acronyms used in AP

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galaxyhunter
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acronyms used in AP

Post by galaxyhunter » Tue Dec 31, 2013 7:32 am

I've noticed that when people enter the world of Astronomy and astrophotography some may not understand what some of the jargon that is used and I though well why isn't there a list? So I have an idea that will everyone's help something can be started to share with those who could find it useful. I'll keep track of the suggestions and if a correction is needed because we all make mistakes be taken in a kindly matter to those attempting to help. I'll start with a basic list of some of the most common (I know I've missed a few) and the rest can be added.


A------------------
AP – “Astrophotography”

Aperture - The size of the opening that lets light into a camera lens, which can usually be adjusted and changed. In a telescope, the aperture is usually fixed, and is defined by the size of the primary mirror or objective lens.

Autoguider - A separate CCD or Webcam that is used to send corrections to the telescope's mounting to guide or follow the stars with high accuracy to compensate for inaccuracies in the mount's tracking.

Afocal - Using a camera with its lens attached to take a picture through a telescope's eyepiece.

Artifacts - Artificial, spurious defects in an image that were not part of the original image or data.

B----------------
Banding - Visible steps in an area that is supposed to be even-toned or smoothly varying, such as a gradient of brightness in a blank sky that fades from light to dark. Banding is usually caused by an insufficient number of digital steps of tone.

Bias Frame - A zero second exposure that records the bias signal present in every frame.

Black Point - The darkest area of an image.

Bulb – imagers use this setting with DSLR’s for Astrophotography. The term "bulb" dates back to when camera were first used when the photographer used a pneumatic bulb release and the term has stayed this since its invention

C--------------
CA - Chromatic Aberration " is an effect resulting from dispersion in which there is a failure of a lens to focus all colors to the same convergence point." Source: https://en.wikipedia.org/wiki/Chromatic_aberration" onclick="window.open(this.href);return false;

Calibrate - To remove unwanted fixed signals (noise) and to correct vignetting

Clip, Clipping - To lose, cut off, “clipped the black point or white point” during image processing

D--------------
Dark’s - A dark frame is a photo taken at the same exposure, ISO and temperature as a light frame, but with no light reaching the sensor. It is a picture of the camera's thermal current and bias current.

Dark frames are used in calibration of digital image data in light frames. By subtracting a dark frame from a light frame, thermal current signal and bias signal are removed.

Diffraction Spike- Are lines radiating from Bright light sources in telescopes that use a secondary mirror such as Newtonian's and even more well know Hubble Telescope. These are either pleasing to some as more of an aesthetic value and some who see it as a nuisance.

DSLR - a camera used for astrophotography that started out as a replacement for film

DSS = Deepskystacker

Dust Donuts - Out of focus shadows that look like donuts that are caused pieces of dust on the sensor or cover glass in front of the sensor. AKA dust motes or dust bunnies

E---------------

EL Panel = electroluminescent Planet used to make flats. This often used by Dr's to view X-rays in a hospital or office but they are used in astrophotography to delete artifacts such as dust motes and such when post processing an image. Some use the T-shirt flat method and a method used is taking flats in the evening when the sky enters Twilight. The use of an El Panel can be done either inside at a desk or the box can be made so its placed on the scope while its still on the mount.

F---------------
Flat’s - A calibration frame taken of an evenly illuminated subject used to correct for vignetting, uneven illumination, dust on the sensor's cover glass, and uneven pixel response.

Flip- Sometimes called Meridian Flip
FF = Field Flattener

F/L = Focal Length - The distance from the lens or mirror in an optical system and the focal plane where the light is focused.

Focal Ratio (F/ratio) - The ratio between the aperture and focal length of a lens or telescope. For example, a 127 mm aperture telescope with a focal length of 1016 mm has a focal ratio of 1016/127 or f/8.

FR = Focal Reducer (Telecompressor) - An optical component made of a lens or glass elements that decrease the focal length (and focal ratio) of a telescope.


Focus - Focus is when the focal plane of an optical system is coincident with the focal plane of an eyepiece or digital camera. An optical system can be considered focused when the maximum amount of light from a star is concentrated into the smallest possible area at the photodetector sensor surface, yielding the smallest possible star size.

FOV = Field Of View

G--------------
Guiding - Manually or automatically following a star by making corrections in right ascension and declination to produce higher tracking accuracy.
Image - 1.) Used as a noun, an image is simply a picture. For example, "That is a very nice image of the Orion Nebula." 2.)Used as a verb, to image is to take a picture. For example, "Tonight I am going to image the Veil Nebula."

Light’s - An exposure to the light from the subject through a lens or telescope. The actual object you are pointing at with your lens or telescope

Light Polution (LP) – LP is associated with any man made light source beginning with the discovery with the electric light bulb. This is the main source of frustration to those in the astronomical community are always in a constant battle for viewing and photographing NEO's(near Earth objects such as the ISS) DSO, and planetary objects in space.

MDL = MaximDL - Image Capturing & Processing Software

Near Earth Objects(NEO) – Any object man made or naturally occurring object that is found circling or coming in close contact with the Earth.

NB = Narrow Band

OAG - Off-axis Guider

Piggyback - Mounting a camera and lens on top of a telescope on a mounting. Piggyback photography is usually used for long-exposure wide-angle astrophotography where the camera and lens take the picture while riding on top of a telescope on an equatorial mount that is polar aligned and tracking the stars to compensate for the Earth's rotation.

PS = Photoshop

PI = PixInsight

Polar Alignment - Making the polar axis of an equatorial mount parallel to the Earth's axis of rotation by pointing it accurately at the North Celestial Pole in the Northern Hemisphere, or the South Celestial Pole in the Southern Hemisphere. The Northern hemisphere uses Polaris in polar alignment because of is distance away from the NCP(North Celestrial Pole) which is within one degree. The Southern hemisphere is more complex due to no reference star and a method of using Octans as its reference point
Raw - Unprocessed data directly from the sensor.

Stack - A generic term that means to combine images to one single image for processing. The term originates in the days of film astrophotography where images were literally stacked on top of one another to improve contrast and color.

Sub Exposure(Sub’s) - A sub exposure is one of many shorter exposures that are made and then added or averaged together to equal a single longer exposure.

Vignetting - Light falloff in the corners of an image due to optical, geometrical or mechanical reasons.

White Point - The brightest area of an image that is mapped to the highest level available (pure white) based on the bit-depth of the image (Level 255 for an 8-bit image) when setting the dynamic range during a levels adjustment in image processing.
Last edited by galaxyhunter on Wed Jan 15, 2014 9:05 pm, edited 7 times in total.
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Re: acronyms used in AP

Post by MikeM » Tue Dec 31, 2013 8:19 am

Nice list john, should probably e made into a "sticky".
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Re: acronyms used in AP

Post by Doug » Tue Dec 31, 2013 8:25 am

mamill wrote:Nice list john, should probably e made into a "sticky".
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Re: acronyms used in AP

Post by galaxyhunter » Tue Dec 31, 2013 9:49 am

Thanks Mike :) any additions or corrections are welcome. :)
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Re: acronyms used in AP

Post by Doug » Tue Dec 31, 2013 10:25 am

Here are a few to add to the list. Please edit as you see fit.

FRFF = Focal Reducer Field Flattener
FR = Focal Reducer
FF = Field Flattener
PS = Photoshop
PI = PixInsight
FOV = Field Of View
NB = Narrow Band
DSS = Deepskystacker

Great thread John!

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Re: acronyms used in AP

Post by Doug » Tue Dec 31, 2013 10:35 am

MDL = MaximDL - Image Capturing & Processing Software
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Re: acronyms used in AP

Post by MikeM » Tue Dec 31, 2013 10:53 am

OAG - Off-axis Guider
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Re: acronyms used in AP

Post by Doug » Tue Dec 31, 2013 4:36 pm

Looking better each time I see it! I like how you Divided the Index with the RED separators! Good work John! Thanks!
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Re: acronyms used in AP

Post by galaxyhunter » Tue Dec 31, 2013 4:38 pm

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Re: acronyms used in AP

Post by IOTA » Wed Jan 01, 2014 5:44 am

Thanks fellows!!!!
I just printed this out...
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...
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Re: acronyms used in AP

Post by galaxyhunter » Wed Jan 01, 2014 7:48 am

IOTA this is a start of a list and I'm sure it will grow and grow and grow. I ask that you enjoy it use it and if you see a word that isn't on the list share it pretty please :) The definitions part is going to be the hardest because so many words mean different things and some I may or may not be so clear of its original intention. Regards
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Re: acronyms used in AP

Post by Boris Sputnik » Tue Nov 10, 2015 4:39 pm

Pretty cool list. Thank you !
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Re: acronyms used in AP

Post by Doug » Sat Apr 23, 2016 10:05 am

CA - chromatic aberration
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Re: acronyms used in AP

Post by Craig » Wed Sep 20, 2017 3:12 pm

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Re: acronyms used in AP

Post by h2opolo » Thu Sep 21, 2017 9:23 am

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Re: acronyms used in AP

Post by Europa » Sun Sep 24, 2017 7:32 am

Great idea,

Differential flexure: when one part of the imaging system shifts slightly, while other parts do not.

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