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Trading Post Member
 
Group: Forum Members
Last Login: 25/03/2009 10:16 PM
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For many years I have been buying and selling Telescopes, most people I find dont try to find out what they want or need or even if their Children can use it.
If I can help please contact me.
Jim.
See my Blogs.
http://jimssky.spaces.live.com
http://www.blognow.com.au/myskyplace/
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Trading Post Member
Group: Forum Members
Last Login: 25/03/2009 10:16 PM
Posts: 5,
Visits: 4
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Eyepieces.
On a Telescope, you will find that the piece you look through (the Eye Piece) can be removed. Now there is a reason for this as I was talking to Tim the other day. Tim’s daughters and wife had just bought him a Telescope for Christmas and I had visited him to help show him around the sky.
Now to magnify an image you need a lot of light, this is up to Mirror or the Primary Lens. This Light now has to the Focal point (this is the Focal Length of F stop) which is also the length of the Telescope. Now we can work with the light with the Eyepiece which has its own focal length.
If you can’t workout the F length, the telescope will have that stuck to the side of the tube and Eyepiece will be the same. Now, the magnification of a Reflecting Telescope is Focal length by the Eyepiece or F ÷ E = M. There is more to this that I will be covered later. So now we have the Magnification and we can go on to Eyepiece techniques.
You start with a large Eyepiece size; this is going to give you a wide view and a small magnification. So once you have gotten to the part of the Sky you want, you can see what you’re after though it may be too small. Centre the image of this object and change the eyepiece to the next size down, now you have a larger image. Go on with this process until you get to the magnification you want.
Good views and clear skies. Jim.
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Trading Post Member
Group: Forum Members
Last Login: 25/03/2009 10:16 PM
Posts: 5,
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In your Eye.
Now we have an image of some distant object in deep space that you want to see in detail. That’s great, But, and that’s a big but, you need to know about what is doing the seeing, you.
You are not only using your eye, that a human’s first problem next is the brain. I have to tell you as god made or the penicil of evolution, your eye isn’t the best one, in fact it’s on the edge of note only useless but distracts the Brain completely. This is documented in a lot of accident reports for many years.
1. The Human eye is not a recorder, it is a detector. This is any particle of light that hits a cell of the Retina will be detected, but, will take time to reset. In most Hospitals you will find the Surgeons wearing green aprons. This is allow the surgeons eyes to adjust to see the blood better as having red all over the place the surgeon can miss things or loss his way. Bad for him, worse for you.
2. The eyes connection to your Brain and its Blood supply are at the back centre of the Reina. Even though there are enough Cells to see during the day the cells for night vision are rare, so in that spot things just disappear.
3. In an older Eye the jelly lens we focus with gets hard and opaque, so we need glasses or the lens removed completely. Long and short sightedness is in your geans and glycoma is caused by over exposure to bright sun light.
4. Day light and bright lighting will no allow your night vision to work right away, the cells in your Retina that sees dim light can take up to half an hour to start working.
With all of this in mind you can use some techniques to use your telescope better.
Good views and clear skies. Jim.
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Trading Post Member
Group: Forum Members
Last Login: 25/03/2009 10:16 PM
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It’s all in the Mind, you know.
Now we know how to use an Eyepiece and what the Eye can and can’t do, let work on how to see things.
1. If you are going to spend some time out that night, wear Sun glasses and don’t use garden lighting or spot lighting later in the evening. This will give you better night vision.
2. Overt your eye to the Eyepiece, this will get the light to the part of your Eye that can see dim light.
3. Run the eyepiece over your nose and look on the side, this will get the eyepiece closer to your pupil and get more light to your retina.
4. Move your eye around or move the telescope this will move the light across the retina letting other parts rest.
5. Use a low red light to see what you’re doing or read maps, a red light has a lower power and not give you night blindness. Most star maps, charts and planispheres are set up to be used in a red light.
These techniques will give you a better view of some very dim objects.
Good views and clear skies. Jim.
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Trading Post Member
Group: Forum Members
Last Login: 25/03/2009 10:16 PM
Posts: 5,
Visits: 4
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What’s in a tube.
After talking about the Eye Piece and how to use it, it would be a good idea to mention the working part of the telescope, the Tube.
Reading about telescopes it seams that bits and pieces of them have been floating around separately for a thousand years. Just using a tube to look through by its self can sharpen a view. Lenses however were seen in Rome, with the Byzantines and even the Norseman (Vikings) and Mirrors have been known of in Egypt, Babylon and earlier.
It wasn’t till a Dutch Sceptical Maker saw what two lenses could do that what we know as a Telescope came into being (Galileo came later). To start with what a Telescope realy does we must look at what light is and does.
There are a few things you can do with light beside feel it and see it:
1. Reflect it, Light will bounce (its not really Bouncing) of anything that’s how we get the colours of the Universe in to our minds. Ok, very dark, matt or black surfaces will absorbs light but you still see surface by reflection.
2. Refract it. Bending light can be done in a few ways, by slowing it down though glass, water or air or by a magnetic or gravity fields.
3. Infract it. Infraction is a property of light where by splitting a beam then projecting it on a sheet will show that it will cancel itself out.
Using the first two methods you now collect an amount of light and focus it into one point.
Heavy hey, well just seat on all this for a while and i’ll continue next time.
Jim
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