Clear skies / "Bright skies aren't empty skies" (James Mallaney)
My best solar system sketches / My deep sky sketches
Chris Nexstar 8SE; Celestron AVX mount; Hyperion 8-24 mm zoom; Orion 9x50 RACI; Baader Sky Surfer Messier count 110/110 "Though my soul may set in darkness, it will rise in perfect light; I have loved the stars too fondly to be fearful of the night" 51N, 2W My Gallery
14" Strut; 10"XT; 102ES; 22 in Process; 3.5,5,7,10,14,20mm Pentax XW; 17.3 & 12mm Delos; 27mm Panoptic; 20&24mm ES 68; 24mm ES 82; 30mm ES 82; 6&10mm BCO;
Quote:@ Jake: I know there's a lot of debate about it. I used the formula on http://unihedron.com/projects/darksky/NELM2BCalc.html. A well known Dutch observer uses another (more optimistic) formula: =8,5-5*LOG10(1+10^(4,4-(SQM/5))). But for me it is all Chinese. And I must admit, I never check/control the NELM myself I let the machine do the work!