Why can't I resolve deep sky objects?

I have a 12" Meade LX90 just outside Las Vegas. Light pollution is a
problem, but I don't think a major one. I've been trying with no
success to get a clear view of M13, using eyepieces ranging from 40mm
down to 10.4mm. At the lower magnifications, it looks like a
moderately bright star; at higher magnifications, it looks like an out-
of-focus blob that seems very roughly to have the shape of M13 (based
on photos). I cannot resolve even two stars, much less the dozens
that I think should be distinguishable. I'd appreciate any thoughts
or suggestions.

Bob Feduniak

Bob Feduniak wrote:
I'd appreciate any thoughts
or suggestions.

Collimate.

Bob Feduniak wrote:
I have a 12" Meade LX90 just outside Las Vegas. Light pollution is a
problem, but I don't think a major one. I've been trying with no
success to get a clear view of M13, using eyepieces ranging from 40mm
down to 10.4mm. At the lower magnifications, it looks like a
moderately bright star; at higher magnifications, it looks like an out-
of-focus blob that seems very roughly to have the shape of M13 (based
on photos). I cannot resolve even two stars, much less the dozens
that I think should be distinguishable. I'd appreciate any thoughts
or suggestions.

Bob Feduniak

If what you wrote is true, then either you're out of focus or need to
collimate that scope. The latter you can get the instructions through a
Google search. Try the search strings "collimate" and "SCT".

--- Dave

Bob Feduniak writes:


I cannot resolve even two stars, much less the dozens
that I think should be distinguishable. I'd appreciate any thoughts
or suggestions.

First of all, eliminate turbulence. Allow some time for the telecope
to coold down (at least 1 hour). Make sure there are no sources of
heat creating turbulent air in the sourrounding, such asphalt,
chimneys, etc. AFTER that has been taken care of, check collimation of
the scope.

pej
--
Per Erik Jorde

On Oct 8, 11:07*pm, Bob Feduniak wrote:

I have a 12" Meade LX90 just outside Las Vegas. *Light pollution is a
problem, but I don't think a major one.

In addition to what other people have said, if you're just outside Las
Vegas, then light pollution is a genuinely huge problem for you.
Nonetheless, you should be able to see a few stars in M13 through a 12-
inch telescope.

- Tony Flanders

I cannot resolve even two stars, much less the dozens
that I think should be distinguishable. I'd appreciate any thoughts
or suggestions.


It sure sounds like you have an optical problem. Even though a laser
collimator is not the best tool for SCTs, in this case it would give you a
quick and easy indication of your optical alignment. If that is wildly off,
then I would check if either the secondary mirror (more likely) or the
primary mirror are not being mechanically well supported, e.g. are loose,
shifted, etc.

Are you a member of your local astro club? There will be folks there that
can help you to diagnose the problem(s).

Dennis

wrote in message
...
On Oct 8, 11:07 pm, Bob Feduniak wrote:

I have a 12" Meade LX90 just outside Las Vegas. Light pollution is a
problem, but I don't think a major one.

In addition to what other people have said, if you're just outside Las
Vegas, then light pollution is a genuinely huge problem for you.
Nonetheless, you should be able to see a few stars in M13 through a 12-
inch telescope.

While I agree that light pollution is a major problem, I think I have had
better views of M13 than those described with much less aperture from just
outside of NYC. I have to believe that some severe optical problem is the
primary cause.

Dennis

On Oct 8, 11:07�pm, Bob Feduniak wrote:
I have a 12" Meade LX90 just outside Las Vegas. �Light pollution is a
problem, but I don't think a major one. �I've been trying with no
success to get a clear view of M13, using eyepieces ranging from 40mm
down to 10.4mm. �At the lower magnifications, it looks like a
moderately bright star; at higher magnifications, it looks like an out-
of-focus blob that seems very roughly to have the shape of M13 (based
on photos). �I cannot resolve even two stars, much less the dozens
that I think should be distinguishable. �I'd appreciate any thoughts
or suggestions.

Bob Feduniak

I have a 12" Mead and with a 25mm ep M13 looks like a street light

On Oct 9, 10:52�am, " wrote:
On Oct 8, 11:07 pm, Bob Feduniak wrote:

I have a 12" Meade LX90 just outside Las Vegas. Light pollution is a
problem, but I don't think a major one. I've been trying with no
success to get a clear view of M13, using eyepieces ranging from 40mm
down to 10.4mm. At the lower magnifications, it looks like a
moderately bright star; at higher magnifications, it looks like an out-
of-focus blob that seems very roughly to have the shape of M13 (based
on photos). I cannot resolve even two stars, much less the dozens
that I think should be distinguishable. I'd appreciate any thoughts
or suggestions.

Bob Feduniak

I have a 12" Mead and with a 25mm ep M13 looks like a street light

I should have added that I live just outside of Philadelphia

Thank you all for your responses. I neglected to add that I get very
clear images of jupiter, saturn, and their moons and that individual
stars down to around 5.0 magnitude appear as points, as they should.
Does this suggest that collimation might not be the problem, or is it
a problem that tends to show up mostly in the deep sky arena?

Bob Feduniak