Subject:
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Re: (not quite) Looking at Mars
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Newsgroups:
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lugnet.space
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Date:
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Sat, 16 Aug 2003 16:28:43 GMT
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Viewed:
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318 times
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In lugnet.space, Tony Alexander wrote:
> * First, how the heck do you aim one of these things accurately at a
> little dot in the sky and keep it still long enough to see anything?
High-magnification telescopes will have one or two miniscopes mounted to
the side to use for pre-aiming, but your telescope probably isn't powerful
enough to warrant one of those. There should be two adjustment knobs to control
rotation and elevation. In order to accurately aim it, you'll need to adjust
those knobs so they're just barely tight enough to hold the telescope from
moving. The result is that if you apply very gentle pressure to the barrel, you
can move it just a tiny bit. Too tight and you'll need to apply so much
pressure that the movement will stutter and you'll likely overshoot or rock the
base. Too little and it won't hold true or it will swing wildly whenever you
bump it. And once you've got it aimed, DON'T TOUCH IT! Just peer into it with
your hands behind your back or something, and only touch it when you have to
readjust the aim (the higher the magnification, the faster it will move out of
your field of view). Expensive telescopes have gizmos designed to maintain the
view on your selected subject, but basic store-bought scopes require gentle
reaiming every so often.
> * When I use the different lenses, I think that the lower the number the
> higher the magnification. Is this right, or is it the other way around?
Should be higher=higher. Test it out on the moon or some local landmark
just to be sure.
> I wear glasses; should I take them off to focus an image in?
It depends. If you've got astigmatism, then absolutely not. Basic
near-sightedness/farsightedness can be adjusted for, but lumpy eyes require
specially shaped lenses, and I guarantee your telescope doesn't have those.
Also, regardless of what you do, anyone who does not wear the exact same
prescription will still have to readjust the focus to see it. Anyways, if
there's a rubber ring around the eyepiece that can be folded flat against the
eyepiece barrel or flipped out to form a sorta bowl shape, it's intended for use
with or without glasses. I _think_ the bowl shape is intended to prevent the
lens on your glasses from bumping the lens on the eyepiece (and possibly
scratching one of them), but I could be wrong. It's been a while since I had to
care about this kind of stuff.
> Are the focus settings similar for each different lens, or will I need to
> exend the lens tube farther and farther for each lens?
Not sure, but I suspect each lens might require at least a slight amount of
adjustment.
> Should I move the actual telescope tube itself, and refrain from touching the >lens tube?
I'm not sure if I understand this, but if there is a focal adjustment knob,
you should use that, and only that, to adjust the focus. Sliding tubes in and
out lacks accuracy, and bumping them with anything could knock them out of
allignment.
> * Do I need a special camera adapter to take pictures of any images I'm
> lucky enough to get?
Pretty much, yeah. Your camera will not see things quite the same as your
eye, so chances are you'll just get a bunch of blurry photos. Digital cameras
would be easiest to work with if you're just doing the point-n-shoot thing,
since you'll immediately know if it's worthless, and you won't waste any actual
film.
> I understand that the images are upside down and flip-flopped, but believe
> that to be correctable with image-editing software
Something like that. It really depends on the telescope design.
Straight-barrel scopes will show you an image that's been rotated 180 degrees.
You'll still be seeing exactly what you could see without the scope. If the
eyepiece is mounted at 90 degrees, it will have a mirror/prism in it that will
flip the image in one direction, so you will be seeing a true mirror image. If
the eyepiece sticks out the side, the image you see will be flipped vertically.
If the eyepiece sticks out the top, the image you see will be flipped
horizontally. Now, if you've got a twisty sort of lens that first sticks out
the side, and then sticks up, if you stand so you're looking perpendicular to
the main focal tube and look straight down, you will be seeing a true image, but
I've never seen a telescope built like that.
Anyways, yeah, even MSPaint has that level of image-correction capability
built in.
> (or a very expensive (IMHO) correcting lens.
Yeah, I'm sure they make those as well, and yeah, they're probably not
cheap.
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Message has 1 Reply:
 | | Re: (not quite) Looking at Mars
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| (...) Purple Dave, Thank you for your description!! This will actually help; I knew about those knobs, but I think I had them too tight, and had to keep bumping the 'scope harder than I should have. (...) Again, thanks! This echoes Dan's comments (...) (21 years ago, 16-Aug-03, to lugnet.space)
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Message is in Reply To:
| | (not quite) Looking at Mars
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| Greetings, fellow .Spacers! A few years ago I went to Target and bought a little telescope from the toy section: a Discovery Channel telescope, 300 power, 50 mm; I forget the actual manufacturer's name, but it was a real telescope company, and this (...) (21 years ago, 16-Aug-03, to lugnet.space)
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