Posts Tagged ‘Diffraction Limit’
Solar telescope
A Solar telescope is a special purpose optical telescope used to observe the sun
Professional solar telescopes
Solar telescopes need optics large enough to achieve the best possible diffraction limit but they do not need the associated light-collecting power of other astronomical telescopes. Because solar telescopes are operated during the day and image a very bright object, and because the seeing limit imposed by atmospheric turbulence is much worse than that experienced by night-time telescopes, the objectives of such telescopes are about 1m or under in diameter. The heat generated by the tightly-focused sunlight also poses a design problem. Professional solar observatories may have main optical elements with very long focal lengths and light paths operating in a vacuum to eliminate air motion due to convection inside the telescope. Since this makes the telescope relatively massive (some are the most massive optical telescopes in the world), and the object that they image (the Sun) travels on a narrow fixed path across the sky, solar telescopes are usually fixed in position (sometimes buried underground) with the only moving part being a heliostat to track the sun. These telescopes use filtration and projection techniques for direct observation, in additional to filtered cameras of various types. Specialized tools such as spectroscopes and spectrohelioscopes are used to examine the sun in different wavelengths.
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Planet Earth White Decorative High Gloss Ceramic Drawer Knob |
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Handcrafted in the USA to the highest standards using a specialized heat fused, high definition image transfer, that is tripled sealed with a UV resistant glass like gloss finish to ensure durability, easy cleaning, and to obtain an enamel hard like finish... |
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Map of Our Solar System Decorative Night Light |
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Handcrafted in the USA to the highest standards using licensed materials with great individual care and attention to detail. We are certain that you will be completely delighted and satisfied with our product... |
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Planet Neptune White Decorative High Gloss Ceramic Drawer Knob |
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Handcrafted in the USA to the highest standards using a specialized heat fused, high definition image transfer, that is tripled sealed with a UV resistant glass like gloss finish to ensure durability, easy cleaning, and to obtain an enamel hard like finish... |
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Our Solar System Decorative Night Light |
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Handcrafted in the USA to the highest standards using licensed materials with great individual care and attention to detail. We are certain that you will be completely delighted and satisfied with our product... |
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Cosmic Solar Flares Decorative Night Light |
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Handcrafted in the USA to the highest standards using licensed materials with great individual care and attention to detail. We are certain that you will be completely delighted and satisfied with our product... |
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Hubble: 15 Years of DiscoveryReviewsGreat on pictures but lack a good history background. Would prefer that Amazon place on their site some write-up from the DVD maybe get more of idea what was on the DVD before purchase. I give it 3 stars ONLY because of the overwhelming beauty of the pictures shown. But the production of this DVD is at a very low standard. For the slightly interested layman like me there wasn't bit of new information. Not to mention differing cosmological theories (electric universe versus gravitational/ big bang etc.) The speaker was boring to the max, he is probably a scientist with very few social skills. It would have been better to hand a script to a professional speaker who may even had more enthusiasm while he is explaining the unfolding of the universe. Its the standard model for highschool kids. I was more than a little disappointed with this considering the fact that the Hubble telescope is one of humankind's most spectacular technological and scientific achievements. Instead of giving the viewer specific detail about what Hubble has achieved we get instead a kind of generalized, gee whiz hype about what a wonderful instrument it is. More--much more--information about how it was built and how it works and what its features are and what it has discovered and taught us could have been including in the narrative. In fact, the narrative is dumbed down to an annoying degree. For example we are told that Hubble has discovered the most distant object ever seen, but we are not told how distant that object is. It's as though the narrative were written for people who just want to trip out on the images without being burdened with any specific knowledge. Also annoying is the way the magnificent photos of the heavens are just displayed on the screen usually too quickly for any real contemplation and without detailed information about what is being shown or why it was photographed in the first place. ESA and NASA should have hired somebody knowledgeable to write an image-coordinated script for this that would inform and really entertain, and they should also have hired a professional to read the script, somebody with more enthusiasm and skill than Bob Fosbury displays. The images need to be explained so that we can understand what we are seeing. The clouds and nebulae, the points of light, the halos and the shapes are not self-explanatory. And when the images have been augmented or enhanced in some way, that needs to be explained as well. Some side by side contrasts between what is seen in the visual spectrum and, say, the infrared would be nice. Distances should be revealed. There are two discs, one a DVD video, and another a CD audio which plays the soundtrack. There is a booklet full of statements like, "The planets of our Solar System have captured the imagination and interest of scientists and thinkers from the earliest times." Or, "Stars are social objects. They like to hang out together in star clusters or as large islands of stars..." This sort of empty expression or anthropomorphic nonsense is typical of what is heard on the video. It's as though the entire production was aimed at children. Actually what I think happened is the production was designed by a committee of ESA and NASA political types who just wanted to massage the public and were afraid that too many facts and numbers and ideas would simply turn them off. It pains me to have to say this, because I love astronomy and cosmology, but shame on you ESA and NASA! We loved the movie, an excellent family must see!!! The animation, imagry and sound effect were all excellent and each added to the other. We first saw the movie at our friends house, and thought we had to buy our own copy. Its interesting how much more there is to see the more times you watch it. The children were facinated by the animation and images. We all enjoy listening to the amazing soundtrack. Always when we listen to the soundtack in the car it gets us all into conversation of the movies amazing images and animation. I was very pleased with information in this movie and how it was presented. The animations and images were fascinating. My kids and I watched it together, and we all learned a lot about both the Hubble and the history of the universe. The narration was a bit dry at times, but the soundtrack livened things up and added a lot to the film. Average Rating:![]() |
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Genius - GalileoReviewsNeither glamorizing nor demonizing this important man of science, this video is a good overview of his life, his scientific contributions, and his controversy with the church. Recommended as a serious introductory examination of his life. Average Rating:![]() |
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No Description Available.Genre: DocumentaryRating: NRRelease Date: 25-APR-2006Media Type: DVD |
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Eclipse Chasers |
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How far would you go to see an eclipse? For a true eclipse chaser, the answer is "as far as I need to." Especially when it comes to a Big One: a total eclipse, when the moon's shadow completely erases the sun... |
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Celestron NexImage Solar System ImagerReviewsCelestron really needs to catch up with technology. More and more people are running x64 operating systems and more and more people are upgrading from the very poor Vista OS to Windows 7. Celestron has no drivers for either Windows 7 or x64 systems. My camera is now a paper weight until I can find someone to "dump" it on. I recently bougth a camera and it is not compatible with Windows 7, and CELESTRON people said they don't have the drivers for W7 only for XP (Should i change my computer!!, ja...)- so my camera is in the box on the top of the bookshelf in my house - ít's very expensive to return it since I don't live in the USA. It's a gadget without future technology, in other words it is a waste of time and money. neximage doesn,t work with windows 7 os. when i pluged in the camara to the usb port windows wouldn,t recognize it so i could download the drivers. i contacted celestron they agreed told me to keep checking their website. This camera is not compatible with Windows Vista 64 bit operating system. If you're running 32 bit Vista you're fine except you have to download and install the new driver. I'll gladly sell you mine. It's never been used. I used the NexImager with my Celestron 130 SLT. It was very good for moon viewing but it struggled a bit with the planets. For example, I found that viewing Saturn through a normal eyepiece produced a better and sharper image than using the NexImage. Also the CCD resolution of 640x480 is low in this day when megapixel CCD's are commonplace even in low price cameras. My unit also produced a fair amount of noise when viewing a dark sky. But it is fun to play with and given it's low price, it is worth having. A more expensive and useful add-on would be to make it wireless to avoid the cable that runs from the telescope to your PC. As a side note, I'm using the NexImage with a Macintosh Macbook laptop. Though the software is written for a PC, I am using it fine via VMWare Fusion hosting a Windows XP OS. Average Rating:![]() |
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NexImage is a complete solar system imager that is compatible with most any telescope and gives users all the light sensitivity and color fidelity that only a true CCD chip can provide |












