Terms in photography.
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Okay, I'll try to compile some. Don't be afraid to edit for me or add more terms that I missed out. Though I think I will miss out on quite a lot.
Aperture: An aperture is an opening in which light is admitted. But the f-number (e.g. f/2.8) is the opposite of how big the aperture is opened. A small f-number like for example f/1.4 means the aperture is opened wide, while a big f-number like for example f/11 means the aperture is very small.
Aperture is mostly used for Depth of Field (DOF) shots. A small f-number (meaning big aperture) will make the subject you are focusing on to be in clear focus, while the background is blurred. A big f-number (meaning small aperture) will still make the subject you are focusing on to be in clear focus, but background is not so blurred.
Autofocus: Also known as “AF”. It means the lens will automatically focus for you the object that falls into the AF-point.
Bokeh: It refers to the blurred background of a photo caused by a shallow Depth of Field (DOF). Bokeh is a Japanese term and it means "blur". So bokeh can also be used to refer to DOF.
CCD sensor versus CMOS sensor: CCD means "Charge-Coupled Device" and it is the first light sensor used in digital cameras. CMOS means "Complementary Metal-Oxide Semiconductor" and it's a newer technology.
CMOS first appeared on camera phones because it is easier to implement and uses less battery power and it’s cheap but picture quality is poor, hence CMOS is suitable for camera phones. But CMOS soon progressed to a stage where it can compare with the more matured CCD technology in terms of picture quality. That was when CMOS became more widely used in digital cameras and DSLRs. The advantages is less power consumption, faster processing speed and cheaper to produce. It is also rumoured that CMOS has better noise suppression than CCD, whether is it true or not, I'm not sure.
Depth of Field: As mentioned when I talked about aperture and bokeh, DOF affects how blurred the background is. The smaller the f-number (meaning the wider the aperture), the shallower the DOF. And a shallow DOF means a blurred background.
Exposure: It is the total amount of light allowed to fall on the photographic medium during the process of taking a photograph. Shutter speed and aperture opening determine how much exposure there is. Longer shutter time and wider aperture will result in greater exposure, and vice versa.
There is also something called the Exposure Value (EV). It can be seen on most digital cameras where you can adjust the EV in 1/3-steps or ½-steps, ranging from positive to negative value. Positive values means greater exposure while negative values means lesser exposure.
Focusing: For most Point-and-Shoot (PnS) digital cameras, focusing is determined by the camera itself. But for some prosumer bridge cameras and DSLRs, you can determine how your camera focuses on subjects.
For a DSLR camera, there’s the single-servo AF, used in most conditions and mostly for stationary objects. Then there’s the continuous-servo AF, used for moving objects. The camera constantly Autofocus on the object even if it’s moving, used for Sports Mode on DSLRs and also for panning shots. And finally there’s Manual focus, where you focus manually.
ISO speed: ISO stands for “International Organization for Standardization”, and yes, this is the ISO you see printed on products like “ISO9500”, “ISO9660”, etc. ISO speed can also be referred to as film speed. Films with high sensitivity only need a short exposure time, while low sensitivity films need a longer exposure time. Thus high sensitivity films are said to have a fast film speed, while low sensitivity films have slow film speed. After ISO standardized the measurement of film speed, everyone started calling it the ISO speed.
Digital cameras also have ISO speed. It determines how “sensitive” you want the image sensor to be. With low ISO speed like ISO-100 or ISO-200, you need longer exposure time, meaning lower shutter speed. With higher ISO speed like ISO-800 or ISO-1600 or even ISO-3200 in some DSLRs, you can increase the shutter speed while still achieving the same amount of exposure. But higher ISO speed usually translates to more noise.
Metering: There are 3 kinds of metering for exposure. There’s (1) Center-Weighted Metering, (2) Matrix/Evaluative/Pattern Metering, and there’s (3) Spot Metering.
(1) Center-Weighted Metering the whole picture frame is evaluated, but priority is given to the center of the picture. Used mainly for Portrait Mode for taking pictures of a person. Some cheap PnS digital cameras without metering options have Center-Weighted Metering as standard.
(2) Matrix/Evaluative/Pattern Metering. Different camera manufacturers call it differently, but this is usually the most common metering mode used in digital cameras. It measures the whole picture to determine the right amount of exposure so that the whole picture is nicely exposed.
(3) Spot Metering means only the area around the selected AF-point is metered and exposed accordingly; the rest of the area is ignored. Ideal for situations when your subject is backlit and using Matrix or Center-Weighted Metering will make your subject totally black.
Noise: Noise is the irritating red and blue dots in see in pictures taken low lighting conditions. It appears mostly in the shadow area. Factors that contribute to noise is low lighting and high ISO speed.
Will continue when I’m back, got to go out now!
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Pixels: The image sensor in a digital camera or DSLR consists of a lot of pixels that collect light energy (photons) and convert them to electrical signals. The “Mega” in front of the word “Megapixels” simply means one million. So “6.0-Megapixels” means six million pixels on the image sensor.
There’s also difference between TOTAL number of pixels and EFFECTIVE number of pixels. Let’s say an image sensor in a digital camera has a total of 10.6-Megapixels; it means it has a total of 10,600,000 pixels on the image sensor. But they may promote their digital camera as having 10.2 EFFECTIVE Megapixels. That means even though the image sensor has 10,600,000 pixels, only 10,200,000 is used to compose a picture. The remaining 400,000 pixels are around the border left unused, or used for other purposes that I’m also not sure about. So beware of how camera manufacturers promote their cameras. So the main thing is: TOTAL number of Megapixels is not equal to EFFECTIVE number of Megapixels.
And there’s also this problem with everyone having the misconception that Megapixels equate to image quality/sharpness. This is not true at all. How much pixels does your digital camera/DSLR have does not affect image quality. The bigger the image sensor, the bigger the picture when printed out, that’s all. What affect image quality are the lenses, the image sensor’s dynamic range and quality of the pixels and the image processor (e.g. Canon’s Digic III, Nikon’s Expeed, Sony’s Bionz, etc.) in the camera itself. If you have a 20-Megapixels camera, it also doesn’t mean you can take astonishing pictures if the lenses and image sensor sucks. That is why Nikon’s D40 DSLR only needs 6.1-Megapixels. As long as the lens and image sensor are of good quality, pictures of good image quality can be achieved easily.
RAW: Some of you might have seen this image format. It simply means the picture from the image sensor is stored unaltered/unprocessed. And it is not an acronym that everyone thinks it is. It literally means the picture is still raw, unprocessed.
RAW allows for greater flexibility for professional photographers, because you can still edit white balance, colour enhancements, sharpening, exposure, etc. It is like having a second try at taking a picture of the same scene when your first attempt failed.
There are of course drawbacks to shooting in RAW format. RAW files are much larger than other file formats like JPEG for example. This is because it is not compressed at all. And when shooting in RAW format on a DSLR, number of images you can store in the buffer will be reduced, resulting in slower continuous shooting speed. Another thing is different camera manufacturers have different RAW formats; hence you need dedicated software to process your camera’s RAW files.
Red-eye effect: This happens when taking pictures with flash of people in the dark. The pupils of a person’s eyes dilate when in the dark to admit more light to be able to see in the dark. When you take a picture of someone whose eyes are already accustomed to the dark surrounding, the flash from the camera will reflect off the back of the person’s eyes and hence you see the red eyes. The red colour is actually caused by melanin, which is in abundance, at the back of a human’s eyes.
This can be avoided when you select the red-eye function in your digital camera. When you switch to this mode, you will be able to observe that the flash from the camera actually flashes for a few times before the picture is actually taken. This is done to make the person’s eyes to adjust to the brightness and contract accordingly, so red-eye effect is reduced or eliminated.
But no worries there, a lot of photo editing softwares nowadays offer red-eye fixing features, where you can remove the red-eye effect digitally.
Shutter: One of the very important components of a camera. The shutter is a device that allows light to pass for a determined period of time, for the purpose of exposing a photographic film or a light-sensitive electronic sensor. The two most common types of shutters are the central shutter and the focal-plane shutter. The central shutter is used mainly in PnS digital cameras while SLR/DSLRs uses focal-plane shutter. Central shutter is mounted just after the lens assembly. Focal-plane shutter is mounted just in front of the image sensor. It’s used in DSLR cameras because DSLRs have interchangeable lenses, and with the shutter built onto the camera body, changing lenses will be easier. Focal-plane shutters are more expensive to produce than central shutters.
In most PnS digital cameras, you cannot control the shutter speed, instead the camera will decide for itself what’s the best shutter speed for the current situation. In SLR/DSLR cameras, shutter speed can be controlled. For most DSLRs nowadays, shutter speed is between 1/4000 to 30 seconds. Some are even fast enough to achieve 1/8000 seconds.
Shutter lag: Shutter lag occurs from the moment you press the shutter button to the time when the shutter actually opens to expose the image sensor. In most PnS digital cameras, shutter lag is inevitable. It cannot be avoided and it can be a nuisance when taking pictures of fast moving objects due to the lag.
DSLRs generally have very little or no shutter lag because it has no live view. But shutter lag will occur when you are using the live view of a DSLR camera. When using live view in a DSLR camera, it becomes like a PnS. Shutter lag will occur unless you switch off live view and use the viewfinder instead.
Chromatic Aberration: Also known as “purple fringing”. But strictly speaking, there are also blue fringing, red fringing, etc. It will occur at wide angle on a camera lens and in sunny conditions, where you will see red/blue/purple colour along the edges on some of the objects in the picture. It is unavoidable, but can be reduced with good lenses. Compact digital PnS cameras are more prone to chromatic aberration than DSLRs. But this is due to the lenses and not the image sensor. DSLR camera’s lenses sometimes employ extra-low dispersion lenses to counter chromatic aberration.
Vignetting: The black corners you see in your pictures are the effect of vignetting. More common on PnS digital cameras than on DSLRs. Again, this is due to lens design. It is usually undesirable and best avoided, but can be purposely induced for creative purposes.
This should be all for now.
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i still remembers my S1 IS's CCD spoilt due to a cretain batches problems. but got it fixed for free
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I only know.. Auto Focus.
lol
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im using S3 IS, is stil damn good lor..
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Good thread, alleggertia!
Just throwing my two cents' worth in, here's a demonstration of DOF. The same shot taken at F1.8:
... F7.1:
... and F22:
Note how, as the aperture decreases (the F-number increases), more of the image comes into focus.
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Gadenken using 7-blade aperture lens? Don't tell me you Nikon user?
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Nah, it's a 5-blade - Canon 50mm 1.8 Mk II. There's probably some reasonable explanation of why the reflection off that bezel has seven points, but damned if I know what it is.
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if it is of any help....
PIXEL stands for Picture Element.
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Originally posted by Gedanken:
Nah, it's a 5-blade - Canon 50mm 1.8 Mk II. There's probably some reasonable explanation of why the reflection off that bezel has seven points, but damned if I know what it is.
Yeah, I counted 7-points. Now that's weird.
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Originally posted by Chin Eng:
if it is of any help....
PIXEL stands for Picture Element.
Hmm, I didn't know that. Interesting.
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wah, alot of things i didn't really know! hur hur hur~
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Kopi! I was wondering when you'd turn up!
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turn up to... contribute to the topic?
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Turn up to post gratuitous quantities of photos lah! Abu den?
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photos like these?????