lumpy darkness

Observation notes (with equipment details), photos, sketches, reviews, software tips, random thoughts, by an amateur astronomer.

WEDNESDAY, MAY 9, 2018

darks

Digital astrophotography is light-years better (sorry) than the ole' film days. Stacking of multiple short exposures—a fantastic advance.

The new vexing problem: noise. Analogous to film grain. One type of noise is hot pixels. Happily, these can be reduced or eliminated by capturing dark, black, unexposed frames. "Darks" are affected by exposure time, ISO, and other factors.

It is to one's advantage to build up a library of darks. For my records, I have begun logging my dark frames as produced by the Canon 40D body. Ranked from longest to fastest.

 

duration
(seconds)
     ISO      temp
(°C)
date
(yymmdd)
330 1600   160603
155 1000   180508
120 1600   150714, 150716
  1000   150714, 150716
60 1600   150714
  1000   140704, 140622
45 800   150419
35 1000   170613
30 1000   130701, 160904
  400   150117
25 1000   140704
  400   130817
20 1000   140704, 160904
  800   140203, 130705
15 1600   130705
  800   150117
  400 +18 140805
13 800   130705
10 1600   131002, 130705
  1000   150901, 160904
8 800   130705
6 800   130705
5 1000   160904
4 1000   160904
  800   130705
2 1000   160904
  800   130705
1 1000   160904
  800   130705
1/2 1000   160904
  800   130705
1/8 1600   130505
1/30 1000   160904
1/60 1000   160904
1/80 1000   160904
1/100 1000   160904
1/200 1600   140331
1/250 1600   140331

 

Need some 30s. And longer ones...

With Backyard EOS, will incorporate temperatures soon.

 

 

 

links

    lumpy darkness sites:
    blog proper
    lists home
   
    telescopes:
    SP-C8 SCT
    GoToStar system
    Edmund 6" newt
    ETX90-RA MCT
    FirstScope 3" newt
    accessories
   
    life lists:
    planets, moons, etc.
    constellations
    notable stars
    double stars *
    Messier objects
    NGC objects
    other deep sky objects
    eclipses
    occultations
(*)   photo gallery
    magnitude limit
    to do
   
    resources:
    SkyTools
    Stellarium
    TheSky
    NexStar 11
    Aladin quick query
   
    other lists:
    Greek alphabet in HTML
    judging angular size
    atlases, books, software
    what's up for the year
    meteor showers
  with just your eyes
  assessing darkness
  observing preparation
  presentations
  articles
   tips and tricks
    builds and hacks
    wx dashboards
  
    web site links:
    magazines
  sky conditions
  predicting aurora
  science and research
  space telescopes
    double stars sites
    retail stores
    clubs and associations
    DIY observatories
    miscellaneous