markleton

13 minutes ago, John said:

Well, the image is as good as the weakest link in the optical chain. As long as the barlow lens is of good optical quality it's impact on optical quality should be negligible.

The only snags that I can see are:

- The 12mm ES 92 (which I believe you said you have) is a very large 2 inch eyepiece. Adding a 2.5x barlow to that will make a heavy and tall "stack" to hang out of your focuser.

- The 12 ES 92 already has quite long eye relief and the barlow lens will extend that further. You might find that eye positioning becomes tricky ?

 

My barlow is the Celestron 93436 Luminous 2-Inch 2.5x. It's definitely not high end, but seems to be of good quality and has really given me some impressive views with the 12mm ES. I have no complaints with it. 

It's definitely a tall and heavy stack, but my focuser seems to handle it quite well. I haven't noticed any difference in terms of eye positioning, but I'm still kind of getting used to proper eye positioning in general (still a rookie!)

42 minutes ago, JOC said:

I have an 8" 1200mm FL Dob and I have never got any joy out of anything more magnifying than a 4mm and most times a 5mm.   I have once tried a 3mm in it and it was hopeless - in my opinion I think it you stick at half of what is theoretically possible you won't go far wrong.  I would 100% buy the 4.5mm if you have to get one of them, but I reckon you'd be better off stopping at 5mm IMO.

Got it. Thanks. The 4.5mm option specifically brings up what I'm trying to understand conceptually... My 12mm paired with my 2.5x barlow gets me to 250x. A 4.5mm on its own gets me to 266x. Other than the small magnification increase, Is there any advantage to using a standalone eyepiece without a barlow? Does the barlow impact image quality in any way?

7 minutes ago, John said:

 

 

What sort of budget do you have in mind ?

 

I'd go up to $150ish... Seems like some of the midrange stuff I'm seeing (along with the StarGuider suggested above) are well below $100.

19 minutes ago, John said:

If I had your scope and your current eyepieces, I would be looking for a 6mm to give 200x. Very useful and usable high power.

Do you have anything with lower power than the ES 12mm ? - if not I think you have a niche or two there that might need filling.

Eyepieces that give more than 250x will not get a lot of use whereas the ones I mention above will

Thanks. Any suggestions? I have a 30mm SuperView with a 68 degree FOV that came with the scope. I hardly ever use it anymore.  

25 minutes ago, merlin100 said:

Have you thought about the BST StarGuider 3.2mm ED eyepiece?

https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-32mm-ed-eyepiece.html

Nope, but I'm open to all suggestions. I was intending to stick with ES since I was so happy with my two other eyepieces. Should this be at the top of my list? Thanks

Hello All -

I have an Apertura AD8 8" dob (1200 mm focal length) and am using the 12mm Explore Scientific 92 series and the 8.5mm Explore Scientific 82 series eyepieces. I'm very happy with both eyepieces and am considering a high magnification 3 or 4.5mm eyepiece in the 52 series from ES.

My question is, should I even consider a 3 or 4.5mm eyepiece? My 8.5mm paired with my 2.5x barlow will get me solid magnification, but is there a situation where a 3 or 4.5mm on their own would do a much better job? I know I can't barlow them because my theoretical max magnification is 400x. Should I round out my collection, or is it not necessary?

Thanks again!

Thanks for the replies, guys. I figured an eyepiece in the 8mm range would give me a good high-magnification (non barlowed) option while also giving me the chance to barlow it under awesome conditions.

Hello All -

I have an Apertura AD8 8" dob (1200 mm focal length) which I'm now using a 12mm Explore Scientific 92 series eyepiece with. I'm very happy with the eyepiece and it even barlows well with my 2.5x Celestron barlow.

I was looking into buying a smaller focal length eyepiece to have a couple options for my observation. I've read that magnification limits are 50x aperture, so I've been researching with the assumption that I can magnify up to 400x.

My question is... If I want to use my barlow with my new eyepiece, am I still limited by this 400x number? I assume I am, so I'm looking at the 8mm range for a new eyepiece.

So, the second part of my post... If anyone has recommendations for 8mm, I'd really appreciate it.

Right now, I've narrowed down to the Explore Scientific 8.5mm LEF 82 Series and the Pentax 8.5mm XF Series. I think I'm leaning towards the ES piece since I'm so happy with my current one, and I saw a couple reviews saying that the Pentax isn't that great. I also came across the Baader/Orion 8mm, but saw that it's not a good eyepiece for faster scopes.

Thanks again!

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.

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.

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

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. 

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.

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!

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.

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!