# Tag Info

219

Note: Because of the community-wiki nature of this question, this accepted answer became really long, and difficult to edit and keep current as lens designations evolved. The historical answer has been broken up into individual answers per lens brand, with links to each of the lens brand answers below. Descriptions by Lens Make Brand Lenses Most major ...

186

"The Exposure Triangle" is a catchy phrase meant to encompass the three factors which affect the exposure of a photograph of a scene with a given amount of light. It's often given to new photographers as a learning aid. I'm not sure if he invented it, but it is certainly popularized by Bryan Peterson, as in his book Understanding Exposure. (The popular web ...

103

In layman's terms (assuming a layman who knows some very basic geometry), imagine your nose as the point of a triangle. The left side of the triangle is the left edge of your peripheral vision, and the right side is the right edge. The horizontal angle of view is simply the angle between those edges, and the vertical angle of view is the same thing for up ...

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Most importantly: It's not just the disks rendered from a point source, even though that's the simplest way to describe it and see it. The disk is just a shorthand; the lens characteristics that produce these disks are always present; they're what determines the look of the out-of-focus areas in every photo you take! On the one hand, it's quite well-...

67

An f-stop is kind of a combination of two terms. First off, f/N is generally the notation used to indicate the size of the diaphragm opening, or aperture, in a camera. Let me give a little detail about how that notation came about, before I go on to explain the meaning of a stop. Aperture Values and f/Stops Aperture openings are measured as fractions of ...

55

The exposure triangle refers to the three major settings that effect exposure: ISO Aperture Shutter Speed Digital Photography School has an excellent write up about this, but I will summarize as best as I can. As the name suggests, each element effects image exposure, or how bright/dark the image is. Pick a side of the triangle, increase its value (...

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The top answer covers the decoding of the letters very well. I thought I might add a few comments as to what some of the features actually mean in terms of consequences of the features (it took me a while to work out what some of them meant). Lenses only for reduced frame DSLRs Most low to mid range DSLRs have a sensor that is smaller than a 35mm film ...

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Ok for a change I'm going to dispense with the formulas, photos of rulers and definitions of "magnification" and go with what you actually experience in practice. The major factors that actually matter to shooting are: Aperture. Wide aperture lenses give you a shallower depth of field. This is probably the least controversial factor! This is important as ...

45

STM stands for Stepper Motor and is a applied to a new range of Canon lenses which feature a new design of focus motors which, along with a new iris mechanism are designed to eliminate (auditory) noise during video recording. Canon haven't revealed any information about how the new design works but it's probably the same type of motor used in mirrorless ...

44

I think the best way to describe Bokeh is to show Bokeh: Reference: In the Spotlight by Healzo The blurry background "circles" are what we normally refer to as Bokeh, however in general it more simply refers to the quality of background blur. The picture above has some truly excellent bokeh, as the circles are truly round, generally evenly shaded across ...

43

DCIM is short for Digital Camera IMages and is part of the industry standard outlined by the Design rule for Camera File system. This standard was adopted as the de facto standard for storing digital image and sound files in memory devices by the digital camera industry to insure interoperability from one brand to the next. From wikipedia: Design rule ...

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Short answer So, not being quite satisfied, I did some research. Here's the tl;dr answer, but I hope you find the rest as interesting as I did. In painting and in photography, the "key" of an image is the overall tendency of its tone scheme towards brightness or darkness. When the key is bright, the image is high-key, and when it is dark, the image is low-...

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There are two reasons why an ISO is not made part of the 'normal' range: It is considered a non-trivial drop in quality and you do not want users complaining about its performance. In other words, if the quality difference between ISO 12800 and 6400 is stronger than the one from 3200 to 6400. Note that there may be more changes than simply more noise, ...

36

Aperture simply means "opening", and in photography we use the term to refer to the diameter of the opening in a special adjustable diaphragm within each lens. When this diaphragm is constricted, there's less physical space for light to get in, so naturally the exposure is darker, and a more-open aperture allows more light and results in a lighter exposure. ...

36

I think, in general, you are considered a professional photographer if your primary source of income comes from your photographic work. For example, if you are a wedding photographer by trade, your job is to photograph weddings. You are a "professional" wedding photographer. The same would be true if you were a sports photographer, and sold your work to ...

34

In practice, you're correct and it means that it's a fixed focal length lens. Historically, the term "prime" derives from cine work, where it had a more literal meaning of the primary lens of a multi-lens system. The concrete advantages are typically that they are much more compact, and have a much higher quality/cost ratio, as they're easier to engineer ...

33

This is an excellent question, and one that has different answers depending on context. You mentioned several specific questions each of which might warrant their own answers. I'll try to address them more as a unified whole here. Q. Is it just a property of the lens? A. Simply put, no, although if you ignore CoC, one could (given the math) make the ...

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The aperture range on your lens only shows the maximum aperture for your lens at the extremes of the zoom range; i.e. f/3.5 at 18mm and f/5.6 at 55mm. There is nothing to stop you using a narrower aperture; remember a larger number is a smaller hole (the f number is the diameter of the hole as a fraction of the focal length).

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The hyperfocal distance is the distance at which everything from 1/2 the distance to infinity is in focus. For instance, if the hyperfocal distance of a particular lens at a particular aperture is 100ft, then by focusing at 100 ft you can capture anything from 50ft-infinity in clear focus. A more in depth explanation can be found at www.dofmaster.com

30

SLR - Single Lens Reflex, meaning that there is only one lens through which the viewfinder and the film are exposed to the image. This is in contrast to other types of cameras, like rangefinders, where the viewfinder was a separated optical path than the film, usually in the form of a small lens on the top-side of the body. The Reflex part comes from the ...

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True macro lens gives you a 1:1 magnification -- that is a ratio of size of the subject and its image on the sensor. With 1:1 magnification on APS-C sensor (22×15 mm), you can fill whole picture with area of this size. Other properties of macro lenses include that they have fixed focal lengths, usually very low distortion (see distortion figures of ...

29

USM - Ultrasonic motor (This is the Canon Terminology) This is a big improvement over older micro-motor based autofocus systems, which are significantly slower and louder. There are two types of USM systems "Micro" and "Ring". The preferred type is "Ring Type" which always allows for manual focus without turning off auto-focus. Most, but not all, Micro USM ...

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The aperture affects not only the amount of time required to take a photo, but also the depth of field within it. With a wide aperture (so a low number, like f/1.8) gives a shallow depth of field - sometimes less than a millimetre with a macro lens. Because a lot of light is reaching the sensor (be it film or digital), this allows for fast shutter speeds ...

28

Photography has borrowed the term "gel" (and the technology) from theater. The original colored "gels" were made out of gelatin (and tended to melt). Today, they are made out of other materials that are more heat tolerant (but can still melt....) there's a nice writeup on this on wikipedia: http://en.wikipedia.org/wiki/Color_gel

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Basically all "expanded" means is that this is not part of the standard recommended range. Often the expanded ISOs are implemented in software rather than hardware (which is bad) With ISO 50 you might be getting an overexposed ISO 80 (the native, unamplified ISO) so could end up with less dynamic range. This is done by metering for ISO 50 but actually ...

28

Definition of SLR SLR consists of: SL Single lens. That is, it does not have a separate lens for a viewfinder. If it has a viewfinder, the viewfinder looks through the main lens. R Reflex. This means it has a mirror (called a "reflex mirror") that allows light from the main lens to be bounced upwards onto a ground glass screen. Modern SLRs usually ...

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Don't feel bad. Color theory isn't easy. First, many of your terms come from the many different ways to express a color. What we typically call a "color" (like, 'red' or 'orange') can be expressed in a variety of different ways: RGB: The combination of red, green, and blue light that forms a color. This is also called additive color (when you add more ...

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Exposure fusion is a process that takes multiple images and combines them to create a single image while only keeping the properly exposed elements. In contrast to HDR images, exposure fusion is more basic, gives a more realistic effect, and requires fewer steps. The exposure fusion(fusion, or EF) process takes each individual pixel and assigns a weight to ...

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The definitive answer for the word in English is Mike Johnston's article on the topic at Luminous Landscape. Mike says "it is properly pronounced with bo as in bone and ke as in Kenneth, with equal stress on either syllable." I say "definitive" because Mike is the person responsible for the h on the end of the word in English — he thought it would ward off ...

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The hardness or softness of a lightsource is determined entirely by the number of angles light is coming from (not the number of angles it's going to, that is the spread of the beam). A lightsource producing light from many angles will have the effect of filling in shadows, and provide a gradual falloff (transition from lit to shadow). This is because as a ...

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