D131f700 Refractive Lens For Astronomical Telescope
Thursday, January 7th, 2010 at
2:52 am
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D310F3000 refractive lens for astronomical telescope
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D131F700 refractive lens for astronomical telescope
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Well, for visible light dispersion from glass if wavelength increases, then the index of refraction decreases. So blue light (short wavelength) will have higher index of refraction and refract more (bend more). Red light (longer wavelength) will have lower index of refraction and bend less.
When you have a glass prism, you have light entering at an angle, so by Snell's law, n1sin(x1) = n2sin(x2), you have different angles of diffraction if you use different indeces of refraction for the different wavelengths. So light is dispersed on hitting the first surface, and then it is even further dispersed hitting the second surface, so white light (made up of many different wavelengths) entering will exit as a rainbox spectrum of light with colors spread at different angles.
You need to read a goddamn book mate.
Anybody want to Chat.
Jupiter is just a gas shaped like a planet
Depends on what type of camera you have. Most digital cameras have a lower limit of 30 seconds for taking an exposers. DSLR's such as Canon and Nikon have a port which you can add a piece of hardware that will override that limit. This lets you go for hours.
Another problem is that most cameras (such as the "point and shoot" type) have no direct way of attaching themselves to a telescope. DSLR's (the ones that have removable lenses), you can purchase an adapter ring that allows for a direct connection to the telescope.
As for a telescope, You need something with excellent tracking, focusing and sturdy. A $500 budget will just barely buy you a decent mount.
However, one thing you can try is wide field photography. This is where you use a wide angle lens (28mm or better, non-zoom), mount the camera on a good tripod and shoot the sky. Your not tracking the sky, so you'll need to use short exposer times, but its a great way to get started in astrophotgraphy while you save up for a good mount and telescope
The index of refraction is equal to the speed of light (c) divided by the speed of light through the second medium.
v1/v2 = n
Where v is the velocity of light through the mediums and
n is the refractive index.
c/0.7c = n
n = 1.0/0.7 = 1.428571 = 1.43
If they were able to put a prescription to what my eye was before it would have been around somewhere around minus 24 to minus 26. After this surgery I’m around 20/60.
The lens that came with your D40, the AF-S 18-55 mm ED lens is just perfect for what you want do do.
Stick with Nikon lenses … even a good used Nikon lens is better than any generic lens.
My two most used lenses are the 12-24 mm for landscape and architectural shots and 18-200 mm VR for general editorial shooting and 24-70 mm f/2.8 when shooting fashion.
Great lens.
Kodak EasyShare Z981 14MP Digital Camera with Schneider-Kreuznach Variogon 26x Wide Angle Optical Image Stabilized Zoom Lens and 3.0 Inch LCD
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Date first available at Amazon.com: January 5, 2010
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Telescopes generally fall into three catagories. Refractors, reflectors, and catadioptrics.
Refractors use lenses. Lenses work by collecting "bending" light by a phenomena called refraction. Reflectors, on the other hand, have an open front with a small mirror mounted near the front in the middle of the tube, and a large mirror mounted in the back. The large mirror in the back collects the light and focuses it to the secondary mirror up front, which bounces it into the eyepiece.
Catadioptrics, light schmidt cassagrains, have generally short tubes, a large mirror in the back, and a glass plate up front with a round area in the middle, which is where the secondary mirror is mounted. They work in a similar fashion to reflectors but the specifics are a little different.
For any telescope, the operating principals are generally the same.
1. Take the cover off.
2. Put in the lowest powered eyepiece…this is your 25mm one.
3. Point the telescope at a ground based object in the distance.
4. Looking through the view finder, adjust it using the adjustment screws on it's bracket to get it to be pointing at the same object you see in the eyepiece.
5. Put in a higher powered eyepiece and repeat.
6.Put the lowest powered eyepiece back in.
Once you've aligned the viewfinder properly you can try pointing the telescope at something inthe sky. I'd start with the moon, and then try a bright planet like Mars.
How to tell eyepiece strengths. Eyepieces are listed by their focal lengths. The largest number is the lowest power, and should be the eyepiece which you will get more use out of. The higher powered eyepiece you use, the more difficult it will be to get a good image because you magnify the atmosphere more, you approach the limits of the physical capabilities of your telescope's optics, and the motion of the Earth becomes far more apparent, making it difficult to keep things in your field of view long enough. They are also generally not very comfortable to look through.
use the lensmaker's equation:
1/f = (n-1)(1/R1+1/R2)
1/f=(1.40-1)(1/14 – 1/12) = -1/210
so the focal length is -210 cm and the refractive power is 1/f measured in meters, or -1/2.1 =-0.48 diopters
Its crazy how people take them selves so seriously after all we are nothing compare to the universe. Amazing document it made me have a different point of view on life.
I too am a victim of LASIK. I too bought in to all of the lies telling me that it was painless, safe, proven, and had a 95% success rate. All lies. Every year my eyes get dryer and dryer and I’m wondering if my eye is dying from having had the nerves cut never to regrow since the LASIK FLAP was created. I never had dry eye or eye pain until I paid a LASIK Lying Quack Charlatan $5k to ruin my eyes and thus my life. Every LASIK surgery is a failure because it leaves you with permanent dry eye
I used to do that all the time with contact lenses. then I got zapped when I worked for a refractive surgery clinic lol
RT 1 new US patent granted in portfolio this week "Plasmon-polariton refractive-index fiber bio-sensor with fiber bragg grating"
Whether you have good health insurance or none at all, the costs of medications can be astronomical. Here’s a tip for stretching your dollars at the pharmacy. Photo by Sam Catchesides. First of all, to take advantage of this great tip, the first thing you need to do is run the idea past your doctor. Here’s how it works: With some medications, the higher the dose, the less you’ll pay per milligram to have your prescription filled. In some cases, you might be able to get your medicine at double the dose you normally take, then cut it in half with a pill-splitter. Your doctor or pharmacist can tell you if the meds you take can be safely split, because some can’t (the pill pictured above obviously wouldn’t work so well, for example). If so, ask your doctor to write you a prescription for a higher strength pill and chop them in half yourself. Wisebread blogger Paul Michael runs the numbers on how much money you can potentially save with this method. I take a medication that can be safely…
I have been looking deeper, much deeper. just check out my favs, its full of it.. but what I ment with it is that we look at quantum mechanics and the universe(s) from our point of view which makes everything pretty complicated and rational..
M-Rock Joshua Tree 648, Solid Lens Case for Lenses up to 7″ Long & 4.25″ Diameter with Reversed Lens Hood – Black/ Black/ Grey
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The origin of the term “nova” – Long-time readers of WDTPRS know that I often post about astronomical phenomena. …
Denver, Aurora, Englewood, Colorado Refractive Surgery – Blog
The important part is the – or + 6.00 maximum cut off point they ask for.
The 20/? is just a measurement taken with the eyechart that doesn't really mean much.
It's mainly to verify how well you are seeing with the correction they prescribe for you. The idea is to get you to see 20/20 or better if possible , with your correction on. That's where the eyechart is used to get that measurement.
So, regardless of the power of the lenses, most people are corrected to 20/20 or better.
I think that's what you wanted to know….
It certainly took them long enough, but Olympus has finally (finally!) introduced a Micro Four Thirds camera with a price tag that’s a little closer to earth. If you’ll recall, both of the previous PENs cost upwards of $750, but the E-PL1 touts a much more reasonable MSRP of $599.99. And that doesn’t mean Olympus has been stingy on features. Nope, quite the contrary as the the minuscule body is packed with the same 12.3 megapixel image sensor as the E-30 and E-620 (check the images in the gallery to see a size comparison of the actual sensors), in-body image stabilization, continuous autofocus, a 2.7-inch rear LCD, HD movie mode, in-camera “art filters” and a bundled ED 14-42mm f3.5/5.6 zoom lens (28-84mm equivalent in 35mm cameras). Oh and don’t forget the addition of the pop-up flash which just reminds us of E.T. You won’t be able to nab a E-PL1 until next month, but hit the break for some of our hands-on impressions. Gallery: Olympus PEN E-PL1 hands-on Gallery: Olympus PEN E-PL1…
1:56 DARK SDIE OF THE MOON!!!
Nikon 18-55mm f/3.5-5.6G ED II AF-S DX Nikkor Zoom Lens Gray Market
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I don't remember optics very well, so I'll just interpret your sentence.
For refraction (bending of light) to occur, light must be passing through two materials with different properties. The number that tells us how much 'bend' we will get is the refractive index. So if we have light passing through air with refractive index 'A' and then a lens with refractive index 'L' then the 'relative difference would be 'L-A'. By saying that the focal length is inversely proportionaly to this number they mean that Focal length x (some constant) = 1 / (L-A) x (some other constant) for this example.
At least this is what I think it means. If you're talking about dispersion than it might have to do with the relative difference of refractive indices for different wavelengths of light in the same medium. In any case, the relative different and inverse proportionality concepts are the same.
Just like different colored lights filled with gasses (neon, argon, helium etc) every gas gives off a different color when it's hit with some energy and then releases the energy. The colors are just the natural colors. However, our eyes have a threshold for color perception. In dim light, we really don't see in color so in the small telescopes and binoculars most people have access to, there's not enough light for our color perception to kick in. The film and the solid state cameras don't have these limitations.
Panasonic LUMIX G 20mm f/1.7 Aspherical Pancake Lens for Micro F…' by Panasonic for $595.95
1. is in orbit around the Sun,
2. has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape, and
3. has "cleared the neighbourhood" around its orbit.
An article on the history of the Harper College Astronomical Observatory and its Newtonian telescope.
Plans for observatory approved at historic gardens
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VISITORS to an historic house and gardens will soon be seeing stars after plans were approved for an astronomical observatory. But if you’re concerned that …
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Anybody want to Chat.
Vision w/o glasses: what glasses do is lock the eyes into their refractive
Mid Winter ATAGO Sale: Description: Digital Benchtop Brix /Sucrose / Refractive Index Digit…
what are you trying to say
Ya olduğun gibi görün, ya da göründüğün gibi ol ama böyle de olma be arkadaş
I had it in my earlier class. You have to use SNELL'S LAW OF REFRACTION, to find the refractive index.
U have to make a straight line in a big paper and put two sewing needles along the line separated by about 3-4 cm. Then U have to put the slab with its flat surface lying on the plane of the paper.
U have to see the needles from the other side of the slab and put the other twos so that they are in a same line.
Then, remove the glass slab and join the points of the two needls u fixed later.
Measure the angle b/w the deviated line and initial line.
Use Snell's law Sini/Sinr = Refr.ind
Lol. You better enjoy this now, while you can, because in 20 or 30 million year it might be gone.
as a boy, I remember drawing a very large close up of the Moon's full sphere, copied from an astronomical encyclopaedia. stuck it to my wall
lol thats funny i thought gears 2 came out in 2008 it is 2010 right? brush up your maths there not that far away from each other
yesss got a new lens pics back on deck–leaving for chicago in the morning Detroit saturday
A telescope-toting 747 is about to become astronomy’s most versatile tool In the movies, opening the door on a plane at 45,000 feet is disastrous. But this spring it will be standard procedure on one 747-one carrying a telescope high enough to capture the cosmos better than ever before. Built into the tail end of a Boeing 747, the Stratospheric Observatory for Infrared Astronomy (SOFIA) will soar above the atmospheric water vapor that blocks most infrared light from ground observatories, to shoot detailed images of star-forming nebulae, planets’ atmospheres and clouds of organic molecules. The 2.5-meter mobile telescope-operated by NASA and Germany’s space agency-will best the Hubble and Spitzer space telescopes by scanning the widest range of light of any scope, from ultraviolet to the far infrared. And because SOFIA is easier to design and maintain than a space telescope, it could be built and operated for a third of the cost. Stargazing from a flying plane is no easy feat, but the…
Here are a few web pages with good information on beginner's telescopes:
For more advanced information, read Phil Harrington's Star Ware, 4th edition (Wiley).
You'll get the greatest value for your money with a Newtonian reflector on a Dobsonian mount, such as these:
Buy from a store which specializes in telescopes and astronomy, either locally or online; don't buy from department stores, discount stores or eBay as mostly what they sell is junk. Find your local astronomy club and try out different telescopes at one of their star parties:
Fifty years ago, it used to be very common for people to make their own telescopes. Nowadays it has become very rare, because commercial telescopes have become relatively inexpensive. One result of this is that it is very hard to find the parts needed to build your own scope. Unless you have a very strong motivation to learn how to do this, and to track down the parts needed, I wouldn't recommend building your own scope. Because the parts are hard to find, they are very expensive, and a home made telescope will cost many times more than a commercially built telescope. Labour is so much cheaper in China where almost all telescopes are made nowadays.
excellent, thanks. hope the snake shot involved a powerful lens
KB! How's it going? Sorry to hear about your lens.
Most American companies do not mutate into Ponzi schemes, as Enron did (with the usual results).
The image projected at the focal plane will be 3 times larger in telescope A. Through the eyepiece, you will get identical images if you use an eyepiece in telescope B with 1/3 the focal length of the one in A.
Meteorites are sometimes given names, for example the Hoba West meteorite (which is in Africa). It is large, and I'm pretty certain it is not the only one that has been given a name.
But, in the spirit of your question, the correct answer is asteroids and some of the smaller moons in the solar system (which are asteroidlike in size).