Disappointing maiden run with 10" Dob

[erick (Eric)]

Originally Posted by ngcles

Get ready to be blown away by your first look (and your 10,000th look) at Saturn.

Cannot agree more, Les. Had my first view of Saturn this year at 3am this morning up near Mittagong through my litle C8 with a small band of eager newbies who had all set their alarms for this time!

Great excitement. Then off to Omega Centauri, the Jewel Box then the Sombrero for thoses with keen sight (rogue street light and Sydney sky glow in that dirtection!) Wow and double wow!

And I really liked the near edge-on rings! Very distinctive.

Sorry off topic - but it's such a magic activity.

[GeoffW1 (Geoff)]

Hi DSB,

Terrific to hear of your progress. The first good view is certainly a great moment.

I'd better add in fairness that there are several distinct but effective methods of collimating a dob, all with their strong adherents.

My enthusiasm for the Barlowed laser method is based at least partly on a personal feeling that it is the most visually simple method and therefore possibly the one to start off with on first meeting this problem.

However I would be the last to claim that it is the most sensitive to small errors, and for this reason I bought myself an autocollimator recently.

So there will be a progression for you, and pretty soon you will have an instinctive feel for what is going on with the scope.

Cheers

[ngcles]

Hi DSB, Eric & All,

Originally Posted by erick

Cannot agree more, Les. Had my first view of Saturn this year at 3am this morning up near Mittagong through my litle C8 with a small band of eager newbies who had all set their alarms for this time!

At Mittagong last night!!? Are we talking the same Mittagong here --southwest of Sydney? I was at Bargo just up (down??) the Hume at the same time for the 2nd time in 3 nights. Isn't Mittagong a loooong way from Bacchus Marsh for an observing night?

Originally Posted by darkskybondi

Happy new year all!

Before the 9pm fireworks I had a peek at Venus. Very, very small. I haven't looked it up but I suspect Venus is at its most distant from us right now... I'll have to check that. Anyway, I snuck off between the 9pm and midnight fireworks to look at Orion's neb. Call me crazy. Later, after 2am, I observed a bunch of stuff, including Saturn again. Madness.

Call you crazy? Nope, not me.

Madness ?? Sounds like pretty rational behaviour to me.

DSB, don't sweat the collimation issue too much for the moment. Above all don't let it become an obsession that it makes using the 'scope a stressor or a chore. Some people in their early days end up spending so much of their time collimating to absolute perfection -- they leave almost no time for enjoyable observing.

Do the best with the tools and techniques you have. Do a search of the threads here on collimation a bit down the track and you can then learn how to squeeze the last few percent out -- once youv'e got the basics down pat. Don't stress over it yet -- enjoy the blessed thing. Spend more time instead learning the night sky.

With the difficulties with your eyes/glasses, don't rush headlong into a higher-powered eyepiece. The cheaper more simple ones will have very tiny eye-lenses with very short eye-relief that will be very unpleasant for you to use. Some of the more "premium" brands will be much more user-freindly to the eye-glass wearer.

Best,

Les D

[darkskybondi]

Les, thanks for the advice - and also thank Geoff. Really appreciate it. Turns out I was trying to collimate using the locking screw. I'd been told this was the way to do it! And the manual seemed to suggest that the smaller flathead screw was the adjusting screw. So there's that small challenge solved.

Meanwhile I'll be getting out whenever the weather clears. Summer in Sydney is not what it was 4 or 5 years ago.

I am still concerned that I bought the display model... the primary is grainy when you shine a torch on it at the right angle. I am probably being neurotic (a symptom of n00bness) but I checked the 12" model in the store and it showed similar graininess. Nevertheless, I'm still a little concerned about it, and about anything else that may have happened to the scope when it was on display. Any thoughts?

I'm still looking up in the sky and can't wait to join in on a group observing night later this month! Cheers for all your help, everyone.

Happy new year,
- DSB

[bmitchell82 (Brendan)]

I think its just the way that they build the mirrors, mine has exactly the same thing, though there are no holes in it, there are "lighter" spots. good luck

[erick (Eric)]

DSB - shining a torch on the mirror surface is a sure way to scare anyone! It's amazing how terrible they look - covered in specs of dust!

About the miror lock screw - watch out when following Andys Shotglass video. Last time I looked he is speaking about adjusting the primary collimating screws but the image at the same time shows his fingers on the smaller miror lock screw.

Les, I was at at Yerrinbool at a Summer School - a bit further away than Bargo from the massive Sydney skyglow (but a bit closer to Mittagong's sky glow). But still nice after midnight.

[GrahamL]

what eric said mirror coatings do have small imperfections

Don't stress to much about collimation it'll come with time
while I wouldn't suggest you use the below link on its own
http://www.piscescs.com/astro/collimat/notools2.html
Its usefull to help understand whats going on .

Two parts this one first

cover your primary ( we dont need those extra relections right now ) .. with nothing in the focuser draw tube look down it moving your head closer and centring your view as best you can you should have two concentric circles
the outside of your secondary mirror and the inside of your focuser draw tube,
If you can't then your secondary needs adjusting until there is.


Second part
Now your secondary and focuser are aligned remove the cover off the primary and look down the focuser draw tube again
you should in the refection of your secondary see all the primary if you cant then your primary tilt is off.
backing off the locking screws adjust only two of your primary adjusters while going back and checking the view
If you can get all of the primary in your secondary your done if not pick on another two until your can.

hope this dosn't sound to patronising as I dont mean it to be.. For me I found seperateing these two simple tasks to the most simple form helps undersatand the bigger picture a little sooner

[darkskybondi]

Originally Posted by erick

DSB - shining a torch on the mirror surface is a sure way to scare anyone! It's amazing how terrible they look - covered in specs of dust!

About the miror lock screw - watch out when following Andys Shotglass video. Last time I looked he is speaking about adjusting the primary collimating screws but the image at the same time shows his fingers on the smaller miror lock screw.

Ahh well that's the thing - I was tightening the damn locking screws with a screwdriver to collimate the thing. I had the locking screws so tight I'm worried I've done damage!

Meanwhile, these clouds! When will they end? :|

- DSB

[Stuart78 (Stuart)]

I am fairly sure the grainyness in the primary is normal,my new 10" Bintel dob had same thing out of box shine an led torch down at the mirror it looks all speckled more like tiny speckled metal grains which i thought might be a dirty mirror, but shine the torch on your face and look at the reflection of yourself, the clarity is insane i can see wrinkles i didn't know i had lol, sounds like the mirrors are just like this and it is mistaken for dust and crap, my scope has lovely clear views...