Beginner problems (diagonals and eyepieces)

[Mr niall]

It may be worth pointing out a couple of things about your existing scope to give some context.

It looks to me from reading all of these that you are intentionally leaning away from another reflector because of the reasonably poor experience you have had with your existing reflector.

The reason - the real reason - you have struggled with you Nat Geo reflector is because it is a very very introductory piece of equipment. Without boring you ad nauseum about the shortcomings of it is probably worth realising two important things:

• There are two types of mirror - spherical & parabolic. Both are almost identical but not quite. Spherical are easier to make and much cheaper. They work well at long focal lengths (f10 or above) but get really smushy and aberrated at fast ratios. You have a very fast ratio spherical mirror. So you will never really be able to achieve sharp focus or pleasing views no matter what. The more magnification you add, the worse it will get.
• Collimation is easy. Honestly. It takes about 30 secs if it needs doing. It doesn't need doing that often.

So your experience with a reflector isn't indicative of reflectors in general, you just had a bad start. People here are pushing you toward a reflector because it is, without question, the best value and quality at your price point. £ for £ (or $ for $) you wont beat a reflector for sheer light collecting power at any given price point. Upgrading your eyepieces with that system probably wont attract the return in investment in terms of viewing improvements that you would hope for.

However - refractors are lovely. Contrary to what some have said, I believe that a 70mm refractor and an AZ2 is not a terrible choice. The mount is fairly sturdy and you will see loads and loads with it. The big issue is that you may wish at some point that you could see "more". Things like the AWB onesky would keep you going for a long time. Years in fact. It has a parabolic fully adjustable mirror, and it is bigger - so much easier to find a comfortable viewing angle. You wouldnt definitely need to set it up on a table for it to work.

But, as above, a long focal length refractor is a lovely choice too. I just thought I'd add some context to the debate. A 70mm is a fine choice. 

Edited July 30, 2020 by Mr niall

[Elio_C]

13 hours ago, chrisv said:

How about the secondary mirror, does it have any collimation screws?

I think so? These are the screws it has on it: 

There are also these screws near the primary mirror:

I don't know if they're for collimation though. 

 

13 hours ago, Cosmic Geoff said:

Can you detatch your Dob from its table top mount and attach it to a tripod mount or camera tripod? There might be a screw hole on it that will engage with a camera holding screw.

I think there might be, that might actually be a great idea for the heritage dob some time in the future. 

 

Just a question: I'm keen not to spend hundreds of dollars on an eyepiece, but would a cheap plossl do more harm than good? 

I've heard that cheaper plossls are really not that beneficial, so would it be a bad investment to get plossls similar to this one?: 

https://www.ozscopes.com.au/skywatcher-12-5mm-1-25-super-plossl-eyepiece.html

[Elio_C]

23 hours ago, Mr niall said:

It may be worth pointing out a couple of things about your existing scope to give some context.

It looks to me from reading all of these that you are intentionally leaning away from another reflector because of the reasonably poor experience you have had with your existing reflector.

The reason - the real reason - you have struggled with you Nat Geo reflector is because it is a very very introductory piece of equipment. Without boring you ad nauseum about the shortcomings of it is probably worth realising two important things:

• There are two types of mirror - spherical & parabolic. Both are almost identical but not quite. Spherical are easier to make and much cheaper. They work well at long focal lengths (f10 or above) but get really smushy and aberrated at fast ratios. You have a very fast ratio spherical mirror. So you will never really be able to achieve sharp focus or pleasing views no matter what. The more magnification you add, the worse it will get.
• Collimation is easy. Honestly. It takes about 30 secs if it needs doing. It doesn't need doing that often.

So your experience with a reflector isn't indicative of reflectors in general, you just had a bad start. People here are pushing you toward a reflector because it is, without question, the best value and quality at your price point. £ for £ (or $ for $) you wont beat a reflector for sheer light collecting power at any given price point. Upgrading your eyepieces with that system probably wont attract the return in investment in terms of viewing improvements that you would hope for.

However - refractors are lovely. Contrary to what some have said, I believe that a 70mm refractor and an AZ2 is not a terrible choice. The mount is fairly sturdy and you will see loads and loads with it. The big issue is that you may wish at some point that you could see "more". Things like the AWB onesky would keep you going for a long time. Years in fact. It has a parabolic fully adjustable mirror, and it is bigger - so much easier to find a comfortable viewing angle. You wouldnt definitely need to set it up on a table for it to work.

But, as above, a long focal length refractor is a lovely choice too. I just thought I'd add some context to the debate. A 70mm is a fine choice. 

Hi there! I'm so sorry, I actually didn't see your reply earlier today! 

That's really helpful, thanks. I'll start looking into reflectors then, thanks for clearing that up for me. 

So you're absolutely sure it wouldn't be a better investment to just get better lenses for my current scope? 

Just one thing: I'm not sure I understand your wording. You said about the AWB onesky that 'you wouldn't definitely need to set it up on a table for it to work.'

Maybe it's just a different speaking style than where I'm from but this is sort of contradictory, could you please rephrase/elaborate? Sorry! 

Again, thanks for the reply! 

 

Edit: 

I've just had a look at the AWB OneSky and it looks like a great scope, pretty much perfect, except for the fact that it isn't available where I live (southern hemisphere). 😢

Actually, correct me if I'm wrong, but I think in in the southern hemisphere it's rebranded as the skywatcher heritage mentioned above? It just doesn't have the collimation tool and I don't think the eyepieces are achromatic, (Super brand kelner design) which is very annoying. 

Thanks for the recommendation, I'm still keen to hear your advice on my above question though!😁 

Edited July 31, 2020 by Elio_C

[Cosmic Geoff]

1 hour ago, Elio_C said:

So you're absolutely sure it wouldn't be a better investment to just get better lenses for my current scope? 

Not if it as bad as the other poster says.

 

1 hour ago, Elio_C said:

Actually, correct me if I'm wrong, but I think in in the southern hemisphere it's rebranded as the skywatcher heritage mentioned above? It just doesn't have the collimation tool and I don't think the eyepieces are achromatic, (Super brand kelner design) which is very annoying. 

Apparently the Heritage 130 and the AWB Onesky are essentially the same.  I assume that like the Heritage, the Onesky can be remounted on an astro tripod mount.  Or stood on a camping box?

This is typical of kit eyepieces.  If you expect the manufacturer to include two quality eyepieces and increase the price of the kit by  $100 AUD, that's not going to happen.  In other words, the kit eyepieces are meant to get you started while maintaining an attractive lower selling price.

[Mr niall]

1 hour ago, Elio_C said:

Hi there! I'm so sorry, I actually didn't see your reply earlier today! 

That's really helpful, thanks. I'll start looking into reflectors then, thanks for clearing that up for me. 

So you're absolutely sure it wouldn't be a better investment to just get better lenses for my current scope? 

Just one thing: I'm not sure I understand your wording. You said about the AWB onesky that 'you wouldn't definitely need to set it up on a table for it to work.'

Maybe it's just a different speaking style than where I'm from but this is sort of contradictory, could you please rephrase/elaborate? Sorry! 

Again, thanks for the reply! 

 

Edit: 

I've just had a look at the AWB OneSky and it looks like a great scope, pretty much perfect, except for the fact that it isn't available where I live (southern hemisphere). 😢

Actually, correct me if I'm wrong, but I think in in the southern hemisphere it's rebranded as the skywatcher heritage mentioned above? It just doesn't have the collimation tool and I don't think the eyepieces are achromatic, (Super brand kelner design) which is very annoying. 

Thanks for the recommendation, I'm still keen to hear your advice on my above question though!😁 

Yep sorry lazy use of a double negative! What I mean is when I had one it was big enough so I could still use it comfortably if I sat on the floor next to it. Im 5' 11. But as said above, they can be removed from the base anyway if you decide to get a tripod as they have a universal dovetail anyway which is another nice touch.

Yes we call it the Skywatcher Heritage 130p flextube. In USA they call it the AWB Onesky. Its the same scope.

Skywatcher have just released a slighty bigger 150p flextube. I've got one, its brilliant. its also comes with a collimation cap. But it may be above your budget.

I probably wouldn't bother upgrading the eyepieces on your existing scope. 

I actually think the eyepieces are MA:

https://www.rothervalleyoptics.co.uk/skywatcher-super-ma-eyepieces-125.html

Those are the ones that normally ship with the scope. Either way, millions have used them and they're not too bad. Not something to worry about upgrading straight away.

 

[Elio_C]

8 minutes ago, Mr niall said:

Yep sorry lazy use of a double negative! What I mean is when I had one it was big enough so I could still use it comfortably if I sat on the floor next to it. Im 5' 11. But as said above, they can be removed from the base anyway if you decide to get a tripod as they have a universal dovetail anyway which is another nice touch.

Yes we call it the Skywatcher Heritage 130p flextube. In USA they call it the AWB Onesky. Its the same scope.

Skywatcher have just released a slighty bigger 150p flextube. I've got one, its brilliant. its also comes with a collimation cap. But it may be above your budget.

I probably wouldn't bother upgrading the eyepieces on your existing scope. 

I actually think the eyepieces are MA:

https://www.rothervalleyoptics.co.uk/skywatcher-super-ma-eyepieces-125.html

Those are the ones that normally ship with the scope. Either way, millions have used them and they're not too bad. Not something to worry about upgrading straight away.

 

Great! I'll check that out! So you have a link you could please refer me to? Is this the 150p Heritage? 

18 minutes ago, Cosmic Geoff said:

This is typical of kit eyepieces.  If you expect the manufacturer to include two quality eyepieces and increase the price of the kit by  $100 AUD, that's not going to happen.  In other words, the kit eyepieces are meant to get you started while maintaining an attractive lower selling price.

Ok, in a while I will upgrade to better eyepieces, thanks.

Edited July 31, 2020 by Elio_C

[Elio_C]

https://skywatcheraustralia.com.au/product/6-tabletop-dobsonian/ 

@Mr niall Do you mean this one? 

It says it doesn't need collimation between uses yet still has a collimation eyepiece as an optional accessory...? 

 

[Mr niall]

4 hours ago, Elio_C said:

https://skywatcheraustralia.com.au/product/6-tabletop-dobsonian/ 

@Mr niall Do you mean this one? 

It says it doesn't need collimation between uses yet still has a collimation eyepiece as an optional accessory...? 

 

Yeah thats the one. Funny, mine came with a collimation cap - collimation caps are dirt cheap and easy to use though. I'd assumed they were standard issue with these? Interesting.

Thats a bold statement about collimation though! They are perhaps stretching the truth a bit there... 

But yes collimation has gotten a bit of a bad reputation but honestly its a 30 second job - personally I dont think its something to factor into a buying decision. It takes less time than carrying the scope outside in the first place. And its not even an "art" or a "practised skill". 

Collimation is just making sure everything is lined up. You have two mirrors, the main primary and the little secondary (which you know already). The little secondary almost never needs adjusting at all so dont worry about it for now (although it is a bit of a pain). The primary has a dot in the middle. Your collimation cap has a hole in the middle, a cheshire collimator has cross hairs.

The back of the telescope has three big adjustable screws that you can turn by hand. If the dot of the primary mirror isnt exactly in the middle of the hole of your collimation cap or the centre of the cross hairs of your cheshire collimating tool, then you turn those screws to fractionally adjust the main mirror until it is. Thats it.

The kicker is that even if it is a little bit out it wont really make much difference. And even better - alot of the time it doesn't need touching at all! Dead easy. 

I would throughly recommend the 150 if your budget can stretch. Its really built on the success of the 130p and improved it considerably in my opinion. 

But I'm biased. Like I say, a refractor is a fine choice. But the 150 will show you Jupiters GRS, the cassini division in Saturns Rings. A 70mm refractor wouldnt be able to do that.

[Elio_C]

On 01/08/2020 at 02:58, Mr niall said:

Yeah thats the one. Funny, mine came with a collimation cap - collimation caps are dirt cheap and easy to use though. I'd assumed they were standard issue with these? Interesting.

Thats a bold statement about collimation though! They are perhaps stretching the truth a bit there... 

But yes collimation has gotten a bit of a bad reputation but honestly its a 30 second job - personally I dont think its something to factor into a buying decision. It takes less time than carrying the scope outside in the first place. And its not even an "art" or a "practised skill". 

Collimation is just making sure everything is lined up. You have two mirrors, the main primary and the little secondary (which you know already). The little secondary almost never needs adjusting at all so dont worry about it for now (although it is a bit of a pain). The primary has a dot in the middle. Your collimation cap has a hole in the middle, a cheshire collimator has cross hairs.

The back of the telescope has three big adjustable screws that you can turn by hand. If the dot of the primary mirror isnt exactly in the middle of the hole of your collimation cap or the centre of the cross hairs of your cheshire collimating tool, then you turn those screws to fractionally adjust the main mirror until it is. Thats it.

The kicker is that even if it is a little bit out it wont really make much difference. And even better - alot of the time it doesn't need touching at all! Dead easy. 

I would throughly recommend the 150 if your budget can stretch. Its really built on the success of the 130p and improved it considerably in my opinion. 

But I'm biased. Like I say, a refractor is a fine choice. But the 150 will show you Jupiters GRS, the cassini division in Saturns Rings. A 70mm refractor wouldnt be able to do that.

Thanks for the recommendation, I'll look into that. 

I've been looking around for mounts for the reflector, and they're quite expensive! Anyway, I've noticed on all the AZ3 mounts that the part that connects to the ground is quite small and pointy, why is this? Does this make the mount really unstable, or is it a benefit I'm missing?

https://www.ozscopes.com.au/skywatcher-az3-mount.html

Thanks! 

[barkis]

A good solid mount is most essential , otherwise tiny wobbles become very large wobbles when
observing astronomical targets, and it can become very frustrating. 
There are good tripods, and there are poor ones, and as usual the price rises accordingly.

On the subject of you buying a system for yourself, don't forget to have a look around the used market place.
Many bargains can be found there, people move on quickly in the Astronomy fraternity, and often will
sell their  old setup to help fund new kit.  Definitely worth a look.
Good Luck.
Ron.

 

[Elio_C]

25 minutes ago, barkis said:

A good solid mount is most essential , otherwise tiny wobbles become very large wobbles when
observing astronomical targets, and it can become very frustrating. 
There are good tripods, and there are poor ones, and as usual the price rises accordingly.

On the subject of you buying a system for yourself, don't forget to have a look around the used market place.
Many bargains can be found there, people move on quickly in the Astronomy fraternity, and often will
sell their  old setup to help fund new kit.  Definitely worth a look.
Good Luck.
Ron.

 

Thanks, I'll have a look. 

[Elio_C]

Great news, we've managed to stretch the budget enough to accomodate for the SkyWatcher 150p. 

I'm very excited, and we'll most likely be ordering in October. But first, I do have a few questions. 

I've noticed it uses a helical focuser, I've never used one of these before. Is it annoying to have to spin the whole focuser and eyepiece to get into focus? I don't quite understand the advantages. 

On 01/08/2020 at 02:58, Mr niall said:

mine came with a collimation cap - collimation caps are dirt cheap and easy to use though. I'd assumed they were standard issue with these? Interesting.

Actually, I think you're right! I thought you meant it comes with a cheshire collimator, but I think the dust cap for the focuser is the collimator you're talking about. How do you use one like that? 

I found it at 11 minutes 51 seconds in this video: https://www.youtube.com/watch?v=xyhViri1utU&t=14s 

 

Also, as I've never used a larger telescope than my current one, is it an awkward height for sitting/lying on the ground and viewing? Because there's not always a table around and it'll be a while before I can invest in a mount. 

 

On 01/08/2020 at 02:58, Mr niall said:

the 150 will show you Jupiters GRS, the cassini division in Saturns Rings.

You've got me very excited now! Will that be achievable with just the eyepieces that come with the scope? Obviously I'll probably upgrade eventually but in the meantime I'll just be using the default eyepieces. 

Thanks for the help! 😁

[Pixies]

I think the mention of collimation between uses was to avoid confusion with the large truss dobs, which do. It mentioned no need to reassemble, too!

Collimation isn't hard once you've done it a few times. It takes only a few minutes when you are practised.

For some info/suggestions about this scope, see our very own DIY Astronomy: 

He has several videos.

[Elio_C]

43 minutes ago, Pixies said:

I think the mention of collimation between uses was to avoid confusion with the large truss dobs, which do. It mentioned no need to reassemble, too!

Collimation isn't hard once you've done it a few times. It takes only a few minutes when you are practised.

For some info/suggestions about this scope, see our very own DIY Astronomy: 

He has several videos.

Yeah, I saw that video. It looks like a great project!

[Mr niall]

22 hours ago, Elio_C said:

Great news, we've managed to stretch the budget enough to accomodate for the SkyWatcher 150p. 

I'm very excited, and we'll most likely be ordering in October. But first, I do have a few questions. 

I've noticed it uses a helical focuser, I've never used one of these before. Is it annoying to have to spin the whole focuser and eyepiece to get into focus? I don't quite understand the advantages. 

Actually, I think you're right! I thought you meant it comes with a cheshire collimator, but I think the dust cap for the focuser is the collimator you're talking about. How do you use one like that? 

I found it at 11 minutes 51 seconds in this video: https://www.youtube.com/watch?v=xyhViri1utU&t=14s 

 

Also, as I've never used a larger telescope than my current one, is it an awkward height for sitting/lying on the ground and viewing? Because there's not always a table around and it'll be a while before I can invest in a mount. 

 

You've got me very excited now! Will that be achievable with just the eyepieces that come with the scope? Obviously I'll probably upgrade eventually but in the meantime I'll just be using the default eyepieces. 

Thanks for the help! 😁

An excellent choice (but I would say that!....)

Collimation cap - thats good news. A collimation cap is a low-tech version of a cheshire. But its the same idea and all I use. Just look through it and try to line up the centre spot on the mirror with the hole in the collimation cap (which is what you are looking through).

Helical focusser. Its quirky - there are no advantages whatsoever. Well there is one - it is significantly cheaper than basically every other type so it keeps the cost of the scope down! No it makes totally zero difference to anything having to rotate the whole eyepiece vs a standard type. In fact I prefer it now I'm used to it! I would do the PTFE tape wrapping thing though. Its basically a standard issue modification that every 130/150 owner in the whole world does immediately! Costs almost nothing and steadies everything up.

I've never used any sort flocking of shield on the open tube.

No you totally dont need to lie down to use it at all - I sit on a cushion on the ground in fact and have never had a problem with any target.

And finally - yes the supplied eyepieces will show you all of those things. Just be aware that the planets are quite low in the sky for the next couple of years so their views are a bit "smushy" in general. But they will start to improve over the next 24 months.