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Meteorite Times Magazine Meteorite Times Magazine Contents Paul Harris Featured Articles Accretion Desk by Martin Horejsi Jim’s Fragments by Jim Tobin Meteorite Market Trends by Michael Blood Bob’s Findings by Robert Verish Micro Visions by John Kashuba Norm’s Tektite Teasers by Norm Lehrman Mr. Monning’s Collection by Anne Black IMCA Insights by The IMCA Team Meteorite of the Month by Editor Tektite of the Month by Editor Terms Of Use Materials contained in and linked to from this website do not necessarily reflect the views or opinions of The Meteorite Exchange, Inc., nor those of any person connected therewith. In no event shall The Meteorite Exchange, Inc. be responsible for, nor liable for, exposure to any such material in any form by any person or persons, whether written, graphic, audio or otherwise, presented on this or by any other website, web page or other cyber location linked to from this website. The Meteorite Exchange, Inc. does not endorse, edit nor hold any copyright interest in any material found on any website, web page or other cyber location linked to from this website. The Meteorite Exchange, Inc. shall not be held liable for any misinformation by any author, dealer and or seller. In no event will The Meteorite Exchange, Inc. be liable for any damages, including any loss of profits, lost savings, or any other commercial damage, including but not limited to special, consequential, or other damages arising out of this service. © Copyright 2002–2015 The Meteorite Exchange, Inc. All rights reserved. No reproduction of copyrighted material is allowed by any means without prior written permission of the copyright owner. Meteorite Times Magazine The Felix Carbonaceous Chondrite: A 3.3 from 1900. Martin Horejsi Thirty minutes before noon on May 15th 1900, a single stone flew down from space through a clear blue sky. It attracted the attention of those in that region of Alabama having generated the sound of thunder during its supersonic passage through the thin atmosphere of earth. Using the metaphors of the day, one witness described the meteor’s noise as “a big piece of red-hot iron being struck with a hammer, causing many sparks to fly in all directions.” The classic dark matrix of Felix contains many colorful and well-formed chondrules. As a CO carbonaceous chondrite, its namesake is Ornans, but was often compared to Lance’ in the literature. And in the case of Merrill’s work, the Warrenton. In 1901, George Merrell published the authoritative account of the fall of Felix, as well as a chemical analysis and a few pictures. From what I’ve read, not only is Felix the only CO3.3 witnessed to fall, but it seems Felix is the only CO3.3 period. The British Natural History Museum’s catalog initially listed the classification of Felix as a CO3.2 which would have provided it some overseas relatives including Kainsaz and Rainbow, but the Meteoritical Society suggest Felix be known as a CO3.3. On the far end of the family, there is a transitional hot desert find known as NWA 062 that straddles the line between 3.3/3.4 Crust is always welcome on a historic fall, and as 115 years old, Felix is historic. Below is the full text of Merrill’s tome on this Felix, Alabama fall. I especially appreciate the descriptions of the fall provided by the witnesses. Until next time…. Meteorite Times Magazine Meteorite Imaging James Tobin One of the wonderful things that the Internet has brought to us is the vast amount of images available on every topic. For meteorites many different issues can create challenges for getting images done well. Even as I write this I realize that I will not be able to show the images in this article at their hi resolution. We are forced by bandwidth and speed to compress our images and reduce their size. Still it is possible to capture and offer nice meteorite images. This is an image of a fascinating impact rocks from Australia. This is Jeerinah Layer spherule rich rock that is very old. The spherules that are so noticeable in this image are not even recognizable with the naked eye. The image was taken with a 50mm Macro lens set at f22 with a lifesize extension ring which makes the set up about f32. When this set up was used with 35mm film cameras the image exposed on the film was the same size as the real subject being shot. Thus the name “lifesize” extension ring. Sensor size and other factors change that some when the ring is used with a digital camera. I thought for this month’s article I would do it on one of the areas of imaging that we use frequently with meteorites. Close up, macro and ultra close up, are terms often seen. They are different in slight ways but they are an area that has many similarities and can be discussed as a single topic. For the sake of simplicity lets just call it macro photography. No microscope will be involved. I went digital years ago and had a point and shoot digital camera that did acceptable macro as one of its dedicated functions. By today’s standards it did not give me much control of exposure or lighting. And when the camera was so close to the object at .7 inches it was difficult to light the subject. With most point and shoot cameras there was no way to take the picture except by pushing the actual shutter button. I could put it on timed delay and that helped with vibration some if I used a tripod. But the camera was not very macro friendly. I got a Canon DSLR a while back to be my general photography camera. I use it for astrohotography and much of my meteorite imaging. I have normal and telephoto lenses for outdoor pictures to use with it. I was considering what to do for my macro and ultra close up work. Did I want to get a dedicated macro lens, extension tubes, bellows and all the rest? I should mention that I have a very nice 5 megapixel digital microscope for when I need to get in really close, but I enjoy using a regular camera more. How deeply did I want to get invested in new macro equipment? I had kept all my lenses from film days and had a full line of equipment for macro and closer work to fit my Minolta SRT 201. A little exploring on the net and I found that conversion rings were available for my old Minolta lenses to let them fit on my Canon T4i. If I wanted to use my Minolta normal and telephoto lenses I needed a conversion mounting ring that had a corrector lens in it. Otherwise it would not be able to reach infinity. You don’t have to reach infinity with macro photography. The lens-less converting mount was perfect. So suddenly I had all my old equipment back to use with the Canon DSLR. My biggest problem with that Nikon point and shoot digital which did macro was it had a small diameter lens and only went to f8. That is not going to ever be very good for advanced macro work. You need a little larger lens that you can really stop down to at least f22 or f32. And it will go to even slower settings when you start putting on extension tubes or bellows. So I needed the wide aperture control of a DSLR with a manual mode. My Minolta stuff mounted on the Canon gave me that. I was back in business for only a few dollars investment in the conversion mounting ring. In close up photography there are two topics that are just more important than anything else. Focus and depth of field. And they work hand in hand. In outdoor photography there might be times when the background is of no interest or even something you do not like. Well you can crank open the lens and focus on the foreground and like magic the background is blurry and not a problem. Other times you may want the background and the foreground to both be in great focus. So you squeeze that aperture down and the camera will take a longer exposure or you run up the ISO and there you are; the whole shot front to back is in focus. In close up photography you have the issues of the last paragraph to deal with. But the distances from foreground to background are compressed to usually a fraction of an inch or at most one or two inches. If your close up subject is a 3D object that you want well focused in all parts you have a real challenge. Even if you learn to control the depth of field. Briefly this is how it works. When the lens is wide open you have rays of light coming into the lens at all different angles which are bent to strike the film or sensor. The rays hitting the center of the picture will be focused at one setting but those hitting the edges of the film or sensor will not be focused at that same setting. When the aperture is stopped down so that only the very center of the lens is used the rays of light enter the camera nearly parallel without having to be bent by the system of lens elements very much. The light is much decreased in strength but it focuses across the whole piece of film or the digital sensor very close to the same focal point.
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