YES o If you're interested in the possibilities of this kind of light manipulation, visit the LEE Filters website. They are a company that specializes in large sheets of plastic and gelatin filters for film, television, theater and architectural lighting, as well as still photography.
Can a macro lens function as a regular lens of its particular focal length?
YES.
Can macro lenses be of any focal length?
YES. Although they are typically 50mm or 105mm
Are filters available for point-and-shoot cameras?
Yes
Name one disadvantage to digital lenses.
You can't use a digital lens on your 35mm film camera because it won't cover the larger surface area of the film. o Although you can get good results with a film camera lens on your digital camera
Can you use color-correcting filters with DSLRs?
You don't need them! o You can achieve similar results by selecting different white balance options when you make your photograph, or correct any unwanted color cast after you make the photograph using image editing software. o Most DSLRs offer a few options, including automatic presets, manual adjustment of color temperature, and custom white balance. For color correcting, the automatic presets will work very well in most situations. In addition, many of the more professional editing solutions like Adobe Lightroom, Adobe Photoshop, and Apple's Aperture will allow you to fine-tune the presets.
What is a disadvantage to threaded filters?
You need to have a filter that's the same size as the front diameter of your lens. If you have a lot of lenses, you might need to have several different sizes of each filter.
What have lens manufacturers done to try to eliminate flare?
almost all modern lenses are coated on both surfaces of each element with microscopic layers of chemicals that reduce the reflectivity of these surfaces. o While the coatings can reduce flare, they can't eliminate it altogether, especially when the lens is pointed directly toward a source of very bright light.
Filter Manufacturers: o Heliopan. This German filter manufacturer started in 1949,
and Heliopan is the only filter maker using glass from legendary Schott Glass Manufacturers.
You should compose and focus your picture ____________ you adjust the polarization.
before o If you're using a zoom lens, zoom to the desired focal length first. That's because with some lenses, focusing and zooming may rotate the outer lens element and the filter, changing the amount of polarization you've carefully set.
Filters with a Gimmick These should be used more sparingly, but in the right situations they can be used to create interesting effects. • Remember, what may be artistic in a few carefully chosen images, can easily sink into a __________ ____________ if overdone. Discretion is the operative word here.
boring sameness (Diffusion, mist, and soft filters can be used to smooth skin surfaces while retaining overall image clarity. They let you create dreamy, misty, romantic photographs. They soften hard edges, lower contrast, mute colors, and can add slight shimmering halos around highlights.)
What is another way to determine the normal lens for a given film/sensor size?
by measuring the diagonal dimension of the film/sensor frame.
When a lens is pointed up, all vertical lines ____________________________________________.
converge toward the center. This effect can be unpleasant if you're nearer one side of a building than another, since the parallel walls of the building will converge at different angles.
In a fisheye lens...A straight line through the center will remain straight, but straight lines in all other parts of the picture will ___________.
curve
Closing down (also called stopping down) one full ƒ-stop ___________________________.
cuts the light in half
Telephoto Lenses: Review: Focal Length is the .....
distance to the image sensor or film from the center of the lens.
You can use a polarizer to ____________________ a blue sky in either a color or black-and-white picture.
darken o The blue of the sunlit sky is partially composed of polarized light, and a polarizer can cut down the amount of this light that enters the camera. If you reduce the amount of light, you darken the image—as a result, the sky appears darker.
Many of Photoshop's filters are inspired by ______________________________ and can be used to recreate the classic aesthetics from various techniques used to manipulate an image.
darkroom techniques
Don't confuse the ______________________________ with its focal length.
diameter of the lens Often lenses of different focal lengths have different diameters, and lenses of similar focal lengths from different camera manufacturers also have different diameter sizes.
What is a full frame camera?
digital cameras with full frame sensors, which are the same size (24mm × 36mm) as a frame of 35mm film.
Name one advantage to a digital lens.
digital lenses can be made smaller, lighter, and cheaper than lenses for film cameras, because they don't need to cover a full-sized 35mm sensor, But you'll still need to multiply their focal lengths by your camera's multiplication factor to determine their 35mm equivalent focal length.
A Fast lens enables you to take pictures in light that is too _______ for a slower lens without going to ________________________________.
dim a slower shutter speed
The amount of darkening (from a polarizer) depends upon the angle of the sun relative to your camera. o If the sun is ________________________________ of the camera, the polarizer won't help. o The sun should be at approximately______________________________ to the direction the camera is facing. o The polarizer will work best when the sun comes from ___________________________________.
directly in front or in back a right angle the side or from directly overhead
The size of the image is ___________ ___________ to the focal length that was used.
directly proportional If you double to focal length, you double the size of the image (all other things equal).
A wide-angle lens ________________ distort perspective any more than any other lens, provided you photograph the subjects from the same distance with all the lenses.
doesn't
However, to assure razor-sharp images, we suggest that you set your shutter speed even faster. We recommend that you set it to ___ the focal-length of the lens.
double That is, a 100mm lens should not be handheld less than 1⁄200 sec, a 500mm lens should not be handheld less than 1⁄1000 sec.
Shutter Speed Rule of Thumb: (Hand holding the camera) • To assure razor-sharp images, you should set your shutter speed to _________________.
double the focal-length of the lens o That is, a 100mm lens should not be handheld less than1⁄200 sec o A 500mm lens should not be handheld less than 1⁄1000 sec.
Opening up one full ƒ-stop ____________ the amount of light entering the camera.
doubles
What do they mean when they say a "Full" f-stops?
each one is a whole stop away from the previous or succeeding one.
The size of the aperture is indicated by a number called the ___________
f-numbers, or f-stops
A ___ ___enables you to take pictures in light that is too dim for a slower lens without going to a slower shutter speed.
fast lens
Do not confuse and fast and slow lens with the ability to capture _____.
fast-moving objects. The term fast, when talking about a lens, has little to do with its ability to stop motion. (That would be shutter speed)
What you need to know is your camera's _____________ ___________ ___________ ____________. This is the factor by which you can multiply the actual focal length of a lens to determine its 35mm equivalent length.
focal length conversion factor (or multiplication factor)
the ƒ-number system is not illogical; it's just a bit confusing at first. It's based on
fractions, and just as ¼ of an inch is smaller than ½ of an inch, so ƒ/4 is a smaller opening than ƒ/2.
Neutral density filters are designed to ______________________________________________________.
hold back some of the light in the scene, reducing the amount of light that enters your camera
How much light reaches the digital sensor or film depends, in part, on...
how far the lens is from the sensor or film.
How does the focal length of a lens affect the picture area?
it determines how much or how little of a scene will fit into the picture area
What does it mean if a lens is designated as a "portrait lens"?
it is designed to produce a soft focus, thereby camouflaging the subject's wrinkles and blemishes. o These, however, are probably not the lenses for you unless you're shooting with a big 4 × 5 inch or 8 × 10 inch studio camera. • As for the soft-focus effect, there are special filters you can put on your lens to achieve the desired look, or you can create the effect with image-editing software.
A longer focal length produces a ________ image.
larger image And of Course, when the image is larger, only a smaller part of a scene can fit into the picture area.
Your minimum shutter speed to use depends on the ___ of your lens
length
What is a prime lens?
lenses with a single, fixed focal length. In order to shoot with a different focal length, you have to detach one lens from your SLR or DSLR and attach another.
A longer focal length, means more or less will be in focus from near to far?
less
Reproduction Ratios for Macro Lenses: o A ratio of 1:1 (pronounced "one to one") means that ________________________ o A 1:2 ratio means that __________________ o A 1:3 ratio means that _____________________
o A ratio of 1:1 (pronounced "one to one") means that a life-size image is produced on the sensor or film. o A 1:2 ratio means that the image is one-half the size of the actual object. o A 1:3 ratio means that it's one-third the size, and so on.
List 4 effects that a polarizing filter does.
o Darkening skies o Enhancing clouds o Increasing color saturation o Reducing glare from non-metallic surfaces.
How and why does linear distortion happen?
o If you're using a wide-angle lens, you figure you can get in close and still take in the entire structure if you just tilt your camera up a little bit. Result: Buildings or trees appear to be falling • What has happened is that by tilting the camera upward, you aimed your lens in a direction that caused the sides of the building or trees to act like the classic railroad tracks that converge toward the center, creating the normal perspective of depth.
Name 4 types of filters and what they are used for.
o Neutral density filters reduce the amount of light coming into the camera. Used with slow shutter speeds in bright conditions o Graduated neutral density filters are darker on top and lighter on the bottom. Good for shooting landscapes with sky o UV Filters are clear glass Often used to protect a lens o Polarizing filters reduce reflections and glare. Good for shooting glass and water They have 2 rings that can be adjusted to align the way the light comes into the lens.
What is the difference in optical zoom vs digital zoom?
o Optical zoom means that the actual glass elements of the camera's lens cover the entire zoom range offered by the camera. o Digital zoom is used to extend the maximum magnification of the lens beyond that which can be captured optically by the lens. A digital zoom simply crops into its largest magnification and then "stretches" that information as the computer calculates what additional pixels would look like and inserts them into the image.
What are 2 disadvantages to Cat Lenses?
o The best cat lens doesn't produce as sharp an image as the equivalent telephoto lens. o A cat doesn't have a variable diaphragm. Instead, the aperture is fixed. Typically it's fixed around ƒ/8 or ƒ/11. Although you can adjust your exposure by changing shutter speeds, you can't adjust the diaphragm opening to change the amount of light passing through the lens.
List 3 disadvantages to a telephoto lens.
o The longer the lens, the more expensive. o Large and heavy o The longer the lens, the harder it is to hold the camera steady to avoid blurring the image.
What can cause vignetting?
o You've used a filter that's too small for the lens o You're lens hood is too small or extends too far out o Your lens is too small for the camera o Too many filters are stacked on top of each other
A zoom lens often has 2 maximum apertures, explain...
one for the position where it takes in the widest view of the scene, the other for where the lens is zoomed in as far as possible. • For example, if you have a zoom lens that is marked ƒ/3.5-ƒ/5.6, it means that, at the wide end of its range, its speed is that of an ƒ/3.5 lens, but, at the other end, it drops to ƒ/5.6.
Aperture is another word for _______
opening
Some digital ______________________ cameras have a built-in neutral density filter.
point-and-shoot or compact o This isn't an actual physical filter, but rather an electronic adjustment that's made internally.
Shooting with a telephoto lens may cause a "______________" distortion.
reverse
The function of a polarizing filter is to block this vibrating light. That's why the polarizing filter has to be ____________ to a place where it achieves optimal results.
rotated As you rotate the filter, you cut down the amount of vibrating light that can get through.
However, if you measure a long lens, you will probably find that the lens is considerably _____________ than their indicated focal length.
shorter o For example, the typical 400mm lens is not 16 inches long. It's usually under 10 inches long.
These aspects of perspective are true of all lenses. o The farther away an object is, the _______________ it appears. o The _________________________ the lens is from the object, the less the change in apparent size.
smaller farther away
What are digital lenses?
specifically engineered to work with digital image sensors of a specific size. o Basically, these lenses are engineered to project a smaller image circle that's more appropriate to a sensor that's smaller than a 35mm piece of film.
What do telephoto lenses do?
take in a narrower view of the scene and make the subject look closer than it is. (150mm focal length)
What does a wide angle lens do?
take in more of the scene, and make things look farther away than they really are. (24mm focal length)
Because of special optical design, a lens can be constructed with a long focal length in a shorter barrel. Such lenses are technically called ______________________.
telephoto lenses
The effects of a polarizing filter are very difficult to reproduce in _________________________.
the digital darkroom
An aperture of ƒ/8, represents a specific amount of light reaching the sensor or film. It's a figure that already takes into account ...
the focal length of the lens and the size of the aperture. o Any lens set at an aperture of ƒ/8 admits exactly the same amount of light that is admitted by any other lens open to ƒ/8.
How is the light hitting the digital sensor affected when the lens is closer (short focal length)?
the light is more intense.
Lens speed refers to...
the maximum amount of light that a given lens can transmit in a given length of time.
There are also macro lenses that conveniently ___________________________.
zoom to several focal lengths. Don't confuse these with zoom lenses that have a so-called macro setting and may be called "macro-zoom lenses." The macro setting on a zoom lens is actually only a close-focusing setting since it doesn't give you the 1:1 reproduction ratio of a true macro lens. Nevertheless, the macro setting can be a very useful feature.
Name the 13 "Full" f-stops:
ƒ/1 ƒ/1.4 ƒ/2 ƒ/2.8 ƒ/4 ƒ/5.6 ƒ/8 ƒ/11 ƒ/16 ƒ/22 ƒ/32 ƒ/45 ƒ/64
Why does flare happen?
• A camera lens is composed of a number of different individual glass lenses—called lens elements—mounted together as a group. When a bright light passes through a camera lens, part of the light will reflect off the various surfaces of these lens elements. This internal reflection can cause ghost-like blobs of light to appear in the resulting image. o Flare can also cause an overall fogging of the image, almost as if a veil had been thrown over it.
What is the difference between a circular and full frame fisheye lens?
• Circular Fisheye Lens: The image will usually form a circle within a sensor or frame of film and not fill the rectangle • Full-Frame Fisheye Lenses: a lens that will produce an image that will fill the entire frame
What are Color-Compensation (CC) Filters?
• Color-compensation filters were created for film photographers using view cameras to make slight color modifications during exposure. • Today these filters are very rare. They have been largely displaced by the shift in professional photography from film to digital. • CC filters come in six colors: Red, Blue, Green, Cyan, Magenta, and Yellow. They're made in both gelatin and glass. The amount of color in each filter is in units of 5, so you might see a CC20 Blue filter specified for a certain color correction. It would be 4 times stronger than a CC05 Blue filter.
What is a PC or Shift Lens?
• These special lenses are useful in architectural photography. • The PC Lens - or Shift Lens - is designed to straighten out the lines when photographing tall buildings. o With a normal lens, sometimes a tall building's walls will not appear straight or the building looks like it is about to tip over.
