Can't see the Moon

[Blackspear]

I live on the northern end of the Gold Coast in Queensland, and have purchased a 2nd hand Sky-Watcher Traditional Dobsonian Telescope 254mm/1200mm (10") for Christmas for my 11yr old daughter who wants to be a astrophysicist (at this point in time). The telescope still has 2yrs of warranty (the owner purchased it new from Slacks Creek in Brisbane).


All caps are off, and we can locate the moon with the finderscope, but no matter what we do, we can't see it through the focus tube using a 10x or 25x eyepiece.


I left the telescope outside to come down to temperature for over 30 minutes.


I am seeing a brilliant bright line when looking through the focus tube, it appears in the centre coming from the edge of the angled secondary mirror.


What obvious thing am I doing wrong?



Cheers :D

[StuTodd]

The mirrors need collimating, the primary mirror is way off line to direct the image to your secondary etc.

Many "how-to's" on google but have a look at http://www.skyandtelescope.com/astronomy-resources/how-to-align-your-newtonian-reflector-telescope/ for an idea.

[Blackspear]

Thank you, now I know what to look for, and it makes sense.


I found this video after reading what you wrote:


https://www.youtube.com/watch?v=8G98RTP6jbY


Does anyone know a good 2nd generation' laser collimator, and can they be purchased on the Gold Coast?



Cheers :D

[m11]

Hi Craig,

Stu is right in that collimation between the primary and secondary is probably not aligned.

Laser collimation for me makes it easier to do. Laser in the middle of the primary and for the secondary in the bullseye for the laser collimator itself.

Give us an update on how you go and if you need collimating.

M11

[gaseous]

Hi Craig,

I assume you've shifted/nudged the scope slightly when trying to see the moon, and racked the focuser fully in and out to see if you can get a focused image - it doesn't take much for a finderscope to be misaligned with the main scope, so just because you can see it through the finderscope doesn't mean it'll be bang in the middle of the eyepiece. No doubt you probably need some collimation, but I've never heard of a dob being so far out of whack that you can't even get some sort of rudimentary image focused. At this point of the lunar cycle, even a very unfocused moon should present as a fairly blinding light taking up a fair bit of the field of view with the 25mm EP and probably covering the field of view with the 10mm EP.

[Blackspear]

Hi Patrick, yes, had 3 of us trying everything. You should have heard the squeals of delight, and the sheer excitement from my little girl seeing the moon through the finderscope, she can't wait to see the moon through the main scope :)


Cheers :D

[gaseous]

She's in for a treat! That's great - hope you get it sorted.

[astroron]

It also could be that your finder scope is not lined up with the telescope
First thing to do in the daylight is find something like a power pole about a a 100 meters or more away in the main scope using the lowest magnification eyepiece and center it.
25mm,not the 10mm.
Look in the finderscope and see how far out of alignment you are.
With the adjustment knobs on the finderscope align it to the telescope
Not the other way round.
Then you will see if your scope is out of colimation when you can find some stars later on.
I hope this helps.
Cheers:thumbsup:

[Blackspear]

Thanks Ron, I'll try that tomorrow.


I have just ordered a SVBONY 7 Bright Level 1.25” Next Generation Laser Collimator+Adapter Sleeve from eBay:


https://www.ebay.com.au/itm/261854809495



Cheers :D

[astroron]

Even if your scope is out of collimation the moon should be visible in the eyepiece if your finder is aligned properly.
Don't touch the collimation until you get a bit more confident with the telescope.
Weather can make things like planets and stars fuzzy,so get used to the scope a bit first.
Enjoy your new views into the night sky.:)
Cheers

[Wavytone]

Simpler solution:

Ask here if there’s someone local who could drop by and show you how.
A modest token of appreciation would probably seal it.
Or join a local astro society and take it to one of their members nights.

[m11]

Second that :thumbsup:

[Oddity]

Hi Craig. From the way you describe it, it sounds like the focuser is not functioning.

Does anything happen when you turn the focus knobs? Does the bright light change in size?

Does the focuser/eyepiece move in and out when you turn the focus knob? If not then perhaps it has some kind of focus lock engaged (a thumbscrew you can turn) and/or a focuser traction knob that needs to be tightened. Some focusers/scopes have both, meaning you'll need to disengage focus lock and engage the traction screw.

[raymo]

It just occurred to me that Skywatcher Newtonians[dobs] have an unusual
focuser/eyepiece adaptor set up, and maybe you are using it wrongly, or not all the parts are there. There is a large black collar about 60mm long with a bevelled end and an opening for a 2" diameter eyepiece at the other end.
This is not used with the 1.25" diameter eyepieces that come standard with the scope. There is a plate with a bevelled side and a short tube for the
eyepiece on the other side. This plate fits directly into the focuser opening,
and is secured by the chrome screws on the side of the focuser. If you are
using the set up wrongly you will not be able to come even close to focus.
raymo

[luka]

Just a warning that the cheap laser collimators may need collimating themselves. I have the same one as you ordered and it definitely was not collimated.
It is easy to do, 4 nails in a block of wood and a hex-key will get the job done. Just google "laser collimation v-block".

[Blackspear]

Thanks for the suggestion, where on the forum would I ask this?


Cheers :D

[RB]

In the General Chat area will be fine.

RB
:)

[Blackspear]

Yeah, I'm out of my depth now, definitely going to need someone who knows how to set up what I have purchased.


Cheers :D

[doppler]

Skywatcher newt's / dobs have their mirrors setup for astrophotography. My 10" dob needs an extension tube to get focus when using an eyepiece, defiantly don't start messing with the mirrors and collimation yet.

[Blackspear]

Thanks, yes, I have that extension tube as well, tried adding it, still no go. Time to get some help :)


My little girl is chomping at the bit to see her present work, and I must say, me too, having seen the craters in the moon with the finderscope, that was just stunning.


Cheers :D

[m11]

Hi Craig,

Might be worthwhile to get some pictures in the meantime while you wait for help. :hi:

This is the screen capture of the Skywatcher adapter for 1.25inch and 2inch.

[Blackspear]

Thanks Mel, yes, I have both of those installed, tried it only with the 1.25" adapter, then added the 2" adapter, which is more like what I would call an extension tube.


Cheers :D

[Blackspear]

A huge thanks goes out to Jeremy, the mirrors were out of alignment, as well as the 20mm eyepiece rattled, and had a missing piece from it. Jeremy collimated the secondary and primary mirror, and lent us a 10mm eyepiece.


We had about 30 minutes of clear sky tonight and were able to see the moon as clear as a crystal, my little girl was squealing with delight, she kept pushing us out the way to look through her scope. She also was quite firm in that she wanted to line up the moon with "her finderscope".


We walked the scope across the road to elderly neighbours, whom couldn't believe how clearly and with so much detail they were able to see the moon. And again my daughter wanted to line up the scope (I was pushed out the way).

Thanks everyone for their help and suggestions.


Cheers :D

[Imme]

Awesome....well done jeremy

[m11]

Glad it worked out and your daughter had a great time.

Well done to Jeremy for helping out. :thumbsup:

[Sconesbie]

Fantastic result. I love how she kept pushing you out of the way. Wait for the moon to phase down and keep looking at the skies. It gets better.

[Blackspear]

Exactly, she had just gone to bed a little late last night after finishing her homework, and I thought I would see how the sky's were: full moon, large cloud to the right, heading out to sea, clear to the left. Do I, don't I, yes, let's see if she is still awake. You awake? Yes. Do you want to come and have a look outside? YES!!!


Talk about a stampede, and every time I went phwoar, she just pushed me out the way like a rugby player giving a shoulder charge. MOVE!!! (from the depth of sound in her voice I thought I had a son). It made me laugh, and she said, "I know that sound, it means something really good."


The moon was so bright I ended up with a huge reddish blind spot in my eye.



Paige loves her Christmas present, and as a parent, it is fantastic to see her so excited at the beginning of a journey.

[erick]

A very happy story! Time for you and Paige to bring your scope to an astro camp!

Full moon is the time to examine the ejecta rays from the "newer" craters. Tycho, Copernicus, Kepler for example. Did you see them? As the illumination moves away from 100% in the days ahead, the rays become less visible.

Cheers
Eric

[gaseous]

If you haven't done so already, a neutral density / polarizing filter might be worth an investment to take a bit of the glare off the full moon - should be less than $25 on ebay. The polarizing type allow you to adjust the brightness level - they're very handy if you're a moon enthusiast.

[Blackspear]

Hi Eric, yes, the ejecta rays were crystal clear to see :)

[Blackspear]

Thanks Patrick, we will get one of those, as I wasn't too keen to look again at that much light (wasn't sure what damage it was/may be doing to my eye).


Cheers :)

[raymo]

It does no harm to your eyes, just look at the moon from about 75-100mm
from the eyepiece, and slowly move up to the eyepiece over about 15secs.
raymo