NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: NG's "Midnight Fun"
From: Peter Fogg
Date: 2010 Jun 15, 07:42 +1000
From: Peter Fogg
Date: 2010 Jun 15, 07:42 +1000
George Huxtable wrote:
No. George is wrong. I have been careful, unlike George himself, even in his latest post, to distinguish apparent distortion, such as the effects of perspective, from other distortions caused, by example, by the shortcomings of lenses.
As in a lot of stuff you post, George, you confuse the theoretical with the practical. The examples of "use of cameras for making celestial measurements" that's I've seen here involve the sun's image near the centre of the image field. In this case there is nothing, in any practical sense, to worry about in respect of what may happen to other parts of the image towards the edges of the field, from whatever cause. Once again, like so many of these you trumpet so loudly so often as matters of grave concern, its just a furphy.
As that posting confused distortion with perspective, it had little
relevance to the matter in hand.
No. George is wrong. I have been careful, unlike George himself, even in his latest post, to distinguish apparent distortion, such as the effects of perspective, from other distortions caused, by example, by the shortcomings of lenses.
This question takes on a bit of importance because postings appear on this
list, quite often, from proponents of the use of cameras for making
celestial measurements. The geometrical distortions discussed here, that
arise from portraying a spherical surface on to a plane array, add serious
complications to interpreting measurements, and deriving scale factors;
complications which are often neglected.
As in a lot of stuff you post, George, you confuse the theoretical with the practical. The examples of "use of cameras for making celestial measurements" that's I've seen here involve the sun's image near the centre of the image field. In this case there is nothing, in any practical sense, to worry about in respect of what may happen to other parts of the image towards the edges of the field, from whatever cause. Once again, like so many of these you trumpet so loudly so often as matters of grave concern, its just a furphy.
