Intro and a quick first question.

[sharptrack2 (Kevin)]

Thanks Sil,

Appreciate the advice. I took some time to investigate the difference between Plossl and Nagler eyepiece, so I would have a small understanding of what I would be looking for. You mention specific brands, which I'll now look up, thank you! I'm still a little clouded by the fact that most of you use eyepieces with focal lengths greater than 10mm. My understanding of magnification indicates this it counter intuitive, but then I'm also sensitive to the fact your telescopes are probably 100x better than what I'm currently working with (focal ratios greater than f/5) coupled with barlows of various magnifications. Practical experience will help me get my brain around this.

I managed to get out this evening for a short viewing of Saturn, it was very impromptu and in my back yard. The light pollution was horrible but I did get what I think was reasonable view of the planet with its moon Titan just below and to the right (looking through the scope). The view matched what Stellarium displayed in the Occular view with one major exception, both objects looked prismatic. I could not focus a clear "round" spot of light. This goes back to my original question, which is what could be causing this aberration? I'm now quite open to the possibility it could be the eyepiece but could both the 20mm and the 10mm have the same response? Maybe this should be another thread, I don't want to wear out my welcome in the beginners intro area. Plus I haven't searched for similar posts yet.

Thanks again for the advice... I'm looking forward to attending a star party (hopefully close to my home) and making a nuisance of myself with lots of questions.

[barx1963 (Malcolm)]

Originally Posted by sharptrack2

Thanks Sil,

Appreciate the advice. I took some time to investigate the difference between Plossl and Nagler eyepiece, so I would have a small understanding of what I would be looking for. You mention specific brands, which I'll now look up, thank you! I'm still a little clouded by the fact that most of you use eyepieces with focal lengths greater than 10mm. My understanding of magnification indicates this it counter intuitive, but then I'm also sensitive to the fact your telescopes are probably 100x better than what I'm currently working with (focal ratios greater than f/5) coupled with barlows of various magnifications. Practical experience will help me get my brain around this.

I managed to get out this evening for a short viewing of Saturn, it was very impromptu and in my back yard. The light pollution was horrible but I did get what I think was reasonable view of the planet with its moon Titan just below and to the right (looking through the scope). The view matched what Stellarium displayed in the Occular view with one major exception, both objects looked prismatic. I could not focus a clear "round" spot of light. This goes back to my original question, which is what could be causing this aberration? I'm now quite open to the possibility it could be the eyepiece but could both the 20mm and the 10mm have the same response? Maybe this should be another thread, I don't want to wear out my welcome in the beginners intro area. Plus I haven't searched for similar posts yet.

Thanks again for the advice... I'm looking forward to attending a star party (hopefully close to my home) and making a nuisance of myself with lots of questions.

Hi Kevin and welcome.
Firstly Saturn. It was probably low in the west when you saw it. Planet especially are disappointing when viewed low, the turbulence and extra air the light has to travel through pretty much ruins the view. Plus early evening is often the worst seeing with the atmosphere boiling away.
Best way to test your scope is to wait until it nicely dark and then pick a moderately bright star high in the sky. See how that focuses. If you cannot get good focus, there may be an issue. Most likely cause is collimation. If you have not yet done so,here is a basic guide to collimation that I have found useful.http://www.astro-baby.com/collimatio...on%20guide.htm
Also has some good info on various aberrations that you may see.

Eyepiece focal lengths can be confusing. If you know anything about photography, you are used to longer focal things giving more magnification. But you have to remember that an eyepiece is part of a system along with a fixed focal length telescope. Magnification is arrived at by dividing the scopes focal length by the eyepieces focal length.
So if your scope is say 900mm and you use a 10mm EP then you get 900/10= 90x. Easy!!

Cheers

Malcolm

[sharptrack2 (Kevin)]

5 hours of research, reading post after post, webpage after web page, 4 hours of tedious disassembly and re-assembly has rewarded me with the view I have been striving for... the rings of Saturn clear and defined, with Titan a glimmer slightly below the rings.

A deviant engineering alter ego escaped this morning after a very disappointing attempt to once again view Venus and Jupiter before the sun crested. Venus was a sparkling diamond in the view finder, literally sparkling and I started to dismiss the symptoms as atmospheric, as has been previously suggested, when it happened, that reckless, forever curious, "damn the torpedoes" engineer, I keep locked away (mostly for fear of my bank account dwindling excessively), escaped and decided to start removing screws and turning, twisting, and generally testing everything he could get his hands on.

When skies cleared this evening, I decided to try and take a look, and miraculously, in less than 3 minutes, I had Saturn sighted and could almost count the rings ( just kidding, it was an excellent view though). The only disappointing aspect is that I don't know exactly what did the trick, however I now know every intimate detail of a Celestron 130 EQ Astromaster, down to the failings of the red dot star finder (haven't figured out a fix yet but it can be removed so a replacement is seriously being considered). I'm even more surprised that all of this was accomplished with nothing more than a homemade collimating cap (originally the focuser protection cap).

I have to thank Malcolm for opening the door, some of Astro-Baby's collimation steps are quite unique and probably triggered the Dr. Jekyll evil genius that had to know exactly how everything was put together and how it was designed to work. Having worked as an electronics hardware designer in a past life, he has never trusted mass production assembly lines and thinks that he is the only one who can assemble something properly.

Here it is nearly midnight and I have every intention of being up at 5 am again to not only watch Venus and Jupiter rise but also now attempt to find the Orion nebula. I am also now looking forward to taking my training wheels up to Barrington Tops, in just over a week, when the wife and I go camping for a week or so.

A big thanks to every one who has commented on this thread and the many others I spent hours reading today, it has been invaluable. I'm already thinking I'll be saving up for a Cassegrain, for when I am ready to shed the training wheels.

[barx1963 (Malcolm)]

Kevin
Glad you have made progress!!
The collimation steps on the Astro Baby site are very easy to understand. And once you actually done it, it starts to make sense in terms of what you are trying to achieve.
The other important message that I try to give beginners is that collimation is a game of diminishing returns. You may not have the collimation quite perfect, but spending hours trying to do so is not really worthwhile for the small improvement in image quality.

Which is not to say you should ignore poor collimation just realise that time can be better spent in other ways.

Malcolm

[sharptrack2 (Kevin)]

Venus was a rousing success, could almost make out some colour. Jupiter, not so much, sun was too bright by the time Jupiter cleared the nearby trees. Did get a glimpse of Mars, when viewing Venus but again too much sun.

The Orion Nebula was a tad confusing... I definitely could sight it with the naked eye but when I put the telescope on it, I had trouble actually discerning anything but stars, and the ones I saw didn't seem to match up very well.

Two disadvantages I can name straight off are that 1) the sun was rapidly increasing its interference and 2) I need more experience with the reversal of orientation when viewing with some eyepieces. As best I can deduce from looking at Stellarium is that I centred on the 5 brightest objects on the lower end of the Greater Nebula, 42 Ori, 45 Ori, V1046, HIP 26234 & 26257.

I've decided that my backyard, at the intersection of the Central Coast highway and Brisbane Waters road is probably the worst place to be attempting some of these viewings. Street lights every 25 metres and major commercial business parks nearby, dark skies, do not make, but adversity breeds innovation and perseverance. Onward into the night, say I!

P.S.

My collimation is just a tad off when tested by an out of focus star... the image of the secondary and support doesn't get concentric in the center of the view, I'm maybe a 0.5 to 1mm off into the lower left quadrant, viewing with 20mm EP. The question now are, do I fix it, and what to adjust? Something to ponder over the next few weeks while I enjoy what I can see.

[barx1963 (Malcolm)]

Kevin
Couple of points. The orientation things is nothing to do with the eyepieces, it should be the same for all of them.
Secondly, M42 (Orion Nebula) should be easily visible even with light pollution. I have seen it clearly with naked eye in suburban Melbourne.
What finder scope are you using? And has it been correctly aligned?
With the collimation beyond the star test, how else are you testing it? Do you have any collimation gear? If you don't, here is an aticle on "no tools" collimation that should work.http://www.garyseronik.com/?q=node/238 It does require that you are able to track a star, so reasonable polar aligning and a motor on the RA axis would help.

Cheers

Malcolm

[sharptrack2 (Kevin)]

Thank you Malcolm,

The 20mm EP has the image right side up, while the 10mm has the image upside down. I don't understand it either as the only way I thought it could be reversed would be by another mirror. Haven't thought too much about it yet, hasn't been too much of an obstacle until now.

I have removed the cheap red dot finder and have been sighting along the side and top of the tube. With the 20mm EP that has been getting the target in the FoV. Once centred, I switch EP's. Am thinking I will be buying a better finder and adapting it to the OTA, shouldn't be too difficult. I can easily spot the object with the naked eye as well when it is dark. At the time of my viewing, about 5:30am, I was running out of dark skies very quickly.

The only collimation tool I have at the moment is the dust cap for the focuser with a centre hole drilled. I have a suspicion the secondary is just a bit twisted, it was extremely fiddly when putting it all back together. The method for securing the secondary is very weak and susceptible to shifting if not set-up perfectly. I am pondering a modification to stabilise the mounting and adjustment screws. A Cheshire EP is also on the shopping list.

For the moment, I am happy with what it can show me. I am hoping to use the marginal viewing, as leverage to persuade "the boss" that $1k will multiply the viewing experience 1000 fold. I can only cross my fingers that she'll fall for it! Our camping trip up in Barrington Tops next week will be the moment of truth.

[barx1963 (Malcolm)]

I have just found a review that mentions that the 20mm is an erecting eyepiece with this scope!! It is designed for terrestrial as well as astro use. Surprised they didn't mention that in the manual?

Personally I wonder why a maker would do that. An eq mount is about as useful as a chocolate fireplace when it comes to terrestrial viewing and having two eyepieces presenting different views just makes life confusing.

I think it comes back to marketing. These scopes are sold to beginners. The marketing dept put stuff in there about being able to be used for terrestrial viewing and beginners who simply don't realise that is, while technically correct, factually misleading are sucked in.

Rant over!!

Malcolm

[sharptrack2 (Kevin)]

Well that certainly explains why the 20mm is a bit longer than I think it should be.

Getting excited about my trip to Barrington Tops this weekend. Staying at Ferndale Park camping grounds. Not the most open area, but for my purposes should be fine.

[sharptrack2 (Kevin)]

Just a quick update on my trip... a little disappointing. My own fault though, I carefully packed the tube and mount, had all the essentials in a easy access computer bag (don't have anything fancy yet for the telescope and accessories). Solar panel for charging battery used with inverter, etc. etc.

First night was a wash out, literally, overcast and drizzling most of the night. The second night was forming up to be a cracker night with clear air from the rains and the clouds running off to the East, and I find that in my haste to leave, I left the essentials behind.

Had to settled for 8x21 hiking binoculars and a blanket away from the camp fire (I decided it was much too dark to try and use the telescope but regretted that later at 3 am when my night vision was settled). I was however rewarded with 9 satellites, my first knowledgeable view of Orion nebulae and 3 meteors, one that spectacularly disintegrated into multiple fragments (possibly the start of the Orionids?). Without my planisphere, I was lost trying to find constellations amid the thousands of stars I could now see.

While not yet ready to commit to being a true enthusiast, I am in information overload and need to digest some more. Have ordered The Backyard Astronomer's Guide, the IIS 2016 Yearbook, DVD's, a couple of calendars, and Chris Woodhouse's The Astrophotography Manual.

Now all I need is time! Retirement is looking very appealing.