Abbreviations and Explanations

[Thomas]

Here it is: What you always wanted to know but where afraid to ask!
The concise Camera Labs guide to abbreviations and technical terms.

Abbreviations:
AA-Filter = Anti-Aliasing filter, in front of the sensor reduces moiree on fine optical structures
AF = autofocus
APS-C = half size sensor (approx. 24x16mm)
CA = color aberrations
CZ = Carl Zeiss (lens manufacturer)
DR = dynamic range
dof = depth of field
ETTR = expose to the right
EXIF = exchangeable image file format. Stores shooting info in images.
EV = exposure value
FF/FX = full frame sensor (24x36mm)
Four/thirds = standard lens-mount using 17.3x13mm sensor
fov = field of view
fps = frames (=shots) per second
HDR = High dynamic range photos
HSM = HyperSonic Motor - quick & quiet focusing in Sigma's better lenses
IQ = image quality
IS = image stabilization (=VR@Nikon, =OS@Sigma, =VC@Tamron)
L = Luxury! Canon's brand for it's best quality lenses. Red ring around barrel.
MF = manual focus
MFD = minimum focus distance
MTF = Modulation Transfer Function
NR = noise reduction
P&S = p+s = point & shoot camera
pp = post-processing, sometimes simply called "post"
RTFM = read the f*cking manual (deemed offensive, don't use it in this forum!)
s/n ratio = signal to noise ratio
SSWF = SuperSonic Wave Filter - the Olympus / Four Thirds anti dust system.
SSM = SuperSonic Motor - quick & quiet focusing in Sony's better lenses
SWM = Silent Wave Motor - quick & quiet focusing in Nikon's better lenses.
TC = tele-converter
USM = Ultra Sonic Motor - quick & quiet focusing in Canon's better lenses.
WB = white balance

Explanations:
Aperture: http://en.wikipedia.org/wiki/Aperture
Autofocus: http://en.wikipedia.org/wiki/Autofocus
Bokeh: http://en.wikipedia.org/wiki/Bokeh
color aberrations = high contrast edges display false color borders
Depth of field: http://en.wikipedia.org/wiki/Depth-of-field
Diffraction: http://www.cameralabs.com/forum/viewtopic.php?t=17506
EXIF: http://en.wikipedia.org/wiki/EXIF
EV: http://en.wikipedia.org/wiki/Exposure_value
Focal length: http://en.wikipedia.org/wiki/Focal_length
Focus: http://en.wikipedia.org/wiki/Focus_%28optics%29
HDR-imaging:
1. http://en.wikipedia.org/wiki/High_dynamic_range_imaging
2. http://www.naturescapes.net/072006/rh0706_1.htm
ISO: http://en.wikipedia.org/wiki/Film_speed
Image Quality of an APS-C DSLR vs. a point&shoot: http://www.cameralabs.com/forum/viewtopic.php?t=10781
Longitudinal CA: http://www.cameralabs.com/forum/viewtopic.php?p=45013
Macro-photography: http://en.wikipedia.org/wiki/Macro_photography
Magnification with close-up lenses: http://www.cameralabs.com/forum/viewtopic.php?t=17847
Normal lens: http://www.cameralabs.com/forum/viewtopic.php?t=18189
parfocal: http://en.wikipedia.org/wiki/Parfocal_lens
Pixel-binning: http://www.cameralabs.com/forum/viewtop ... 4737#74737
Sensor sizes: http://www.cameralabs.com/forum/viewtop ... =8790#8790
Shrink-factor: http://www.cameralabs.com/forum/viewtopic.php?t=17854
Siemens-star: a test-target to judge sharpness/resolution: http://oly-e.de/pdf/siemensstern.pdf
varifocal: http://en.wikipedia.org/wiki/Parfocal_lens
vignetting: http://toothwalker.org/optics/vignetting.html
White balance: http://en.wikipedia.org/wiki/White_balance (Uh-oh: someone needs to find a better article on white balance than this )
Zoom, how it works: http://www.cameralabs.com/forum/viewtopic.php?t=19148

And there is a nice thread with a collection of some more in depth Qs (and answers ) about some of the above here.

We'd love to include your questions/suggestions/explanations/links in this post. So come on: there is no such thing like a dumb question!
__________________
Thomas (beware: Nikon-fanboy and moderator!) My Pictures, My Photography Blog
D300+assorted lenses

[John_0812]

Hello Thomas,

Thanks a lot for these really very useful information.

Now I see things much clearer.

Cheers,

John_0812

[TelexStar]

Great idea for a sticky thread. Well done.

[Bob Andersson]

Following a recent question in the Canon forum I became aware that compact digital camera manufacturers often use a somewhat bizarre method of describing their sensors. For example, you see the sensor described as 1/1.7" so that obviously means the sensor size is about 0.59 inches or 14.8 millimetres doesn't it? If, like me, you thought this then you'd be wrong, even without considering whether the size measures height, width or diagonal!

There are a number of pages on the Net describing the actual corresponding sensor sizes but they all seem to have drawn as their source an article by Vincent Bockaert. From Wikipedia

Code: Select all

Sensor Type     1/3.6"   1/3.2"  1/3"    1/2.7"   1/2.5"   1/2"    1/1.8"   1/1.7"   2/3"     1"       4/3"    APS-C    35mm

Diagonal (mm)  5.00     5.68    6.00     6.72      7.18    8.00     8.93     9.50    11.0    16.0     22.5      28.4      43.3
Width (mm)      4.00     4.54    4.80     5.37      5.76    6.40     7.18     7.60    8.80    12.8     18.0      25.1      36
Height (mm)     3.00     3.42    3.60     4.04      4.29    4.80     5.32     5.70    6.60      9.6     13.5      16.7      24

Despite the apparent precision sizes may still vary.

Apparently this discrepancy between reported size and actual size has its roots in the old days where television manufacturers would quote the diagonal of the cathode ray tube rather than the diagonal of the viewable area of the screen. In my opinion the only reason the manufacturers get away with this in this day and age is that they refer to "Sensor Types" rather than "Sensor Sizes". My word of choice when considering this practice is "Harrumph".

Bob.

P.S. If you are wondering why the word Code: appears before the table, BBCode doesn't do Tables so I used the "code" tag to force a Courier font so I could control the formatting. I hope this displays correctly in your browser - you may have to maximise the window if the text is "wrapping".

[DavidL]

Wow.. ! !

Thanks Bob

Have always thought 'sensor' listed in brochures was 'sensor size'..
Now i feel like a complete fool

[Bob Andersson]

Have always thought 'sensor' listed in brochures was 'sensor size'..
Now i feel like a complete fool

Don't worry. Gordon very kindly deleted a post I made elsewhere without researching this subject where I was a complete fool and fell into the trap I've described! I composed this post as a penance.

Bob.

[Gordon Laing]

Don't worry - this one gets all of us at some point!

The inch dimension refers to the diameter of an imaginery circle around the sensor itself from the old days when they were surrounded by vacuum tubes.

[luis]

For abbreviations that are unique to Nikon / Nikkor lenses, look here.

[Elan]

Maybe one thing to add is that USM can also stand for Unsharpen Mask.

[Bob Andersson]

Hi folks,

Canon have recently published a table showing the FOV (field of view) available from various (35mm equivalent) focal lengths. None of this information is new but I thought it would be handy to drop it into this Abbreviations and Explanations thread. If you are using a cropped sensor camera then you need to multiply your lens focal length by the crop factor before you enter the table.

FOCAL LENGTH & FIELD OF VIEW (FOV) TABLE

Focal Length....Horizontal FOV....Vertical FOV

....14mm................104°..................81°
....16mm..................98°...............74.1°
....17mm..................93°..................70°
....20mm..................84°..................62°
....24mm..................74°..................53°
....28mm..................65°..................46°
....35mm..................54°..................38°
....40mm...............49.2°..................34°
....50mm..................40°..................27°
....70mm..................29°................19.3°
....100mm................20°..................14°
....200mm................10°....................7°
....300mm...............6.5°...............4.35°
....400mm...............5.1°.................3.3°
....500mm.................4°................2.45°
....600mm..............3.3°..................2.2°
....800mm............2.35°..................1.4°

[Thomas]

Thanks Bob. I've linked your post from my first post.

[Joe_AUT]

i'm just wondering but in which situations do i need these FOV information?
i mean do you ever guys keep those numbers in mind and how is this relevant to take photos anyway?
and another question i'm asking myself since day one but as i'm learning to get into photography step by step and not by buying any photographic book which i personally find kinda annoying:
i own a canon 40d, so of course i have to deal with a cropped sensor BUT do i always have to multiply the focal length with 1.6 to get the 'real' focal length of my lens? till now i always thought i only have to do this with EF-mounted lenses but not with EF-S (or Di II on tamron and DC on Sigma) lenses.
so to say it maybe a little bit clearer: let's say i had an EF-S 18-55 lens .. is it still 18-55 or something around 29-88 in 'reality'?
thanks in advance!

[jgmatthews]

Yep Joe, all focal lengths (including crop only lenses) relate to what they would give on a 35mm format camera thus any lens you mount has to be multiplied by the crop factor. An 18-55 on a 1.6 crop factor is a 29-88mm.

Hope that helped
Justin

[Joe_AUT]

oh ok, thanks!
finally i can make a line under that one

to my other question .. what's about that FOV information? where/when do i need those or do you guys ever keep them in mind?

[Thomas]

added (a link to) a very thorough explanation of the different causes of vignetting.