Help me choose a GoTo telescope?

[DanielC]

Hello everyone,

I am a professional astronomer who is embarrassingly bad at backyard astronomy. I have two pairs of binoculars that I use infrequently. I used to have a table top 4'' telescope, and when I was a grad student I did sky tours for the public. So I know the basics. I recently decided that I want to buy my own telescope for personal use. I think I have narrowed it down a 150mm reflector with a GoTo mount. My prototype for what that my look like is the Orion StarSeeker IV:

https://www.telescope.com/catalog/product.jsp?productId=113917

I was hoping someone could help me figure out whether this is a good choice and whether there's an alternative that I should be considering. I live in a suburban area with a fairly polluted sky --- lightpollutionmap.info says that my location has SQM = 19.6 which apparently translates to Class 5 in the Bortle scale. I also have relatively poor eyesight, even with eyeglasses. So here are some concrete questions that I hope someone can answer:

• Am I right to think that a GoTo mount would be especially helpful in a light polluted sky? I'm thinking that star hoping could be difficult.
• What do you think I would realistically be able to observe with a 150mm telescope from my location? Would M31 look like anything more than a tiny fuzzy blob?
• The website above says that the Orion StarSeeker IV comes with "3-Element" eyepieces. Can someone tell me what the heck that means? Is that a brand? Are they ok?
• Anything else I should know?

Other considerations: The telescope above is around the maximum price / weight / size that I think I can handle. I know that I could get a bigger aperture for a lower price with a Dobsonian, but I want to keep it small enough that I could realistically take it on a road trip to a national park once a year, and my spouse is keen to have the GoTo mount.

Thanks in advance for the help. Cheers!

[vlaiv]

Hi and welcome to SGL.

If you are set on 6" Newtonian then that StarSeeker IV is configuration that I would recommended. That is Alt-Az goto mount + Newtonian OTA.

I'm not sure that I would recommend that particular model. What is your budget like?

With that particular model, my concerns are that it will be under mounted scope and scope that is of not too high mechanical quality - rather basic model (due to weight savings).

If you like purchasing as a single package and you don't mind it being rather basic model, then yes, by all means - go for that one. Alternatively consider these (I'm going to link you to website I know stock these, but you'll have to do a bit of searching for USA retailers that sell them):

https://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-ds-ota.html

Mounted on something like this:

https://www.firstlightoptics.com/skywatcher-mounts/skywatcher-az-eq5-gt-geq-alt-az-mount.html

or mount like this:

https://www.firstlightoptics.com/ioptron-mounts/ioptron-az-mount-pro.html

Telescope model is basically the same as Orion one (same parent company for Skywatcher and Orion - same mirrors used) but has dual speed 2" focuser that is higher quality and in general optical tube will be of higher quality as Skywatcher version that I linked is meant for astrophotography as well.

Two mounts that I linked are sturdier, higher capacity and overall better mounts - much more stable.

Alternative that you might consider is something like this:

https://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-200p-flextube-goto.html

Version that I linked to is 8" version, but I believe there is also 6" goto dob version of that scope (not 100% sure though).

I prefer dob mount and only time I really want for driven mount is when observing planets / moon (I'm not double star observer but there driven mount is good thing to have too). I guess only difference between the two will be in observing position. Tripod mounted one is more suited for standing type of observing while dob is more suited for seated down type of observing.

30 minutes ago, DanielC said:

I was hoping someone could help me figure out whether this is a good choice and whether there's an alternative that I should be considering. I live in a suburban area with a fairly polluted sky --- lightpollutionmap.info says that my location has SQM = 19.6 which apparently translates to Class 5 in the Bortle scale. I also have relatively poor eyesight, even with eyeglasses.

Yes, that SQM reading is not ideal, but it's not bad either. If you are simply near/far sighted - that really does not matter for telescope observing as focusing will deal with that. If you have astigmatism or other issues then you'll need to wear glasses when observing and you'll need to pay attention to choice of eyepieces. Choose those with longer eye relief so you can comfortably observe with glasses on.

32 minutes ago, DanielC said:

Am I right to think that a GoTo mount would be especially helpful in a light polluted sky? I'm thinking that star hoping could be difficult.

Not really. I'm in SQM 18.5 and I happily star hop. You'll see plenty of stars with your telescope. To me, goto or rather tracking mount makes most sense for planets (as mentioned). Some people enjoy finding stuff and navigating night sky and star hopping is part of experience for them. Others prefer for scope to find object for them and concentrate on observation. Depends what your personal preferences are.

35 minutes ago, DanielC said:

What do you think I would realistically be able to observe with a 150mm telescope from my location? Would M31 look like anything more than a tiny fuzzy blob?

Everything will be a fuzzy blob . Even in large scopes in darker skies - things are still fuzzy blobs - at first, but as time goes on and you gain observing experience - things get sort of brighter and description fuzzy blob shifts to obscure NGC galaxies and such

Planets - check (again don't expect too much), globulars - very nice rendition, galaxies too (after a while when you gather some experience), open clusters - check. There will be plenty to see and it will all be either very exciting or very underwhelming - depends on your expectations. Don't expect Hubble type images or anything close to that and you'll be fine.

Btw - if you can mange it in terms of weight and budget - ideal scope for you to start with would be something like 8" dobsonian telescope (with goto if you choose so - but there are other means of tracking for dobs - like EQ platform - those don't find you stuff, but let you track objects - again good for planets / moon, or anything that you observe in high power).

39 minutes ago, DanielC said:

The website above says that the Orion StarSeeker IV comes with "3-Element" eyepieces. Can someone tell me what the heck that means? Is that a brand? Are they ok?

Not a brand, nothing meaningful except that they are probably rather poor quality (3 element - 60 degrees AFOV - yeah, not going to be good). There are different eyepiece designs and each of them has certain properties that you might like or dislike.  That is whole separate topic. What you should know is that stock EPs are usually lowest quality and only good to get you going. It is probably the first thing being upgraded - plan to leave some budget for that.

43 minutes ago, DanielC said:

Anything else I should know?

Yes, bunch of things, but this is why we are here for If you have any more questions just fire away.

44 minutes ago, DanielC said:

Other considerations: The telescope above is around the maximum price / weight / size that I think I can handle. I know that I could get a bigger aperture for a lower price with a Dobsonian, but I want to keep it small enough that I could realistically take it on a road trip to a national park once a year, and my spouse is keen to have the GoTo mount.

Ok, this puts things into perspective, and much of my recommendations above don't make sense, note to self - read the whole post before starting to answer .

Hopefully at least some of what I've written will be helpful to you.

 

[Shaun Sr]

im by no means a pro here, im a newbie who does alot or research and asks alot of questions..  my first telescope as an adult was gonna be the Celestron Nexstar 8se   that make a 6 in version, but id get the 8.  i went a little higher in price to the edge hd but they have the same goto system.  man its a good time i love my scope, you should take a look at the 8se  its got a good price.  

[DanielC]

48 minutes ago, vlaiv said:

Hi and welcome to SGL.

With that particular model, my concerns are that it will be under mounted scope and scope that is of not too high mechanical quality - rather basic model (due to weight savings).

If you like purchasing as a single package and you don't mind it being rather basic model, then yes, by all means - go for that one. Alternatively consider these...

Thanks for all the help! From what you are saying, it sounds like I might need to revise my budget and maybe also pick the components myself rather than grab a pre-packaged set so I don't get stuck with a crappy mount and crappy eyepieces. Can you explain a little more what an "under mounted scope" is? What are the downsides of a basic model compared to a higher quality one? I want to make this choice carefully because if I end up throwing away the basic model and buying the expensive one anyway then I wasted my money. You mentioned that the heavier mount would be more stable and I definitely see how that is very important. Is that the main difference? You said the other mounts you suggested were overall better quality; so what else would be different about them? Likewise, what are the advantages of the OTA you suggested? Is it mainly that it will have better optics? I can see that it has a 2'' focuser so I could buy a wider field eyepiece and take a huge picture of the galaxy.

I think I can find components similar to what you suggested:

1) OTA

https://www.telescope.com/All-Telescopes/Orion-6-f4-Newtonian-Astrograph-Reflector-Telescope/rc/2162/p/116530.uts

This is a 6'' Newtonian reflector that looks very similar to the one you suggested. I found it in the "Astrophotography" page.

2) Mount -- version 1: equatorial, not GoTo

https://www.telescope.com/All-Telescopes/Orion-SkyView-Pro-Equatorial-Telescope-Mount/rc/2162/p/9829.uts

This mount says it can handle 20lbs and the telescope above weighs 12.7 lbs. So I guess it must be a sturdy mount. But there is no GoTo.

3) Mount -- version 2: equatorial + GoTo

https://www.telescope.com/All-Telescopes/Orion-SkyView-Pro-Equatorial-GoTo-Telescope-Mount/rc/2162/p/24709.uts

This is the same mount as before, but with GoTo included.

4) Eyepieces

https://www.telescope.com/All-Telescopes/Orion-Expanse-Wide-Field-125-Eyepieces/rc/2162/e/55.uts

I don't know anything about eyepieces, but these ones say 4-5 elements (why do I care how many elements it has?), the opening looks much larger than the cheap eyepieces I saw earlier, the eye relief is 15-18mm which sounds like a lot to me.

Do these look similar to your suggestions?

Let's see... my initial suggestion was $550 and the combination above would be $800 - $1,200 depending on whether I get the GoTo. I also found an 8'' Dobsonian alternative for about the same price. So I need to take this information and think a bit more.

Thanks for the help!

[vlaiv]

6 hours ago, DanielC said:

Thanks for all the help! From what you are saying, it sounds like I might need to revise my budget and maybe also pick the components myself rather than grab a pre-packaged set so I don't get stuck with a crappy mount and crappy eyepieces. Can you explain a little more what an "under mounted scope" is? What are the downsides of a basic model compared to a higher quality one? I want to make this choice carefully because if I end up throwing away the basic model and buying the expensive one anyway then I wasted my money. You mentioned that the heavier mount would be more stable and I definitely see how that is very important. Is that the main difference? You said the other mounts you suggested were overall better quality; so what else would be different about them? Likewise, what are the advantages of the OTA you suggested? Is it mainly that it will have better optics? I can see that it has a 2'' focuser so I could buy a wider field eyepiece and take a huge picture of the galaxy.

Under mounted scope means that one is using telescope on a smaller mount than would be suitable for that particular telescope. In the end it is subjective thing - there are no rules except weight limit of the mount (and even that is a guide line in most cases). It creates general bad experience of using scope - things get shaky and it takes long time for view to settle. Whenever you touch eyepiece or focuser - resulting vibrations take multiple seconds to settle. Sometimes it is very hard to properly focus in such conditions - you are never sure you have right focus due to motion blur of the shake.

This mount can handle telescopes up to 13lbs. It would be a good idea if someone who actually used this mount would step in and give their comments on mount performance.

As for telescope itself - both models probably have same optics. Mass produced mirrors from China (not meaning they are bad - they are quite good optically). It is optical tube (OTA) that differs. With this particular model, you get rather rudimentary 1.25" focuser. I would not be surprised that it is in part plastic:

You want your focuser to be smooth, precise and rigid enough. Having 2" focuser extends range of eyepieces that you can use (they nowadays come in mostly two flavors 1.25" and 2"). 2" are very nice for wide field low power viewing.

Another "drawback" of this basic model is that it does not have collimation screws for primary mirror.

It comes precollimated from factory and that is it. Sometimes optics gets out of alignment and you need to adjust it - collimation. Regular newtonian scopes come with collimation screws to do that (rather simple procedure). People say it is not big deal and scope is well aligned, but I would not feel at ease owning the scope that I can't adjust if need be.

6 hours ago, DanielC said:

1) OTA

https://www.telescope.com/All-Telescopes/Orion-6-f4-Newtonian-Astrograph-Reflector-Telescope/rc/2162/p/116530.uts

This is a 6'' Newtonian reflector that looks very similar to the one you suggested. I found it in the "Astrophotography" page.

I would not suggest this scope for visual - it is too fast. It has focal ratio of only F/4. With Newtonian telescopes, primary aberration is coma and it depends on speed of mirror. Fast scopes will have more coma and there are coma correctors for this purpose (mostly used for photographic applications but there are a few models used for visual). Fast scopes also require more expensive eyepieces in order to have well corrected image.

If you can - look for F/6 scope for visual. F/5 is still ok but it is considered fast scope.

6 hours ago, DanielC said:

2) Mount -- version 1: equatorial, not GoTo

https://www.telescope.com/All-Telescopes/Orion-SkyView-Pro-Equatorial-Telescope-Mount/rc/2162/p/9829.uts

This mount says it can handle 20lbs and the telescope above weighs 12.7 lbs. So I guess it must be a sturdy mount. But there is no GoTo.

3) Mount -- version 2: equatorial + GoTo

https://www.telescope.com/All-Telescopes/Orion-SkyView-Pro-Equatorial-GoTo-Telescope-Mount/rc/2162/p/24709.uts

This is the same mount as before, but with GoTo included.

If you can avoid it - don't use Equatorial type mount with Newtonian telescope. Due to focuser placement on newtonian telescopes and the way EQ mount tracks - eyepiece ends up in very awkward positions and this usually requires you to rotate telescope in rings. This gets rather tiring after a while (unlock tube rings, loosen them, rotate tube, lock tube rings ....)

EQ mounts are better with telescope designs that have focuser at the end of the tube (refractors, folded telescope designs).

7 hours ago, DanielC said:

4) Eyepieces

https://www.telescope.com/All-Telescopes/Orion-Expanse-Wide-Field-125-Eyepieces/rc/2162/e/55.uts

I don't know anything about eyepieces, but these ones say 4-5 elements (why do I care how many elements it has?), the opening looks much larger than the cheap eyepieces I saw earlier, the eye relief is 15-18mm which sounds like a lot to me.

Number of elements is important because it shows what type of design eyepiece could be and it is believed that fewer optical surfaces means more light throughput (and it was certainly so some time ago, but with modern optical coatings differences are minimal).

For first upgrade / first set of eyepieces, look at these:

BST Starguider range or Celestron X-Cel range.

[DanielC]

24 minutes ago, vlaiv said:

Under mounted scope means that one is using telescope on a smaller mount than would be suitable for that particular telescope. In the end it is subjective thing - there are no rules except weight limit of the mount (and even that is a guide line in most cases). It creates general bad experience of using scope - things get shaky and it takes long time for view to settle. Whenever you touch eyepiece or focuser - resulting vibrations take multiple seconds to settle. Sometimes it is very hard to properly focus in such conditions - you are never sure you have right focus due to motion blur of the shake.

Ah! This is all very helpful. Yes, I remember being very frustrated in the past with shaky telescopes.

 

 

24 minutes ago, vlaiv said:

Another "drawback" of this basic model is that it does not have collimation screws for primary mirror.

It comes precollimated from factory and that is it. Sometimes optics gets out of alignment and you need to adjust it - collimation. Regular newtonian scopes come with collimation screws to do that (rather simple procedure). People say it is not big deal and scope is well aligned, but I would not feel at ease owning the scope that I can't adjust if need be.

Thanks for catching that! Yeah, back when I had my small table top telescope I learned how to collimate it. It never occurred to me that a $550 telescope would not have collimation screws. I thought it was standard because my little $50 table top had them.

 

24 minutes ago, vlaiv said:

I would not suggest this scope for visual - it is too fast. It has focal ratio of only F/4. With Newtonian telescopes, primary aberration is coma and it depends on speed of mirror. Fast scopes will have more coma and there are coma correctors for this purpose (mostly used for photographic applications but there are a few models used for visual). Fast scopes also require more expensive eyepieces in order to have well corrected image.

If you can - look for F/6 scope for visual. F/5 is still ok but it is considered fast scope.

That's also very helpful. I will aim for an F/6 then. Going in the other direction, how much focal ratio is too much? I just saw a Maksutov-Cassegrain with F/15. I know that if the focal ratio is too high you end up with a small field of view so it's impossible to see wide things like the Milky Way. I am looking for a general purpose telescope that works fine for "everything". One day I'll try to see Saturn, the next day I might want to see the Pleiades.

 

24 minutes ago, vlaiv said:

If you can avoid it - don't use Equatorial type mount with Newtonian telescope. Due to focuser placement on newtonian telescopes and the way EQ mount tracks - eyepiece ends up in very awkward positions and this usually requires you to rotate telescope in rings. This gets rather tiring after a while (unlock tube rings, loosen them, rotate tube, lock tube rings ....)

EQ mounts are better with telescope designs that have focuser at the end of the tube (refractors, folded telescope designs).

Good to know. I will look for alt-az mounts then. I liked the iOptron mount that you suggested. I'll try to find something like that here.

 

24 minutes ago, vlaiv said:

Number of elements is important because it shows what type of design eyepiece could be and it is believed that fewer optical surfaces means more light throughput (and it was certainly so some time ago, but with modern optical coatings differences are minimal).

For first upgrade / first set of eyepieces, look at these:

BST Starguider range or Celestron X-Cel range.

Thanks!

[vlaiv]

34 minutes ago, DanielC said:

Thanks for catching that! Yeah, back when I had my small table top telescope I learned how to collimate it. It never occurred to me that a $550 telescope would not have collimation screws. I thought it was standard because my little $50 table top had them.

This is fairly recent thing. My first impression was that they changed mirror cell for weight savings / cost cutting. Most of the scopes that don't have collimation screws are small scopes mounted on very light weight mounts.

Not many reports coming in on these, but what I did hear - people say that such scopes are ok and well collimated out of the box. Time will tell if missing collimation screws is as big issue as it seems now (at least to me).

38 minutes ago, DanielC said:

That's also very helpful. I will aim for an F/6 then. Going in the other direction, how much focal ratio is too much? I just saw a Maksutov-Cassegrain with F/15. I know that if the focal ratio is too high you end up with a small field of view so it's impossible to see wide things like the Milky Way. I am looking for a general purpose telescope that works fine for "everything". One day I'll try to see Saturn, the next day I might want to see the Pleiades.

F/6-F/8 is good range of focal ratios for general usage. Field of view depends both on design of the telescope (internal baffles and focuser size) and focal length. Focal lengths of about 600-900mm are considered best for general viewing (both wide field and high power with suitable barlow lens). For planets you want higher magnification, but that is easily solved with barlow lens / telecentric amplifiers. Shortening focal length is problematic.

Slower scopes have longer focal lengths - for example even 4" F/13 scope will have larger focal length than 8" F/6 scope and hence narrower field of view. For this reason Maks are usually considered planetary scopes, although they can be used as general purpose scopes with a bit smaller FOV.

Slower light beam is a good thing - cheaper eyepieces will give you nice / sharp image with slow scopes while faster scope require expensive multi element (8 or more elements) eyepieces to be sharp to the edge of field of view.

Here is nice tool that you might want to check out:

https://astronomy.tools/calculators/field_of_view/

It will give you idea of field of view that you can expect with different telescope / eyepiece combinations. For example:

Pleiades with F/5 6" scope and 25mm X-Cel eyepiece - very nice framing.

 

[Cosmic Geoff]

GoTo or not GoTo is a perennial question on which no three backyard astronomers will agree. It is particularly useful in urban skies, or if you want to look at objects rather than look for them.  On the other hand, some people just don't get on with GoTo or are confused by the setup procedures and prefer the traditional simpler mounts.

Since you have expressed a preference for GoTo, you should go for it. 🙂

For your initially quoted budget you would have more choice of outfit if you go for a smaller aperture, i.e. 127 or 130mm, which is still enough to give you many nights of enjoyment, particularly if you can actually find the objects with a GoTo.  A 127mm Maksutov, unlike some of the entry level reflectors, will be a good quality instrument optically and mechanically.  It is the kind of instrument you will keep even if you graduate to something bigger.

The lower cost mounts tend, alas, to be on the wobbly side.  If you want a decent aperture telescope on a really solid mount, the total cost rockets to a wallet-emptying degree.

Three element eyepieces should be avoided.  Plossl eyepieces are adequate in many situations, particularly for longer focal ratio telescopes, while f5 Newtonians will probably benefit from a more exotic eyepiece design.  I am not an eyepiece expert though

[DanielC]

21 minutes ago, Cosmic Geoff said:

For your initially quoted budget you would have more choice of outfit if you go for a smaller aperture, i.e. 127 or 130mm, which is still enough to give you many nights of enjoyment, particularly if you can actually find the objects with a GoTo.  A 127mm Maksutov, unlike some of the entry level reflectors, will be a good quality instrument optically and mechanically.  It is the kind of instrument you will keep even if you graduate to something bigger.

The lower cost mounts tend, alas, to be on the wobbly side.  If you want a decent aperture telescope on a really solid mount, the total cost rockets to a wallet-emptying degree.

Three element eyepieces should be avoided.  Plossl eyepieces are adequate in many situations, particularly for longer focal ratio telescopes, while f5 Newtonians will probably benefit from a more exotic eyepiece design.  I am not an eyepiece expert though

 

After spending the last few hours trying to make the 6'' reflector idea work, I don't think I can stretch my budget that far. So I'm ready to consider a lower aperture and longer focal length. You gave the example of a 127mm Mak. What can I expect from an instrument like that? How do I know if I'm looking at a quality instrument? The first 127mm Mak that I found has a focal ratio of F/10.

https://www.telescope.com/All-Telescopes/Orion-Apex-127mm-Maksutov-Cassegrain-Telescope/rc/2162/p/9825.uts

Using the field-of-view tool that @vlaiv suggested, and seeing that the above telescope comes with a 25mm eyepiece with a 52deg FOV, it looks like it would work well for several Messier objects including the Crab Nebula and globular clusters, but  the FOV is too small for the Orion Nebula. If I add a 6mm eyepiece I'll see Jupiter's moons, but I'd need some luck and/or a filter to see a band on Jupiter.

I think I can work that that. I need to think a little more, but I am persuaded that a small high-quality instrument is a better investment than a large poor-quality one.

You said that a 127-130mm Mak is an instrument I one would keep even after graduating to something bigger. What would you do with a 130mm Mak if you also have a 150mm telescope? Do you have smaller telescopes that you often use?

Thanks for the help!

[Nerf_Caching]

9 minutes ago, DanielC said:

 

After spending the last few hours trying to make the 6'' reflector idea work, I don't think I can stretch my budget that far. So I'm ready to consider a lower aperture and longer focal length. You gave the example of a 127mm Mak. What can I expect from an instrument like that? How do I know if I'm looking at a quality instrument? The first 127mm Mak that I found has a focal ratio of F/10.

https://www.telescope.com/All-Telescopes/Orion-Apex-127mm-Maksutov-Cassegrain-Telescope/rc/2162/p/9825.uts

Using the field-of-view tool that @vlaiv suggested, and seeing that the above telescope comes with a 25mm eyepiece with a 52deg FOV, it looks like it would work well for several Messier objects including the Crab Nebula and globular clusters, but  the FOV is too small for the Orion Nebula. If I add a 6mm eyepiece I'll see Jupiter's moons, but I'd need some luck and/or a filter to see a band on Jupiter.

I think I can work that that. I need to think a little more, but I am persuaded that a small high-quality instrument is a better investment than a large poor-quality one.

You said that a 127-130mm Mak is an instrument I one would keep even after graduating to something bigger. What would you do with a 130mm Mak if you also have a 150mm telescope? Do you have smaller telescopes that you often use?

Thanks for the help!

Have you considered a push-to instead of a goto mount? It only shows you the way to the object via a supplied handset but you have to manually adjust the telescope accordingly. You can get more aperture for your budget that way. Since you are in the US, perhaps the push-to version of the Orion Starblast 6 is a good idea. Just my 2 cents.

[vlaiv]

5 minutes ago, DanielC said:

 

After spending the last few hours trying to make the 6'' reflector idea work, I don't think I can stretch my budget that far. So I'm ready to consider a lower aperture and longer focal length. You gave the example of a 127mm Mak. What can I expect from an instrument like that? How do I know if I'm looking at a quality instrument? The first 127mm Mak that I found has a focal ratio of F/10.

https://www.telescope.com/All-Telescopes/Orion-Apex-127mm-Maksutov-Cassegrain-Telescope/rc/2162/p/9825.uts

Using the field-of-view tool that @vlaiv suggested, and seeing that the above telescope comes with a 25mm eyepiece with a 52deg FOV, it looks like it would work well for several Messier objects including the Crab Nebula and globular clusters, but  the FOV is too small for the Orion Nebula. If I add a 6mm eyepiece I'll see Jupiter's moons, but I'd need some luck and/or a filter to see a band on Jupiter.

I think I can work that that. I need to think a little more, but I am persuaded that a small high-quality instrument is a better investment than a large poor-quality one.

You said that a 127-130mm Mak is an instrument I one would keep even after graduating to something bigger. What would you do with a 130mm Mak if you also have a 150mm telescope? Do you have smaller telescopes that you often use?

Thanks for the help!

In that case, how about this one:

https://optcorp.com/products/celestron-nexstar-6se

It is still 6" instrument so you won't be loosing any light grasp over 6" newtonian. It is much lighter and compact - cheaper GOTO Alt/Az mount should be able to carry it without too much trouble.

It is F/10 instrument and hence provides same focal length as F/12 Orion Apex 5" Mak - same FOV.

Only drawback is that it is limited to 1.25" eyepieces and won't provide you with wide field of view. Here is what 32mm Plossl gives you (about as wide as 1.25" go):

Only drawback of these types of scopes that you should be aware of - is dew and cool down time. Both Mak and SCT are susceptible to dewing up and all scopes needs some time to reach thermal equilibrium with surroundings. Scopes with front corrector plate and mirrors take more time than other (open) designs.

 

[Cosmic Geoff]

The various Maksutovs, sold under various brands, seem to mostly originate from the same Chinese factory.  The one you link looks the same as mine except for the colour. One sees very few complaints about any of them and the design is robust and unlikely to ever need any adjustment. So buy with confidence.

You should be able to see bands on Jupiter easily with a 127mm Mak.  If you search through the Planetary Imaging section of this forum you should find some images showing what 127mm Mak optics can do - but caution, a visual observer will be unlikely to see as much.

I recently used my 127mm Mak to view Venus in the daytime, using the Sun as a Goto reference (extreme caution required.) I use my 102mm f5 Startravel refractor for EEVA imaging, and a couple of nights ago put it in the only position in the backyard from which I could view Comet Neowise.  The smaller scopes are far handier for brief grab'n go exercises (a 127 may not seem much smaller than a 150mm, but it's about half the bulk.)

By the way, the Mak you link is outfitted for daytime use. For astronomy you'd want a 90 deg star diagonal (mirror or prism) not the  45 deg correct-image prism.

Edited July 20, 2020 by Cosmic Geoff
Terrestial Mak

[DanielC]

7 hours ago, vlaiv said:

In that case, how about this one:

https://optcorp.com/products/celestron-nexstar-6se

It is still 6" instrument so you won't be loosing any light grasp over 6" newtonian. It is much lighter and compact - cheaper GOTO Alt/Az mount should be able to carry it without too much trouble.

It is F/10 instrument and hence provides same focal length as F/12 Orion Apex 5" Mak - same FOV.

Only drawback is that it is limited to 1.25" eyepieces and won't provide you with wide field of view.

Perfect. I'll get this one. I saw it earlier and I liked it. I had ignored it because I had it in my mind that Newtonians were always the best value for money. But now I see that it's not so simple. The drawbacks of the NexStar 6SE look like things that I can handle better than the drawbacks of the reflector. Not getting a wide FOV is unfortunate, but not as bad as a shaky mount or low quality components; and I still have my binoculars. To deal with the dew and cooling time, I will keep the telescope in my garage, or I'll make sure to bring it outside early.

Thanks for all the help!

[Cosmic Geoff]

5 minutes ago, DanielC said:

To deal with the dew and cooling time, I will keep the telescope in my garage, or I'll make sure to bring it outside early.

I never found the cooling time a serious problem with my C8 SE.  One can view less demanding targets first.

  A dew shield is an essential accessory.  If you don't want to buy a smart-looking plastic one, you could make your own shield.

[DanielC]

2 hours ago, Cosmic Geoff said:

I never found the cooling time a serious problem with my C8 SE.  One can view less demanding targets first.

  A dew shield is an essential accessory.  If you don't want to buy a smart-looking plastic one, you could make your own shield.

Ok. Dew shield.

Is a light pollution filter a good investment or is it a waste for money? I live in a suburban area, and I won't be doing astrophotography.

EDIT:  I just thought of another question. Do you collimate SCTs? Or is that something you only have to do for Newtonians?

Edited July 20, 2020 by DanielC

[Cosmic Geoff]

1 hour ago, DanielC said:

Is a light pollution filter a good investment or is it a waste for money? I live in a suburban area, and I won't be doing astrophotography.

EDIT:  I just thought of another question. Do you collimate SCTs? Or is that something you only have to do for Newtonians?

Light pollution filter: I don't use one.  The old street lights could be filtered out but the new LEDs emit a continuous spectrum and are far more difficult to filter out. There are filters that are claimed to work, but they are expensive and of limited effect.

SCTs can be collimated, but are much less prone to going out of collimation than Newtonians.  You may never have to touch this adjustment.  My used C8 was horribly out of adjustment when I bought it, but I collimated it on a bright star and have never had to touch it since.

[vlaiv]

2 hours ago, DanielC said:

Ok. Dew shield.

Is a light pollution filter a good investment or is it a waste for money? I live in a suburban area, and I won't be doing astrophotography.

EDIT:  I just thought of another question. Do you collimate SCTs? Or is that something you only have to do for Newtonians?

Just to add - while LP filter is not very usable for visual there are filters that are really good for visual applications.

UHC probably being most versatile one - very useful for emission type nebulae.

[Zermelo]

Hi, I'm not sure from the thread above if you've quite given up on your original Orion Starseeker, but it seems to be almost identical to this model available in Europe (Synta make for both Orion and SW), though the Orion tube is described as steel, whereas the SW 150i is ABS. The Starseeker is also available in the wifi version like the 150i, if you are happy to work with a phone app rather than a dedicated controller, and will save you a few dollars.

I have the 150i so I can comment on some of the points mentioned above, and I think they apply equally to the Orion.

The tube is within the capacity range of the mount. The Orion appears to be slightly heavier than the SW, but I've not had any issues, and combined with the steel tripod I've found it to be very stable. The short F/5 tube is also important here - a longer one, even of the same weight, would not be so stable (though there are several reports of people pushing the Star Discovery mount beyond its rated capacity).

Yes, the main mirror is fixed. I was initially concerned by this, but apparently this is not a particularly recent feature and does not seem to be causing issues. Note that the secondary mirror can still be adjusted if necessary. I have not needed to do so as yet.

Yes, it is generally true that faster scopes will be less forgiving on cheaper eyepieces. But I was surprised how usable some of my stock EPs were with my SW, so if you do go with the Orion I would try them out first before splashing out, and even then don't assume you need to spend a fortune.

The weakest point on the 150 is the focuser, and it looks like the Orion has the same one. With some EPs I find it can be difficult to focus precisely, as the "in focus" range is very small and the rack is tight.