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APERTURE- Find a volunteer, a flashlight, and a partially darkened room. Look closely into the eye of your volunteer. Examine the size of the person's pupil (the black, center portion of the eye). Now, while still looking at the eye, shine the flashlight towards the person's eye. The pupil will become dramatically smaller as the iris closes to let less light into the eye. This is how the aperture of a camera works. The aperture is an iris in the lens that can be opened or closed to allow more or less light into the camera. The smaller the aperture the less light it allows to enter through the lens. This is one of the ways a camera regulates exposure.

BOTTOM WEIGHTED - Refers to the area of the pictue that the camera will meter for exposure. When making an auto exposure the camera is programmed to look at a number of spots in the scene, and if the camera was designed to use bottom weighted metering, most of those spots will be in the lower half of the picture.

CCD - This the light sensitive device in most all digital cameras that turns the light entering though the lens into electronic signals that can be digitally processed and saved. It stands for Charge Coupled Device.

CENTRE WEIGHTED - Refers to the area of the pictue that the camera will meter for exposure. When making an auto exposure the camera is programmed to look at a number of spots in the scene, and if the camera was designed to use centre weighted metering, most of those spots will be in the centre area of the picture.

COMPACT FLASH - Also known as CF cards, this is the other type of removable memory card. The controller is built onto these cards, so as new and faster controllers are designed you can purchase the newer card and take advantage of faster write times. These tend to be a bit more expensive than Smartmedia (SSFDC) cards. Any device that is designed to use a CF card can use any brand of CF cards so long as it meets the CFA (Compact Flash Association) standards (virtually all of them do). There are palmtop computers, voice recorders, and other devices that can use the same cards as your CF compatible camera.

COMPRESSION RATIO - Compression is a function of the camera's internal programming to take a picture and store in less space than it would normally fill. Virtually all digital cameras save their pictures as JPG (Jay-peg) images because JPG images can be easily compressed. The program in the camera looks at the picture and sees if there are similar pixels in an area., If there are it remembers this and only saves some of them, but uses them to reconstruct the surrounding area of the picture later.

The compression can be of different ratios such as 1:2, 1:4, 1:11, 1:19 and so on (these ratios are sometimes referred to in the camera with terms like Good, Fine, Better, Best, Normal, etc. by the manufacturers). Ratios above about 1:10 are quite high. When the compression is that high, the uncompressed image will have "artifacts" in it. That is, stray pixels that don't match what is around them because the un-compressing didn't guess very well as to what the picture use to look like. 1:19 makes a real mess of even the best photographs. 1:4 is almost unnoticeable in most cases. (The compression and decompression when saving and viewing JPG images is automatic for the most part.) It would not take long for even the largest memory cards to be filled with images in the 1280x1024 range if they were stored full size, so some compression helps. The physical size of a compressed image will vary depending on the subject matter. A pure white wall will compress well, but a large tree with lots of leaves (and thus detail) will not. All compression ratios are not always available in all resolutions- read the specification to be sure that these can be selected separately.

DEPTH OF FIELD - A photograph that shows the area close to the camera and things far away all in good focus is said to have a large depth of field. A narrow depth of field is when only a thin section of the scene, say from ten to twelve feet away from the lens, is in focus. With a film camera, setting a large aperture (wide open iris) gives narrow depth of field, and a small aperture (closed down iris) gives a wide depth of field. Few cameras in the price range below $1500 can control depth of field from user input. A change in aperture means that the camera should also change the shutter speed to maintain correct exposure.

DIGITAL ZOOM - In some digital cameras the manufacturer makes the choice to not include an optical zoom lens. This makes the camera quite a bit smaller as can be seen with some of the pocket-sized digitals on the market. Some of those pocket cameras offer digital zoom. The camera takes a portion of the image and magnifies it digitally. Unfortunately, these images get fuzzy in a hurry because a smaller amount of information is being used to create a larger image because the camera has to create the missing information.

DIOPTER CORRECTION - This is like a focus adjustment that matches the focus of the camera's optical viewfinder to the user's eyesight. This way, users don't have to wear their glasses when using the camera. As some of the viewfinders are quite small and difficult to use with your glasses on, diopter correction can be a welcome option for eyeglass wearers.

EXPOSURE - The exposure setting in a camera is what regulates how much light is used to create the image. It doesn't matter whether it is a film camera or a digital camera. The exposure can be controlled in two ways; aperture adjustment and shutter speed adjustment.

EXPOSURE COMPENSATION - Many cameras have the ability to force the camera to overexpose or underexpose an image during capture. This can be done for effect or to compensate for some particular lighting situation. This is often referred to as EV compensation.

F STOP - The f-stop of a lens is a number that represents the aperture opening. A large opening is a small f number, and a small opening is a large f stop. Lenses are rated in the range of f-stop numbers they can be set to. Pay particular attention to the lowest number. If a lens is rated, "f3 to f22," the f-3 is what you care about. This represents the lens' ability to pass light. The smaller the number the more light the lens can admit which improves the camera's ability to capture images in places with low light. Some of the best 35mm film cameras have lenses that are rated at around f1.2 and f1.8. In digital cameras you will do well to get a lens in the area of f2.8.

FLASH SYNC - A special socket on a camera that allows to attachment of an auxiliary strobe light for flash pictures. It is synchronized to the camera's shutter so the light goes off at the right time. Most all 35mm SLRs and a few digital cameras have this feature. Some 35mm SLRs have a "hot shoe" which is a special mount built into the camera that allows for attaching a strobe light.

FLASH RANGE - The effective distance the strobe light can illuminate the subject. Most digital cameras that have built-in strobe lights are effective to about 12 to 15 feet. It varies by brand so check the specifications carefully.

FOCAL LENGTH ("35mm EQUIVALENT") - The lens in a digital camera is almost always smaller than in a 35mm SLR (single lens reflex) camera. Because of that the actual focal lengths mean little to those who are already familiar to photography. To assist in understanding, digital camera manufacturers state the focal lengths of the lenses in terms of "35mm equivalent."

FOCUS - Camera lenses have to be focused on the subject to create a clear image just like your eyes do. Some cameras feature a lens with "fixed focus." This means that the lens was designed to be in focus all the time. This range is usually from about ten feet to infinity. Fixed focus lenses are usually found in cameras in the lower price ranges. Better cameras have auto focus. There is some sort of mechanism in the camera that moves the lens elements to bring the image into focus. Some cameras are quite good at this and some have difficulty in low light situations. Most digital cameras have some sort of setting to force the camera to focus into some range such as Macro and Distant. A number of digital cameras also feature manual focus. If the camera has a decent auto focus feature then manual focus is not necessary.

MACRO - Macro focus is the ability of the camera to focus on objects close to the camera- closer than about 12". When used in conjunction with a zoom lens, macro can allow the photographer to fill the viewfinder with small objects- with some cameras, a dime can nearly fill the frame. This is useful with flowers, insects, and other such small items. Some cameras have a different macro distance for the wide angle setting and the telephoto setting.

MATRIX METERING - When a digital camera has to set the exposure automatically (the aperture and shutter speed) it often uses matrix metering. The matrix is a set of areas, or spots, in the picture that the camera looks at and averages to decide on aperture and shutter speed settings- the exposure settings. Sometimes this is "center weighted" meaning the most of the spots are in the center of the frame, and sometimes it is bottom weighted.

MEMORY CARDS - These are small memory modules that can be inserted into the camera to hold images. When the card is full it can be removed and another card inserted. The memory on these cards is non-volatile-m that is, they don't lose their images when they are removed form the camera. The images can be later downloaded from the card, and when the images are erased from the card it is ready to be reused. These cards are good for a lot of reuses- one manufacturer just warranted their cards for a minimum of 1,000,000 images.

MULTI CAPTURE - Allows a number of pictures to be captured in fast succession. It is the electronic counterpart to motor drives and power winders in film cameras. It allows the camera to take a series of pictures, one right after another, by holding down the shutter release. It can take pictures as fast as from two to four frames per second. As many as from eight to twenty pictures can be captured at one time. The speed and number of frames varies depending on the specific brand and model of camera. This is almost always accomplished in lower resolution modes with the flash off to limit the amount of memory needed and increase the speed of the capture.

NiMH - Stands for Nickel Metal Hydride. A type of rechargeable battery that produces sufficient current for digital cameras. They are rechargeable like Nicad batteries but they are safe to throw away in landfills. They also do not exhibit the "memory" effect that Nicad batteries have shown to exhibit. They need chargers that are specifically made for NiMH batteries.

OPTICAL ZOOM - A zoom lens that achieves its magnification by moving parts of its lens forward or backwards. This usually takes place inside the camera, out of view, but can often be heard as the sound of a small motor and other mechanical parts.

OVER EXPOSED - An over exposed picture means that too much light was allowed to strike the film (or the proper amount of light was allowed to strike the film for too long), That means that the aperture was too large for the exposure time, or the exposure time was too long for the aperture setting. This will give an image that is too bright or washed out.

RED EYE REDUCTION - We have all seen "Red Eye" in still photos. It is when the flash reflects off the back of a person's eyes and they appear to glow red in the picture- thus "red eye." The trick to help eliminate this is to make sure that the iris of the subject's eyes are as small as possible before taking the picture. Cameras can do this by flashing a bright light at the subject just before the picture is taken. The first bright flash causes the person's eyes to close, and then the picture is taken with the regular flash of the strobe.

RESOLUTION - This is the amount of information in a digitally captured image. It is measured in pixels. These are the individual elements that are like little tiles, that make up a digital image. The more of these pixels there are, the higher the resolution the picture has, and thus the more photographic the image will be. Higher resolution images can also be printed at larger sizes with more photographic results. A high resolution camera will be capable of capturing images in the 1280x960 and above. These are referred to as "mega-pixel" cameras. That is because if you multiply the height by the width, the total is greater than 1,000,000 (a meg is one million). It means that the picture is made up of over one million pixels. This is one of the major aspects that controls the price of a camera. Generally, the higher the resolution the more the camera costs. Many cameras usually give you the choice of at least two resolutions. A high resolution such as 1280x1024 for high resolution images, and a low er resolution of 640x480. A lower resolution is handy because it allows you to get more pictures in the available memory, and will still print well at 4x6 (but not larger). The larger resolutions take a lot more room in memory, but allow for printing at sizes up to about 8x10. The larger pictures also allow liberal cropping leaving an image that can still be printed with good results. A few cameras achieve their upper-most resolution through interpolation- that is, the camera actually can only achieve a lower resolution, and then it electronically makes the image larger. These interpolated images are usually not as sharp as a normally captured image.

SELF TIMER - The self timer allows the camera to take a picture unattended. With it you can take a picture of yourself. Once the timer is set, you usually have about ten seconds to get into the picture. A flashing light or a tone signals when the picture is about to be taken.

SHUTTER SPEED - Somewhere in the camera is a shutter. In film cameras this can be some sort of metal door or a cloth screen. In digital cameras it may be purely electronic. The shutter opens (or turns on) and starts the capture of the image. When the image is correctly exposed it closes (or turns off). The amount of time is usually very small. Normally it is 1/60th of a second or less- speeds up to 1/10,000 of a second can be reached by some digital cameras, although speeds in the 1/125 to 1/500 are more common for most picture taking environments. Few, if any, digital cameras allow the user to adjust shutter speed. This is usually done automatically in the camera. The faster the shutter speed, the better the camera is at 'freezing' motion. Slower speeds are good in dark environments to allow more time for the image to be exposed. Be aware that not all shutter speeds are always available at all resolutions, so read the specifications carefully.

SLAVE STROBE - If a camera does not have a flash sync socket or a hot shoe and you wish to use an auxiliary strobe light, you can get a slave strobe. This is a strobe light that has an electronic eye that senses when another strobe goes off which then sets off the slave strobe. Slave units are also available to trigger a regular strobe. Some digital cameras need special slave strobes because they fire a pre-flash before the actual flash for the picture. This pre-flash fools the slave strobe causing it to fire before the picture is taken.

SPOT METERING - Spot metering for exposure is a method used in some SLRs and some digital cameras as well. It works like this:
There is an area marked in the optical viewfinder in the center of the image. This is the area that the camera uses to set exposure- the area of the scene that is metered. You view the scene so that the main area of the subject (such as a person's face) is in this marked area and half depress the shutter release button. This locks the exposure for that area. Now compose your shot keeping the shutter half depressed. When you fully depress the shutter release the photo is taken at that setting. Some cameras also have spot metering for focus. In the case of the Nikon CP900 it works in conjunction with spot metering for exposure, and in some cases, such as in the Kodak DC260, it is only spot metering for focus and not for exposure. Do not confuse the two when looking at specifications.

SSFDC - This is a type of removable memory card- it stands for Solid State Floppy Disk Card (also known as "Smart Media"). It should be called "Dumb Media" because it is just a memory card with no processor. The processor is in the device that uses this type of memory card. They are convenient because they are very small, and are fairly inexpensive. It is not interchangeable with CompactFlash cards.

TELEPHOTO LENS - You can think of telephoto as the opposite of wide angle. This is the range from about 55mm and above. Film cameras can have lenses that range up to and above 1,000mm. With digital cameras, most only go to about 115mm. It is like using a pair of binoculars or a telescope.

THREADED LENS - Some cameras allow the addition of additional lenses to increase the telephoto range or allow greater magnification for macro work. The most convenient way to add these accessory lenses is by means of a threaded lens. The end of the lens housing has threads that these other lenses can thread into, or onto which an adaptor can be attached to accept the accessory lenses.

UNDER EXPOSED - An under exposed picture means that too little light was allowed to strike the film (or the proper amount of light was allowed to strike the film for too short a period of time). That means that the aperture was too small for the exposure time, or the exposure time was too short for the aperture opening. This will give an image that is too dark.

VIEWFINDERS - OPTICAL and DIGITAL- Film cameras feature viewfinders that are optical. You look into a little "window" on the back of the camera and there is the approximate picture that will be taken when the shutter release button is pressed. The view can be either TTL (through the lens) or through a separate, smaller set of lenses. Many digital cameras feature the latter type of viewfinder, and some even offer true TTL viewing (the Olympus D500 and D600 are the examples). Many digital cameras also feature an LCD (Liquid Crystal Display) viewfinder as well. These color screens are about 2" in size and show a fairly accurate preview of the scene about to be captured. Some cameras that have LCDs do not use them for preview of images- only for review after a picture has been captured and saved. Some cameras feature both, and overall, those types are the best choice. The LCD is very handy: it can be used to view images after capture so you can delete unwanted images in the field to save space. It can be used to frame pictures that would be difficult to compose otherwise, such as shots below waist level or overhead. Avoid cameras that feature only an LCD viewfinder. Without an optical viewfinder, shots taken in full sunlight can be difficult or impossible to compose as the LCDs are not bright enough for use in bright sunlight.

VIDEO OUTPUT - Some cameras have an outlet built-in that allows the user to attach a cable from the camera to a VCR or other video device that accepts NTSC ( in Europe, PAL) video signals. The camera can then show its pictures on the television screen. This can be used to look at the images without a computer for a slide show or presentation. Images can also be saved on video tape to be sent to people who do not have computers, or used as presentations.

WHITE BALANCE - This is the ability of the camera to adjust the color balance of a picture to compensate for the ambient lighting. It is easy to see that flourescent lights have a different color from incandescent lights. These are both different from the light that a photo flash gives off, and they are all different from the color of the light from the sun. This is often adjusted automatically in digital cameras, and it makes picture taking easy. If a camera possesses this function it is said to have "auto white balance."

WIDE ANGLE LENS - The normal angle of view of the human eye is approximately equivalent to a 50mm lens. That is, if you stood without moving your eye, the portion of the scene from left to right that is in your "normal" view. Less than that is considered wide angle- about 24mm to 45mm. Below about 24mm is considered "fish eye, and adds considerable distortion to the scene- a useful special effect.]

ZOOM LENS - Some lenses have the ability to change their magnification level through a range of focal lengths (wide angle through telephoto). This is called a zoom lens as is seen on most all camcorders. With digital cameras the range varies by brand and model, but ranges in the area of 35mm to 115mm are fairly common. This range would often be referred to as "3X" (three times) zoom (3x35=105, so the telephoto setting is about 3 times the wide angle setting). The best cameras achieve this by moving various elements in the lens. This would be referred to as optical zoom. Cameras using optical zoom are generally larger than those without because of the more complicated and thus larger lens elements.
 
G

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Hey Ken,

I have been reading thorugh this periodically throughtout the day. Thanks for taking the time to compose it.

It should come in handy for when I purchase a new camera...which will be soon :cheers
 

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Discussion Starter · #3 ·
<{POST_SNAPBACK}>[/post][/right]
As I am, Darrick. That why I posted this thread
I'm currently looking at a Fuji S3500 digi cam 4.2 megapixel (I can't afford the Canon that I would love) :giggle
 
G

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WOW!

Thats is some glossary! You should keep this one sticked at the top of the Photgraphy forum. It will be handy for everyone for a lot of time.

Thanks for your time, excellent work :nicejob
 
G

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<{POST_SNAPBACK}>[/post][/right]
:iagree :iagree Ken i think i'll just send you the money i know you'll buy the right one for me :giggle
thankyou for that info....but i must admit i'm a bit :confused :shipwrecked and :tease more senior moments i guess :cheers
 
G

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Great reading Ken thanks for the info, i too am looking at a new digital camera....

I have a idea which one but we shall see...
 
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