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Hello,

I've been on these forums a couple of times for the last 2 weeks and ive found amazing advice, on telescopes, mounts and eyepiece. Besides reading countless of information on the internet about various equipments; pros and cons; and i got some queries about how to upgrade my setup.

My original purchase was a 15x70 Celestron Binoculars last year, and boy ive seen amazing things with it, specially globular clusters, Jupiter and Saturn and the Orion's Nebula; for me these were amazing; i still use them given how easy it is to look at the sky with them and how bright and full everything looks.  A couple of months ago i got a 70x400mm Gskyer Telescope with an AZ mount (The cheap 99$ one that Amazon is displaying on all its adds for the last two months)  it came with a 25mm and a 10mm eyepieces as well as a x3 barlows (which i didnt even count as part of my scope as it is too bad quality and i havent managed a single decent view with it).

Currently My Celestron Binoculars (x15) seem better for visualizing the sky than the 25mm eyepiece (x16) (things seem a very bit dimmer). And since the Barlow is a "no go", the 10mm (x40) eyepiece is what i really use, it has decent zoom and detailed views , it is my go to eyepiece most of the nights.

However from reading all around, ive read that most of the stuff that come with the Telescope (aside from the scope itself) are actually really bad quality, specially no name brands without even webpage, so if i were to maximise my telescope i should update some of those items.
-Recently i ordered a new Start diagonal to replace to default one (ive heard on Refractors its usually the weakest link next to eyepieces) as well as an economic x2 Barlow lens

Keep in mind i recognize my 70mm cheap telescope will not suddendly become the Hubble Telescope, and that it doesnt matter how hard i push it, in the end such a low scope will be bound to hit its limit pretty fast, thats why i avoid 70$+ eyepieces and barlows for now.

I expect to keep using this telescope for a good couple of months; at least until around August, when Jupiter and Saturn are more in the night sky, rather than morning.

Now, im very satisfied with my current telescope; while the phone mount is garbage and the phone weight and the sound of my heartbeats pretty much shake the telescope out of position, as well as how cheap the mount is; it still gets the job done for seeing interesting stuff in the sky and i have managed to do some AP for some of the globular clusters, bunch of 1-2s images (with the wrong lens), not the best, not even good pictures; but decent overall for my equipment. I am currently interested in stargazing in general and some minor AP (as i dont have a camera, currently an Iphone 7s with the mount) Buuut im interested in borrowing a camera for the low sky photos without a telescope.

I do most 97% of my Skywatching on my backyard, i live in a small country, there is some light pollution, but i can see the pleiades and the orion's nebula core on the naked eye most nights (so i guess its not that contaminated lol)
Now; currently i like finding stuff by myself and show it to the other people around me who cant be bothered to find the moon in the sky, so setting up, finding and seeing stuff is part of what i like. 

With all the above in mind..... Id like to plan ahead for my next purchases.

First, im thinking a x3 barlow lens (to replace the original crappy one) and a 15mm lens (to have a bit better view than the 10mm, but less spread than the 25mm) in two or three months (with this id be able to check if my new eyepiece outperforms my default ones, but given the quality of the scope, i dont expect this to be noticeable).

And Afterwards id love to get a new Scope, but im not quite sure what i want... and i would like some advice and help in choosing my next Scope upgrade.

-I entered with and im liking the refractors; however i dont wanna spend 300-400$ on another refractor that is 20-30% better for triple the price
-Ive heard really long focal lenght might bring some distortions; and also make the scope much bulkier, annnd most importantly i know that magnification is not everything; so a 1000mm long tube would prob bring too much magnifications for me to use properly on my backyard skies. So i think id settle for a maximum of 600-700mm.

-Originally i was againts Newtonians in general, those inverted views scared me, i have a hard time of my own with my finderscope. Then i found out that Reflectors are the name of efficiency as they have more value per aperture than refractors; and as someone once mentioned "There is not really up and down in space, you will get used to it" annnd its true... save for references on the ground, like buildings, trees and mountains to help you locate where you are in the sky; once you are on it, you dont need right ups and downs.

-I did see some 90mm Orion's Refractors as well as 90-102 Celestron Astromaster Refractors (these are 350-400$)

-Im thinking a 130mm reflector is what im looking for; i think the 130mm aperture is a nice upgrade for my 70mm, and will keep me occupied for quite a long time; ive read about Orion SpaceProbe 130EQ and Celestron Astromaster 130EQ (ive also read, Power Seekers and Astromaster's are made out of pretty much garbage lol) Ive read that the main issue is the constant collimation required for them; but ive also read its something that can be learned and once you get used to it; its a pretty easy thing to do to keep getting amazing views.

-Ive also seen people recommending  6-8'' Dobsonians; i know the deal with them; if anything i could aim for a 6'' one i found a litter under 300$ ive read they are amazing values for their aperture

So, TL;DR: I have a 70x400mm Telescope, im new to stargazing, im really amazed and excited by what im seeing with my current scope, but would like an stable upgrade before the end of the year that will last me a year or two. I am interesteted both in regular and deep sky stargazing and astrophotography;  im not currently interested in an motorized mount; could deal with a regular Equatorial mount. But overall i am looking for  more aperture (100-150mm) to have clearer views; than focal lenght for zoom.

Im also open to the fact that at one point i might have to get a scope for stargazing and another for AP; but would like an upgrade that could help me all around for both while i get initiated.

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Sorrry for the Huuuuuuuuge post, i was very excited while writing it; please let me know what you think and if there's anything else you'd want me to add to help understand my situation, thanks in advance!

 

 

Edited by AlvinP
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Welcome !

That certainly is a long first post  🙂  I only have time to make a few short responses though ...

I think you have made a really good start by beginning with binoculars and finding your way around the sky. Your telescope is not a fabulous , expensive refractor , but as long as you don't expect too much from it , it will show you plenty.

I'd suggest you search out the threads on here which talk about 'st80' telescopes, which are 80mm aperture, 400mm focal length cheap ones, very similar to yours, which will give you an idea of what may be possible, and how to get the best out of yours.

If you have , or can borrow, a photo tripod with a pan tilt head , and if your telescope has a suitable socket for a standard photo tripod screw , you could try your 'scope on that.  It might be a steadier, easier to adjust mount for your telescope than the one which comes with it. I use my st80 on a photo tripod, and it works very well.

If you can't use a photo tripod, try improving the one you have by adding a weight of some kind , a bag with some stones, or a plastic bottle of water , hanging off the centre of the tripod. This adds some mass and steadies the thing.

The reflector 'wrong way up' effect is only really a confusion for me when I am looking at the Moon or Mars , and using maps to identify features, so I don't think it is a worry !

Heather

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I would suggest you plan any future purchases in terms of where you want to be in a couple of years' time.  A 70x400 mm scope does not seem like much of an upgrade from your 15x70 binoculars.  If you do buy eyepieces, buy decent ones that you can re-use later with a decent scope.   A  Dob scope would give you a significant increase in aperture for a modest outlay.

x3 Barlows are not necessarily very useful except for imaging.

If you are looking at refractors, note that small short-focus refractors (like yours) can have significant chromatic and other aberrations, but in small long-focal length refractors the aberrations are much less apparent.  Beyond this, refractors become heavy, sometimes very long, sometimes eye-wateringly expensive, and require expensive heavy mounts to support them. 

An 1000mm focal length telescope with a 25mm eyepiece will give a magnification of x40, which is not a lot, so no worries there.

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Thanks for the replies; another thing i read on a website was: "A key advantage of the refractor is that there is no central obstruction. The secondary mirror of the reflector blocks some of the light coming into the tube which reduces the effective aperture. In telescopes with 5” or less aperture the refractor is typically considered to have about a 1-inch advantage. This means that a 5” reflector and a 4” refractor would be considered about equal in light gathering ability, a key measure of the power of a telescope."

How accurate is this? would this mean that a 90mm Refractor would perform similar/close than a 114mm Reflector? Or is this based on older designs and has been reduced in newer models?

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Hi Alvin,

That's a short question but the answer is perhaps a little longer...

It's true that the central obstruction reduces the effective aperture, though there are other things in play that could have a bigger impact on performance.

The amount of obstruction varies by telescope design, but ~30% reduction in area is fairly typical for a reflector. So in the case of the examples you give, a 90mm refractor has an area of pi*(90/2)^2=6362 square mm of unobstructed aperture , whereas the 114mm reflector has an aperture area of pi*(114/2)^2 = 10,207 square mm, but a 30% obstruction means that you only get 70% of that area - so that's 7144 square mm. It's still 12% more collecting area than the 90mm refractor, but all other things being equal I doubt you would see much difference (but read on...)

There are a couple of other points to bear in mind. There may be a little bit more "loss" in the reflecting design than the refractor (mirror reflectivity tends to be a little lower than lens transmission), and that further narrows the gap between the refractor and reflector examples you chose if we're just considering how much light they collect.

However there  are other considerations. The angular resolution of the telescope goes as the diameter of the aperture as well, and in principle the 114mm reflector offers improved resolution over the refractor. The central obstruction does have some practical effect on that as well, but if the optical quality of the two telescopes is equal, and the reflector is well collimated, then the advantage is certainly real.

My view is that based on the points above, then what the view through the eyepiece looks like (or the image, if you're using a camera) will be determined more by parameters such as the focal length of the telescope assuming that the optical quality of the two is comparable. And if the focal length is similar, then I would expect the views to be similar - again assuming optical quality is comparable in the two systems. If the reflector has a "spider" holding the secondary mirror, then it will produce diffraction spikes in the image, which the refractor won't do. Some people like the spikes, some don't - it's a personal choice, but the kind of thing that might persuade you to go with one over the other.

So while I would not disagree with the statement you quote as a broad guideline, there are always other factors to consider, particularly when the two options are as closely matched as the ones you suggested.

If there are specific models you're looking at, post the model numbers here - you'll get lots of advice from SGL members considering the specific details of the telescopes along with user experiences, and that is probably more useful in helping you to reach a decision.

Best Regards


Nigel

 

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52 minutes ago, AlvinP said:

Thanks for the replies; another thing i read on a website was: "A key advantage of the refractor is that there is no central obstruction. The secondary mirror of the reflector blocks some of the light coming into the tube which reduces the effective aperture. In telescopes with 5” or less aperture the refractor is typically considered to have about a 1-inch advantage. This means that a 5” reflector and a 4” refractor would be considered about equal in light gathering ability, a key measure of the power of a telescope."

How accurate is this? would this mean that a 90mm Refractor would perform similar/close than a 114mm Reflector? Or is this based on older designs and has been reduced in newer models?

That quote sounds like a rather partisan refractor user's defence of their chosen instrument !

Large aperture refractors of decent quality are expensive. Very expensive. Comparable aperture reflectors are less expensive, even if you apply some reduction in aperture. If one type of telescope was better than all the rest, no-one would buy any other , and no one would own more than one type of telescope . I'm a relative beginner, and own 3 types !

Every type of telescope has its advantages and disadvantages, every type of telescope has a vast price range, some are better for certain purposes than others. And then there are various kinds of mounts to consider as well.

If you can set a budget, think about what storage you have for the equipment, consider how easy it needs to be to transport it to where you view from , and decide what sorts of targets are of most interest to you, we can give some suggestions.

 

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1 hour ago, NigeB said:

Hi Alvin,

That's a short question but the answer is perhaps a little longer...

It's true that the central obstruction reduces the effective aperture, though there are other things in play that could have a bigger impact on performance.

The amount of obstruction varies by telescope design, but ~30% reduction in area is fairly typical for a reflector. So in the case of the examples you give, a 90mm refractor has an area of pi*(90/2)^2=6362 square mm of unobstructed aperture , whereas the 114mm reflector has an aperture area of pi*(114/2)^2 = 10,207 square mm, but a 30% obstruction means that you only get 70% of that area - so that's 7144 square mm. It's still 12% more collecting area than the 90mm refractor, but all other things being equal I doubt you would see much difference (but read on...)

There are a couple of other points to bear in mind. There may be a little bit more "loss" in the reflecting design than the refractor (mirror reflectivity tends to be a little lower than lens transmission), and that further narrows the gap between the refractor and reflector examples you chose if we're just considering how much light they collect.

However there  are other considerations. The angular resolution of the telescope goes as the diameter of the aperture as well, and in principle the 114mm reflector offers improved resolution over the refractor. The central obstruction does have some practical effect on that as well, but if the optical quality of the two telescopes is equal, and the reflector is well collimated, then the advantage is certainly real.

My view is that based on the points above, then what the view through the eyepiece looks like (or the image, if you're using a camera) will be determined more by parameters such as the focal length of the telescope assuming that the optical quality of the two is comparable. And if the focal length is similar, then I would expect the views to be similar - again assuming optical quality is comparable in the two systems. If the reflector has a "spider" holding the secondary mirror, then it will produce diffraction spikes in the image, which the refractor won't do. Some people like the spikes, some don't - it's a personal choice, but the kind of thing that might persuade you to go with one over the other.

So while I would not disagree with the statement you quote as a broad guideline, there are always other factors to consider, particularly when the two options are as closely matched as the ones you suggested.

If there are specific models you're looking at, post the model numbers here - you'll get lots of advice from SGL members considering the specific details of the telescopes along with user experiences, and that is probably more useful in helping you to reach a decision.

Best Regards


Nigel

 

Thanks! this is really good

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So; these are the models im currently looking into:

Refractors 

Reflectors - (i understand they all require constant collimations to keep focused and sharp)

 

Thanks

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I would avoid any alt-az mount that places the load above the alt axis.  They tend to tip over backward above about 45 degrees due to the imbalance.  That rules out the first two.

EQ (specifically, GEM) mounts can be frustrating for beginners doing visual only.  Their only advantage for visual is you need turn only one knob to keep an object in view once roughly polar aligned.  They also tend to be over-taxed in these beginner kits and can be very wobbly/shaky as a result.

There are quite a few really good alt-az mounts out there, but they are mostly out of your price range before you even add a telescope OTA.

That leaves you with the 6" Dob as your best bet, though shipping to DR could be quite high due to its size.  You'd want to also get a cheshire tube or similar to check and perform collimation on it.

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You have had a lot of good advice in this thread already but I see some similarities with how I started so I wanted to add some advice from my personal experience and hope it might help.

I started the same as you, with the same binoculars, and I was instantly hooked. It only took me about 2 weeks to find a second hand telescope to buy. I did a bit of research and I decided that for visual use you couldn't beat a dobsonian reflector and I bought a Skywatcher 200P, with 8" aperture. The views I got from this even with the basic included eyepieces I found very impressive - across galaxies, planets, the moon, etc. Again I was more hooked. The ease of use of a dobsonian - just take it and put it on the ground - was amazing. People get scared of collimation with reflectors but there are some incredibly good guides online and once you have practiced it is no big deal and (in my experience) if you don't roughly move the scope a lot then you won't need to do it very often. It's a great way to continue learning the sky using the finder scope and some star maps to hop around and locate your targets. A good skill to have in this hobby for sure.

However, once I started to look at astrophotography (AP), things escalated very quickly :) If you are serious about AP then starting off you need to look a spending a lot more money on a good equatorial mount. You can take great photos with an average scope / camera and a good mount, but even with the best scope and camera in the world, if you have a poor mount, your images will likely be poor as well. I ended up buying another reflector, a Skywatcher 130-PDS - there is a great thread of images from users with this scope here: 

 This scope was not expensive, however after doing some reading I paid around 5x the price of the scope on the mount to ensure that I had good tracking. Only now, many years later, am I considering paying more for a better camera.

 

Astrophotography, for me, has completely overtaken visual use, and my 200P dobsonian sits in the shed unused most of the time. So you maybe need to consider if you are likely to be heading into a lot more AP in the future, or if it is only visual use that interests you, because very often the hardware for one is not so good for the other (although of course there are exceptions).

 

Anyway, my final word would be do not be too afraid of reflectors. I believe for the price/aperture you can't beat them for visual use! They can also be great for AP, but that requires a lot more expensive hardware.

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I highly recommend the 130PDS as a first scope. It's my first and only scope so far. Yes you will have the usual brain aches with regards to collimation but that's par for the course I think with everyone new to Reflectors. Once you get your head around it, no problem.

The thing that is of the most importance is the mount. I'd say, at the very least, you want an HEQ5Pro. I started out with the EQ3pro with my 130PDS and sold it within 3 months and upgraded. Look out for good used stuff as well as that can save you a lot of $£$.

Play, learn, watch video's, tutorials, read everything you can. Know in your mind what you want to achieve and what you need to achieve it before hitting the Buy Now buttons. Fools rush in. 👍

(*EDIT*) Looking at people's signatures on here helped me with my purchases. Look at people's images and see what gear they use.

Edited by Jamgood
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Posted (edited)

Thanks for all the quality comments; jesus; everyday i learn lots of new stuff.

Im liking the comments about the 130PDS or similar scopes.

I think ill pass on the refractors for now; maybe in the future ill revisit them.

Edited by AlvinP
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