#1  
Old 25-08-2018, 12:40 AM
TwistedRider (Drew)
Registered User

TwistedRider is offline
 
Join Date: Jun 2018
Location: Melbourne
Posts: 125
Not sure what's wrong.

So took the scope out for a few hours tonight.

1. Had a lot of issues finding alignment points for the goto. Mainly lack of knowledge on my part.

2. By the coast is a bit wet without a dew heater.

Now the troubling parts.

How do you turn down the brightness?
Looking at the moon was like starting into a torch.
After looking away, all I could see was black for a couple of minutes. Hope I'm not damaging the old eyes.

Focusing on the moon was good. Nice and clear.
Mars or Jupiter were just blurry blobs. Not sure if I was getting moisture build up or something else.

I do wear glasses and I'm wondering if I need different glasses for using the scope? Any advice.

Also having an issue with eyes watering like mad each time I look into the eyepiece. Not sure if it's wind in my eyes or the directed light. Any glasses wearers for some words of wisdom?

Did get this with the phone though.
Once I'm focusing ok, I'll get the DSLR out.
Attached Thumbnails
Click for full-size image (IMAG1301.jpg)
163.6 KB48 views
Reply With Quote
  #2  
Old 25-08-2018, 01:33 AM
Outcast's Avatar
Outcast (Carlton)
Always gonna be a NOOB...

Outcast is offline
 
Join Date: Oct 2008
Location: Cairns, Qld
Posts: 1,285
I'm no expert but, I have encountered some of the issues you have mentioned & here is my 2 cents worth:

Can't comment on your alignment issues without knowing a bit more detail on what your problems were. If you have a smart phone, you might like to download Skysafari, there is a fully functional free version for both android & iphones. It might help you with identifying stars.

Do you have a dew shield, it won't prevent dew but, it does delay the onset; otherwise, you may consider a dew heater.

To 'turn down the brightness' you need filters. First two filters I ever bought were two Neutral density filters. If you are using a 1.25" diagonal or eyepieces, then buy yourself an ND96 0.9 & ND96 0.3 in the 1.25" size. You can attach them to the diagonal (the bit you insert into the telescope) if it is threaded (intenal) then you can just put the eyepiece you want in; otherwise, you can screw them on to the bottom of the eyepiece but, that is a PITA when changing eyepieces & having to unscrew & rescrew to change them.. They are available for about $19 each. If you have a 2" diagonal or eyepieces they get a bit more expensive. Essential for viewing the moon; .9 is the darkest one & I use it pretty much all of the time when viewing the moon. the .3 is somewhat lighter & is useful for brighter planets. There are other filters out there, colours, emission filters & plenty of others. Do a google search for astronomy filter use, there are some great guides to filter use online.

Viewing of planets can be hit & miss depending on viewing conditions. Clouds, jetstream, moisture can all effect the view & how sharp a view you can get. Try starting with a low powered eyepiece; don't know your scope or setup but, you should be able to achieve pretty sharp focus with a low powered eyepiece, then you can start moving up to higher powers. The better the seeing conditions, the more high powered you can go (in theory). Sometimes, you may find an eyepiece that won't come to focus in your scope; this can be due to not enough intravel or outtravel on your focuser for that particular eyepiece. I have a 15mm GSO Superview that will not come to focus in my 80mm APO. There are solutions, mine was purchasing a Televue adapter that effectively lifted the eyepiece up a little & allow it to come to focus. Other options include trying a different type of eyepiece design, changing to a different focal length eyepiece, etc...

I wear glasses but, I am long sighted with some astigmatism so, whilst I can view through my scope with glasses, I don't need to & I prefer not to. Eyepieces & specifically their cup are designed to place the eye at the right distance from the eyepiece for viewing. If you are wearing glasses, you should fold the rubber down as your glasses will give you the effective eyerelief. I hate doing that so, that's why I don't use my glasses. Your situation may be different. Have you tried viewing without them? You may be able to bring your scope to focus for you without them. I still need them to read stuff, like my handcontroller, use my finderscope, etc... so, bit of a pain taking them on & off but, I still prefer viewing without them.

Watery eyes, can't comment... don't have the problem sorry.

Hope this all helps

Quote:
Originally Posted by TwistedRider View Post
So took the scope out for a few hours tonight.

1. Had a lot of issues finding alignment points for the goto. Mainly lack of knowledge on my part.

2. By the coast is a bit wet without a dew heater.

Now the troubling parts.

How do you turn down the brightness?
Looking at the moon was like starting into a torch.
After looking away, all I could see was black for a couple of minutes. Hope I'm not damaging the old eyes.

Focusing on the moon was good. Nice and clear.
Mars or Jupiter were just blurry blobs. Not sure if I was getting moisture build up or something else.

I do wear glasses and I'm wondering if I need different glasses for using the scope? Any advice.

Also having an issue with eyes watering like mad each time I look into the eyepiece. Not sure if it's wind in my eyes or the directed light. Any glasses wearers for some words of wisdom?

Did get this with the phone though.
Once I'm focusing ok, I'll get the DSLR out.
Reply With Quote
  #3  
Old 25-08-2018, 08:32 AM
Benjamin's Avatar
Benjamin (Ben)
Registered User

Benjamin is offline
 
Join Date: Jun 2013
Location: Moorooka, Brisbane
Posts: 906
If you are observing through a 10” Dobsonian chances are it came with a dust cap that you can use to stop down the aperture when observing the moon. There should be a removeable small cap on the larger dust cap (see picture). This makes things much less bright, especially when the moon is quite full. I’m not much of a lunar observer but enjoy observing it when it’s less than half full (not too bright) and like viewing along the terminator (the division between the dark and light side of the moon). When it’s full the detail gets a bit harder to discern. Mars probably is a blurry blob at present (haven’t checked lately) but Jupiter should show some bands. Play with focus and a higher power eyepiece (10mm should be fine) and make sure you’ve let the scope cool down (around 30 minutes or so). See if you can find a nice adjustable chair to observe with (an observing chair is well worth the investment). It will make the process a bit more relaxing and should assist with relaxing the eyes :-) There’s lots of trial and error to start with (identifying stars, getting used to setting things up, trying different eyepieces etc.) so aim to keep it simple and roll with the punches.
Attached Thumbnails
Click for full-size image (3E866C04-52DE-4DB0-BC54-9C2A977AE29B.jpeg)
27.0 KB22 views
Reply With Quote
  #4  
Old 25-08-2018, 08:37 AM
Allan_L's Avatar
Allan_L (Allan)
Member > 10year club

Allan_L is offline
 
Join Date: Mar 2008
Location: Central Coast NSW
Posts: 3,336
Hi Drew,
A Skywatcher 10" Dob is a wonderful instrument.
GoTo is especially helpful for finding and tracking.
(previously I had a goto SW 12" Dob)
I have switched back to a 10" with Argo Navis (push to) but alignment is still important.
So this is a subject I have researched.

Alignment is always important to get right.
But first you need to level your scope. I use a bullseye level.
You may need to build a levelling platform with adjustable height legs (from Bunnings).

Picking your alignment stars.
Try to pick two stars on the same side of the meridian (imaginary line from north pole to south pole).
Pick stars between 15 to 60 degrees above horizon. and with a difference of 10 to 30 degrees in height.

Your stars should be close to 90 degrees difference in compass direction. But can be between 45 to 135 degrees apart.

(example: Antares and Achernar.)

The Moon.
Yep. Try to avoid it near FULL. (ie after first Qtr and before Last Qtr).
Its too bright, the sun is direct on to it, and you don't see much in the way of detail. If you must, one quick cheap way to reduce light is to put the big plastic tube end cap on the top of the scope with the small plastic cap removed. Make sure to position the hole away from the secondary supports.
Alternatively use filters as Carlton suggested.
One thing, Carlton referred to putting the filter on a diagonal. BUT, we don't use a diagonal when viewing through a DOB.
Another type of filter is a variable polarizing filter set. You can adjust the two filters to adjust the amount of light coming through.

But you will get much more detail and satisfaction from viewing the moon when it is half or less. The sun is side on to it (so to speak) and you get shadows that provide depth of image. The line between dark and light (called the Terminator) is where most detail is usually present.

As Carlton said, the planets can be problematic depending on seeing conditions.
Over magnification in less than ideal conditions presents a fuzzy blob.
A general rule is to try for about 150 magnification at most.
That would be around an 8mm eyepiece in your scope.

Glasses.
Yes I wear them.
Like Carlton, I prefer to view with glasses off.
This of course effect the view of others, and of your camera to eyepiece (nice photo by the way.)
What type of glasses do you have?
My main pair are variable (from distance to reading in one).
I find these difficult for astronomy.
So when I get a two for one offer on new glasses, I order a pair of straight distance lens. If you want to view with glasses, to get "proper" focus point (for others or camera shots) then I find these much better.

Dew.
Yeah, its a pain isn't it.
When you are not using the scope (ie taking a break) try to put the scope horizontal to the ground and cover the opening and eyepieces (finder too if you like).
Additionally, if you are likely to be viewing in dewy conditions a lot, you may want to invest in a dew heater controller and straps.
I have a heater for my secondary. One for eyepieces. and one for viewfinder.
A shroud will also help.
Some people instal a small computer type fan on the base of the scope to blow fresh air onto the mirror. This is also good before viewing to speed up cooling the mirror to ambient. (This will help with viewing quality and could be another reason if your planet viewing is sloppy). if you install a fan to the base, make sure it does not create vibration, which will upset your viewing as well. Maybe turn it off when viewing.

Hope some of this helps and keep asking questions.
Clear skies
Allan

EDIT:
Haha:
Ben got his post in while I was typing.
and I agree with everything he said.
BTW Ben, that other protrusion on the Dust Cover is to put the removable (small) cap on when open, so as not to loose it in the dark.
Reply With Quote
  #5  
Old 25-08-2018, 08:45 AM
Benjamin's Avatar
Benjamin (Ben)
Registered User

Benjamin is offline
 
Join Date: Jun 2013
Location: Moorooka, Brisbane
Posts: 906
Sorry Allan! You’re far more comprehensive than I

And of course Drew keep the questions coming as everyone is mad keen to help where we can

Last edited by Benjamin; 25-08-2018 at 08:58 AM.
Reply With Quote
  #6  
Old 25-08-2018, 10:50 AM
TwistedRider (Drew)
Registered User

TwistedRider is offline
 
Join Date: Jun 2018
Location: Melbourne
Posts: 125
Thanks all. Lots of good info.

I did not know about the removable cap in the dust filter.
I'll try that.

I have a dew heater controller... Just no heaters yet. Have to work out which ones I need and order them.

I was using alpha cent and be achenar to align, Antares i just couldn't find in the scope. But I I'm certain the base was not level, so I'll reserve any complaints until I know I've got my end of the deal sorted

My glasses are for short sightedness, and good old astigmatism. From what I've read I think this sentences me to viewing with glasses. I may just need new glasses to be clear up far off objects.

As far as equipment I was using
I found my vixen 20mm plossl was great for the moon
Long eye relief is nice.

For the planets, I was trying a TV 5mm radian and I think the 15mm skywatcher plossl.
Both had much the same focusing issues given the info below I think eyepiece selection may have been a contributing factor. Lots to learn.

Focusing,. I should clarify that in the focuser, I can see that he image vegetation getting smaller and getting better, but to just looks blurry/hazy. Sort of like looking at a light through baking paper. The attached image is Mars and similar to what I was seeing in the scope.

Looks like I need to:

1 Level scope

2 Get the dew heaters

3 Pick the right eyepiece

4 Get glasses sorted
Attached Thumbnails
Click for full-size image (IMAG1302.jpg)
281.8 KB35 views
Reply With Quote
  #7  
Old 25-08-2018, 03:04 PM
Allan_L's Avatar
Allan_L (Allan)
Member > 10year club

Allan_L is offline
 
Join Date: Mar 2008
Location: Central Coast NSW
Posts: 3,336
That looks close to what I would expect with poor seeing and too strong magnification.

But Mars is very bright at the moment.
Made worse by the planet wide dust storm (ie extra reflective).
Both of which make seeing any detail hard.

It is difficult to focus on any planet …
A tip I received when first starting is to
find a nearby Star, and focus on that until the image is at its smallest.
That should set your focus for the planet.
Note that if the star image doesn't become a tiny sharp dot, not much chance of getting joy with the bright planets.
Reply With Quote
  #8  
Old 25-08-2018, 03:51 PM
gaseous's Avatar
gaseous (Patrick)
Registered User

gaseous is offline
 
Join Date: May 2016
Location: Brisbane
Posts: 782
+1 for a polarizing filter - you can get them on eBay for peanuts. Although the full moon will hurt your eye temporarily, I've read it does no long-term damage and your vision should return to normal in a minute or two. Not sure if it was mentioned to you or on another thread, but using Antares (or any star which is very much overhead at the moment) for one of your alignment stars is probably to be avoided with a dob.
Reply With Quote
  #9  
Old 25-08-2018, 04:00 PM
Stonius's Avatar
Stonius (Markus)
Registered User

Stonius is offline
 
Join Date: Mar 2015
Location: Melbourne
Posts: 1,495
Filters will retain the resolving power of your telescope more so than stopping down by restricting the amount of light hitting the objective. But stopping down costs you nothing :-)
Reply With Quote
  #10  
Old 25-08-2018, 04:02 PM
Allan_L's Avatar
Allan_L (Allan)
Member > 10year club

Allan_L is offline
 
Join Date: Mar 2008
Location: Central Coast NSW
Posts: 3,336
Quote:
Originally Posted by gaseous View Post
There's a handy app (for Android at least) called SynscanInit 2.0 - basically gives you all the setup info (coordinates, timezone, dalylight saving, etc), in the order you need to enter them. I find it's quite a useful tool.
If you haven't already found this, I found it to be a great help and time save.
Can't recommend it highly enough.
Reply With Quote
  #11  
Old 26-08-2018, 09:44 AM
Allan_L's Avatar
Allan_L (Allan)
Member > 10year club

Allan_L is offline
 
Join Date: Mar 2008
Location: Central Coast NSW
Posts: 3,336
Quote:
Originally Posted by gaseous View Post
... Not sure if it was mentioned to you or on another thread, but using Antares (or any star which is very much overhead at the moment) for one of your alignment stars is probably to be avoided with a dob.
OOPs! My bad. I meant to suggest Altair (not Antares).
But depends on what time you do your alignment.
Reply With Quote
  #12  
Old 26-08-2018, 10:23 AM
RyanJones
Registered User

RyanJones is offline
 
Join Date: Jun 2018
Location: Melbourne,Australia
Posts: 1,439
Hi Allan

Don't want to hijack this post but I just have a quick question

I read this :

Picking your alignment stars.
Try to pick two stars on the same side of the meridian (imaginary line from north pole to south pole).
Pick stars between 15 to 60 degrees above horizon. and with a difference of 10 to 30 degrees in height.

Your stars should be close to 90 degrees difference in compass direction. But can be between 45 to 135 degrees apart.

I've been picking stars either side of the meridian

So closer together and same side gives better alignment ? Close to the object you're going to be viewing or in my case photographing ?

Sorry for the hijack
Reply With Quote
  #13  
Old 26-08-2018, 10:57 AM
Karlzburg (Karl)
No moon for you!!

Karlzburg is offline
 
Join Date: Jun 2018
Location: Mudgee, NSW
Posts: 330
I've read picking stars in the area you wish to view or AP is the best way for alignment as Ryan posted.
Though I have done 3 star alignment with my SW and basically did 3 even points around the sky, roughly the same altitude, worked okay.
Alt-Az mode i found to be a little sloppy in tracking a star and will drift out of view relatively quick and had to move the scope to centre again.
Reply With Quote
  #14  
Old 26-08-2018, 01:43 PM
Allan_L's Avatar
Allan_L (Allan)
Member > 10year club

Allan_L is offline
 
Join Date: Mar 2008
Location: Central Coast NSW
Posts: 3,336
Quote:
Originally Posted by RyanJones View Post
Hi Allan
Don't want to hijack this post but I just have a quick question
I read this :
Picking your alignment stars.
Try to pick two stars on the same side of the meridian (imaginary line from north pole to south pole).
Pick stars between 15 to 60 degrees above horizon. and with a difference of 10 to 30 degrees in height.
Your stars should be close to 90 degrees difference in compass direction. But can be between 45 to 135 degrees apart.

I've been picking stars either side of the meridian
So closer together and same side gives better alignment ? Close to the object you're going to be viewing or in my case photographing ?
Sorry for the hijack
Hi Ryan,
Some people say the alignment stars on the same side of the meridian helps.
Sometimes limited options make that difficult. Don't be over concerned.
But if you can, same side and 90 degrees apart with a height difference of 10 to 30 degrees.
But the Main thing with a SW DOB is a level base.
Also, balancing with a counter weight helps I found with my 12".
Just a couple of rare earth magnets, especially if using big EPs or a camera.
Always trying to improve the goto accuracy and tracking.

And yes, I always find accuracy best in the quadrant of the alignment stars, As Karl said.
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 12:52 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Testar
Advertisement
Bintel
Advertisement