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sub-amateur has dumb questions
Someone gave my son (and by extension, me) a Meade 155W telescope, and
as far as I can tell, it's complete. With the Mars conjunction underway, I have been trying to work out how I can actually see anything a 6 year old will find interesting. I can see Mars with the naked eye, get it centered in the viewfinder and in the telescope eye piece: I see a brilliant orange thing, bright but tiny. So far so good. I crank the eyepiece end of things out and watch the orange thing get bigger but increasingly blurry until it fills the eyepiece completely. Now what? How can I focus the telescope to see any actual detail? Or am I doomed to see nothing more than the Neanderthals saw the last time Mars was this close? It seems to me there should be some more granular controls somewhere, but other than the knobs that lock and unlock the telescope barrel from moving, I don't see anything. here's a picture thay may help, if you need more detail: http://buy.overstock.com/images/products/L929792.jpg Thanks for any help. |
#2
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sub-amateur has dumb questions
All I know Paul, that if the image is getting bigger and blobbier,
you're cranking the focus the wrong way....to properly focus a scope, it is better to pick a bright star first, center it, and move the focuser until the star reaches its minimum size--should be an extremely small pin-point, or as close as you can get to it....(atmospherics plays a role here, in addition to 'cool down' time for the scope. A scope of that size you should allow about 30-60 minutes cool-down time outside.) NOW you are focused on infinity. Now move the scope back to Mars. Same holds true for focusing on Mars, if you must...the minimum size you obtain will be the "in focus" position, whether Mars 'looks good' to you, or not. Clear Skies, Tom W. paul beard wrote: Someone gave my son (and by extension, me) a Meade 155W telescope, and as far as I can tell, it's complete. With the Mars conjunction underway, I have been trying to work out how I can actually see anything a 6 year old will find interesting. I can see Mars with the naked eye, get it centered in the viewfinder and in the telescope eye piece: I see a brilliant orange thing, bright but tiny. So far so good. I crank the eyepiece end of things out and watch the orange thing get bigger but increasingly blurry until it fills the eyepiece completely. Now what? How can I focus the telescope to see any actual detail? Or am I doomed to see nothing more than the Neanderthals saw the last time Mars was this close? It seems to me there should be some more granular controls somewhere, but other than the knobs that lock and unlock the telescope barrel from moving, I don't see anything. here's a picture thay may help, if you need more detail: http://buy.overstock.com/images/products/L929792.jpg Thanks for any help. |
#3
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sub-amateur has dumb questions
All I know Paul, that if the image is getting bigger and blobbier,
you're cranking the focus the wrong way....to properly focus a scope, it is better to pick a bright star first, center it, and move the focuser until the star reaches its minimum size--should be an extremely small pin-point, or as close as you can get to it....(atmospherics plays a role here, in addition to 'cool down' time for the scope. A scope of that size you should allow about 30-60 minutes cool-down time outside.) NOW you are focused on infinity. Now move the scope back to Mars. Same holds true for focusing on Mars, if you must...the minimum size you obtain will be the "in focus" position, whether Mars 'looks good' to you, or not. Clear Skies, Tom W. paul beard wrote: Someone gave my son (and by extension, me) a Meade 155W telescope, and as far as I can tell, it's complete. With the Mars conjunction underway, I have been trying to work out how I can actually see anything a 6 year old will find interesting. I can see Mars with the naked eye, get it centered in the viewfinder and in the telescope eye piece: I see a brilliant orange thing, bright but tiny. So far so good. I crank the eyepiece end of things out and watch the orange thing get bigger but increasingly blurry until it fills the eyepiece completely. Now what? How can I focus the telescope to see any actual detail? Or am I doomed to see nothing more than the Neanderthals saw the last time Mars was this close? It seems to me there should be some more granular controls somewhere, but other than the knobs that lock and unlock the telescope barrel from moving, I don't see anything. here's a picture thay may help, if you need more detail: http://buy.overstock.com/images/products/L929792.jpg Thanks for any help. |
#4
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sub-amateur has dumb questions
Paul wrote:
I can see Mars with the naked eye, get it centered in the viewfinder and in the telescope eye piece: I see a brilliant orange thing, bright but tiny. So far so good. I crank the eyepiece end of things out and watch the orange thing get bigger but increasingly blurry until it fills the eyepiece completely. When Mars appears as small as you can get it through the telescope then that would be when it is properly focused. If the image is too small for you at that point, then you need a more powerful eyepiece. Your eyepieces have numbers on them. Numbers like: 25mm, 18mm, 12mm, 6mm, and etc. The smaller the number, the more powerful the eyepiece. On the tube of that scope somewhere you should see its focal length. . .Something like 480mm, 700mm, 910mm. Divide the number on the eyepiece into the focal length of the telescope to derive the power of the scope using that eyepiece. Good luck. Martin |
#5
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sub-amateur has dumb questions
Paul wrote:
I can see Mars with the naked eye, get it centered in the viewfinder and in the telescope eye piece: I see a brilliant orange thing, bright but tiny. So far so good. I crank the eyepiece end of things out and watch the orange thing get bigger but increasingly blurry until it fills the eyepiece completely. When Mars appears as small as you can get it through the telescope then that would be when it is properly focused. If the image is too small for you at that point, then you need a more powerful eyepiece. Your eyepieces have numbers on them. Numbers like: 25mm, 18mm, 12mm, 6mm, and etc. The smaller the number, the more powerful the eyepiece. On the tube of that scope somewhere you should see its focal length. . .Something like 480mm, 700mm, 910mm. Divide the number on the eyepiece into the focal length of the telescope to derive the power of the scope using that eyepiece. Good luck. Martin |
#6
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sub-amateur has dumb questions
paul beard wrote:
snip I can see Mars with the naked eye, get it centered in the viewfinder and in the telescope eye piece: I see a brilliant orange thing, bright but tiny. So far so good. I crank the eyepiece end of things out and watch the orange thing get bigger but increasingly blurry until it fills the eyepiece completely. Most likely it was in focus when it appeared "tiny". I can tell you that if it fills the entire eyepiece, it is most certainly out of focus. ;-) In focus, it'll probably look the size of a dime from 6 feet away. (not a scientific measure, just the way I perceive it to look) Now what? How can I focus the telescope to see any actual detail? Or am I doomed to see nothing more than the Neanderthals saw the last time Mars was this close? You should probably be able to see a fair amount of detail, but it's not going to look like Hubble. Take some time, focus the image, and stare at it for a while. You may be able to see the ice cap and some dark areas on the surface. It seems to me there should be some more granular controls somewhere, but other than the knobs that lock and unlock the telescope barrel from moving, I don't see anything. Some higher-end telescopes have finer focusing controls. What you've got is probably adequate though, just focus carefully. HTH -Matt -- Remove 'TINLC' to reply. |
#7
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sub-amateur has dumb questions
paul beard wrote:
snip I can see Mars with the naked eye, get it centered in the viewfinder and in the telescope eye piece: I see a brilliant orange thing, bright but tiny. So far so good. I crank the eyepiece end of things out and watch the orange thing get bigger but increasingly blurry until it fills the eyepiece completely. Most likely it was in focus when it appeared "tiny". I can tell you that if it fills the entire eyepiece, it is most certainly out of focus. ;-) In focus, it'll probably look the size of a dime from 6 feet away. (not a scientific measure, just the way I perceive it to look) Now what? How can I focus the telescope to see any actual detail? Or am I doomed to see nothing more than the Neanderthals saw the last time Mars was this close? You should probably be able to see a fair amount of detail, but it's not going to look like Hubble. Take some time, focus the image, and stare at it for a while. You may be able to see the ice cap and some dark areas on the surface. It seems to me there should be some more granular controls somewhere, but other than the knobs that lock and unlock the telescope barrel from moving, I don't see anything. Some higher-end telescopes have finer focusing controls. What you've got is probably adequate though, just focus carefully. HTH -Matt -- Remove 'TINLC' to reply. |
#8
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sub-amateur has dumb questions
Also remember Paul,
Mars is only 25 arc-seconds in diameter at its closest.....and within 10% of that value until about the end of September. But 25 arc-seconds is not very large....a pretty double star up in Cygnus, Albireo (or Beta Cygni, at the end of the "northern cross" asterism) is split by 34 arc-seconds! Mars' diameter could easily fit between those two components! We aren't talking a huge ball here, like the moon in a scope. Mars is only 4200 miles in diameter, and out there about 34.6 million miles...that's only about twice the diameter of our own moon, and only half the Earth's diameter.....only Mercury and Pluto (if you consider Pluto a.....UGH! planet) are smaller than Mars. We're not talking a large gas giant here, like Jupiter at 88,000 miles in diameter. So you have to keep that in mind.....PLUS, it doesn't look like you are using a 6 or 8 or 10 inch glass there, are you? More like 2 or 3 inches of glass.... so with a very small scope, don't expect to see an "orange" filling half the field of view (when in proper focus)....it ain't gonna happen with a 2 or 3 inch scope, at only 25 arc-seconds in diameter. Sorry. {Remember, our moon probably fills the entire field of view in your scope, but that's 1/2 degree across, or 1800 arc-seconds!) Mars is only 1.4% (25/1800) the angular size (image size) of our moon in that same eyepiece, at its best!} Clear Skies, Tom W. paul beard wrote: Someone gave my son (and by extension, me) a Meade 155W telescope, and as far as I can tell, it's complete. With the Mars conjunction underway, I have been trying to work out how I can actually see anything a 6 year old will find interesting. I can see Mars with the naked eye, get it centered in the viewfinder and in the telescope eye piece: I see a brilliant orange thing, bright but tiny. So far so good. I crank the eyepiece end of things out and watch the orange thing get bigger but increasingly blurry until it fills the eyepiece completely. Now what? How can I focus the telescope to see any actual detail? Or am I doomed to see nothing more than the Neanderthals saw the last time Mars was this close? It seems to me there should be some more granular controls somewhere, but other than the knobs that lock and unlock the telescope barrel from moving, I don't see anything. here's a picture thay may help, if you need more detail: http://buy.overstock.com/images/products/L929792.jpg Thanks for any help. |
#9
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sub-amateur has dumb questions
Also remember Paul,
Mars is only 25 arc-seconds in diameter at its closest.....and within 10% of that value until about the end of September. But 25 arc-seconds is not very large....a pretty double star up in Cygnus, Albireo (or Beta Cygni, at the end of the "northern cross" asterism) is split by 34 arc-seconds! Mars' diameter could easily fit between those two components! We aren't talking a huge ball here, like the moon in a scope. Mars is only 4200 miles in diameter, and out there about 34.6 million miles...that's only about twice the diameter of our own moon, and only half the Earth's diameter.....only Mercury and Pluto (if you consider Pluto a.....UGH! planet) are smaller than Mars. We're not talking a large gas giant here, like Jupiter at 88,000 miles in diameter. So you have to keep that in mind.....PLUS, it doesn't look like you are using a 6 or 8 or 10 inch glass there, are you? More like 2 or 3 inches of glass.... so with a very small scope, don't expect to see an "orange" filling half the field of view (when in proper focus)....it ain't gonna happen with a 2 or 3 inch scope, at only 25 arc-seconds in diameter. Sorry. {Remember, our moon probably fills the entire field of view in your scope, but that's 1/2 degree across, or 1800 arc-seconds!) Mars is only 1.4% (25/1800) the angular size (image size) of our moon in that same eyepiece, at its best!} Clear Skies, Tom W. paul beard wrote: Someone gave my son (and by extension, me) a Meade 155W telescope, and as far as I can tell, it's complete. With the Mars conjunction underway, I have been trying to work out how I can actually see anything a 6 year old will find interesting. I can see Mars with the naked eye, get it centered in the viewfinder and in the telescope eye piece: I see a brilliant orange thing, bright but tiny. So far so good. I crank the eyepiece end of things out and watch the orange thing get bigger but increasingly blurry until it fills the eyepiece completely. Now what? How can I focus the telescope to see any actual detail? Or am I doomed to see nothing more than the Neanderthals saw the last time Mars was this close? It seems to me there should be some more granular controls somewhere, but other than the knobs that lock and unlock the telescope barrel from moving, I don't see anything. here's a picture thay may help, if you need more detail: http://buy.overstock.com/images/products/L929792.jpg Thanks for any help. |
#10
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sub-amateur has dumb questions
paul beard:
Someone gave my son (and by extension, me) a Meade 155W telescope, and as far as I can tell, it's complete. With the Mars conjunction underway, I have been trying to work out how I can actually see anything a 6 year old will find interesting... Others have answered your questions. I would only note that you shouldn't belittle yourself because: a) You are an amateur like all other amateur astronomers. b) Your questions are not dumb. Davoud -- usenet *at* davidillig dawt com |
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