Questions tagged [terminology]

Questions about specific terms used within photography

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151
votes
10answers
55k views

What is the “exposure triangle”?

What is the exposure triangle? How do the "sides" affect my photographs?
68
votes
5answers
10k views

What exactly determines depth of field?

There are several questions here about the definition of depth of field, about focal length, and about subject distance. And of course there's the basic how does aperture affect my photographs. And ...
195
votes
15answers
129k views

What do all those cryptic number and letter codes in a lens name mean?

When looking at a lens name, there are a lot acronyms describing its features (often specific to the manufacturer). Examples, Nikon: Nikon AF-S DX 16-85mm VR f/3.5-5.6G IF-ED Nikon AF-I 600mm f/4D ...
57
votes
9answers
142k views

What is aperture, and how does it affect my photographs?

How does aperture affect my photographs? Why should I care about the aperture with which a photo was taken?
17
votes
4answers
5k views

What is the difference between perspective distortion and barrel or pincushion distortion?

I've heard of: perspective distortion barrel distortion pincushion distortion mustache distortion What are these different types of distortion, and how do they relate? What causes them, and can they ...
43
votes
7answers
7k views

What is “Hyperfocal Distance”?

I'd like a clear & easy-to-understand (especially for non-physics-types) explanation of what Hyperfocal Distance is, how it affects photographs, and what determines its value.
34
votes
6answers
46k views

What is one “stop”?

I always hear this term, e.g., I had to go down one stop Increasing X by Y raises Z by one stop I turned down the flash/the light two stops This lens/sensor/strobe/Photoshop tweak raises X by around ...
68
votes
4answers
152k views

What does f-stop mean?

What does f-stop mean? Is it the same thing when people say "2 stops" for example?
37
votes
5answers
21k views

What is a macro lens?

I've read a few threads on here that mention some elementary descriptions of macro lenses and found some marketing fluff in the box for my Canon about them as well, but being a complete novice I was ...
121
votes
7answers
12k views

What is bokeh, exactly?

I understand that "bokeh" refers to out-of-focus areas of an image — but there is obviously more to it than that. What does the term mean exactly? How well is bokeh really understood? Is it purely ...
30
votes
3answers
4k views

What is the meaning of “white balance”?

I would like to understand the term white balance. My camera has settings for white balance with the following options: Auto white balance Daylight Cloudy Shade Flash Incandescent lights White set1 / ...
31
votes
2answers
25k views

What is T-number / T-stop?

Usually, when discussing aperture of a lens, F-stop and F-number are used for quantifying. But some photographers, and especially videographers, also mention T-stop. The concept and numbering used (e....
15
votes
7answers
8k views

What is a normal lens?

I've heard people call 50mm lenses "normal lenses". For a lens to be considered normal, does it have to be exactly 50mm or is there some leeway? Does the normal focal length depend on crop factor of ...
43
votes
5answers
16k views

What does it mean for a photograph to be “high key”?

As I learned the term, a high-key image is one where the shadows are effectively eliminated, and the mid-tone detail pushed into brighter zones. My question is simple: is this an accurate definition, ...
12
votes
4answers
17k views

What is the EV scale?

I have seen an "EV" (exposure value) scale that's sometimes used to express a camera's exposure settings, or scene brightness. How exactly does this scale work?
21
votes
4answers
4k views

What is GAS and how can I avoid it?

What is this GAS that all the pros talk about? It sounds pretty bad. How do I avoid it? Is there a cure?
48
votes
3answers
393k views

What does STM mean on a Canon lens?

The Canon EF 40mm f/2.8 has a designation of STM on the lens. What does this mean? What are the advantages of having it and does it replace an older technology? We have a terminology thread that ...
30
votes
2answers
7k views

How does exposure fusion work?

I understand that "exposure fusion" is a method for combining different exposures into a single image. How exactly does it work, and how is it related to HDR?
29
votes
4answers
11k views

What is focal length and how does it affect my photos?

What is focal-length? Are focal-length and zoom synonymous? How does the focal length of a photo affect it? Are there common uses for different focal lengths, and how can I decide what to use when?
25
votes
6answers
7k views

What is exposure compensation?

What does exposure compensation do? If I take a photo with a given shutter speed, aperature, and ISO, and then take the same shot with +1EV or -1EV, what is actually happening? Is this just a gain ...
20
votes
3answers
2k views

What is Chromatic Aberration?

What is Chromatic Aberration? Is it a physical part of the lens, or just an optical illusion?
4
votes
4answers
4k views

What is “Dragging the Shutter”?

I've heard this term of "dragging the shutter". What does this mean and why would I use it?
16
votes
2answers
39k views

What does DPI mean?

What does DPI mean and how does it affect images displayed on screen versus printed?
22
votes
7answers
12k views

How can aperture be f/11 on a lens with an aperture range designation of 3.5-5.6?

I made a series of outdoor shots with Nikon D5000, with the 18-55mm 1:3.5-5.6G VR kit lens. On some shots, I see in the EXIF info f/11, and in another shot, f/9. How can that be, that the f-number ...
25
votes
4answers
6k views

What is a “fast” lens?

I've been reading lots of camera reviews lately and have ran across several references to "fast" lenses. What exactly is a fast lens and what are its advantages compared to other lenses?
22
votes
3answers
4k views

What is color temperature and how does it affect my photography?

I have seen color temperature mentioned with regard to white balance, mixing different sources of light, etc., but I haven't come across a clear explanation of what it means to talk about the '...
9
votes
4answers
10k views

What does 'how much zoom' mean?

I have Canon 18-135 and 70-300 zoom lenses. People ask me how much zoom my camera supports. What am I supposed to tell them? "135 ÷ 18 = 7.5" and "300 ÷ 70 = 4.2"?
18
votes
5answers
2k views

What is an ultra-wide lens?

What is the point at which a lens is considered "ultra-wide angle" vs just wide angle?
13
votes
2answers
40k views

What is CLA service?

I've seen the term used in used lens listings, e.g "recently CLA'd". I have a few questions, but I think they're related enough to only warrant one post: What does CLA stand for, and what is it? How ...
3
votes
2answers
1k views

How does photography (as opposed to physics) define “focal-plane”?

This wikipedia article concerning focal-plane shutters opens with the following statement (bold emphasis added by myself): In camera design, a focal-plane shutter (FPS) is a type of photographic ...
12
votes
6answers
23k views

What are the differences between a bridge camera and a DSLR?

What are the differences between a bridge camera and a DSLR?
7
votes
2answers
2k views

What is “veiling glare”? How does it affect my photos, and how can I avoid it?

Someone mentioned that "veiling glare" or "veiling flare" was to blame for reduced contrast in a photo. What does this mean exactly? What causes veiling glare, and how can it be avoided? How does it ...
22
votes
5answers
22k views

What is dynamic range and how is it important in photography?

Wikipedia says that the dynamic range is the "ratio between the largest and smallest possible values of a changeable quantity". Ok, I get that. I suppose that's why HDR photos have a "high dynamic ...
56
votes
8answers
43k views

What does “expanded ISO” mean?

The ISO specification for the Canon EOS 7D reads as follows: High ISO For handheld shooting in low light, the EOS 7D offers ISO speeds of up to 6400. Expandable to ISO 12800, for low light ...
31
votes
10answers
120k views

What is the difference between a telephoto lens and a zoom lens?

Looking at the product page for Nikon lenses, I notice a distinction between telephoto lens and zoom lens. What is the difference between the two? Why would I want one over the other? I wiki'd ...
18
votes
4answers
8k views

Why are effective pixels greater than the actual resolution?

This page compares Canon EOS 550D and Canon EOS 500D cameras and mentions 18.7 million effective pixels for 550D. However the best resolution possible using this camera is 5184 * 3456 = 17915904 ~...
15
votes
5answers
34k views

What is “infinity focus”?

I have been reading a bit about astrophotography and the term infinity focus keeps coming up. What is infinity focus and how do you set the camera to infinity focus?
21
votes
1answer
7k views

What is background compression?

What does the term "background compression" mean? How would you tell you're achieving it, and how would you achieve it? Ideally, the right answer would also explain how this is related to ...
34
votes
6answers
3k views

What is the definition of a “prime lens”?

There are many discussions of differences between prime, zoom and macro lenses. I have not heard about prime lenses until recently. Could someone explain what exactly a prime lens is? Is it ...
9
votes
3answers
2k views

How can a 24-70mm and a 10-22mm both be “wide angle” lenses?

I've been looking at a 10-22mm lens for my Canon T2i. I've also come across some other "wide angle" lenses, like the Sigma 24-70mm F2.8. I don't understand how a wide angle lens can have such high ...
14
votes
6answers
11k views

What is the meaning of “stopped down”?

Was reading this answer (emphasis mine): It also tells us that the lens was stopped down, as if it were wide open there would be no corners to cause diffraction, regardless of the number of ...
7
votes
5answers
18k views

What's the difference between exposure and shutter speed?

Is there a difference between exposure and shutter speed, or are the terms interchangeable? I read that "If you use a quick shutter speed, you can just raise the exposure to compensate." Is this ...
8
votes
2answers
12k views

What is the effect where some objects are a single bright color but the rest is black and white?

There is an option to filter only one color (R,G,B,Y) in my camera. What I want to know is can this effect be achieved in photoshop? And what is this called? I tried googling monochrome and came up ...
19
votes
2answers
15k views

What is the difference between luminance and illuminance?

The more I read about this, the more confused I become. Illuminance, as I understand it, measured in lux, is the perceived brightness of light on a surface. It's what you'd measure with an incident ...
18
votes
3answers
2k views

What makes a camera an “SLR”?

My question, specifically: why is the Fujifilm HS 10 not an SLR?
9
votes
3answers
1k views

Image processing & editing: what is an “unmanipulated” image?

What is considered an "unmanipulated" image? As defined by photo.net: Unmanipulated a single uninterrupted exposure cropping to taste common adjustments to the entire image, e.g., color ...
6
votes
1answer
746 views

Why would a photographer do focus stacking?

Recently, I come across the term called Focus Stacking where you combine different pictures with different focus points. My question is, why do the focus stacking? Are there any benefits from the ...
13
votes
3answers
13k views

What is Nano USM and how does it compare to an STM or USM lens?

The Canon EF-S 18-135mm f/3.5-5.6 IS USM has a designation of Nano USM on the lens. What does this mean? What are the advantages of having it vs STM or USM? We have a terminology thread that usually ...
6
votes
6answers
4k views

Why is the Tamron 90mm 2.8 marketed as Macro and not as a “portrait” lens?

My question is if a lens like a Tamron 90mm 2.8 could be used also for portrait. If not, why ? What are the difference between a specific portrait lens (like any 85mm 1.4) and a 90mm 2.8 ? Only the ...
4
votes
1answer
2k views

What is Effective Aperture?

What is Effective Aperture? And how it can affect my exposure? Also how does it relate to magnification? A question that talks about effective aperture but without details

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