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08/26/2006 04:59:43 AM · #1 |
i would like to build a telescope, just for the fun of it... and i found this place that sells very old lenses very cheap.. so i can use lense elements from.
anyone tried that before.. and what is the typical focal length of a good telescope..
can you achieve a very long focal length from a combination of small focal length lenses ?
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08/26/2006 05:17:18 AM · #2 |
| Some of the cheap ones I have seen have a focal length of 700mm, so if you want a good one you will need more than that. |
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08/26/2006 08:25:13 AM · #3 |
| You should be able to build a small refractor telescope. The hard part is the eyepiece. Just buy a cheap one from ebay. |
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08/27/2006 04:41:15 AM · #4 |
what about the objective lens.. where an i get a 500-1000 mm lens ?
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08/27/2006 06:02:25 AM · #5 |
| here is a link to a place where you can get a load of cheap stuff to make a scope, if you want to seedeep sky objects then you might be disapointed unless you have a diameter of at least 4" but planets can look good with a scope of just 70 - 90 mm diameter, here is a great site that is full of people that will help you sort it out as well as having plans on how to put your scope together when you have all the bits. |
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08/27/2006 07:04:28 AM · #6 |
| good links richard42, thanx alot |
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08/27/2006 12:00:07 PM · #7 |
By far, the easiest scope to build is a Dobsonian mount reflector.
All you need is a good main mirror and the rest is pretty simple fabrication.
If you're exceptionally dedicated, you can make the mirror too, but it's a lot of tedious work.
As far as making one out of assorted optical junk, I suppose you could, but it'd likely be a lot more trouble than it's worth. |
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08/27/2006 01:15:01 PM · #8 |
Originally posted by Spazmo99:
As far as making one out of assorted optical junk, I suppose you could, but it'd likely be a lot more trouble than it's worth. |
It worked for Galileo : )
I have pretty regular access to some exceptionally rigid cardboard tubes, 13" L x about 2-1/2" ID, if anyone needs something like that. I've always wanted to turn one into a kaleidoscope, but have never gotten around to making a successful model : ( |
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08/27/2006 02:29:53 PM · #9 |
Originally posted by GeneralE:
Originally posted by Spazmo99:
As far as making one out of assorted optical junk, I suppose you could, but it'd likely be a lot more trouble than it's worth. |
It worked for Galileo : )
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Of course it did, but, he spent hours and hours polishing his optics to build an instrument that would not even compare to a junk telescope you can get at Walmart for $50. Don't get me wrong, for the time, it was an amazing piece of equipment, but a lot of advances have been made in the past 400 years.
Keep in mind that his efforts led him to be branded a heretic. |
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08/27/2006 04:09:29 PM · #10 |
Originally posted by Spazmo99:
Originally posted by GeneralE:
Originally posted by Spazmo99:
As far as making one out of assorted optical junk, I suppose you could, but it'd likely be a lot more trouble than it's worth. |
It worked for Galileo : )
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Of course it did, but ... |
I was trying to be funny and yet supportive of inventiveness as a characteristic -- there's too little creative thinking going on as it is ... I agree that it may be more trouble than it's "worth" -- but that's true of a lot of art and mechanical prototypes/models. |
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08/27/2006 05:44:54 PM · #11 |
Originally posted by GeneralE:
Originally posted by Spazmo99:
Originally posted by GeneralE:
Originally posted by Spazmo99:
As far as making one out of assorted optical junk, I suppose you could, but it'd likely be a lot more trouble than it's worth. |
It worked for Galileo : )
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Of course it did, but ... |
I was trying to be funny and yet supportive of inventiveness as a characteristic -- there's too little creative thinking going on as it is ... I agree that it may be more trouble than it's "worth" -- but that's true of a lot of art and mechanical prototypes/models. |
I guess it depends on whether you want a telescope or a converstaion piece.
I'm all for ingenuity and inventiveness, but if you want to build a telescope, a Dob is the way to get the most bang for your effort.
The San Francisco Sidewalk Astronomers even have a class: Building a telescope
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