Re: Dumb newbie question.
John Kulczycki
> x-no-archive: yes
>
> I purchased an inexpensive short tube 90mm telescope made by Orion. For
> terrestrial viewing
> and for viewing stars it's very good. It's not broken.
>
> When I looked at Jupiter and Saturn, I couldn't get them into focus unless
> they were right in the middle of the field of view. How can I describe it ?
> They were flat disks with a straight beam of light coming from the center.
> Moving the telescope and/or my head helped. Is this how an an inexpensive
> telescope normally functions ?
>
> I don't know anybody who owns an expensive telescope, so I can't compare :~)
Short tube 90's are fast scopes ( F5?) and to do that they have a lot
of curve in the lens assembly. What you need to look for is eyepieces
that work well with faster refractors. If you used a barlow it may
flatten the field a bit and let you get over to the edges a bit but
you will have much higher magnification.
Can you tell us what eyepieces you were using at the time?
William Hamblen
> They [Jupiter and Saturn] were flat disks with a straight beam of
> light coming from the center.
I bet you have a 45 degree erecting diagonal. Is that right?
Bud
Howard Lester
> I purchased an inexpensive short tube 90mm telescope made by Orion. For
> terrestrial viewing
> and for viewing stars it's very good. It's not broken.
Specifically which model telescope do you have? So far, responders are
figuring you have a refractor, but you may have a Maksutov. I suggest that
because of all Orion's "beginner telescope" offerings, the only 90 is a
Maksutov or Maksutov-Cassegrain design.
In any case, the use of a 45 degree erecting prism does indeed degrade the
image, but it shouldn't to the extent you describe. After telling us what
model/name Orion telescope you have, what eyepiece(s) did you look through
when you were observing the "defective" image? What focal length is the
eyepiece? (It will be listed in millimeters.)
Howard Lester
> Ack, sorry, I have the short tube 80mm refractor. It is a good value for
> the money
10 years ago many of us on this newsgroup bought these telescopes and found
they actually perform pretty well, considering. Mine does nicely up to about
40x or so. You don't say what Vixen eyepiece you're using, its focal
length, or what diagonal you're using. They could all matter. Being a
newbie, the issue may be more the operator than the instrument. ;-)
TBerk
> x-no-archive: yes
>
What I'm more curious about is this:
> Note: The author of this message requested that it not be archived.
> This message will be removed from Groups in 5 days (Sep 5, 4:20 pm).
Why would someone not want to be 'archived? (As if Newsgroup posts
aren't copied and 'archived' all over the place.)
Tberk
TBerk
> x-no-archive: yes
>
> someplace else, I bet they respect
> "x-no-archive: yes" too
>
> I don't care if my telescope question is archived, but I don't want other
> more sensitive posts archived
>
> By default I add it to everything
Oh, I understand the 'what', it was the general 'why', and not just in
particular but everybody else I've ever noticed doing it also.
Stuff I understand can still make me tilt my head over like a dog
sometimes.
In any case; "Clear Skies".
TBerk
TBerk
I didn't mean the hijack the thread.
Did we ever get a model number of the Orion scope?
TBerk
Howard Lester
>
> I didn't mean the hijack the thread.
>
> Did we ever get a model number of the Orion scope?
Partially. He? said it is a short tube 80 for $100, Alex, but Orion offers
more than one. Getting the OP to spew forth with detailed answers to our
questions seems to be quite an effort.
j
I didn't know if the details made a difference... I don't use the erect
image prisim
Is there something else I could do ?.... Is this what you always get for $99
?... Stars look ok,
I like the wide view. Planets still have a "ray" of light comming off them.
This is the telescope
http://www.telescope.com/control/telescopes/refractor-telescopes/orion-goscope-80mm-tabletop-refractor-telescope
http://vixenoptics.com/acc/npl_eyepieces.html
And this is the 25 mm eyepiece I got on sale. It's better than the ones the
scope came with, but there's no great improvement.
Howard Lester
"j"
> Thanks for the help... :~)
> I didn't know if the details made a difference... I don't use the erect
> image prisim
> Is there something else I could do ?.... Is this what you always get for
> $99 ?... Stars look ok,
> I like the wide view. Planets still have a "ray" of light comming off
> them.
I looked at the telescope. It's a "ridiculously" slow f/4.3 refractor that
has to be "ground to perfection" if you are to expect a real quality view. I
wouldn't consider using any magnification above, oh, maybe 20x. Your Vixen
25mm eyepiece gives you 80mm diameter x 4.3 = 344mm focal length / 25mm =
13.76x. The supplied 20mm one gives you 17.2x; the 10mm 34.4x. So you can
see that it's really designed for very low magnifications = wide field. Why
there is one ray of light coming off a bright object, I don't know. One way
to find out is to look at a planet through it as you normally would, and
rotate the 90 degree diagonal, that was supplied with the telescope, in the
focuser's drawtube. If the ray rotates around the planet as you rotate the
diagonal, then you know the problem is with the diagonal. If not, try
rotating the eyepiece. Still no change? Then try rotating yourself ;-)
If, when you look through the eyepiece from different directions around the
axis of the eyepiece, and the ray stays put, then you know the issue is with
the 80mm objective. But again, this telescope is not designed for planetary
use - hardly even the moon, though you can still see interesting features.
Barry Schwarz
>x-no-archive: yes
>
>seriously, I only thought Google made Usenet archives..... If posts are kept
>someplace else, I bet they respect
>"x-no-archive: yes" too
>
>I don't care if my telescope question is archived, but I don't want other
>more sensitive posts archived
Anything you post to usenet can be seen by anyone and they can keep it
for as long as they like. You may think something is sensitive but
once you post it you have absolutely no control over it anymore.
--
Remove del for email
John Kulczycki
> x-no-archive: yes
>
> > One way to find out is to look at a planet through it as you normally
> > would, and rotate the 90 degree diagonal, that was supplied with the
> > telescope, in the focuser's drawtube. If the ray rotates around the planet
> > as you rotate the diagonal, then you know the problem is with the
> > diagonal. If not, try rotating the eyepiece. Still no change? Then try
> > rotating yourself ;-) If, when you look through the eyepiece from
> > different directions around the axis of the eyepiece, and the ray stays
> > put, then you know the issue is with the 80mm objective. But again, this
> > telescope is not designed for planetary use - hardly even the moon, though
> > you can still see interesting features.
>
> If I get Jupiter in the very center it's OK
>
> I'm not complaining, the scope is doing what it was designed for...
>
> The scope is a good value for the price..... I got a Vixen eyepiece and a
> tripod on sale... not a bad setup :~)
>
>
>
> >> This is the telescope
> >>http://www.telescope.com/control/telescopes/refractor-telescopes/orio...
>
> >>http://vixenoptics.com/acc/npl_eyepieces.html
> >> And this is the 25 mm eyepiece I got on sale. It's better than the ones
> >> the scope came with, but there's no great improvement.
How dewy was it that night? Could it be that you were looking through
dew on the objective?
Howard Lester
"j" <7> wrote
>> But again, this telescope is not designed for planetary use - hardly even
>> the moon, though you can still see interesting features.
> Good advice.. I tried what you said. The objective lense is the cause.....
> If I get Jupiter in the very center it's OK
>
> I'm not complaining, the scope is doing what it was designed for...
>
> The scope is a good value for the price..... I got a Vixen eyepiece and a
> tripod on sale... not a bad setup :~)
OK, good. That's a good attitude. :-) Enjoy it.
j
dew on the objective?
hmmmm.....no