83 replies to this topic

[SeattleScott]

Let’s remember that it takes more effort to get the best planetary views out of a Dob than an Apo. I’m not saying a premium Apo couldn’t possibly deliver more aesthetically pleasing planetary views than a mediocre Dob, but how many times were these comparisons made with a Dob that was slightly out of collimation, or not fully acclimated?

[triplemon]

I do have a good 4" refractor and many other bigger and reasonable quality, but not really "high end" scopes. For the first 10 years of my now 30 year astronomy life, I had nothing but refractors and could not imagine what the point of anything else would ever be.

 

But, honestly, my 6" Mak is ususally a bit ahead of my 4" Frac even if its just by being notably brighter. The 8" imaging newt, even with its giant CO, beats both of them, every single time, on every object I ever looked at. Very obviously sharper and brighter, not even close. So at very high power there are some effects due to the central obstruction, but you can account for that by the widely used aproximation of "aperture - CO diameter" for the high magnification resolution of any reasonable reflector. so the 8" dob then still has 6" worth of high magnification resolution. Back in the 70ies, in the heydays of the orange c8 and with smaller 'department store' mirrors there are lots a medioce ones, but any GSO, Synta or similar mass produced 8inch or above mirror (say one that is least 200 dollars worth) will beat any refractor under 6 inches, on DSO even every single 6" frac out there.
 

I do also second Jon's take that a 10" f5 solid tube dob differs in size, handling unwieldyness and cost so little from an 8" f/6 that, if you have a choice, its a no brainer. And yes, I have a 8" dob, too. A travel dob that fits in the carry on, something a 10" simply won't fit.

 

On the other hand, any 5" frac or 6" cat needs some extra tripod and mount that IMO are at least as unwieldy, heavy and cumbersome to manage, if not worse.

Edited by triplemon, 25 March 2025 - 01:56 PM.

[Tony Flanders]

Its completely OBVIOUS you/they've NEVER EVER looked through a GREAT refractor.

This seems to me like a frivolous claim. You have stated in essence that if person X using a 100-mm APO sees less detail than the same person sees at the same time through an 8-inch Newtonian, then that APO is by definition NOT GREAT. It's an irrefutable claim. Any possible counterexample is automatically ruled out by that definition.

 

Have you considered the possibility that different people have different experiences with identical equipment? I do not claim that you're lying when you see vastly more planetary detail with your GREAT refractors than optical theory suggests is possible. I don't even claim that you're deluding yourself. But I am 100% sure that I, using exactly that same refractor, would not see that level of detail. And I think that statement is likely true of at least 99 out of 100 experienced observers, and 100 out of 100 novices.

[TheReboot]

I've watched Ed Ting rate the 8inch dob as his "if i could only have 1 scope", even more than the 10 inch due to size,awkwardness etc.

I have never looked through one before.
Biggest Ive used is a 5inch dob and I found my 80mm ed apo more contrasty and sharper on planets and moon.

Does anyone have any stories or comparisons between an 8 inch dob and smaller apos. Was it a wow moment viewing the moon, planets or dso after using a smaller scope (which scope)

I had no idea or may have forgot a 8inch dob is only £370. Going to keep my 80mm apo and get a dob as opposed to 120mm skywatcher ed ( would have cost over £2000 incl a mount).

I personally use a 6inch dob as my goto. There is nothing like it. They're a little difficult to line up properly at first, most because there's no technology and it's pretty big. After getting used to it though, it has shown me some of my favorite sights. Jupiter and Orion look incredible. If you already have a scope, you should have an idea as to what to expect in reality when viewing. A larger aperture usually just makes the image look clearer, and allow for more magnification without sacrificing too much of the view.

[scotsman328i]

Like I said earlier, get both! That way Dob guys are happy, frac guys are happy…and the guy with the dob and frac is REAL HAPPY! 

[Neanderthal]

..... What can you expect from a 200mm dob (8inch)?

An outstanding tool to look into the universe that we live in! I'd recommend an 8" over a 10" simply for re-sale purposes if that time ever comes, unless you've already got experience with a smaller Dob and know you want something larger.

[scotsman328i]

Yrs For Sure scotsman, its not an either or.

An 8inch Dob is a Potent performer definitely !

Its just got mirror reflective scatter and that hobbles it for extreme FSC detection.

For many its a Great choice !!


And the refractor needs to be very Good !


CSS
Lance

I completely agree. With the Newtonian telescope, there is a degree of reflective scatter, diffraction spikes, need for collimation, need for mirror cleaning depending how often or where it is used, softer images than a high quality refracting telescope and a few other issues that can be chalked up as minimal stuff. Over time gaining the experience of observing through the Newt, I’ve learned to tune out many of the differences a Newt has like the diffraction spikes, light scatter and the need for collimation. I kinda put my ‘Dob’ brain in, and don’t expect the razor sharpness my Televue gives. I expect those diffraction spikes and softer images as to when I was looking through the APO. I know I have to sacrifice certain things the APO offers for the gain in aperture and light gathering to punch deeper into space. It’s hard for me personally to say I have one favorite over another.
    It’s like my younger days in the Army when I was a young Corporal, always had a couple girlfriends. One has strengths and weaknesses over the other, and vice versa. Never wanted to give either of them up. LOL! It boiled down to having a selection to choose from. Sometimes I was in the mood for a premium night out with ‘Penelope the looker!’ so everyone could get a good view of my fine ‘optics’…and other times, it was a comfy night in with ‘rugged ‘ole Betsy’ to enjoy an night with a ‘bigger and brighter’ view. LOL! I loved them all, just like my scopes.  

[PKDfan]

I completely agree. With the Newtonian telescope, there is a degree of reflective scatter, diffraction spikes, need for collimation, need for mirror cleaning depending how often or where it is used, softer images than a high quality refracting telescope and a few other issues that can be chalked up as minimal stuff. Over time gaining the experience of observing through the Newt, I’ve learned to tune out many of the differences a Newt has like the diffraction spikes, light scatter and the need for collimation. I kinda put my ‘Dob’ brain in, and don’t expect the razor sharpness my Televue gives. I expect those diffraction spikes and softer images as to when I was looking through the APO. I know I have to sacrifice certain things the APO offers for the gain in aperture and light gathering to punch deeper into space. It’s hard for me personally to say I have one favorite over another.
It’s like my younger days in the Army when I was a young Corporal, always had a couple girlfriends. One has strengths and weaknesses over the other, and vice versa. Never wanted to give either of them up. LOL! It boiled down to having a selection to choose from. Sometimes I was in the mood for a premium night out with ‘Penelope the looker!’ so everyone could get a good view of my fine ‘optics’…and other times, it was a comfy night in with ‘rugged ‘ole Betsy’ to enjoy an night with a ‘bigger and brighter’ view. LOL! I loved them all, just like my scopes.

LOL. Thats a Lovely anecdote !

I'd be happy with just one fine woman though !


CSS
Lance

[scotsman328i]

LOL. Thats a Lovely anecdote !

I'd be happy with just one fine woman though !


CSS
Lance

Of course! Eventually I settled down with some fine German optics from the Rheinland in Germany, she’s been my best scope and only scope since I settled down way back when. She’s my Newt, Refractor, SCT, Mak, RC all rolled into one! 

[FiddleHead Galaxy]

Whenever I look at planets with my 8-inch, I can see quite a lot of detail in planets. I dont expect to see as much detail as other more refined optical telescopes like an SCT or quality refractor, but the 8-inch more than makes up for that in magnification. On January 30th at about 11 PM, Mars was in its opposition phase so it was quite large compared to now. Because of a mixture of really good conditions (very steady air/no wind, the stars at the horizon were not twinkling at all, a very slight haze in the air, and Mars was positioned very high), I was able to view Mars at 974x. I wasn't able to resolve more detail after about 270x, so the details at 974x were those at 270x but a lot less defined, more blurred so to speak, although they were significantly larger. It is still the best view of any planet I ever had. That was an extremely rare night though, so expect magnifications of 200-300x on most nights. But when the conditions allow, the 8-inch will not disappoint.

[sevenofnine]

I chose my 8" Dob primarily because of Ed Ting's written and video reviews. I have never regretted the decision. Of my three scopes (tres amigos) the Dob shows me the most by far. For example, M13 and the Double Cluster are noticeable in binoculars but not impressive. In the 80mm refractor, the shape and structure are obvious but the stars are dim and only the brightest are seen. The 5'' Mak does a lot better but still lacks a memorable view IME. Now the 8" Dob with a 2" 28mm eyepiece really makes these two objects come alive. Breath taking to me anyway.

Good luck with your decision! 

Edited by sevenofnine, 25 March 2025 - 03:18 PM.

[Jay_Reynolds_Freeman]

 

I posted an image of valis alpes with some measurements and i'll post it again here as testimony of what a Supreme apochromat can do.

 

Blowup AlpineValleyRille-LO4115H_annotated.jpg

 

Click on it and expand it fully to see what a GREAT refractor can do. My 100ED had it even BETTER than what that grainy blowup shows [...]

 

The original of that posted image was taken in the 1960s by an unmanned NASA spacecraft, Lunar Orbiter IV, from low orbit around the Moon. What was posted is a portion of the original image, enlarged and cropped for careful study of the width of the rille.

 

Here is a link to an on-line report of the study in question, showing the enlarged and cropped image.

 

Here is a link to the NASA image.

 

Wikipedia's page about the Alpine Valley may be a useful reference. It also shows the NASA image.

 

Clear sky ...

Edited by Jay_Reynolds_Freeman, 25 March 2025 - 03:39 PM.

[PKDfan]

The original of that posted image was taken in the 1960s by an unmanned NASA spacecraft, Lunar Orbiter IV, from low orbit around the Moon. What was posted is a portion of the original image, enlarged and cropped for careful study of the width of the rille.

Here is a link to an on-line report of the study in question, showing the enlarged and cropped image.

Here is a link to the NASA image.

Wikipedia's page about the Alpine Valley may be a useful reference. It also shows the NASA image.

Clear sky ...

Yes Jay, i thought it clear that that was a lunar reconnaisence image and not mine. I hope no one thought otherwise and if they did; its on me, as i didn't make it clear and they have my apology.


Good links !


CSS
Lance
Edit and i was mistaken as it was a predecessor Orbiter IV as Jay has pointed out. Thanks !!

Edited by PKDfan, 25 March 2025 - 03:53 PM.

[Jay_Reynolds_Freeman]

Yes Jay, i thought it clear that that was a lunar reconnaisence image and not mine. I hope no one thought otherwise and if they did; its on me, as i didn't make it clear and they have my apology.

No problem -- I only posted because the topic originator wanted to know what could be expected from a small refractor, presumably Earth-based and sufficiently inexpensive for mere mortals to purchase, whereas the lunar orbiters had the advantage of a ring-side seat, as well as a rather large budget to get there ...

 

Clear sky ...

[Arkade]

I chose my 8" Dob primarily because of Ed Ting's written and video reviews. I have never regretted the decision. Of my three scopes (tres amigos) the Dob shows me the most by far. For example, M13 and the Double Cluster are noticeable in binoculars but not impressive. In the 80mm refractor, the shape and structure are obvious but the stars are dim and only the brightest are seen. The 5'' Mak does a lot better but still lacks a memorable view IME. Now the 8" Dob with a 2" 28mm eyepiece really makes these two objects come alive. Breath taking to me anyway.
Good luck with your decision!

I think you see less in the refractor but what you do see, it is super vivid. Whereas on bright objects , it is easier for a smaller refractor to see better as the moon even looks great in my 70/400 achro but i guess on dimmer objects, that is where the extra inches from the dob show,that is surpasses the smaller refractor.
That is the conculsion ive come to from all this.
Hopefully the dob is back in stock soon, i will then give my real life opinion

[Jay_Reynolds_Freeman]

I think you see less in the refractor but what you do see, it is super vivid. Whereas on bright objects , it is easier for a smaller refractor to see better as the moon even looks great in my 70/400 achro but i guess on dimmer objects, that is where the extra inches from the dob show,that is surpasses the smaller refractor.

Two things:

 

(1) One must make a distinction between a detailed view and an aesthetically pleasing one: In so-so seeing, which affects larger apertures more than smaller ones, a small aperture might continually present an image that shows all the detail the aperture can produce, so that when the observer selects a magnification sufficient to show that detail clearly (but not too much magnification), the result will be a continuous view of a sharp, clear image. Given the same seeing, the user of a larger aperture will likely select a higher magnification -- in proportion to aperture -- but most of the time the view will be blurry, because of the poor seeing. Now and then, however, the seeing will momentarily steady, and at those moments the larger aperture will show much more detail than the smaller one can deliver. Thus the smaller aperture delivers a continuous aesthetically pleasing view which always shows low detail, but the larger one delivers a view that is almost always aesthetically not pleasing but occasionally shows a lot more detail than the smaller one can. Which you prefer is up to you, but it is probably worth your time to be aware of the distinction when deciding what to purchase and how you want to observe.

 

(2) In poor seeing, there is an interesting observational effect in comparing telescopes side-by-side. In many such comparisons, telescope owners tend to spend most of their time looking through their own telescope, and only occasionally look through telescopes belonging to other people. Therefor, when the infrequent moment of good seeing does come along, observers are more likely to be looking through their own telescopes. In such circumstances, it would be possible for every observer to conclude -- correctly! -- that his or her own telescope had shown the best images, and that would be true even if all the telescopes were absolutely identical. Go figure ...

 

 

Clear sky ...
 

[PKDfan]

Hmmm Jay,

I detect the opposite scenario.

& I so hate to be contrary.

The difference in aperture from 62mm to 100mm is indeed small and i had a few years to detect how seeing affected a high resolution optic (my 100ED) to a smaller one, and also of very high quality, and i detect zero times when the seeing was 'better' for the smaller one.

If the seeing was on then ultimately i could see when it faltered and was limited in my magnification potential despite a Tiny aperture.

So i guess i'm saying IF you've got a Gooder then you'll Always be seeing limited.


YMMV.


CSS
Lance

[WillR]

Two things:

 

(1) One must make a distinction between a detailed view and an aesthetically pleasing one: In so-so seeing, which affects larger apertures more than smaller ones, a small aperture might continually present an image that shows all the detail the aperture can produce, so that when the observer selects a magnification sufficient to show that detail clearly (but not too much magnification), the result will be a continuous view of a sharp, clear image. Given the same seeing, the user of a larger aperture will likely select a higher magnification -- in proportion to aperture -- but most of the time the view will be blurry, because of the poor seeing. Now and then, however, the seeing will momentarily steady, and at those moments the larger aperture will show much more detail than the smaller one can deliver. Thus the smaller aperture delivers a continuous aesthetically pleasing view which always shows low detail, but the larger one delivers a view that is almost always aesthetically not pleasing but occasionally shows a lot more detail than the smaller one can. Which you prefer is up to you, but it is probably worth your time to be aware of the distinction when deciding what to purchase and how you want to observe.

 

(2) In poor seeing, there is an interesting observational effect in comparing telescopes side-by-side. In many such comparisons, telescope owners tend to spend most of their time looking through their own telescope, and only occasionally look through telescopes belonging to other people. Therefor, when the infrequent moment of good seeing does come along, observers are more likely to be looking through their own telescopes. In such circumstances, it would be possible for every observer to conclude -- correctly! -- that his or her own telescope had shown the best images, and that would be true even if all the telescopes were absolutely identical. Go figure ...

 

 

Clear sky ...
 

Well put.

[Jay_Reynolds_Freeman]

The difference in aperture from 62mm to 100mm is indeed small and i had a few years to detect how seeing affected a high resolution optic (my 100ED) to a smaller one, and also of very high quality, and i detect zero times when the seeing was 'better' for the smaller one.

I have fairly often -- though by no means always -- encountered conditions in which large telescopes were more adversely affected by seeing than small ones, though these instances generally involved at least one aperture substantially larger than 100 mm. My favorite example was when my 90 mm Vixen fluorite could get a solid split of Antares when an Astro-Physics 180 mm set up five meters away continuously showed it as an amorphous wiggly blob. Both I and the owner of the 180 spent a long time looking through both telescopes, and both of us and several others as well had star-tested both instruments in excellent conditions and could find no fault with them. I have also been present when seeing greatly limited views of fine planetary detail (Jupiter, Saturn) in the 36-inch refractor at Lick Observatory, while high-end refractors (Astro-Physics, Takahashi, 127 to 180 mm) set up in the parking lot outside were showing much more detail.

 

At other times, with better seeing, the AP 180 mentioned showed vastly more lunar or planetary detail than my 90 mm fluorite, and the Lick 36-inch showed much more detail than the smaller instruments.

 

 

Clear sky ...
 

Edited by Jay_Reynolds_Freeman, 25 March 2025 - 06:50 PM.

[PKDfan]

I have fairly often -- though by no means always -- encountered conditions in which large telescopes were more adversely affected by seeing than small ones, though these instances generally involved at least one aperture substantially larger than 100 mm. My favorite example was when my 90 mm Vixen fluorite could get a solid split of Antares when an Astro-Physics 180 mm set up five meters away continuously showed it as an amorphous wiggly blob. Both I and the owner of the 180 spent a long time looking through both telescopes, and both of us and several others as well had star-tested both instruments in excellent conditions and could find no fault with them. I have also been present when seeing greatly limited views of fine planetary detail (Jupiter, Saturn) in the 36-inch refractor at Lick Observatory, while high-end refractors (Astro-Physics, Takahashi, 127 to 180 mm) set up in the parking lot outside were showing much more detail.

At other times, with better seeing, the AP 180 mentioned showed vastly more lunar or planetary detail than my 90 mm fluorite, and the Lick 36-inch showed much more detail than the smaller instruments.


Clear sky ...

If only we could only hold objective quality equal among all those apertures Jay !


And to be fair i haven't used both at the same time (and really should) but i suspect very little if any change in their image fidelity, mainly since their size diff is so little.

Our seeing i believe cannot be interchanged willy nilly so no transference of one observers view to another can be infered or should even be made.


Let me be clear- my tests of both apo's have been determined in perfectly still nites with great clarity or transparency and over extended periods of time and time after time -as i am very hard to convince- so the optical lords have seen fit to grace me with some optics that i'm not afraid to shout to the rooftops again and again how great thou art, as a poet i couldn't resist.

Now that my kit is complete i long desperately to bring along other experienced observers and their kit to REALLY see if my myriad objectives views stack up against other optics.

I imagine i have very little to fret about.

A DPAC would help out abit too !


CSS
Lance

[dnrmilspec]

I have unlocked the thread after moving over 15 posts.  Editing them individually was FAR to difficult to even try. 

 

Folks please pay attention to the TOS.  We are to be respectful to one another.  Bickering is not what we do here.

[Jay_Reynolds_Freeman]

I have unlocked the thread after moving over 15 posts.  Editing them individually was FAR to difficult to even try. 

 

Folks please pay attention to the TOS.  We are to be respectful to one another.  Bickering is not what we do here.

At the risk of being found terminally whimsical, I shall take a deep breath and post ...

 

Freeman's Homilies for Simulating Wisdom on the Internet:

    1)  There’s no point trying to separate the foot and mouth of a fool.

    2)  Stupidity is contagious: Avoid carriers.

    3)  Facts don’t go away.

    4)  Unsent comments won’t return to embarrass you later.

    5)  Cat-fighting annoys the spectators, and only proves you’re a cat.

    6)  People who call each other names are usually right.

    7)  Truth is in the details, but nobody takes the time to learn the details.

    8)  No one cares about the last word on anything.

    9)  On the net, nobody knows who you are, but everybody knows what you are.

 

 

Clear sky ...

[mikeDnight]

I think you see less in the refractor but what you do see, it is super vivid. Whereas on bright objects , it is easier for a smaller refractor to see better as the moon even looks great in my 70/400 achro but i guess on dimmer objects, that is where the extra inches from the dob show,that is surpasses the smaller refractor.
That is the conculsion ive come to from all this.
Hopefully the dob is back in stock soon, i will then give my real life opinion

If you ever wondered what would happen if you stuck your finger in a hornet's nest, well now you know! 

 

To be honest, I'm on both sides of this discussion. The 8" Dob/Newtonian is a great scope to begin with, and for many it is a lifetime scope capable of showing pleasing views of everything in its aperture class. But its' not just a pleasing scope, its a scope that can be used for serious double star, lunar, planetary, variable star and comet observations; solar too with a full aperture solar filter. It's a great all-rounder! You might find however, that with the possible exception of double stars and objects at the absolute limit of the 8" Dob's light grasp and resolution, that everything you see in your 8" can also be seen in a 6", the British lunar observer and Selenographer Harold Hill pointed this out after comparing the detail seen on the Moon through his 10" F10 reflector to that seen through his old 6" reflector. Of course he was a highly skilled observer which is something that must be taken into account.

 

 You did mention in an earlier post £ and not $, so I'm assuming you're observing from the British Isles? If so, Lance's passionate suggestion of a good 4" refractor is something to consider seriously. Refractors for whatever reason seem to cut through poor seeing far better than other scopes, and a good 4" refractor will easily match a good 8" reflector for Lunar and planetary observing. The refractor will also give you breathtaking rich field views of star fields like no other scope can. Only two nights ago while observing with my 100mm F8 refractor and nothing but a 23mm Pentax XW eyepiece, I spent three and a half hours simply drifting through the constellations, stopping for a while at every cluster, asterism,  colourful double star and nebula that dared to enter my field of view. I've had bigger reflectors and refractors, but the 4" refractor is my most prized possession and I'd never part with it. 

 I'd hate to think how my back would feel after 3 1/2 hours at the eyepiece of a Dobsonian. With a refractor observing is so comfortable and effortless. And I can carry the whole scope along with tripod and altazimuth mount with just one hand, not that I would! When on a driven equatorial, I can really relax, as the scope just follows whatever object I'm studying. After 45 years of observing, a 4" refractor is my most used scope, and because of this, it is the scope that has shown me the most.

 

Of course I'd hate to influence you either way as it's your decision. 

Edited by mikeDnight, 27 March 2025 - 02:55 AM.

[Sketcher]

The real world isn't so simple that one would be able, in good conscience, to make very many blanket statements concerning the comparisons you're asking about.  The fact that you found you 80mm apo to be more contrasty and sharper on planets and the moon than the 5-inch Dob (127mm I presume) that you looked through kind of highlights this. 

 

Furthermore, what you've mentioned concerning Ed Ting, highlights one of the considerations that can lead some to prefer a smaller aperture telescope over a larger aperture telescope -- considerations other than raw performance (light-grasp and/or resolution).

 

I don't have an 8-inch reflector, but long ago I had an 8-inch SCT, and among my current telescopes I have 10 and 12-inch reflectors, as well as a 130mm (5.1-inch) apochromat.  Also, long ago, I recall observing a few objects (particularly Saturn) with a friend's 8-inch reflector.  So, maybe, I can write a few words on this topic.

 

First, that word "expect" (and expectations in general) brings up unpleasantries for me in this hobby, especially concerning the visual use of astronomical telescopes.  Different people, with different levels experience, will see (some) different details when making observations -- all other things being equal -- same telescope, same magnifications, same object, etc.  So, all of this about what to expect can quickly turn into a murky mess.  When different people see different details with identical equipment, their views on what others might expect will also differ.

 

Then there's that (very important) observation that you made -- contrasting the differences that you saw between your views with a 5-inch Dob and with your 80mm apo.  That's important because a) Dobsonian telescopes tend to vary more in the quality of their optics than do apochromat refractors, and b) Dobsonians are more sensitive to, more reliant on user "tweaking" (collimation being a "biggie") and user knowledge (dealing with potential thermal effects, etc.).  Also, as apertures increase in general, telescope performance becomes more dependent on external factors -- especially seeing conditions.

 

So, anything that anyone has to say on this topic needs to be taken with a grain of salt -- as the expression goes.

 

With the above preface, basically sowing a seed of doubt concerning what anyone, including myself, has to say concerning what one might expect in using a 200mm Dobsonian I'll try to get around to providing some kind of response your actual question:

 

In my experiences, larger Dobs should pretty much always provide brighter views, as long as the aperture difference isn't to terribly small.  And performance wise, that's about it unless all (or most) of those other things fall into place in a positive manner -- those things mentioned above that can, and will, affect a reflecting telescope's performance.  In other words, if the seeing conditions cooperate, if the reflector's optics are thermally stable, if tube currents are not causing problems, if the telescope owner/user has done his/her part in "tweaking" everything just right -- then the larger Dob ought to provide more detailed views of the moon and planets than a somewhat smaller apochromat.

 

The problem, especially for beginners, is understanding and getting all of those other factors right and to cooperate in providing the best views that the reflecting telescope is capable of providing.  The odds of a beginner succeeding here drop quickly if the beginner is alone with the telescope and lacking in critical knowledge -- and unfortunately, that's precisely where many beginners stand.

 

But of course, a beginner has to begin somewhere.  You already have experience with your 80mm apo -- and that was an excellent way to begin.  Due to all of the sensitivities of reflecting telescopes, I tend to recommend that beginners start with a refractor.  This you've done.  So, moving up to a larger reflecting telescope is a perfectly reasonable next step for you.  Hopefully, you've learned enough through extensive visual use of your refractor that you'll be in a better position to understand and deal with those more critical reflecting telescope areas.  You should be better able to tell if it's seeing conditions, or cool-down issues, etc. that are impairing the Dob's performance when its performance isn't as great as it should be.

 

Oh, and while, when everything is working right for the Dob, you should note improved image brightness and resolution, you will likely also note that a Dob tends to scatter the light around planets, etc. a bit more so than do refractor optics.  So the Dob views, while being brighter and more detailed, may give the impression of being less sharp than an apochromat's views, when they are actually more detailed.

 

I do recommend getting the 200mm Dob.  But hopefully you now have a better idea concerning expectations and how those expectations can be quite dependent on other factors -- some of which you will have control over, and others that you will have no control over.

 

I've watched Ed Ting rate the 8inch dob as his "if i could only have 1 scope", even more than the 10 inch due to size,awkwardness etc.

I have never looked through one before.
Biggest Ive used is a 5inch dob and I found my 80mm ed apo more contrasty and sharper on planets and moon.

Does anyone have any stories or comparisons between an 8 inch dob and smaller apos. Was it a wow moment viewing the moon, planets or dso after using a smaller scope (which scope)

I had no idea or may have forgot a 8inch dob is only £370. Going to keep my 80mm apo and get a dob as opposed to 120mm skywatcher ed ( would have cost over £2000 incl a mount).

Edited by Sketcher, 26 March 2025 - 10:08 AM.

[Takuan]

I'd hate to think how my back would feel after 3 1/2 hours at the eyepiece of a Dobsonian. With a refractor observing is so comfortable and effortless.

In my case, I can sit with my astronomy chair/ dob for an entire night and my back will be perfect. If it isn't the case, something is wrong, either with the type/use of chair or the position of the back.

Edited by Takuan, 26 March 2025 - 10:15 AM.