How To Buy A Telescope : Eyepieces For Telescopes
Tuesday, December 8th, 2009 at
10:04 pm
Discussion of the varieties of telescope eyepieces available. Learn how to choose the right eyepiece for you in this free home astronomy equipment video from a telescope designer and manufacturer.
...
 |
 Meade triangle metal telescope tripod eyepiece tray NEW  US $1.49
|
 2 yellow Barlow focuser Caps for Telescope eyepiece US $2.95
|
 Telescope 1 1 4 Eyepiece Filter Case New US $2.60
|
very nice post,, lots of info, could you help me w a couple things, first i have nexstar 130,, and bought the celestron 2 inch eyepiece kit, do diagnols work in reflectors,it doesnt fit right. also i am thinking about purchasing a vixen 3.5(3856) eyepiece as my first good eyepiece, is this a good all around choice for my scope for viewing planets,agian thanks for the post
Yow!! whats up with the hair, en the t-shirt ??
all astronomical pictures are false colour to a certain extent.
at the very minimum, the colours are what we would see if our eyes were many times more sensitive to light.
the colour rendition may be adjusted to match the phenomenon being observed. in this case they assign colours, which do not necessarily match what colour our eyes would see for the same wavelength. this is particularly true for wavelengths our eyes cannot see.
Try this site, it might help!
http://www.holloworbs.com/Venus.htm
Thank you…
Ha ha ha! Rather sadly, he didn’t say shitload of light, which would have been excellent. he actually said shedload. It’s a slang UK expression. I’ve always taken it to be like truckload, only in the amusing units of the shed. Ahh, How we laughed.
I’ve been thinking about these space observatories recently. They are very simple compared to those on the ground – what makes them special is the precision to which they are made.
Check out the Space Twitter list I've added to Listorious #nasa #space #esa #astronauts #telescopes #sattelites
Check out My Bunk latest shots from the Astrofactory telescope! Good stuff!
Celestron NexStar 130 SLT Computerized Telescope
by Celestron
276% Sales Rank in Camera & Photo: 380 (was 1,431)
(18)
Buy new: $439.00 $375.00
14 used & new from $339.00
(Ranking is updated hourly. Visit the Movers & Shakers in Camera & Photo list for authoritative information on this product’s current rank.)
if you cant get the full version, why put up the video at all?
The "smallest resolvable angle" A is given, for visible light, by a formula known as Dawes's limit:
A = 116 / D
where A is the angle in arcseconds (one second = 1/3600 degree)
and D is the aperture — diameter — in millimetres.
The shortest possible distance between an Earth telescope (including the Hubble in low Earth orbit) and the Moon is still more than 300,000 km (the mean distance is around 380,000 km).
We'll be generous and use 300,000 km.
The smallest resolvable distance on Moon's surface is:
300,000 km * tan(A)
The Hubble space telescope has an aperture of 2.4 m (= 2400 mm)
The smallest resolvable angle is 116/2,400 = 0.048333…"
smallest resolvable distance =
300,000 km * tan(0.000013426°) = 0.070298 km
Call it 70 metres (230 feet)
The largest telescope on Earth has a somewhat ellipsoidal mirror (in segments) and the largest axis of the aperture is 11.1 m.
(Southern African Large Telescope = SALT)
A = 116/11,100 = 0.0145045" = 0.000002903°
Smallest resolvable distance :
300,000 * tan(0.000002903°) = 0.0152 km = 15.2 m (50 feet).
Unfortunately, even with one of the best adaptive optic systems, SALT is still at the "bottom" of an ocean of air (our atmosphere) which probably only allows it to occasionally match the seeing that the Hubble space telescope gets.
So, 50 feet is the theoretical limit, while 230 feet would be the practical limit.
—
We could get around the brightness problem by using interferometry: using mirror segments in pairs and letting a computer figure out what the image looks like, based on the interference fringes of the light combined from two segments.
However, would you still consider this "viewing"?
NASA’s Wide-field Infrared Survey Explorer, or WISE, is hard at work on its task of mapping the entire sky with infrared light. Why? Planet-killing asteroids,
Which record was this one on? I have taste and third wave already and it’s not on either of those. By the way i loove Loop and don’t forget swervedriver
Though they are the largest and most widely scattered objects in the universe, galaxies do go bump in the night. The Hubble Space Telescope has photographed many pairs of galaxies colliding. Like snowflakes, no two examples look exactly alike. This is one of the most arresting galaxy smash-up images to date. At first glance, it looks as if a smaller galaxy has been caught in a tug-of-war between a Sumo-wrestler pair of elliptical galaxies. The hapless, mangled galaxy may have once looked more like our Milky Way, a pinwheel-shaped galaxy. Now that it’s caught in a cosmic blender, its dust lanes are being stretched and warped by the tug of gravity. Unlike the elliptical galaxies, the spiral is rich in dust and gas for the formation of new stars. It is the fate of the spiral galaxy to be pulled like taffy and then swallowed by the pair of elliptical galaxies, which will trigger a firestorm of new stellar creation. If there are astronomers on any planets in this galaxy group, they will…
NcStar Cartridge Laser Bore Sighter For 30-06
by NcStar
Buy new: $25.00
(Ranking is updated hourly. Visit the Hot New Releases in Binoculars, Telescopes & Optics list for authoritative information on this product’s current rank.)
Astronomers have developed a technique to probe the atmospheres of distant planets which could help to identify signs of extraterrestrial life.
UGHH weee ha
it is a bit more than that
telescopes use large lenses because it permits more light to enter
microscopes use small lenses for sharpness
sharpness is not much of an issue in telescopes.
the camera uses a compromise for resolution aberration…
For example in an inspection microscope say 10 to 30X if you change the eye piece for larger magnification the colors don't focus at the same place anymore.
the solution is to change the first lens for a smaller one and bring the instrument closer to the subject
the draw back is no room to work
it is all a balancing act
Guru
There are several different kinds of telescopes and all of them have some excellent features. Refractors and Reflectors, plus Schmidt-Cassegrain, APO refractors, Mac-Cass, and many more. There are also several mounts to chose from and the mounts are just as important, if not even more important, than the scope is. All of the different scopes and mounts have some features that some people like and do not like. No two eyeballs are the same and the perfect scope for one person might be completely wrong for another person.
There is no one scope that is "better" than another —except for the junk scopes out there which are all just a waste of money. Never, ever buy from Walmart, Costco, Target, or any other discount store like that. Junk scopes are flooded into the market from those stores. You will be buying nothing but bad optics and plastic.
If you are new at this, then stay away from anything used from any site. If you don't know what you are buying and who you are buying from you will most likely be getting someone else's headache—with no warranty either. Buyer beware you know. Some great deals on used equipment, by people who know how to use and take care of scopes, are out there but if you don't know what you are doing, you might be spending a lot of money on junk.
______________________________________…
I recommend:
Orion is the very best for value and for customer service too. I have 2 of their scopes and I will only buy from them from now on. My first scope was a manual controlled scope and I am very glad that it was because it forced me to learn where things are in the night skies. Go-To type scopes can be frustrating to use. If you do not have them aligned exactly perfect, they do not find the targets. If you are a beginner, you will be frustrated unless you spring for a GPS Go-To. An object locator is just that—it will locate objects for you (must be aligned first) but an object locator is not a tracking motor. It will not keep the scope on the target.
The Orion site has some excellent diagrams and explanations of all types of scopes and mounts.
Things to consider are size–can the user lift and transport the scope to the viewing site easily? Does it fit in your car? If not, then it will gather dust in a closet. I recommend a carrying case too so it is protected in storage and transport. Can the viewer reach all the knobs and buttons? I have a long tube large manual refractor and it is very difficult for me to reach the knobs when I am pointed to Zenith. I am not a tall person.
Take your time in making your decision.
+++ I would like to suggest that you join a local astronomy club or astronomical society BEFORE you spend your money on a scope. There are many different kinds of scopes and what is perfect for one person is not perfect for another. Everyone has their own set of eyeballs and no two are the same. If you join a club, you can attend a few of their star parties and try out members scopes to see what works best for YOU, before you buy a scope. The members can also help you when you get your scope and show you how to get the most out of your new scope as well as to help teach you where the treasures in the sky are located. Most clubs have loaner scopes and extensive libraries that you can gather more information from too. Most clubs will have monthly membership meetings with informative presentations given by members and by guest speakers. You can really learn a lot from these clubs and an added plus is all the great new friends you make there too.
Some people will suggest that you purchase binoculars. Not a bad idea but don't buy anything less than 10×50 and you must have a tripod too or you will not be happy with your astronomical views because they will be too shaky from your movements. Personally, I prefer a scope to binos because if binoculars are not aligned properly at the factory, then you get double images and distortions that cant be fixed. Most of the cheaper binoculars are not properly aligned. That is not as important for terrestial viewing but it is a killer for astronomical viewing. Binos can also be bumped out of alignment and become useless for astronomy.
When you buy go Orion and you wont be disappointed. Don't try to learn everything all at once or you will be overwhelmed and discouraged. Patience is the key to Astronomy.
You will need a good star chart program too.
This is great freeware that you can download. Tell it where you are and it will tell you what you see. Ask it where something is and it will show you.
I wish you all the best! Enjoy!
RT Technique lets ground-based telescopes parse exoplanet atmospheres
Hey…I would recommend a cool down time of at least 30 minutes. This means – try to take your telescope outside and leave it out there, and come back in about 30 minutes. The temperature does not matter…it can be -12 C, or 26 C…the problem is the change in temperature from a warm room temperature in the house, to the cold outside temperature. The telescope’s lenses require some time to become rigid and adjust…after the temperature change.
Subject: Eyepieces and Mak for sale – by: raymond: hi stevie
I would be interested in the 7 mm Nagler my ph is… #fb
you can see detail of the moon surface with binoculars! there is a regular laser pulse sent to the moon which is returned by a reflector put there by astronauts, that is how it has been determined that the moon is currently moving farther away from the earth.
Nice and informative, But what should we do if we happen to get sweat in the eyepiece, and it happens to dry out? follow the same process? thanks.
Yaaasss those are eyepieces are pure taste… #Sickening
It’s November, BITCH.
It is pretty tough to describe, since it depends on a lot of related issues like light pollution, eyepieces, and your own observing skills. As Tina suggested, the only way to really compare these is to try them yourself. We can tell you that the 10 inch has roughly 36% more light gathering capability than the 8 inch, but to translate that into a level of brightness as perceived by your own eye is an exercise in futility. I personally own an 11 inch SCT with premium eyepieces, and under clear skies I can see more than most people can imagine. But some folks can look through my scope at a target that is absolutely stunning to me and see virtually nothing. They don't quite know how to look; it takes some practice to see what is out there.
So, if I were you, I would check out the views at a local astronomy club star party. If that is not possible, I would go with the 10 inch.
I was actually referring to the monicals, as in the eyepieces (ex: haha! Do love your pizza, though!
There are plenty of sites that will tell you what telescopes and spectroscopes do — just try Googling "telescope" and "spectroscope." Basically what every telescope does is to gather light. Spectroscopes break light down into its component wavelengths to study what emits the light. All of these tools have told us how stars work and how the universe is structured.
Thanks!!!NICE VIDEO!
In this case, you have a telescope with two eyepieces and thus the figure of merit is the angular magnification of each. Using ray tracing we get
Angular Magnification = f_primary / f_eyepiece
For eyepiece 1 we have
Angular Magnification = 800 / 18 = 44
For eyepiece 2 we have
Angular Magnification = 800 / 30 = 26
I'm not sure why you don't want your children to look through the eyepiece, as that's usually the best way to use a telescope.
There are two kinds of projection, optical and electronic. With optical projection, you just rack the eyepiece slightly outward, and it will act like the lens on a projector. This works for the Sun and Moon, because both are bright. In fact, eyepiece projection is one of the traditional ways of observing the Sun, since the projected image is dim enough to be safely viewed, though I worry about heat buildup inside the telescope and the heat in the beam as it emerges from the eyepiece. I prefer using a full aperture solar filter over the telescope's objective and viewing with a normal eyepiece; the heat never gets inside the scope. Here's one source of solar filters:
The other way is electronic: a webcam or something similar replaces the eyepiece, and allows viewing on a TV or computer screen. There are cameras specifically designed for use in telescopes, like this one:
As for pointing the scope at the Sun, it's really very easy: you use the shadow of the scope on the ground. You just adjust the scope until its shadow disappears, and then it will be pointed exactly at the Sun. It's always best to keep the finder capped, as it can cause burns too.
She went over to the telescope to look, as Lex shot Clark a dubious gaze. The telescope was aimed right at his office.
Rotring Esprit (ebay link – ) telescopes down small, takes standard ink cartridges. Parker sell a version too
New Blog post binoculars telescopes
Slaggers is right, except he has reflector and refractor names and descriptions reversed. Reflector has a mirror, and refractor has a lens.
Good discussion!
dark matter as gravity is a force not matter
This telescope is in Perfect working condition.
Includes Meade Electronic Eyepiece ? send live video images from the telescope to your TV!
Product Features
60mm optical diameter
700mm focal length
f11.7 focal ratio
Altazimuth mount; dual-axis manual slow-motion control system
Includes adjustable aluminum tripod, StarLocator software, and 3 eyepieces
Technical Details
Brand Name: Meade
Model: DS-60ME
A catadioptric telescope is primarily a reflecting telescope with a correcting lens somewhere in the optical path. In the Schmidt designs, this is a thin aspheric correcting plate at the front of the telescope. In the Maksutov designs, it is a fairly thick, deeply curved meniscus lens, also at the front. There are also a few designs which have a smaller correcting element elsewhere in the system, such as near the secondary mirror. Vixen manufactures a couple of these.
So close, Panasonic. Your 3D camera would have been MUCH cooler (and useful) if it had two eyepieces. How did they miss that?!
Well, …, it depends on the eyepiece diameter. The XT8 comes with a 2" focuser. So if your Newtonian eyepieces are 1.25" in diameter, you will need an adapter ring (which I believe Orion already supplies with the XT8). 2" eyepieces should work very well. So, yes, your eyepieces should work in the XT8. Any other diameter eyepiece will have to be adapted and you can usually pick one up (or make one yourself) from Orion.
- Edit – Thanks for the extra info. Yes, you should be able to use those eyepieces. BTW, this was a great question! It's not often that we get to answer observing questions on this forum.
tags: birds, mystery bird, bird ID quiz
[Mystery bird] photographed on the Anahuac National Wildlife Refuge, Houston, Texas. [I will identify this bird for you in 48 hours]
Image: Joseph Kennedy, 11 November 2009 [larger view].
Nikon D200, Kowa 883 telescope with TSN-PZ camera eyepiece 1/1000s f/8.0 at 1000.0mm iso400.
Please name at least one field mark that supports your identification.
Read the rest of this post… | Read the comments on this post…
Also check out the featured ScienceBlog of the week: Collective Imagination
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.
Congratulations on building your scope. That is quite a nice accomplishment, If you mean the box down by the mirror? Sure, as long as it is convenient for you. BTW one of the very popular finders is the Telrad. You can attach it with double side tape that comes with it and it never will get unstuck. You dont have to worry about drilling a hole in the tube.
There are different estimates. Pessimists might say we really can't do better than about 50 light years reliably. Others may claim two or three hundred. Our ability will increase with more orbiting measuring devices planned in the future.
Parallax works by shooting an angle to a star from two positions which form the bottom two angles on a very long triangle. We use trigonometry to figure out how far away the other vertex of the triangle is. Our ability to do this is limited over long distances. Here's an example. Suppose you could see and point at some point in California from your position in Maryland. Now you shoot an angle to it. Now you move over a half an inch and shoot another angle. You can see how close these two lines are to being parallel. And it is very difficult to tell where they intersect, or how far off of 90 degrees they are to the 1/2-inch baseline. It is actually about these same proportions that we are trying to measure stars with. The earth's orbital diameter would be the half inch. Mind boggling that we can do even a fraction of this.
Excluding refracting, reflecting and radio telescopes leaves very little to talk about. Please rephrase your question.
Well, you've asked this in the astronomy section, which is not exactly the right spot for this.
However, you do *not* want an astronomy telescope for your stated purposes. Most telescopes used for astronomy will invert the image (unless you buy a diagonal for your eyepiece). Plus they will be more money than you want to spend for this purpose.
I'd say a spotting scope would work fine, but I'd consider a good pair of binoculars first.
!: Kendrick Dew Remover Heater for .965" Eyepieces & Finder Scope's
So close, Panasonic. Your 3D camera would have been MUCH cooler (and useful) if it had two eyepieces. How did they miss that?!