Disappointed With New Dobsonian - Help!

[markleton]

Hello, All - This is my first post. Apologies in advance for both the length of this post, and if I ask any questions that have repeatedly been asked by others in the past. I recently got a new dob and was hoping for some advice from you guys.

Some background... I had a very cheap telescope as a kid and I never really enjoyed it as it was so difficult to see anything. I recently decided to give telescopes another shot, but wanted to get something fairly decent so I could really enjoy the experience. After doing a bunch of research, I settled on the Apertura AD8. 

After two nights with it, I have two big gripes.

1. It moves around a lot. Once I lock in on something (mostly the moon in the past two nights), the scope tends to easily shift, even when I tighten all tensioners as much as possible. Is this normal for a dob? Is it something I need to get used to? Can I remedy this in any way?

2. The viewing experience through the eyepieces isn't very good. I don't easily see through the eyepieces and I have to keep trying to find a sweet spot to position my eye into. Even when I have a good view, I can't really settle on it and see it for too long. I hope I'm articulating this correctly... It just seems impossible to steadily look through the eyepiece precisely where I should. I mostly just see black even if the moon is perfectly filling the lens. Am I seeing the edges of the lens...? I don't know. This was the exact problem I had as a kid, and I'm frustrated it's happening again. I had assumed that was happening before because I had a cheap scope. Is there a proper method of actually looking through an eyepiece that I need to get accustomed to? Or should I buy some higher end eyepieces? I'm currently using the two that the scope came with, which are a 1.5" 9mm Plossl eyepiece and a 2" 38mm 60 degree eyepiece.

Thanks in advance for the replies!

[teoria_del_big_bang]

Hi,

I am relatively inexperienced myself only getting my first scope ever only just over a couple of years ago but I also got a Dobsonian, albeit a skywatcher, but I would think most Dobsonians are very similar as they are so simple and although not familiar with your model it does look to be of a good specification and has some very good reviews. So I would not be disheartened as I think the issues are just nebies issues and nothing actually wrong with the scope.

From what I see it looks to be a manual dobsonian which means you cannot actually get a star into view and expect it to stay there as the earth is rotating and thus the star appears to move across your view, and it is quicker than you may expect. Looking at planets is the same and the moon looks to move at one hell of a rate. With the dobsonian you have to get used to sort of guiding with your hand slowly to follow the target. It is not as difficult as you may think. I think I tended to lock things up to a degree so it does not move on its own accord but will move with a little pressure without jerking.

Regarding the eyepiece others will give you better advice but it does also take a bit of getting used to and some eyepieces are different to others. For sure start out with the lower mag ones do not be tempted to just get as higher magnification as you can stich to lower mag until you get used to your scope. It may help to say what eyepieces are you using.

As I say I am also a relative newbie,  and also moved onto imaging mostly now so not so hot on visual anyway so cannot offer much advice butt I am sure other much more experienced members will help you much more.

do not despair this is a great hobby but it takes time but can be very rewarding so stick with it.

Steve

 

[markleton]

13 minutes ago, teoria_del_big_bang said:

Hi,

I am relatively inexperienced myself only getting my first scope ever only just over a couple of years ago but I also got a Dobsonian, albeit a skywatcher, but I would think most Dobsonians are very similar as they are so simple and although not familiar with your model it does look to be of a good specification and has some very good reviews. So I would not be disheartened as I think the issues are just nebies issues and nothing actually wrong with the scope.

From what I see it looks to be a manual dobsonian which means you cannot actually get a star into view and expect it to stay there as the earth is rotating and thus the star appears to move across your view, and it is quicker than you may expect. Looking at planets is the same and the moon looks to move at one hell of a rate. With the dobsonian you have to get used to sort of guiding with your hand slowly to follow the target. It is not as difficult as you may think. I think I tended to lock things up to a degree so it does not move on its own accord but will move with a little pressure without jerking.

Regarding the eyepiece others will give you better advice but it does also take a bit of getting used to and some eyepieces are different to others. For sure start out with the lower mag ones do not be tempted to just get as higher magnification as you can stich to lower mag until you get used to your scope. It may help to say what eyepieces are you using.

As I say I am also a relative newbie,  and also moved onto imaging mostly now so not so hot on visual anyway so cannot offer much advice butt I am sure other much more experienced members will help you much more.

do not despair this is a great hobby but it takes time but can be very rewarding so stick with it.

Steve

 

Thanks, Steve. The scope is definitely moving, too. It won't fully lock. Maybe I just have to get used to this. The eyepieces are the included Apertura 1.5" 9mm Plossl and 2" 38mm 60 degree eyepieces.

[johninderby]

First thing. Have you cillimated your dob. Quite likely to arrive needing collimation due to being bumped about durring shipping.

Edited May 8, 2020 by johninderby

[teoria_del_big_bang]

11 minutes ago, markleton said:

Thanks, Steve. The scope is definitely moving, too. It won't fully lock. Maybe I just have to get used to this. The eyepieces are the included Apertura 1.5" 9mm Plossl and 2" 38mm 60 degree eyepieces.

Odd, is it the swivel base moving, or the elevation ? or both.

I assume it is this scope you have

I strongly recommend an 8″ Dobsonian Reflector like the Aperture AD8 for beginners

It just looks like most other Dobs and so should lock up fairly rigidly, certainly on the elevation, and should able to set the swivel to be stiff enough not to swivel wildly but as I said you want to be able to move it reasonably freely to follow the target.

I wonder if something else has worked loose in shipping and one of the mirrors is loose or something. If you had it delivered then it would be a very good idea to check the Collimation as mentioned by @johninderby .

Steve

Edited May 8, 2020 by teoria_del_big_bang

[markleton]

10 minutes ago, johninderby said:

First thing. Have you cillimated your dob. Quite likely to arrive needing collimation due to being bumped about durring shipping.

I have not. I'll do that first thing tonight. Thanks!

[markleton]

2 minutes ago, teoria_del_big_bang said:

Odd, is it the swivel base moving, or the elevation ? or both.

I assume it is this scope you have

I strongly recommend an 8″ Dobsonian Reflector like the Aperture AD8 for beginners

It just looks like most other Dobs and so should lock u fairly rigidly, certainly on the elevation, and should able to be stff enouch not to swivel widly but as I said yu want to be able to move it reasonably freely to follow the target.

I wonder if something else has worked loose in shipping and one of the mirrors is loose or something. If you had it delivered then it would be a very good idea to check the Collimation as mentioned by @johninderby .

Steve

Yep, that's it. It's mostly the elevation that doesn't seem fully rigid.

[Cuto100200]

Regarding eyepieces, i'm a newbie, but i believe you need to get an eyepiece with higher eye relief, if i'm correct in saying, the more eye relief, the further the distance your eye can be from the eyepiece in order to see down it properly, essentially the less exact the position of your eye needs to be. Generally i believe an eyepiece with better eye relief would help with your problem. Basically allows for a more comfortable viewing experience, even more so if you wear glasses. Might want to look at different FOV's eyepieces can have, as they provide a wider viewing angle, and a lot of people take comfort in seeing wider.

[Peter Drew]

Just had a first look at an Apertura 8".  General specification seems good.  The altitude bearings look a little small in diameter which won't help the control of movement, a common fault with Dobsonians, getting the balance right will be essential.  Using the eyepieces, as with most of the telescope functions is largely a matter of practice.  Telescopes are not as easy to use properly as one might expect.  Stick with it and you will soon be pleased.     🙂

[johninderby]

It looks like a GSO dob.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p1191_GSO-8-inch-f-6-Dobsonian-Telescope-Deluxe-Version.html

[bomberbaz]

Agree with Peter above, the specs look pretty decent. The 9mm might take some getting used to. Your not viewing with glasses are you?

Steve

[markleton]

5 minutes ago, bomberbaz said:

Agree with Peter above, the specs look pretty decent. The 9mm might take some getting used to. Your not viewing with glasses are you?

Steve

Nope, no glasses. 

[bomberbaz]

11 minutes ago, markleton said:

Nope, no glasses. 

Right ok, although tbh I have never got on with shorter length plossl's either. I have used down to 15mm, then no thanks. However I only sport plossl in 25 and 40 now. I have other eyepieces for lower powers. 

If you want to upgrade the 9mm and stick with the other, which I would do then there are lots of low costing options that would hopefully give you a more relaxed and rewarding result. 

There are starguiders, this is 8mm so similar to the current 9mm.

https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-8mm-ed-eyepiece.html

There are these from opticstar which should perform well in your scope at F5.9.  Go for the 10mm again close to your current 9mm.

http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_320

I have used both eyepieces and currently own one BST and 2 of the Opticstar XS. I prefer the opticstars in my frac and mak, they have a nice wide fov on a low budget and perform well in the slower scopes.

If you can afford it, the celestron x-cels are great eyepieces. A little narrower fov than the opticstars but they would be the best performer overall. And it's available in 9mm

https://www.firstlightoptics.com/celestron-eyepieces/celestron-x-cel-lx-eyepiece.html

Other than perhaps changing the 9mm for something easier to get along with, I wouldn't change anything for now. It's good kit.

Steve

[JOC]

Some eyepieces have different optimum heights to have your eye held above them.  Some are far easier to peer into than others - it's called 'eye relief' and is mentioned above,  It varies from eyepiece to eyepiece and maker to maker.  The dob doesn't want to be too tight, you will need to 'nudge' it to keep up with the rotation of the earth to keep the object in view and 'nudging' will need doing more often the higher the magnification you use (the lower the number printed on the eyepiece) for example an Eyepiece marked 24mm will keep things in view far longer than an Eyepiece marked 8mm because it the view is not as highly magnfied.

Edited May 9, 2020 by JOC

[markleton]

Thanks, all. I'll look into some high relief eyepieces.

[Ricochet]

16 hours ago, markleton said:

1. It moves around a lot. Once I lock in on something (mostly the moon in the past two nights), the scope tends to easily shift, even when I tighten all tensioners as much as possible. Is this normal for a dob? Is it something I need to get used to? Can I remedy this in any way?

I have no experience with your exact scope but one thing to look out for is that you are not tightening the tension too much. If you do this then there is initially some resistance to you moving it, but then a "jump" once it does start moving. It is better to slacken off the resistance a little so that you can move the scope smoothly if this is the case.

16 hours ago, markleton said:

2. The viewing experience through the eyepieces isn't very good. I don't easily see through the eyepieces and I have to keep trying to find a sweet spot to position my eye into. Even when I have a good view, I can't really settle on it and see it for too long. I hope I'm articulating this correctly... It just seems impossible to steadily look through the eyepiece precisely where I should. I mostly just see black even if the moon is perfectly filling the lens. Am I seeing the edges of the lens...? I don't know. This was the exact problem I had as a kid, and I'm frustrated it's happening again. I had assumed that was happening before because I had a cheap scope. Is there a proper method of actually looking through an eyepiece that I need to get accustomed to? Or should I buy some higher end eyepieces? I'm currently using the two that the scope came with, which are a 1.5" 9mm Plossl eyepiece and a 2" 38mm 60 degree eyepiece.

This sounds to me like your biggest problem is your eye positioning. A more expensive eyepiece might help a little, but I think it is more likely that you are the issue and to fix that you need practice. The first thing that I would do is to get hold of some sort of adjustable height chair, I use a drummer's stool, as I think that you are much more stable when sitting and therefore it is easier to hold your head steady. The second thing is to get your dob out in the daytime, and starting with your 38mm eyepiece, just practice putting your head to the eyepiece so that you can see the full field of view. The full field of view will be an illuminated circle, with a solid black area around it. There should be a sharp change from bright to dark and you would expect the image to be contained in a perfect circle. If the change from light to dark is somewhat fuzzy, then it is likely that you do not have your eye the correct distance away from the lens, although this can also be a design fault in some eyepieces. If there are large black patches within the circle, this is because your eye is not in the right position and you will need to adjust it. Unless you can aim on something very far in the distance, it is unlikely that you will be able to focus on any target (the closer it is, the further out the eyepiece will need to be), but this does not matter. All you want to do is to hold your head away from the eyepiece, so that you can see the bright spot that is the exit pupil, and then move your head forward until that bright spot fills your eye and you can see the field of view properly. Repeat this until it starts to be come a natural thing  and then you will find it much easier. Once you can do it with the 38mm, move on to the 9mm. The 9mm will be harder as the exit pupil will be smaller (the same for any 9mm eyepiece in your scope), but also because the eye relief, the distance between your eye and the top of the lens, is much smaller (it will be in the region of 6mm for a 9mm Plossl).

[Scooot]

Point it at Polaris to see how much the scope is moving. 

[cletrac1922]

Mark

First of all welcome from Land Down Under

Most Dobs come with either 20mm or 25mm and a 10mm eyepiece

Which one are you using

For the moon, should be using the higher magnification which is either the 20mm or 25mm

Silly question, under the focuser is usually a locking screw, I always leave my loosen off

If tightened all the way up, then the focuser will not move in or out

I also assume the Dob came with a 1.25" eyepieces

Which adapters are you using, and by chance you also not using a barlow if scope came with one

Pic of your eyepiece focuser might help to resolve your issue

John

 

[Ricochet]

18 minutes ago, cletrac1922 said:

Most Dobs come with either 20mm or 25mm and a 10mm eyepiece

Which one are you using

For the moon, should be using the higher magnification which is either the 20mm or 25mm

In a system where the options are 20/25mm and 10mm the 10mm will give the higher magnification.

Also, the OP has stated his telescope comes with a 1.25", 9mm Plossl and a 2", 38mm 60° eyepiece.

[markleton]

On 09/05/2020 at 02:42, Ricochet said:

I have no experience with your exact scope but one thing to look out for is that you are not tightening the tension too much. If you do this then there is initially some resistance to you moving it, but then a "jump" once it does start moving. It is better to slacken off the resistance a little so that you can move the scope smoothly if this is the case.

This sounds to me like your biggest problem is your eye positioning. A more expensive eyepiece might help a little, but I think it is more likely that you are the issue and to fix that you need practice. The first thing that I would do is to get hold of some sort of adjustable height chair, I use a drummer's stool, as I think that you are much more stable when sitting and therefore it is easier to hold your head steady. The second thing is to get your dob out in the daytime, and starting with your 38mm eyepiece, just practice putting your head to the eyepiece so that you can see the full field of view. The full field of view will be an illuminated circle, with a solid black area around it. There should be a sharp change from bright to dark and you would expect the image to be contained in a perfect circle. If the change from light to dark is somewhat fuzzy, then it is likely that you do not have your eye the correct distance away from the lens, although this can also be a design fault in some eyepieces. If there are large black patches within the circle, this is because your eye is not in the right position and you will need to adjust it. Unless you can aim on something very far in the distance, it is unlikely that you will be able to focus on any target (the closer it is, the further out the eyepiece will need to be), but this does not matter. All you want to do is to hold your head away from the eyepiece, so that you can see the bright spot that is the exit pupil, and then move your head forward until that bright spot fills your eye and you can see the field of view properly. Repeat this until it starts to be come a natural thing  and then you will find it much easier. Once you can do it with the 38mm, move on to the 9mm. The 9mm will be harder as the exit pupil will be smaller (the same for any 9mm eyepiece in your scope), but also because the eye relief, the distance between your eye and the top of the lens, is much smaller (it will be in the region of 6mm for a 9mm Plossl).

Thanks for this... Definitely thought that my eye positioning could have been the biggest issue, so I'm practicing. It was better last night. Also collimated and that seemed to have helped a bit.

[markleton]

On 08/05/2020 at 10:10, johninderby said:

First thing. Have you cillimated your dob. Quite likely to arrive needing collimation due to being bumped about durring shipping.

Thanks for the collimation tip. I did it yesterday and it seems to look a lot better. My laser was pointing pretty far from center.

[johninderby]

Have you collimated your laser? The expensive lasers are fine but the less expensive ones are often in need of collimation themselves before use.

Plenty of threads on the subject though.

Edited May 10, 2020 by johninderby

[JOC]

If you are collimating you might be better off with a cheshire and this accepted definitive guide on the subject - follow every step in turn no matter how odd it sounds http://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/