Image of the day

Captured by
Daniel Carter

Dolphin Head Nebula Sh2-308

My Account

New to Astromart?

Register an account...

Need Help?

Posts Made By: Joseph Babendreier

February 14, 2011 06:10 AM Forum: Beginning Astronomy?

info on tweaking a 10" Dob

Posted By Joseph Babendreier

I'm a new member. I just built a Dob with a 10" mirror.

I was wondering if there is some kind of FAQ for people like me.

I know so little about telescopes in practice -- though I've read several books on the theory -- that I was hoping to gain from the experiences of others.

Unfortunately there is no astronomy club where I live.

February 19, 2011 11:06 PM Forum: Beginning Astronomy?

10" DOB Why can't I see the obstruction?

Posted By Joseph Babendreier

After quite a lively round (Joe's home-made 10" Dob) covering some basics, first let me thank all the fellow star gazers for their advice. I mostly remember how important the tilt of the primary is and how important it is to learn what you're looking at while collimating.

As far as collimating the Dob, I think I followed all your advice and at least the basic instructions available on the websites recommended. But maybe I missed something -- and there was a lot to miss!!!

I have one HUGE question nagging me. Last night I was out viewing, after a lengthy collimation session in the early afternoon. I was expecting to see some kind of obstruction in my view of the sky (because of the shadow from the secondary mirror on the primary).

With no eyepiece in the focuser, I can see the obstruction clear as day. With an EP inserted, I see no obstruction at all, regardless of what I'm looking at.

As far as collimation, the various circles all line up. I think I did that part ok.

Last night, I spent a lot of time looking at the moon. I even used an old barlow and it worked really well. I used all 3 eyepieces I have (none of very good quality but functional) and those include: EPs = 4mm, 8mm and 12mm.

Can anyone give me advice. I must have done something wrong.

Please remember that I constructed this scope myself, working purely off of pictures and website info. I have never seen a real Dob, must less actually used one.


February 27, 2011 06:33 AM Forum: Beginning Astronomy?

query on Orion

Posted By Joseph Babendreier

I looked thru my new home made 10" Dob last night to look at the Orion constellation last night. I was particularly interested in looking at M42. At least I think that is what I was looking at.

It was must first time looking at a nebula. I watched it intently for a fairly long time -- a full 20 minutes non stop. My eyes were nicely dark adapted.

There was not a cloud anywhere in the sky. I sure I was looking at something in the Orion constellation. And the night air was perfectly still -- perfectly.

I was surprised to see how ghostly it looked. I could not make out any edges. Is this normal?

I was using a 8mm eyepiece, which admittedly is not exactly a quality EP. Would that be the reason?

Another factor worth mentioning. I could not get to a dark site. I was viewing from a place not far from the city (Nairobi) and there was significant light pollution (no Milky Way visible).


March 8, 2011 06:13 AM Forum: Beginning Astronomy?

center spot for 10" mirror

Posted By Joseph Babendreier

I read some advice from a guy with a dob website that the best way to center-spot your primary mirror was to use a square (about 1" x 1"). So I did that with masking tape colored red and then carefully marked the exact center of the mirror. Then I stuck a round paper re-inforcer ring (white) on to the red tape and picked off the excess tape (very carefully) with some high quality tweazers, leaving the center of the mirror clean and reflective.

Now I wondering if the square masking tape will interfer with the scope's performance. (The elliptical secondary is about 2.5" x 3").


March 8, 2011 06:58 AM Forum: Beginning Astronomy?

laser beam on secondary

Posted By Joseph Babendreier

I'm trying to tweak the collimation on a home-made 10" dob. I have a laser pointer which I can fix exactly in the center of the focuser (using a small home-made brace). I assume the laser beam should, for peak performance, hit the center of the secondary and get reflected to the center of the primary.

I do NOT have a store-bought collimator of any kind.

Any tips?


March 19, 2011 04:54 AM Forum: Solar System Observing

solar viewing

Posted By Joseph Babendreier

After reading through the exchange about the solar proms, I had my own amateur-among-amateurs question.

I see all kinds of ads for solar filters. I am not about to buy a new scope just to look at the sun.

I'm not so much interested in proms. I am really down there. I don't even know where the ladder is, let along the first rung. In other words, I'm at the point where I would never dare aim the scope anywhere near the sun for fear of blinding myself.

Is there a beginner's website for solar observing?

I have a home-made 10" dob.


April 28, 2011 11:42 PM Forum: Beginning Astronomy?

what galaxy is good for beginners?

Posted By Joseph Babendreier

I'd like to see a galaxy with a 10 inch Dob. I've seen several star clusters and nebulae. I've never managed to get a look at something that even remotely resembles the shape of a galaxy.

Which one should I try first?

BTW, I live on the equator, so M31 is out of reach for me.

I can see M4 next to Antares and the Omega cluster in Centaurus without trouble at all.


May 3, 2011 04:02 AM Forum: DVDs and Music and Books That You Recommend

There Be Dragons

Posted By Joseph Babendreier

I'd like to recommend a movie coming out this week:

There Be Dragons

It's based on a true story. One of the characters is a Catholic priest named St Josemaria, the Founder of Opus Dei. I always like to say that he's the priest that got me to be a priest.

Anyway, the director, Roland Joffé, has a good track record: The Mission and The Killing Fields.

Clear skies dusk to dawn,

May 14, 2011 08:59 PM Forum: Beginning Astronomy?

building up an eyepiece collection

Posted By Joseph Babendreier

I think I've reached the point where I want to get a good 2 inch EP somewhere in the range of 9 - 12mm. (I don't have ANY eyepiece in the range of 9 - 25mm. I just have 8mm and 25mm 1.25" EPs and the 8mm is a cheapie.)

I am slightly bewildered when looking thru the classifieds in Amart. It seems -- please correct me if I'm wrong -- that the standard is 1.25" unless specified otherwise. (Most ads do not specify.)

I'm working under the assumption that bigger is better, all things being equal. In other words, that 2" is better than 1.25".

Clear skies dusk to dawn,

May 17, 2011 07:40 AM Forum: Beginning Astronomy?

finder scope

Posted By Joseph Babendreier

I am beginning to wonder if people actually use a finder scope on a 10" dob. I have one on mine (home made).

But I noticed, when asking about the eyepieces, that some responded by saying they use a low power EP to find objects.

Any opinions on this?

Clear skies dusk to dawn,