From: Martin Shough <parcellular.nul> Date: Tue, 18 Oct 2011 16:14:43 +0100 Archived: Tue, 18 Oct 2011 11:26:11 -0400 Subject: Re: Was 'First Photographed UFO' A Comet? >From: Ray Dickenson <r.dickenson.nul> >To: <post.nul> >Date: Tue, 18 Oct 2011 01:58:58 +0100 >Subject: Re: Was 'First Photographed UFO' A Comet? >>From: Kentaro Mori <kentaro.mori.nul> >>To: post.nul >>Date: Mon, 17 Oct 2011 10:47:38 -0200 >>Subject: Re: Was 'First Photographed UFO' A Comet? >>>From: Ray Dickenson <r.dickenson.nul> >>>To: <post.nul> >>>Date: Sun, 16 Oct 2011 22:54:26 +0100 >>>Subject: Re: Was 'First Photographed UFO' A Comet? ><snip> >>>www.perceptions.couk.com/bonilla.html#trail >>>original Spanish text version >>>www.perceptions.couk.com/bonilla2.txt ><snip> >>Mexican researcher Luis Ruiz Noguez wrote an excellent summary >>of Bonilla's photos, available in Spanish: >>http://www.anomalia.org/perspectivas/in/ovnisbonilla.htm >>http://www.anomalia.org/perspectivas/in/ovnisbonilla2.htm >>Noguez quotes that even Fort speculated the objects could have >>been birds or insects. The idea of a comet, I think we can all >>agree, is highly unlikely, least of all because it doesn't fit >>the recorded and reported evidence, one of the points which Ray >>mentioned. >>Bottomline is, we don't know for certain what the objects were, >>but it's not unreasonable to suggest they were prosaic objects, >>as we have several other instances of such in contemporary >>observations and records. ><snip> >Hello Kentaro >I took the trouble to read that Noguez piece. Those two really >should have done the same with Bonilla's report. >Bonilla seems to have been a careful chap and took "certain >measures" after the first day's sightings and again after the >second day's, so as to establish some basic facts: Bonilla may have been a careful chap, but I'm not so sure he knew how to use a telescope. >i) he'd carefully focussed his set-up (based on the 'equatorial' >telescope) on the moving objects and not on the Sun. Then, in >the evening/night he steered that pre-focussed 'equatorial' >scope to the visible planets in turn and then to the Moon. The >views so gathered told him that the objects had been at a >distance much less than any planet but only a little less than >the Moon. He then apparently checked the calibration of his >focus set-up, because he was able to refine his estimate of >about 3/4s of the Moon's distance, down to about 2/3s - i.e. >approx. 242,000 kms; We have been around these same houses before, years ago, but as far as Ray is concerned we might as well not have bothered. This is (or ought to be) very basic practical astronomy: All astronomical objects are in a flat plane at effective infinity, for any Earth telescope. Bonilla's idea of being able measure the relative distances of the moon and planets by twiddling his focus knob is ludicrous. All of these subjects will always be in exactly the same degree of focus or defocus whatever you do to your telescope. Near depth of field starts at the hyperfocal distance which is at most a few km from the objective. Absolutely anything beyond the atmosphere produces an image at the same point of focus. If he was truly able to bring the objects and the sun to a different focus then the objects were _not_ astronomical-scale phenomena in space; they were local to the lower troposphere above Zacatecas. This conclusion fits the argument from parallax: other observatories saw nothing. There _is_ one way for objects inside the same depth of field beyond the hyperfocal distance to show differemt focus, but that is if the instrument has a common type of aberration called field curvature (inversely proportional to focal length). This aberration does not prove anything about the relative distances of the objects. In this case stars near the centre of the field can be in perfect focus, whilst stars near the edge of the field can be out of focus, usually with some type of asymmetrical distortion. Imagine the magnified image of the sun filling the projected field of view. This projected focal plane is slightly curved but it is viewed on a flat plate. Imagine that Bonilla focuses on the objects when they are some distance from the centre of the sun - perhaps where they cross the limb of the disc as bright shapes. If, later, he then examines ther image of a star centered in the field of view, as would be normal, he would find that it was out of focus, because of the field curvature. I'm not saying Bonilla made this mistake. There are also possible effects of mechanical relaxation, day/night temperature change etc, on the focus mechanism, as I pointed out last time. But there is no other possible reason than instrument error for differently focusing two objects in space beyond the hyperfocal distance. See: http://tinyurl.com/3s4mwyl or: http://starizona.com/acb/ccd/advtheoryfoc.aspx [QUOTE] Field curvature appears because the outer portion of the field of view may have a different focal point than the center. The focal length increases as you move further out in the fov. You can't get both the center and the edge of the fov in focus at the same time but you can get one or the other in focus. Curvature of field (change in focal length off-axis) can be reduced by using a field flattener. Without the flattener, the outer portions of the field will be slightly out of focus when the center is in focus. Instead of focused pinpoints in the outer field, in the presence of curvature, the star points would be slightly out of focus. Curvature has the tendency to enlarge and blur the circles of light that form the stars in the outer field. Points further out in the fov would be more out of focus and therefore more blurred. (Curvature would cause slightly enlarged circles, assuming no other aberrations are present. However there are almost always other aberrations present, so the distorted image is never that clean). A field flattener is used to help insure much of the entire field is in focus at the same time. With the use of a field flattener, stars in the outer field will be focused and appear just as stars in the center (again, assuming no other aberrations are present). [END QUOTE] Martin Shough Listen to 'Strange Days... Indeed' - The PodCast At: http://www.virtuallystrange.net/ufo/sdi/program/ These contents above are copyright of the author and UFO UpDates - Toronto. They may not be reproduced without the express permission of both parties and are intended for educational use only.
[ Next Message | Previous Message | This Day's Messages ]
This Month's Index |
UFO UpDates - Toronto - Operated by Errol Bruce-Knapp