Search found 5 matches

by Dave Shaffer
Mon Sep 30, 2013 4:37 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)
Replies: 275
Views: 514054

Re: APOD: Mysterious Green Patches on the Sky (2013 Sep 30)

nitpicker may be on to something: long exposures, especially at high ISO can do strange things. Among other things, the camera CCD sensor chip will heat up as time goes by, for long exposures, which might shift the coloration of "strange things." Can the author fill us in on the details of...
by Dave Shaffer
Wed Jun 02, 2010 7:11 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A Twisted Meteor Trail Over Tenerife (2010 Jun 02)
Replies: 157
Views: 12561

Re: APOD: A Twisted Meteor Trail Over Tenerife (2010 Jun 02)

I just downloaded the image. When I look at the EXIF data for the frame, it reports a 1 second exposure. The EXIF data shows a 59-second exposure, which is consistent with the star trails seen in the central image. I stand corrected - I used Canon's ZoomBrowser program first (which reported the 1 s...
by Dave Shaffer
Wed Jun 02, 2010 6:36 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A Twisted Meteor Trail Over Tenerife (2010 Jun 02)
Replies: 157
Views: 12561

Re: APOD: A Twisted Meteor Trail Over Tenerife (2010 Jun 02)

Unequivocal: it is camera shake! I just downloaded the image. When I look at the EXIF data for the frame, it reports a 1 second exposure. Whether or not the camera was tracking, there should NOT BE ANY STAR TRAILING OR OTHER NON-LENS ARTIFACTS IN THE STAR IMAGES for such a short exposure UNLESS THE ...
by Dave Shaffer
Wed Jun 02, 2010 5:35 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A Twisted Meteor Trail Over Tenerife (2010 Jun 02)
Replies: 157
Views: 12561

Re: APOD: A Twisted Meteor Trail Over Tenerife (2010 Jun 02)

I would like to know the camera+lens combination. This is clearly a fish-eye lens, and most (all?) of the scattered light around the brighter stars (which has been commented on by earlier posters) is due to lens flare. Note that as you go around the edge of the picture, the flare tends to be tangent...
by Dave Shaffer
Thu Aug 06, 2009 4:56 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A Triple Sunrise Over Gdansk Bay (2009 Aug 04)
Replies: 338
Views: 50311

Re: Cause of Triple Sunrise (APOD 2009 August 4)

Folks, Plain and simple: It’s the window glass. I hope/think the images discussed below will set to rest all the objections to this explanation. Anybody who thinks otherwise does not understand how the atmosphere works. The atmosphere is stratified horizontally, with small vertical systematic variat...