Beginner problems (diagonals and eyepieces)

[Elio_C]

Hi everyone, 

This is my first post so I hope I'm not doing something wrong... 

I'm looking into a new telescope and I've got a few questions.

Firstly, I've heard talk about how a 45 degree diagonal is bad for stargazing and that it is better for bird watching or terrestrial viewing. For a very much beginner (not like a kid's telescope beginner, but still a beginner), does this really matter that much? How important is it to have a 90 degree diagonal? And could someone please explain (in simple terms) the difference between the different types of diagonals and how they affect your viewing? (like prism, erect, star, etc.) 

Also, I was wondering, is it bad to mix different brands of eyepieces? 

I have a low budget Bresser (national geographic) scope, when I upgrade to a better telescope, can I use my Bresser 2x Barlow on eyepieces of a different brand (Saxon) or is there differences between the brands that will mean I should use eyepieces that are all from the same brand? 

 

Thanks for the help, 

Elio. 

[laudropb]

Hello and a warm welcome to the SGL. It is better to use a 90 degree diagonal because it is much more comfortable when viewing at high altitudes. The more comfortable you are when observing is important but a 45 degree diagonal can be used at a push. The different types of diagonal that you can use are often just a choice of personal preference but erecting diagonals are not favoured because they add an other layer of glass to the light path which will reduce the amount of light getting to your eye. Mixing makes of eyepieces  is no real problem and most of us do. The advantage of sets of the same make is that they are often parafocal ie you do not have to refocus when  you change eye pieces

[Elio_C]

Thanks for the reply, that's been really helpful. 

Another question (sorry): 

As I mentioned I'm looking into a new telescope and I've come down to two options, they are both refractors with an aperture of 70mm, one with a 700 mm focal length, and the other with a 900mm focal length (and a much better mount, albeit a bit out of my budget).

Is there actually any advantage to having the 900mm focal length when both of them have the same highest practical magnification (140x)? What's the benefit? 

I am aware that a longer focal length means a greater f/ ratio and apparently that's good for astrophotography, but astrophotography is not really my thing so that does not hold any appeal to me. 

Thanks!

[laudropb]

I assume these are both achromatic fracs. They will both suffer from achromatic aberrations to some extent, but these should be less in the longer focal length. Which telescopes are you considering ?
Also the quicker scopes ie shorter f ratios are considered better for astrophotography .

[x6gas]

1 hour ago, Elio_C said:

As I mentioned I'm looking into a new telescope and I've come down to two options, they are both refractors with an aperture of 70mm, one with a 700 mm focal length, and the other with a 900mm focal length (and a much better mount, albeit a bit out of my budget).

Is there actually any advantage to having the 900mm focal length when both of them have the same highest practical magnification (140x)? What's the benefit? 

I am aware that a longer focal length means a greater f/ ratio and apparently that's good for astrophotography, but astrophotography is not really my thing so that does not hold any appeal to me. 

Thanks!

Hello and welcome to SGL!

Longer focal length - for the same aperture - means a greater f/ratio and means that the system is 'slower' than a system with a lower f/ratio.  A fast system is usually considered preferable for imaging though it comes with problems (more difficult to get a properly corrected image and very precise focusing required.

For visual, the longer focal length scope will be a bit more forgiving all things being equal... but it would be worth posting the scopes you're interested in so that people can properly comment - we all love spending someone else's money!

 

[Elio_C]

10 hours ago, laudropb said:

Which telescopes are you considering ?

10 hours ago, x6gas said:

For visual, the longer focal length scope will be a bit more forgiving all things being equal... but it would be worth posting the scopes you're interested in so that people can properly comment - we all love spending someone else's money!

Haha sure! I didn't think you would be interested, thanks! 

My budget is $250 AUD but I can add a bit more room to that if I really work for some extra pocket money. 

The scopes I am looking at are these: 

https://www.saxon.com.au/saxon-707az2-refractor-telescope.html 

and https://www.saxon.com.au/saxon-709az3-refractor-telescope.html

However, I have found them for cheaper prices here: (I don't know how they are cheaper than the retail price, but I'll take it) 

https://www.ozscopes.com.au/refractor-telescope-saxon-707az2.html

and https://www.ozscopes.com.au/saxon-709az3-refractor-telescope.html 

I'm very much leaning towards the second one even though it is quite a bit over budget because of what you guys said and that I've read reviews of the AZ2 mount and apparently it is really shaky and it doesn't have an Azimuth slow motion control. 

However, I do have the problem of having to buy a 90 degree diagonal if I splash cash on the second one, which is quite a problem as I'm already over budget. My other problem with the second one is that it contains a Super 10, 25 and SR 4mm which combined with the focal length make magnifications of 90x, 36x, and 225x. This range of magnifications REALLY does not make sense to me, considering that the maximum practical magnification is 180x. Why wouldn't they just include a Barlow 2x instead of the SR 4mm because then the magnifications would be 36, 72, 90, and 180x? 

This isn't really a problem as I already have a (not very good quality) Barlow 2x, but it is rather annoying. 

 

Thanks very much for the help! 

 

[chrisv]

To be honest, I would avoid both of them - the 70mm of aperture is quite small for visual use, you probably won't be able to see much besides planets from an urban region. Dark skies would probably help, but at 900mm focal length, it's not very portable (still doable though). At this price range, a pair of binoculars might be a better match - a lot more portable and you'll probably see the same things.

If you're not set on refractors, I would also consider this one:

https://www.ozscopes.com.au/skywatcher-heritage-5-dobsonian-telescope.html

It's sold also as AWB OneSky and has very good reviews. If you're interested only in visual, it's probably the best choice in this price range. If you still want a refractor, I would consider an 80mm F5 refractor:

https://www.ozscopes.com.au/skywatcher-80mm-refractor-altaz-telescope.html

The aperture is a bit larger than your previous choices (although I don't think there will be a big difference), but the focal length will be a lot shorter - hence more portable. It will be better suited for wide field of views and has the advantage that you can mount it more easily on a motorized mount in the future (e.g. Skywatcher AZ GTi) and maybe even try adding a camera as well. It will have more CA aberrations than your other choices, but you'll see those mainly on planets and brighter starts. A fast achromat that's seeing the stars, even in a rainbow of colors, is more useful than a longer one that's staying at home :).

Also, keep in mind that AZ3 is a very budget mount (in the bad sense). It's very light and easy to carry, but the altitude adjustments is really annoying (you have to push really hard on the scope). The tripod legs are flimsy (the thread on one of my locking bolts stripped in the first week of use) and it shakes a lot at higher magnifications (> 100x). It will probably come with a screwdriver and a wrench - you will definitively need those. With that being said, I don't think there any better options at this price range, unless you go for the reflector with the Dobsonian like mount (tabletop).

Update: I forgot to mention the exit pupil which is affected by the aperture and total magnification (telescope focal length divided by eye piece focal length). With a 70/900mm scope and a 10mm eyepiece, you'll get 90x magnification with an exit pupil of 0.78mm. Looking through it will feel like looking through a very small hole, definitively not comfortable.

Edited July 29, 2020 by chrisv

[Cosmic Geoff]

I have used a terrestrial 45 deg diagonal for astronomical targets. While it handily presented the Moon the right way round, it definitely had an inferior optical performance on critical astro targets. For daytime use ony.

[Elio_C]

1 hour ago, chrisv said:

To be honest, I would avoid both of them - the 70mm of aperture is quite small for visual use, you probably won't be able to see much besides planets from an urban region. Dark skies would probably help, but at 900mm focal length, it's not very portable (still doable though). At this price range, a pair of binoculars might be a better match - a lot more portable and you'll probably see the same things.

If you're not set on refractors, I would also consider this one:

https://www.ozscopes.com.au/skywatcher-heritage-5-dobsonian-telescope.html

It's sold also as AWB OneSky and has very good reviews. If you're interested only in visual, it's probably the best choice in this price range. If you still want a refractor, I would consider an 80mm F5 refractor:

https://www.ozscopes.com.au/skywatcher-80mm-refractor-altaz-telescope.html

The aperture is a bit larger than your previous choices (although I don't think there will be a big difference), but the focal length will be a lot shorter - hence more portable. It will be better suited for wide field of views and has the advantage that you can mount it more easily on a motorized mount in the future (e.g. Skywatcher AZ GTi) and maybe even try adding a camera as well. It will have more CA aberrations than your other choices, but you'll see those mainly on planets and brighter starts. A fast achromat that's seeing the stars, even in a rainbow of colors, is more useful than a longer one that's staying at home :).

Also, keep in mind that AZ3 is a very budget mount (in the bad sense). It's very light and easy to carry, but the altitude adjustments is really annoying (you have to push really hard on the scope). The tripod legs are flimsy (the thread on one of my locking bolts stripped in the first week of use) and it shakes a lot at higher magnifications (> 100x). It will probably come with a screwdriver and a wrench - you will definitively need those. With that being said, I don't think there any better options at this price range, unless you go for the reflector with the Dobsonian like mount (tabletop).

Update: I forgot to mention the exit pupil which is affected by the aperture and total magnification (telescope focal length divided by eye piece focal length). With a 70/900mm scope and a 10mm eyepiece, you'll get 90x magnification with an exit pupil of 0.78mm. Looking through it will feel like looking through a very small hole, definitively not comfortable.

Hi, thanks for the reply and for the suggestions!

Big update: I've taken this knowledge and presented it to my budgeters (parents) and they have asked me to come up with a list of the price to quality range so we can discuss it over the weekend. 

I have my heart set on a long focal length refractor for a few reasons, I'll explain. My current telescope is a low quality tabletop Dobsonian (https://www.amazon.com/National-Geographic-Telescope-compact-9065000/dp/B00A7SSZKM) and I'm reaally keen to steer away from that model for a few reasons: 

1. Often to get good views I have to lie in an uncomfortable position on the ground. Not ideal. So I'm keen to find a scope with a good mount. 

2. Collimation: I'm really keen for a scope that I don't have to regularly collimate/service, just a tool I can whip out when I want to go stargazing. Hence why I'm keen for a refractor. 

3. Aberrations! GAH! I'm so keen to have a scope with (reasonable) quality lenses and a longer focal length because my budget tabletop dob suffers so badly from ghosting and chromatic aberrations and it is really a goal of mine to have a scope that is ok with aberrations so I can actually see with reasonable clarity. 

I'm really keen for a telescope rather than binoculars because you can change magnifications with telescopes and I don't know... I just much prefer the appeal of a telescope. I guess it's more suited to my style and I just really prefer them. Telescopes are my thing. 

Anyway, if you're still kind enough to be with me, I'm wondering what the best (or average) refractor telescopes are that are within $100 or so of my price range are and some pros and cons? 

Preferably fracs with higher f/ ratios, but if that's not possible in my price range then there's nothing I can do about that. 

Also, I was wondering: What is the price for just an average? Average stable mount, average workable aperture and focal lengths, just an average scope for a beginner that can last them for a while. 

59 minutes ago, Cosmic Geoff said:

I have used a terrestrial 45 deg diagonal for astronomical targets. While it handily presented the Moon the right way round, it definitely had an inferior optical performance on critical astro targets. For daytime use ony.

Thanks for the reply, I'll keep that in mind. 

 

Thank you everyone so much, this forum has been a massive help to me. Lots of gratitude, 

Elio. 

[Cosmic Geoff]

6 minutes ago, Elio_C said:

Anyway, if you're still kind enough to be with me, I'm wondering what the best (or average) refractor telescopes are that are within $100 or so of my price range are and some pros and cons? 

Preferably fracs with higher f/ ratios, but if that's not possible in my price range then there's nothing I can do about that. 

$250 AUD will not go far when buying astronomical equipment.  If you don't want something overly compromised, consider spending more (how much did your smartphone cost? 🙂)  The problem with refractors is that they do require a decent mount, typically costing as much as the 'scope.  The mount for a Dobsonian, on the other hand, costs very little.  The oft-recommended 130mm Heritage Dob would be within your budget.

Just as an example, my 102mm f5 Startravel is a short-focal ratio achromat, with a 2" focuser and 1.25" adaptor and has metal rather than plastic parts.  Nothing fancy, quite well made, but it costs 165 UKP (around 300 AUD) here, without any mount.   The Skywatcher Evostar range looks like a longer focal length variant.

[x6gas]

Nothing wrong with wanting a scope instead of binos.  Quite understand.  I want an obsy dome even though I know a roll-off roof makes more sense.  I don't care!

I don't know Saxon as a manufacturer but words like "for children" in the description of the cheaper one doesn't inspire too much confidence.

It's easier to make longer focal length telescopes that suffer from *less* aberration than shorter ones, but the native magnification is higher so you'll need a better mount to make the most of that.

I would also suggest the same Skywatcher scope mentioned above.  A well known brand with better resale potential (here in Europe at least) and it could serve as a guidescope in future if you get into astrophotography.

I'd also suggest checking out Astronomy Tools FoV calculator to get an idea of what you'd see from the eyepiece (in terms of field of view, not quality of image!)

[John]

Saxon kit is usually the same as Skywatcher. They are another brand that is owned by Synta who make Skywatcher stuff.

The Saxon branding tends to be used more in the southern hemisphere.

 

[Elio_C]

14 hours ago, x6gas said:

Nothing wrong with wanting a scope instead of binos.  Quite understand.  I want an obsy dome even though I know a roll-off roof makes more sense.  I don't care!

I don't know Saxon as a manufacturer but words like "for children" in the description of the cheaper one doesn't inspire too much confidence.

It's easier to make longer focal length telescopes that suffer from *less* aberration than shorter ones, but the native magnification is higher so you'll need a better mount to make the most of that.

I would also suggest the same Skywatcher scope mentioned above.  A well known brand with better resale potential (here in Europe at least) and it could serve as a guidescope in future if you get into astrophotography.

I'd also suggest checking out Astronomy Tools FoV calculator to get an idea of what you'd see from the eyepiece (in terms of field of view, not quality of image!)

 

19 hours ago, Cosmic Geoff said:

$250 AUD will not go far when buying astronomical equipment.  If you don't want something overly compromised, consider spending more (how much did your smartphone cost? 🙂)  The problem with refractors is that they do require a decent mount, typically costing as much as the 'scope.  The mount for a Dobsonian, on the other hand, costs very little.  The oft-recommended 130mm Heritage Dob would be within your budget.

Just as an example, my 102mm f5 Startravel is a short-focal ratio achromat, with a 2" focuser and 1.25" adaptor and has metal rather than plastic parts.  Nothing fancy, quite well made, but it costs 165 UKP (around 300 AUD) here, without any mount.   The Skywatcher Evostar range looks like a longer focal length variant.

Thanks for the advice, I've had a look around my price range and what I'm keen to use it for, and I've decided on sticking with the 70 (maybe 90)mm frac. 

I've actually found a 70mm by 900mm EQ frac on sale for only $299. https://www.astronomyalive.com.au/product/saxon-709eq-70mm-refractor-telescope/

Or a 90/900 for $399. https://www.astronomyalive.com.au/product/saxon-909eq2-refractor-telescope-2/

I get that the more expensive the instrument, the better quality it will generally be, but I'm on a tight budget and am really just looking for a mounted frac with a high f/ ratio. 

So, I've got the option of just an altaz mount with the scope, or the above mentioned EQ mount for the same scope. Is using an EQ mount really that hard for a beginner, should I focus on just keeping it simple with an altaz? 

Considering the two options are only $9 apart, I've really got some freedom here, would it be a bad idea to go for the cheap EQ mount while it is still on sale? Or should I wait until I'm more comfortable with the scope before upgrading? 

I just don't really want to miss out on this opportunity, but still don't want to be overwhelmed with a mount I'm not comfortable using. 

Thanks so much for the help!  

 

[chrisv]

I wouldn't go for an EQ2 mount, the minimum would be an EQ3. An EQ mount is more complex than an AltAz mount, because of this it's usually more expensive. In order to provide a scope and an EQ mount at this price, a lot of corners need to be cut. 

EQ mount pros (for visual use):

• it's easier to manually track the object, once it's in sight, you only need to adjust the RA knob

Cons:

• harder to setup: even though polar aligning is not that difficult, it still requires extra time; it's fun when you do it the first time, but you will need to do it (at least roughly) every time; since you're probably in the southern hemisphere, the process may be more difficult
• heavier: most EQ mounts use counterweights in order to balance the telescope; in practice, this means that you'll need to carry a counterweight almost equal to the weight of your telescope
• star hopping is more difficult: you cannot rotate the scope left, right, etc. - the movements need to be on the RA and DEC axes. This may not seem such a big deal, but it's not that intuitive to do in practice. Combining this with a prism/mirror diagonal which flips the image on the left/right axis, it will definitively complicate things.
• the EQ mount will rotate the tube when you move from one area to another; to avoid some odd angles for the eyepiece, you will need to rotate the diagonal or the entire tube itself (i.e. if you want the finder scope in a certain position) whenever you change targets

As you can see, there aren't that many advantages of an EQ mount for visual use. Some EQ mounts can be upgraded with tracking motors and even goto, but I wouldn't invest more in an EQ2 mount.

Now, as for the refractor choice: I know that getting a new scope may seem exciting (it definitively is for me!), but please bear in mind that it may not really be an upgrade in the first place. Your previous scope is a 114/500 reflector, it may not be the highest quality one, but it definitively has a bigger aperture than a 70 refractor (even if we take into consideration the central obstruction). And for visual use the aperture is one of the most important aspects. From the product images and reviews, the bundled eyepieces seem to be low quality. Have you tried a different eyepiece? 

If you don't have a better eyepiece, try to get one before getting an entire new scope. Maybe you can find a used one, at a bargain. You'll be able to use the eyepiece on the new scope as well (which most likely comes with very basic ones). 

  

42 minutes ago, Elio_C said:

I've actually found a 70mm by 900mm EQ frac on sale for only $299. https://www.astronomyalive.com.au/product/saxon-709eq-70mm-refractor-telescope/

Or a 90/900 for $399. https://www.astronomyalive.com.au/product/saxon-909eq2-refractor-telescope-2/

Between these two scopes, I would choose the 90/900 one because it has a bigger aperture. If you can get it on an AltAz mount (even at the same price), it will be easier and more fun to use. 

Edited July 30, 2020 by chrisv

[Elio_C]

36 minutes ago, chrisv said:

I wouldn't go for an EQ2 mount, the minimum would be an EQ3. An EQ mount is more complex than an AltAz mount, because of this it's usually more expensive. In order to provide a scope and an EQ mount at this price, a lot of corners need to be cut. 

EQ mount pros (for visual use):

• it's easier to manually track the object, once it's in sight, you only need to adjust the RA knob

Cons:

• harder to setup: even though polar aligning is not that difficult, it still requires extra time; it's fun when you do it the first time, but you will need to do it (at least roughly) every time; since you're probably in the southern hemisphere, the process may be more difficult
• heavier: most EQ mounts use counterweights in order to balance the telescope; in practice, this means that you'll need to carry a counterweight almost equal to the weight of your telescope
• star hopping is more difficult: you cannot rotate the scope left, right, etc. - the movements need to be on the RA and DEC axes. This may not seem such a big deal, but it's not that intuitive to do in practice. Combining this with a prism/mirror diagonal which flips the image on the left/right axis, it will definitively complicate things.
• the EQ mount will rotate the tube when you move from one area to another; to avoid some odd angles for the eyepiece, you will need to rotate the diagonal or the entire tube itself (i.e. if you want the finder scope in a certain position) whenever you change targets

As you can see, there aren't that many advantages of an EQ mount for visual use. Some EQ mounts can be upgraded with tracking motors and even goto, but I wouldn't invest more in an EQ2 mount.

Hi, thank you very for clarifying this!  

37 minutes ago, chrisv said:

Now, as for the refractor choice: I know that getting a new scope may seem exciting (it definitively is for me!), but please bear in mind that it may not really be an upgrade in the first place. Your previous scope is a 114/500 reflector, it may not be the highest quality one, but it definitively has a bigger aperture than a 70 refractor (even if we take into consideration the central obstruction). And for visual use the aperture is one of the most important aspects. From the product images and reviews, the bundled eyepieces seem to be low quality. Have you tried a different eyepiece? 

If you don't have a better eyepiece, try to get one before getting an entire new scope. Maybe you can find a used one, at a bargain. You'll be able to use the eyepiece on the new scope as well (which most likely comes with very basic ones). 

Hi, 

Thank you for suggesting this.

I think it might be a good idea to invest in a some better lenses rather than a new scope. I currently just have the H20mm and SR4mm and a barlow 2x that came with the scope.

Is there any reasonably economical lenses you can recommend? 

 

As it turns out, I've never actually collimated my scope (I've heard it needs special tools??). I'll do some research tonight. 

Very clear skies for the first time in a while tonight so I'll be stargazing anyway! 

Thanks guys, 

Elio. 

[Cosmic Geoff]

53 minutes ago, Elio_C said:

I currently just have the H20mm and SR4mm and a barlow 2x that came with the scope.

I'd say that these eyepieces are junk.  At least invest in a decent eyepiece suitable for a f4.4 focal ratio reflector and see how that goes. That might cost $AUD 100, but you can transfer it to any 'scope you buy later. 

Ideally you should upgrade to the 130mm Heritage Dob, or to a decent refractor with a decent mount. Money spent on another cheap beginner scope is likely to be money wasted.

Edited July 30, 2020 by Cosmic Geoff

[Elio_C]

17 minutes ago, Cosmic Geoff said:

At least invest in a decent eyepiece suitable for a f4.4 focal ratio reflector and see how that goes

I didn't know there were specific eyepieces suitable to an f4.4 reflector, could you please point me in the right direction? 

19 minutes ago, Cosmic Geoff said:

a decent refractor with a decent mount

I'm confused, how much money would I have to spend for 'decent'? I really haven't been introduced to an average in telescopes. 

[x6gas]

@Elio_C you can easily spend AU$6,000 on even a small aperture refractor, double or treble that on an equatorial mount, and hundreds of dollars on each eyepiece.

No one does that on a first telescope - and that's OK.

You're doing the right thing in asking questions and I think you should do as you are doing: set a budget and find kit that meets your needs and your budget as best as possible while accepting that there will be compromises.

With your budget I wouldn't personally be thinking of spending big on an eyepiece.  A long focal length scope will do you just fine for solar system observing and even a low quality 20mm plossl will probably be just fine to start with.

[Cosmic Geoff]

In telescopes other than the beginner class, f4.4 would be considered a severe focal ratio, requiring a multi-element eyepiece rather than a 'H' Huygenian or a Plossl. For more information, you'll need an expert, or to read the small print in eyepiece listings.

Decent? Look at this: https://www.firstlightoptics.com/evostar/sky-watcher-evostar-90-az-pronto.html

or this: https://www.firstlightoptics.com/evostar/skywatcher-evostar-90-eq3-2.html

And these are nothing fancy, not ED or apochromatic and the mounts are not powered or GoTo.

[Elio_C]

7 minutes ago, Cosmic Geoff said:

In telescopes other than the beginner class, f4.4 would be considered a severe focal ratio, requiring a multi-element eyepiece rather than a 'H' Huygenian or a Plossl. For more information, you'll need an expert, or to read the small print in eyepiece listings.

Decent? Look at this: https://www.firstlightoptics.com/evostar/sky-watcher-evostar-90-az-pronto.html

or this: https://www.firstlightoptics.com/evostar/skywatcher-evostar-90-eq3-2.html

And these are nothing fancy, not ED or apochromatic and the mounts are not powered or GoTo.

Wow, average is expensive! 😅 Thanks for the help! 

So to really get an eyepiece that matches the scope for better viewing, I would need to get a really expensive elaborate one? 

10 minutes ago, x6gas said:

@Elio_C you can easily spend AU$6,000 on even a small aperture refractor, double or treble that on an equatorial mount, and hundreds of dollars on each eyepiece.

No one does that on a first telescope - and that's OK.

You're doing the right thing in asking questions and I think you should do as you are doing: set a budget and find kit that meets your needs and your budget as best as possible while accepting that there will be compromises.

With your budget I wouldn't personally be thinking of spending big on an eyepiece.  A long focal length scope will do you just fine for solar system observing and even a low quality 20mm plossl will probably be just fine to start with.

Thanks for understanding, so getting one of the saxons I mentioned earlier isn't too bad of an idea for just a casual scope? I'm confused. 

All I really want to use the telescope for is viewing the moon and some planets and maybe some double stars, I don't really mind if I can't see DSOs or nebulae. 

I'm so sorry that I'm being so difficult, I really want to understand this stuff so I can make an appropriate decision that I'm not going to regret. Thank you for your patience. 🙏

[chrisv]

1 hour ago, Elio_C said:

As it turns out, I've never actually collimated my scope (I've heard it needs special tools??). I'll do some research tonight. 

You should definitively do this before buying anything else - telescope or lens. I'm not a reflector user, but from what I've read a lot of people use a Cheshire collimator. It shouldn't be very expensive since it's quite simple to make (you can also 3D print one if you have a printer available). Keep in mind that a fast reflector, like yours, will probably be a bit more tricky to collimate, hence you should dedicate some time to it, especially at the beginning. 

As for the eyepieces, keep an eye on the used market - where I live, we don't have a big second hand market, but I was able to find a very good deal on an Explorer Scientific focal extender in a pristine condition. 

Examples that might be a good fit, without spending a lot:

• BST Starguider 18mm - https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-18mm-ed-eyepiece.html
• Celestron X Cel LX - https://www.ozscopes.com.au/celestron-x-cel-lx-18mm-1-25-eyepiece.html
• Explore Scientific 62 or 82

You can also search the forum for other eyepiece recommendations for fast scopes. I think even a Plossl should be better than your current eyepieces. 

Try to get one for a focal length that you don't currently have (take into consideration the barlow as well), but try to stay on the low magnification side for now (18-25mm). 

Again, please wait with the purchase of the new scope until you're really certain that you cannot obtain more from your current scope. My guess is that it can offer you more at the moment. 

Edited July 30, 2020 by chrisv

[Cosmic Geoff]

3 minutes ago, Elio_C said:

So to really get an eyepiece that matches the scope for better viewing, I would need to get a really expensive elaborate one? 

In theory, yes, but your tabletop reflector may not be up to it, so you could try a Plossl (usable in any future refractor purchase) and see if that helps.

As I wrote already, if your budget is restricted, the best course would be to upgrade to the 130mm Heritage Dob, which has significantly more aperture than any of the refractors you are considering.

[Elio_C]

4 minutes ago, chrisv said:

You should definitively do this before buying anything else - telescope or lens. I'm not a reflector user, but from what I've read a lot of people use a Cheshire collimator. It shouldn't be very expensive since it's quite simple to make (you can also 3D print one if you have a printer available). Keep in mind that a fast reflector, like yours, will probably be a bit more tricky to collimate, hence you should dedicate some time to it, especially at the beginning. 

As for the eyepieces, keep an eye on the used market - where I live, we don't have a big second hand market, but I was able to find a very good deal on an Explorer Scientific focal extender in a pristine condition. 

Examples that might be a good fit, without spending a lot:

• BST Starguider 18mm - https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-18mm-ed-eyepiece.html
• Celestron X Cel LX - https://www.ozscopes.com.au/celestron-x-cel-lx-18mm-1-25-eyepiece.html
• Explore Scientific 62 or 82

You can also search the forum for other eyepiece recommendations for fast scopes. I think even a Plossl should be better than your current eyepieces. 

Try to get one for a focal length that you don't currently have (take into consideration the barlow as well), but try to stay on the low magnification side for now (18-25mm). 

Again, please wait with the purchase of the new scope until you're really certain that you cannot obtain more from your current scope. My guess is that it can offer you more at the moment. 

Thanks for the advice! 

I think collimating will be quite a process, as my dob actually doesn't have any collimation screws! I don't know how I'm going to do it... 

6 minutes ago, Cosmic Geoff said:

In theory, yes, but your tabletop reflector may not be up to it, so you could try a Plossl (usable in any future refractor purchase) and see if that helps.

As I wrote already, if your budget is restricted, the best course would be to upgrade to the 130mm Heritage Dob, which has significantly more aperture than any of the refractors you are considering.

I'll look into some plossls but I'm very hesitant to get another dob, I'll explain. 

So every summer we move over to our holiday house away from the urban areas, and there's a golf course/parkland bushy reserve thing there and It has always been a goal of mine to bring my telescope over there during summer nights and stargaze. It's not an official dark sky zone or anything but it's got wide spaces surrounded by bush away from most of the lights and next to the sea so it would just be such a great experience. 

Anyway, there's not really any tables there so a dobsonian would definitely not work. A beginner scope with a mount that I can set up there would be ideal. 

It might be a bit unrealistic but given that our holiday house is right near it it would be a (theoretically) easily attainable goal, and it would just be such a great experience. 

[chrisv]

6 minutes ago, Elio_C said:

I think collimating will be quite a process, as my dob actually doesn't have any collimation screws! I don't know how I'm going to do it... 

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

[Cosmic Geoff]

11 minutes ago, Elio_C said:

Anyway, there's not really any tables there so a dobsonian would definitely not work. A beginner scope with a mount that I can set up there would be ideal. 

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.  The Heritage 130P Dob has a standard dovetail on the tube which means it can be taken off the Dob mount and fixed to almost any astro mount/tripod.

https://www.firstlightoptics.com/heritage/skywatcher-heritage-130p-flextube.html

Some basic reflectors have a fixed primary mirror to eliminate the need for collimating (and cut manufacturing cost).

Edited July 30, 2020 by Cosmic Geoff