Advice on 8" Sky Mentor dobsonion

Hi

I'm planning on buying my first telescope and an really excited about
it. I've gone to two local stores (I live in Toronto, Canada) and they
advised me to get a big dobsonion telescope, since they're not too
pricey, and good for beginners. The people at the stores told me I'd be
able to see pretty much everything in the night sky with an 8" dobsonion
given good conditions. Is this true?

After looking at the prices of the telescopes, I am thinking about
getting a '8" f/6 Sky Mentor dobsonion' , but I'd like a bit of advice
from someone who has used this kind of telescope before buying. Is it a
good quality telescope? Also, I know you have to push the telescope with
your hands to aim it, so how do you find specific objects in the sky?

Also, what other advice can you give me about dobsonions in general?
What should I look for in a good quality telescope? Are there any good
astronomy websites related to dobsonion telescopes I should look at?

I know thats a lot of questions, but any info would be much appreciated!

Thanks a lot!
Alex

Look at Orion's 8" Goto Dob

www.telecope.com

I LOVE my 8" reflector on EQ mount. (Skyview Pro 9)

Chris



"Alex A" wrote in message
. cable.rogers.com...
Hi

I'm planning on buying my first telescope and an really excited about
it. I've gone to two local stores (I live in Toronto, Canada) and they
advised me to get a big dobsonion telescope, since they're not too
pricey, and good for beginners. The people at the stores told me I'd be
able to see pretty much everything in the night sky with an 8" dobsonion
given good conditions. Is this true?

After looking at the prices of the telescopes, I am thinking about
getting a '8" f/6 Sky Mentor dobsonion' , but I'd like a bit of advice
from someone who has used this kind of telescope before buying. Is it a
good quality telescope? Also, I know you have to push the telescope with
your hands to aim it, so how do you find specific objects in the sky?

Also, what other advice can you give me about dobsonions in general?
What should I look for in a good quality telescope? Are there any good
astronomy websites related to dobsonion telescopes I should look at?

I know thats a lot of questions, but any info would be much appreciated!

Thanks a lot!
Alex

"Alex A" wrote in message
. cable.rogers.com...
Hi

Snippage for brevity here
The people at the stores told me I'd be
able to see pretty much everything in the night sky with an 8" dobsonion
given good conditions. Is this true?

8" of aperture is considered the minumum for deep sky observing in average
conditions (suburban, not too much light pollution). I'd say the people at
the stores are steering you in the right direction.

After looking at the prices of the telescopes, I am thinking about
getting a '8" f/6 Sky Mentor dobsonion' , but I'd like a bit of advice
from someone who has used this kind of telescope before buying. Is it a
good quality telescope? Also, I know you have to push the telescope with
your hands to aim it, so how do you find specific objects in the sky?

They usually come with a finder scope or reflex sight. You can locate most
objects with the chart and then the finder scope. You can "star hop" with
practice from a known star nearby the object you're looking for. A telrad
sight is helpful, because it projects a known diameter ring(s) onto its
viewing area, so you can measure angular distance and more easily locate
objects. (sounds complicated, but you'll pick it up, don't worry).
I have never seen, and am not familiar with the brand you describe.

Also, what other advice can you give me about dobsonions in general?

They work best when collimated.
They are relatively low maintenance.
They offer the most aperture for the dollar.
Aperture and mirror figure are most important.
Go to www.cloudynights.com and see what kind of reviews they have for
various dobsonians.
If at all possible try to borrow the scope to do a star test.
Here's how you do it:
http://aberrator.astronomy.net/html/...r-testing.html
If you can't borrow one, you'll have to rely on telescope reviews, like
those found on cloudynights.com, or Ed Ting's site:
http://www.scopereviews.com/

What should I look for in a good quality telescope? Are there any good
astronomy websites related to dobsonion telescopes I should look at?
It should move well--not jerky. Smooth as butter in both elevation and
azimuth (compass direction). If it is sticky, don't buy it. Buy one that's
not sticky.
Sticky scopes are fixable, but you shouldn't be fixing your scope--you're a
newbie. You should be looking through it at the wonders of the sky. ;-)

I have tried SCTs to 8", APOs to 4", 10" Eq Newts, and so on.
I love my big dob. Love it. Absolutely love it. Did I say I love my dob?

I know thats a lot of questions, but any info would be much appreciated!

That will be $4 US. You can pay on your way out. Good luck to you.
You're heading in the right direction. No rush to buy. The sky will wait
for you.

Regards,
Etok




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Alex
I would suggest that you do as I did and build your own Dob.You get
much more bang for the buck and construction is not that difficult.You
will probably end up with a 12" for what you would pay for the 8".
A good place to find pieces and parts is On Astromart.
If you consider building your own there are lots of people including
myself to help you out.
I agree with the comment about a 8" being minimal for DSO's.Hell I
consider my 10" f/5.6 to be minimal and that is why I built a 13" f/4.5.
Don't forget if you want to view DSO's then don't expect great detail
in planets.On the other hand if you get into photos then a big fast
lighbucket is the way to go IMHO
Arthur


Alex A wrote:
Hi

I'm planning on buying my first telescope and an really excited about
it. I've gone to two local stores (I live in Toronto, Canada) and they
advised me to get a big dobsonion telescope, since they're not too
pricey, and good for beginners. The people at the stores told me I'd be
able to see pretty much everything in the night sky with an 8" dobsonion
given good conditions. Is this true?

After looking at the prices of the telescopes, I am thinking about
getting a '8" f/6 Sky Mentor dobsonion' , but I'd like a bit of advice
from someone who has used this kind of telescope before buying. Is it a
good quality telescope? Also, I know you have to push the telescope with
your hands to aim it, so how do you find specific objects in the sky?

Also, what other advice can you give me about dobsonions in general?
What should I look for in a good quality telescope? Are there any good
astronomy websites related to dobsonion telescopes I should look at?

I know thats a lot of questions, but any info would be much appreciated!

Thanks a lot!
Alex

Hi Arthur

Say I do spend a few months and build a larger telescope (given that
it's not too technically difficult). Wouldn't the quality of a
professionally made dobsonion be better than anything I could make?

Alex

C3PO wrote:
Alex
I would suggest that you do as I did and build your own Dob.You get
much more bang for the buck and construction is not that difficult.You
will probably end up with a 12" for what you would pay for the 8".
A good place to find pieces and parts is On Astromart.
If you consider building your own there are lots of people including
myself to help you out.
I agree with the comment about a 8" being minimal for DSO's.Hell I
consider my 10" f/5.6 to be minimal and that is why I built a 13" f/4.5.
Don't forget if you want to view DSO's then don't expect great detail
in planets.On the other hand if you get into photos then a big fast
lighbucket is the way to go IMHO
Arthur


Alex A wrote:

Hi

I'm planning on buying my first telescope and an really excited about
it. I've gone to two local stores (I live in Toronto, Canada) and they
advised me to get a big dobsonion telescope, since they're not too
pricey, and good for beginners. The people at the stores told me I'd
be able to see pretty much everything in the night sky with an 8"
dobsonion given good conditions. Is this true?

After looking at the prices of the telescopes, I am thinking about
getting a '8" f/6 Sky Mentor dobsonion' , but I'd like a bit of advice
from someone who has used this kind of telescope before buying. Is it
a good quality telescope? Also, I know you have to push the telescope
with your hands to aim it, so how do you find specific objects in the
sky?

Also, what other advice can you give me about dobsonions in general?
What should I look for in a good quality telescope? Are there any good
astronomy websites related to dobsonion telescopes I should look at?

I know thats a lot of questions, but any info would be much appreciated!

Thanks a lot!
Alex

Say I do spend a few months and build a larger telescope (given that
it's not too technically difficult). Wouldn't the quality of a
professionally made dobsonion be better than anything I could make?


Most emphatically, NO! Providing you can use tools properly and have a fair
amount of common sense, you can produce a scope easily the equal of what's
commercially available, and in some cases much better. All you are building
in a dobson is a way of holding the optical elements in proper alignment,
and a way of moving them smoothly to point at different parts of the sky.
This is not rocket science. Considering that many low-end dob tube
assemblies are built around beefed up cardboard tubes, you should be able
to make something equally good.

If I were you, I'd hunt around on Astromart for used optics in the 10 to
12.5 inch range. Deep sky objects through scopes around this size start to
become real jaw droppers. Scout around the web for dob designs and
instructions, and there are a couple of good books on the subject. There are
some terrific ATM groups online, too, and people around here can steer you
to info.

I'm not saying that building your own is for everybody - it requires both
patience and the vision to see what can be improved on a design and how it
can be accomplished. But in the bigger sizes it is almost always
cost-effective.

As etok says, take your time and look through a few scopes before deciding.
The sky will wait.

'luck - Chris

If you are handy with tools and a concientous worker, you can build a
significantly better dob than than one commercially made in China. The
Chinese ones that I have tried have poor azimuth and altitude bearings -
there is too much stiction to track at higher powers. This is a pretty
serious flaw, and will soon get on your nerves. On the other hand, they are
very inexpensive and I doubt that you can assemble one yourself for less
unless you grind your own mirror. A fellow in our club rebuilt the bearing
surfaces on his 8" Orion dob with ebony star and teflon, and it now works
much better and is a nice scope. If you want to get one that works better
out-of-the-box, then you have to pay more - but not a lot more. Read the
reviews, and join a club.

Dennis

"Alex A" wrote in message
le.rogers.com...
Hi Arthur

Say I do spend a few months and build a larger telescope (given that
it's not too technically difficult). Wouldn't the quality of a
professionally made dobsonion be better than anything I could make?

Alex

C3PO wrote:
Alex
I would suggest that you do as I did and build your own Dob.You get
much more bang for the buck and construction is not that difficult.You
will probably end up with a 12" for what you would pay for the 8".
A good place to find pieces and parts is On Astromart.
If you consider building your own there are lots of people including
myself to help you out.
I agree with the comment about a 8" being minimal for DSO's.Hell I
consider my 10" f/5.6 to be minimal and that is why I built a 13" f/4.5.
Don't forget if you want to view DSO's then don't expect great detail
in planets.On the other hand if you get into photos then a big fast
lighbucket is the way to go IMHO
Arthur


Alex A wrote:

Hi

I'm planning on buying my first telescope and an really excited about
it. I've gone to two local stores (I live in Toronto, Canada) and they
advised me to get a big dobsonion telescope, since they're not too
pricey, and good for beginners. The people at the stores told me I'd
be able to see pretty much everything in the night sky with an 8"
dobsonion given good conditions. Is this true?

After looking at the prices of the telescopes, I am thinking about
getting a '8" f/6 Sky Mentor dobsonion' , but I'd like a bit of advice
from someone who has used this kind of telescope before buying. Is it
a good quality telescope? Also, I know you have to push the telescope
with your hands to aim it, so how do you find specific objects in the
sky?

Also, what other advice can you give me about dobsonions in general?
What should I look for in a good quality telescope? Are there any good
astronomy websites related to dobsonion telescopes I should look at?

I know thats a lot of questions, but any info would be much
appreciated!

Thanks a lot!
Alex

The
Chinese ones that I have tried have poor azimuth and altitude bearings -
there is too much stiction to track at higher powers. This is a pretty
serious flaw, and will soon get on your nerves. On the other hand, they are
very inexpensive and I doubt that you can assemble one yourself for less
unless you grind your own mirror. A fellow in our club rebuilt the bearing
surfaces on his 8" Orion dob with ebony star and teflon, and it now works
much better and is a nice scope. If you want to get one that works better
out-of-the-box, then you have to pay more - but not a lot more. Read the
reviews, and join a club.

Dennis


This agrees with my experience, though out of the box, the bearings seem to be
reasonable and if kept clean function adequately for quite a while.

I also rebuilt my XT-8 with Ebony Star and Teflon, works a whole lot better and
the cost was minimal. Very nice smooth action in both axi.

Trying to build a scope for less money that the 8 and 10 inch Asians DOBs will
require grinding ones own mirror, not an easy task.

The beauty of the DOB is one can do the upgrades themselves, so it is possible
to exercise those ATM tendencies as you go along. Start with a standard Synta
or GS DOB, enjoy it get to know it and the sky a bit. Then do the Teflon/Ebony
Star thing, rework the focuser and maybe add a cooling fan. You will end up
with a nice scope that did not cost a great deal of time or money.

jon

Hello, Jon,
And the only thing left of the Cheshire cat will be the smile?
Actually what you propose makes a lot of sense for many people if budgetary
considerations are a constraint, and if they have, as you put it, ATM tendencies,
that they are unable to control and that have not responded to psychotherapy or
medication. You argue the case for your approach very well.
I myself prefer to observe than to rebuild, since my free time is so limited
and since I don't have a workshop.
If one's budget for astronomy is not a big constraint, maybe a remark of Tom
Clark (who made Tectron telescopes) is relevant: "Buy the cheap one first. It's
good for the economy if you buy everything twice." There is a lot to be said for a
top quality 8 or 10 or 12 inch Dob -- Portaball, Teleport, CPT, Starmaster --, and
few regret buying too good a telescope, as someone once remarked on SAA. If budget
permits.
Clear skies,
Bill Meyers

Jon Isaacs wrote:

The
Chinese ones that I have tried have poor azimuth and altitude bearings -
there is too much stiction to track at higher powers. This is a pretty
serious flaw, and will soon get on your nerves. On the other hand, they are
very inexpensive and I doubt that you can assemble one yourself for less
unless you grind your own mirror. A fellow in our club rebuilt the bearing
surfaces on his 8" Orion dob with ebony star and teflon, and it now works
much better and is a nice scope. If you want to get one that works better
out-of-the-box, then you have to pay more - but not a lot more. Read the
reviews, and join a club.

Dennis

This agrees with my experience, though out of the box, the bearings seem to be
reasonable and if kept clean function adequately for quite a while.

I also rebuilt my XT-8 with Ebony Star and Teflon, works a whole lot better and
the cost was minimal. Very nice smooth action in both axi.

Trying to build a scope for less money that the 8 and 10 inch Asians DOBs will
require grinding ones own mirror, not an easy task.

The beauty of the DOB is one can do the upgrades themselves, so it is possible
to exercise those ATM tendencies as you go along. Start with a standard Synta
or GS DOB, enjoy it get to know it and the sky a bit. Then do the Teflon/Ebony
Star thing, rework the focuser and maybe add a cooling fan. You will end up
with a nice scope that did not cost a great deal of time or money.

jon

"C3PO" wrote in message
...
Alex
I would suggest that you do as I did and build your own Dob.You get
much more bang for the buck

Arthur

Could you supply a component list with prices and vendors? I would like to
build my own just for better quality, but can't get anywhere near the price
of the complete scope.

thanks,
jon