joining the GS Dob club!

[BLiTZWiNG]

Just got the word from the gf that there a certain package just arrived for me =)

Now, what the heck is this collimation and can anyone point in the right direction on performing this action on my scope when I get home? I don't have a "laser collimator phase warp transmutor dilthium matrix adjustor" like janos, nor do I have 5 billion eyepieces to get past dew =(

[mch62]

Try these links for the hows and whys.

If you can understand the whys the hows will make more sence to you.

I used these when I built my newtonian and had to colliminate from scratch.

At first it might take a while to do but the more you do it the simpler it will be.

It is best to use two people when you are starting out to save on frustration , and remember the final test by doing a star test.

Don't assume it is correct untill you have done a simple star test.

It doesn't take long and will save you asking what the ~!@$@&^ is wrong with this scope.


http://web.telia.com/~u41105032/kolli/kolli.html

http://www.vvm.com/~piscescs/collimat/NoTools2.html

Mark

p.s. feal free to ask questions as a badly aligned Newtonian has given them a bad reputation in the past , and we don't want that now do we?

[BLiTZWiNG]

Thanks Mark!

[iceman]

Here's a couple of other links, the flash movie on the "Andy's Shot Glass" page really helped me understand what collimation is and how to fix it.. it finally opened my eyes and a light bulb went on above my head.

Sky & Telescope - How to Collimate a Newtonian Reflector (http://skyandtelescope.com/printable/howto/scopes/article_790.asp)

Andy's Shot Glass - Collimating Movie (http://www.andysshotglass.com/Collimating.html)

Good luck!

[BLiTZWiNG]

Thanks Ice... though the universe is alerted to my package... the clouds are starting to roll in...

:cloudy: :( :sad:

:prey2: :sunny:

[BLiTZWiNG]

oh man... touching fragile expensive objects with my hands... I get the shakes...

that flash movie was great... but I can see myself breaking my primary mirror...

[iceman]

You don't touch the mirror, you turn some screws which are on the under side of the mirror cell.

You have practically zero chance of breaking your primary by collimating..

[BLiTZWiNG]

well that's good to know... it does make the process simply understandly though, which is great...

Any reason why he would have touched the secondary mirror and showed what happens if you drop it?

Cloud update: getting cloudier :(

[BLiTZWiNG]

cloud cover at 75%

It couldn't have been more precisely timed.

[janoskiss]

BLiTZWiNG,

Few words of about collimation at the business end of the job (...or how not to make things much worse than you have to):

With the secondary you probably only need to tweak the three collimation screws (not the middle one), because the position of the mirror along the length of the tube should be OK. These you should adjust in small steps (less than 1/4 turn!) otherwise the mirror could loose its support. In each step you loosen one screw slightly, then tighten the other(s) to take up the little slack.

Adjustment of the primary wasn't clear to me at first, because I was expecting to see only 3 screws not 6. It is a lot easier than the secondary though, because the mirror is always well supported by 3 springs loaded screws at the back of the mirror. There are 3 other screws flush with the back of the mirror housing. Loosen these first, then adjust orientation of the mirror at the 3 spring loaded screws, finally retighten the mirror housing support screws.

Hope you and I both get some breaks in the clouds. Despite all us Victorians buying all that astro gear, I remain optimistic. Have the dew patrol ready! Resist the temptation to use the eyepiece holder on the side of the dob mount!

[ballaratdragons]

Kids with new toys at christmas!:clap: :rofl: :party: :jump:


I know how you feel. Great isn't it.
:stargaze:

[BLiTZWiNG]

I put the base sides in the wrong sides... I discover this after a 1.5 hours of construction :sad:

Thanks janos... the way I found out I put it together backwards was after I found the holes for that damn eyepiece holder!!

*grumbles* back to work.... *sigh*

[Striker]

Dont worry your not the first!.....hehe

[gaa_ian]

Hmm...think I did that too !

[BLiTZWiNG]

Reversed...

man that is a huge scope... on paper the numbers sound big, but it's a beast to behold in the flesh!

oh, and it's not black! I want a refund!

[BLiTZWiNG]

Ok, it's together... I really don't like the bolts on the side that hold the springs in the mount... they're... loosish... and I acidentally poked one through the other side :(

Not sure if the finder scope is properly seated yet either... oh well

[jackenau]

BLiTZWiNG

I can relate to your anticipation and frustrations in putting a new scope together. Had similar problems, but never poked one through the other side.

Agree with your thoughts on the bolts that hold the springs in the mount.

The actual bolts that hold the round bracket that my scope centres on are loose and can't quite reach them to hold the nuts. Doesn't cause much of a problem except when focusing. Just have to make allowance for it.

Someone on this forum (I think) suggested they only use one spring. Tried it myself and solved the problem (temporarily)

"Must tighten my nuts"

Enjoy, so much to see, just need to know what I am seeing!

Ken M

[BLiTZWiNG]

hehe

[gaa_ian]

See the other GSO dob club post by Janos for some GSO Dob tips :astron:
Think we need a DOB owner FAQ page:confuse3:

[ballaratdragons]

Specifically 'GS' Dobbers FAQ page by the sound of it!

[janoskiss]

BLiTZWiNG,

Trust you've got your scope together by now. (You should have had a closer look at the instructions/diagrams You can actually identify the correct orientations for all panels & components if you study the printouts very carefully under a magnifying glass! :lol: )

I hope your skies are clear. It's pretty good here in Melbourne. Seeing hasn't been too good after the hot day, but no doubt will improve. Saturn should look great by midnight. :D

[BLiTZWiNG]

I'm looking at stars right now, realising I have so much to learn before I can see more than dots of light in the sky...

[BLiTZWiNG]

I'm trying to aim at saturn, but all I'm seeing is a bright dot. I'm pretty sure it's saturn, as it's position relative to the moon seems right, and there is another dimmer star under it (Pollux I presume).

Not sure what I'm doing wrong... I'm pretty sure that either my finderscope is way off or the scope itself is way out of collimation, meaning I have to bring it back in and figure out how to do that...

So much for a quick view of the sky...

[BLiTZWiNG]

Ok, confirmed bright dot with ring around it using 9mm lens.

This is gonna be a real n00bish question, but can you change the magnification on a eyepiece? or is that just what the focus is about?

And what size eyepiece is saturn best viewed with? I have 25, 12.5, 9 & 6.5 (no barlow).

[BLiTZWiNG]

was a bit bigger with 6.5... but still unimpressive. Maybe I was expecting too much?

[Starkler]

Blitz, the focal length of the eyepiece (25, 12.5, 9 & 6.5) gives you different magnifaction depending on the ratio of telescope focal length divided by the FL of the eyepiece.

eg your scopes FL is 1200mm I beleive so your mags are as follows.

25mm = 48x
12.5mm = 96x
9mm = 133x
6.5mm = 184x

Try viewing saturn with the 9mm . If you get a sharp image try the 6.5mm.

[BLiTZWiNG]

I got a sharp image... it was just... small... was definitely saturn, could see the rings around it.. but it was so small... I think all the photographs I've seen have lead me to believe I was going to see it bigger through the eyepiece...

[janoskiss]

BLiTZWiNG,

Size isn't everything! The image might seem small at first, but you can see a lot of detail in that small image. Seeing isn't as good tonight as it was last night here in Melbourne, but you could still see a lot. Did you see the Cassini division, i.e., the dark band in the ring? Did you see the shadow of the planet on the ring?; the darker yellowish-orange bands across the surface of the planet; the four moons? If you didn't, then either you need to collimate the scope, or you need to take your time observing. Was the image sharp, discounting shimmer due to "boiling" atmosphere? If not, then collimation is your enemy. Try the star test, and check out the XT8 guide I linked on the "collimation" thread. Also, Saturn is much more beautiful on a moonless night, and it's easier to see the details.

[BLiTZWiNG]

I'm afraid I didn't see any detail, save for possibly a darker band on the middle of the planet. It's basically a yellowish circle with a ring around it (no divisions).

The image was sharp, and it's now shimmering (wasn't an hour ago).

Maybe it's just my magnification? 184x vs a 200mm scope... If I had a 2x barlow on the 6.5mm, would the resulting 368x be worth it? (Assuming I understand what a barlow is for...)

[janoskiss]

Nah, 184x is plenty. I've also got a 4mm eyepiece, which gives 300x. Yes it's bigger, but it doesn't show me more. Just the noise of the atmosphere is amplified. This is true even for very large professional telescopes. Magnifications beyod 200-300 are rarely useful.

Could you distinguish the ring from the planet itself, or did it look more like an oval shape with two holes in it?

[gaa_ian]

I get my best views at Apox 180x under good seeing with a 10" dob.
Tonight was quite good, mind you I am Lat 12.5deg south :)

[BLiTZWiNG]

I could distinguish the ring from the planet definitely. The magnification might help me, I'm not sure how good my eyesight actually is.

I think also the light from the moon is not helping!

[Starkler]

Could you see the gap in rings called cassinis division ?

On a good night you should see cassinis division clearly and the different shading on the inner rings.

[BLiTZWiNG]

I'm afraid I couldn't see the cassini divisions...

[janoskiss]

I could see the Cassini division clearly, but I agree that the bright moon does not help. Saturn looks more impressive in the darkness of space on a moonless night.

[BLiTZWiNG]

Just spied Jupiter... saw 2 dark bands and all 4 moons! (the only 4 that are currently visible).

[BLiTZWiNG]

I took another look at saturn.. actually it does look more like an elipse with 2 holes in it... I could see what appeared to be 3 moons.. by the patterns they made I'd say Titan, Rhea and Dione.

[iceman]

Well done, you're on your way.

Observing is a technique, and like all techniques, it improves with time, and practise.

Also seeing conditions greatly affect the view that you see - many times i've tried to show my wife Saturn when it was low on the horizon, and all she could see is an oval with 2 holes in it, coloured red white and blue (because of the atmosphere and bad seeing).

I finally showed her during good seeing the other night, with a barlowed 15mm, and it was the best view of it she'd seen. Saturn was as high as it will get in the north (~35-40deg), and seeing was good, and she was impressed with the views.

With patience and practise and good seeing, you'll see the cassini division, the banding on the planet, and of course the moons.

Jupiter is the same with the dark cloud bands, the more you observe, the easier it will be to spot them.

[BLiTZWiNG]

All in all it was a good session... it was a bit frantic trying to get stuff setup, then realising how much I needed to know at the time but didn't know...

Jupiter was the surprise for me, it looked great! I could see 2 dark bands pretty clearly. Saturn unfortunately was very ordinary, even at the top of the arc (seeing was getting pretty wobbly by that stage). But as you say, the more you observe the more you see... I didn't realise the points next to it were moons.

I think the biggest problem for me is that for years I've been looking at photos people take, and expecting to see that through the eyepiece, when it's not the case, even in the 6.5mm EP.

I tried to look at the moon even after reading that a full moon is the worst time to view, and of course that advice got proven 200% correct, even with the moon filter on. I might as well have been looking at my walls! I will try that again in a week or two.

All in all, I call the night a success!