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Greetings all,

I am in need of serious help...and my scope could use some tweaking
as well...:>

Before the period of less snow starts (also known as summer), I'd
like to make use of the expertise of those in the know and have you
look at my scope, and once you're done staring at the tube, I'd like
you all to more precisely look at the optics of the scope.
(I know there;s a witty and Python-esque reply in the making
somewhere)

I'm still not sure if the scope is OK, so-so or total snafu....as
I've only my experience to judge by.

So, if a weekend afternoon/evening can be arranged, I'll make sure to
be mobile and get to wherever I need to be to have you share the
wealth of knowledge I know resides here in OAF Land!

In advance of all your kind offers, I say thank you!

Jean

--- In OAFs@y..., jean_dorais@s... wrote:

I am in need of serious help...and my scope could use some tweaking
as well...:>

Hi Jean!

Welcome to the OAFs!

My next couple of weeks is fairly busy already with either work or
prearranged commitments. In any case, I'm not sure my relatively
limited level of expertise could be of any assistance. Depends on
what the problem is, I guess.

So, here are some questions for you:

What kind of scope again?
What makes you suspect there's any kind of problem?
Has it always been this way or is this recent?
What have you tried, so far?
What kind of help do you think you need and to do what exactly?

Everywhere a Photon!

Rol

So, here are some questions for you:

What kind of scope again?

It's an Antares A520GP...Pythonese for an 8" Newtonian with Discovery
optics on a EQ-4 mount....

What makes you suspect there's any kind of problem?

Well, when I do a star test, I don't see anything resembling
a 'good'or even 'so-so' result....the airy disc looks like...er cow
poopoo....

Has it always been this way or is this recent?

It may have always been this way, and I just didn't know any
better....

What have you tried, so far?

I tried making sure the primary wasn't pinched in it's mirror cell (
looks ok, screws aren't digging into the mirror...)
I tried using the chesire tube and lasermax holographic collimator to
check if I was off( primary or secondary...)I seem to be bang on...
Yet when I do a star test, it doesn't look anywhere near what a good
star test should look like....

I know this is understood, but: yes, I let the mirror cool down each
time I tried the star test....and yes it was a cool down of more than
an hour...(actually 2.5 hours last time I tried...)

What kind of help do you think you need and to do what exactly?

Well personally, I have a fear of cubes....er I mean that I would
like another pair of eyes ( or 10)to look at the optics and
the 'seeing' with my scope and tell me if I'm out to lunch, or if the
optics/collimation/setup are waaaaaaaaaaaaay off.

Everywhere a Photon!

No worries....we'll eventually get together and I can take that 7.5
off your hands!

And thanks in advance for the help!

Jean

--- In OAFs@y..., jean_dorais@s... wrote:
>

What makes you suspect there's any kind of problem?

Well, when I do a star test, I don't see anything resembling
a 'good'or even 'so-so' result....the airy disc looks like...er cow
poopoo....

The star test can be hard to apply. It needs extreemly good
seeing and fully cooled mirror before you will see the
classic airy disks.

However, there are some basic things you can look for even if
you dont see an airy disk:

--- In OAFs@y..., jean_dorais@s... wrote:

I mean that I would like another pair of eyes ( or 10 ) to look at
the optics and the 'seeing' with my scope and tell me if I'm out to
lunch, or if the optics/collimation/setup are waaaaaaaaaaaaay off.

If the laser and chessire seem bang on, then it's difficult to
understand what the problem might be. Not only do you have to let the
optics cool ( as you described ) before you do a star test, but in
winter, there are a couple more problems that I've had to contend
with.

#1) I presume you know about: Local heat sources, including your body.
It took me awhile before I realized what distortions of seeing my
body heat could cause, in sub-zero conditions.

#2) Also any nearby rooftops or chimneys release much heat as well.
Planets look churny from my backyard when I have to observe above the
roof, but look fine from my front driveway... Just trying to narrow
the parameters, Jean, accounting for problems I've had collimating in
the past.

#3) Have you tried to split binary stars of known seperation at high
power? ( on an 8", 200X to 400X or more - depending on seeing.) If
seeing is fairly good, I can usually split ( 8"SCT ) down to 0.7" or a
slight touch less. Ideally, if another observer can split it with a
similar scope and you can't ( even when scopes cooled ), then perhaps
there's a problem to consider.

In any case, next time there's an observing session and you bring your
scope along, I would be curious to take a peek through your scope.

Later,
Rol

--- In OAFs@y..., attilla.danko@s... wrote:

--- In OAFs@y..., jean_dorais@s... wrote:
>

What makes you suspect there's any kind of problem?

Well, when I do a star test, I don't see anything resembling
a 'good'or even 'so-so' result....the airy disc looks like...er

cow

poopoo....

The star test can be hard to apply. It needs extreemly good
seeing and fully cooled mirror before you will see the
classic airy disks.

However, there are some basic things you can look for even if
you dont see an airy disk:

Sorry that post was truncated. Here is the rest:

As you rack in and out of focus, does the star blur stay round?
Does it get elipitcal? Does it have spikes or look lopsided?

At about 200 power rack out of focus a star so that its about 1/10
of the apparant field. Now rack in about the same distance. Do
the two blurrs look different?

If the answer is "yes", then there is a problem with the optics
(assuming good colimation and cooling).

If the answer is "no", then you scope could be good, or not-so
good, but its hard to diagnose in email.

In either case, Its a good idea to have some people look
throught your scope. Planets are a good target for checking
optical quality. It would be even better if someone else had
an 8 inch scope for comparison.

I dont have an 8" to compare with, but I'd be happy to look at,
and through your scope, at an observing session.

Can you arrange for a clear night ?


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As you rack in and out of focus, does the star blur stay round?
Does it get elipitcal? Does it have spikes or look lopsided?

At about 200 power rack out of focus a star so that its about 1/10
of the apparant field. Now rack in about the same distance. Do
the two blurrs look different?

Well, if memory serves me right (boy am I leaving myself open
tonight...)the blurrs look about the same, and they look round-
ish...I don't recall any lopsided-ness to them at all...just that the
view just doesn't 'look' like it does in any picture I've seen....of
course this could all be a problem with my Mark 1 eyeball....

I dont have an 8" to compare with, but I'd be happy to look at,
and through your scope, at an observing session.

Can you arrange for a clear night ?

I'd love for a few pairs of better trained eyes to look through the
scope...and tell me what they honestly think...if the scopes on the
really bad to " yikes' side of things, then a new scope is in my
future...if on the other hand it's all a question of my not knowing
what the heck I'm doing ( quite possible!), then I'm in for a little
ribbing, but I'll have learned something!

I'm working on the clear skies as we speak...and I think I've done a
pretty good job so far tonight!

Again, thanks all for your help...must get out to a real observing
site soon! I hear Perth calling my name..... :)

Jean

--- In OAFs@y..., jean_dorais@s... wrote:

just that the view just doesn't 'look' like it does in any
picture I've seen....of
course this could all be a problem with my Mark 1 eyeball....

You scope might or might not have a problem. We should check
at the next starparty.

But comparing to pictures will be confusing. What one sees in any
scope almost *never* looks like a any picture. Most people say
the picture looks far far better.

(I still perfer to look at a fuzzy dim visual view than dramatic
photograph.)

The difference between visual views and photographs has more to
do with the difference between human vision and film rather than
between telescopes.

It's quite possible that there is nothing wrong with your scope and
you might still not be impressed with the views.

In that case, there are only two cures: astrophotography or a bigger
scope. :)

I'd be happy to look though your scope at the next oportunity.

Clear skies.

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