Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_globular_clusters_winners.thumb.jpg.13b743f39f721323cb5d76f07724c489.jpg

Recommended Posts

Hello All! 

  Currently, I have a Meade ETX 90 telescope. I really like it and get great views of the moon and planets out of it. However, I am hoping to upgrade to a large reflector.

  I am looking at various scopes ranging from the Orion SkyQuest XT8 to the forbiddingly pricey Orion SkyQuest XT12i Intelliscope. I know that aperture is one of the most important things to consider in a telescope, but I also realize that people can get "aperture fever" and go for scopes that are unnecessarily large.

  I am wondering; Is a bigger aperture worth the price jump from 8'' to 10'' or from  10'' to 12''? How much more will I be able to see?  I have heard that the best telescope for a person is dependent on the kinds of things they want to observe. I don't really look at deep sky objects (though I am getting increasingly interested in them), and mostly enjoy the moon, planets, and a few double stars. I want a telescope that will accommodate this, but is also able to have a great grasp on deep sky objects.

  Honestly I think I am on the right track with the scopes I am looking at, but I really want some advice on which size is best for me. What do you think?

  Thanks for the advice!

 

 

Share this post


Link to post
Share on other sites

If you're primarily interested in the moon planets and double stars then aperture is less of an issue than it would be on deep sky targets. Although increased aperture does lead to higher theoretical resolution the atmosphere will be the limiting factor with anything above about 8" especially in the UK. Ease of set up is another major factor. the bigger it is, the harder it will be to set up, the longer it will take to cool down and unless you're very dedicated, the less you may feel inclined to use it. I've tended to observe with scopes in the 4 to 8" range, though I've used scopes up to 30"! My experience has been that you need to double the aperture to make an "oh wow" difference - and that can get very expensive very quickly! I was looking at Jupiter once from a great site overseas with a variety of scopes. The best view was through a 7" astrophysics refractor - an 18" newtonian net to it was good too but there was no more to see than in the 7" and the contrast was ever so slightly less. However the ring nebula through the 18 was very much better than in the 7 :)

Edited by timwetherell
  • Like 3

Share this post


Link to post
Share on other sites

I agree with Tim, From what I've gathered aperture is king as it immediately affects the amount of light that it can gather. though if you're not so much interested in Deep Sky then a smaller aperture might still suit you perfectly. I mean you can still see a lot of the brighter deep sky objects even with a smaller aperture:)

46 minutes ago, timwetherell said:

If you're primarily interested in the moon planets and double stars then aperture is less of an issue than it would be on deep sky targets.

 

Share this post


Link to post
Share on other sites

My husband had an ETX105 and upgraded to an LX90 10inch. It was a bit heavy if you need to carry it in and out but it was very good especially with globular clusters and planetary. I had a Celestron 8SE which was also good and had the advantage that it broke down to 3 sections that were easy to handle.  Also you can use the mount for other short telescopes such as a solar scope. Though I liked my 8SE on a CG5 mount, it had fewer backlash issues and was more stable as well as enabling larger eyepieces to be used as the telescope tube can be balanced better.  You can also upgrade the scope to something else, I eventually switched to refractors for imaging.

If you're into visual, I don't think you could do much better with something like the above. And they work similarly to your ETX.

Anne

Share this post


Link to post
Share on other sites
10 hours ago, Subdeo said:

I don't really look at deep sky objects (though I am getting increasingly interested in them), and mostly enjoy the moon, planets, and a few double stars

The question here is whether you enjoy those things because that is your interest, or because those things happen to be the strengths of your current telescope. If it really is lunar and planetary that interest you most with a small amount of DSO observation thrown in then aperture is not quite as important and so the 8" or even a Mak/SCT would be good choices. On the other hand if you think you would really like to observe DSOs, but it is just the small aperture of your current scope holding you back, then go for the biggest one that you can easily take out under the stars. An 8" under the stars will show you much more than a 12" in storage because the effort of setting it up prevents you getting it out.

  • Like 4
  • Thanks 1

Share this post


Link to post
Share on other sites
2 hours ago, Ricochet said:

An 8" under the stars will show you much more than a 12" in storage because the effort of setting it up prevents you getting it out.

Ain't that the truth!

 

  • Like 1

Share this post


Link to post
Share on other sites

Thanks everyone! I have another question. What do you think about cooling fans? Do they really help? I am trying to decide between the Apertura AD10 (1st link) and the Orion SkyQuest XT10 (second link). What do you  think?

https://www.highpointscientific.com/apertura-ad10-10inch-dobsonian-telescope-ad10?utm_source=google&utm_medium=cse&utm_term=APT-AD10&gclid=EAIaIQobChMIqZPx_6X71QIVQgOGCh1pTwIcEAkYESABEgLLhfD_BwE

 

http://www.telescope.com/Telescopes/Dobsonian-Telescopes/Classic-Dobsonians/Orion-SkyQuest-XT10-Classic-Dobsonian-Telescope/pc/1/c/12/sc/13/p/102006.uts

 

Before I buy though, I plan to go to an event where these scopes are to see them for myself and make sure I want the 10'' over the 8'' versions. Lastly, is the focal ratio important? The Apertura has one that is .2 higher. Thanks!

P.S. The reason I haven't looked for DSOs much is because I really haven't known how to find them in the past.

Share this post


Link to post
Share on other sites

I wouldn't worry about 0.2 difference in focal ratio.

I added a fan to my 8" dob and I am certain that it helps. However, mine is suspended via elastic so that vibrations are not passed through to the scope.

Share this post


Link to post
Share on other sites

On cooling fans, I don't find that I need one (even though I have one fitted) with my 12" dobsonian.

My 12" weighs the same as most 10" dobs so it gets used lots ! :icon_biggrin:

 

Share this post


Link to post
Share on other sites

I don't want to polarize this but my 8" I find it very heavy ):  but maybe it's only a negative state of mind, I have to climb steps too. In my actual condition, 8" is the bigger I am willing to carry, 10" is scary, first time I saw one, I was intimidated by it and still is.

Like the Sensei used to say while doing wall sit with a another person sitting on our legs? or wearing a 220 lbs person and squat walking around the gymnasium? Pain is only a state of mind he said :p ... crazy man.

 

 

  • Like 1

Share this post


Link to post
Share on other sites

Climbing a number steps with a scope puts a whole different spin on the weight and portability of a scope. I have a short, flat carry to my observing place so moving my 12" do there in two short carries is no problem - it takes just a minute to set the thing up. If I had to climb up and down some stairs it would not be practical at all for me.

Each of our circumstances is a little different and it's taken some time to realise what works for me. My previous 12" dob was a Meade Lightbridge which was much heavier than my current Orion Optics 12" dob. Ergo, the Meade did not get used much :rolleyes2:

  • Like 1

Share this post


Link to post
Share on other sites

I have a Dark Star (remember them?) 12" which when I moved house became less useable as street and neighbours' lighting made moving it around necessary and handling precarious. Still have it & dream of a dark site of my own.

Bought a C8 to replace it about 20 years ago, but there is no replacement for displacement! Much more portable though.

Yesterday I bought a 10" F5 1270mm Bresser Messier dob which I hope will be my new DSO eye to the sky, due tomorrow (wanted to stay with solid tubes. ?

 

Edited by 25585
Clarity
  • Like 2

Share this post


Link to post
Share on other sites

I do remember Dark Star - I have a brochure of theirs somewhere I'm sure :icon_biggrin:

About the only affordable big aperture scopes a couple of decades back.

  • Like 1

Share this post


Link to post
Share on other sites
23 minutes ago, John said:

I do remember Dark Star - I have a brochure of theirs somewhere I'm sure :icon_biggrin:

About the only affordable big aperture scopes a couple of decades back.

www.darkstartelescopes.blogspot.co.uk/2012/07/dark-star-html?m=1

Mine is hammerite blue

 

Share this post


Link to post
Share on other sites

As for which size of aperture is best with regards to 8, 10, or 12 inches which you are considering ?

I believe it depends more on the quality of the optics than just size, as resolution will only be as good as the weakest link in the optical train.

  • Like 2

Share this post


Link to post
Share on other sites
On 30/08/2017 at 00:36, Subdeo said:

Thanks everyone! I have another question. What do you think about cooling fans? Do they really help? I am trying to decide between the Apertura AD10 (1st link) and the Orion SkyQuest XT10 (second link). What do you  think?

https://www.highpointscientific.com/apertura-ad10-10inch-dobsonian-telescope-ad10?utm_source=google&utm_medium=cse&utm_term=APT-AD10&gclid=EAIaIQobChMIqZPx_6X71QIVQgOGCh1pTwIcEAkYESABEgLLhfD_BwE

 

http://www.telescope.com/Telescopes/Dobsonian-Telescopes/Classic-Dobsonians/Orion-SkyQuest-XT10-Classic-Dobsonian-Telescope/pc/1/c/12/sc/13/p/102006.uts

 

Before I buy though, I plan to go to an event where these scopes are to see them for myself and make sure I want the 10'' over the 8'' versions. Lastly, is the focal ratio important? The Apertura has one that is .2 higher. Thanks!

P.S. The reason I haven't looked for DSOs much is because I really haven't known how to find them in the past.

+1 for 10", or 12" if you can manage it ;)

If viewing planets/moon, I let my f4.7 10" (SW 250px - cheaper than Orion) cool for 40mins without any fans.  For DSOs at lower power, I can start observing pretty much straight away.

I'm 41 and thankfully healthy - and find my 10" no bother to carry - grab and go.

I'm very happy that I went for the 10" for observing DSOs: I was originally going to go for the 8".

Add a Telrad, and you'll be finding DSOs no prob with Sky Safari from decently dark skies.

I wouldn't be concerned too much about the difference in f ratio.

Best of luck with your decision - I'm sure the views through any of these scopes will delight you :)

-Niall

 

  • Thanks 1

Share this post


Link to post
Share on other sites
12 hours ago, planetman83 said:

The best aperture is the biggest aperture you can transport to a dark sky alone.

^^ Thiis :thumbright:

Share this post


Link to post
Share on other sites
On ‎8‎/‎30‎/‎2017 at 16:38, celestron8g8 said:

12" would be nice but if too big for you go with a 10" . Aperture is your friend just for observing . 

Aperture increases brightness and resolution (detail). Don't consider  the difference in aperture diameter as much as the difference in area of the mirror, which increases as a square function of diameter. My C8 collects almost 45% more light than my C6, from a "mere" 2 inches difference in diameter.

Share this post


Link to post
Share on other sites
1 hour ago, Luna-tic said:

Aperture increases brightness and resolution (detail). Don't consider  the difference in aperture diameter as much as the difference in area of the mirror, which increases as a square function of diameter. My C8 collects almost 45% more light than my C6, from a "mere" 2 inches difference in diameter.

Been knowing what you said for the last 25 yrs . But what is your point , are you not understanding or are you just adding to what I already know but didn't mention ?

Share this post


Link to post
Share on other sites
2 hours ago, celestron8g8 said:

Been knowing what you said for the last 25 yrs . But what is your point , are you not understanding or are you just adding to what I already know but didn't mention ?

Even though I quoted you, it was more addressed at the OP, maybe he didn't know, since he's asking about diameter.

Edited by Luna-tic

Share this post


Link to post
Share on other sites
22 minutes ago, Luna-tic said:

Even though I quoted you, it was more addressed at the OP, maybe he didn't know, since he's asking about diameter.

Well usually when you quote someone the message is directed at the one you quoted so since you quoted me I take it your directing your reply to me since you did not mention the OP . 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By orfest
      [A few more photos are in the imgur album]
      Made this telescope for observing sunspots. The Sun gets projected onto a piece of paper after bouncing from 3 mirrors inside the frame.

      It's compact, light, takes only a few seconds to point at the Sun, and sketching sunspots is as easy as circling the spots on a piece of paper.

      It can even project the Moon:

      The design is inspired by a commerically available telescope, but I’ve done all the designing myself, just for the fun of it.
      Sunspotter is full of little details that make it interesting. How do you fix the eyepiece in the exact place where it needs to be? How do you keep the lens in place and perfectly aligned?
      Building the telescope was a lot of fun, I’ve learned to use a jigsaw, X-Carve and a 3D printer. The plan is to use it to complete the Astroleague Sunspotter Observing Program, but unfortunately I completed it at the minimum of a Sun cycle, and won’t see any sunspots until next year.
       
      Telescope parameters:
      Magnification: 75x Size: 41cm x 41cm x 15cm Weight: 1kg Design: Keplerian Projection size: 75mm Materials needed:
      Lens: Ø52mm f=750mm achromatic doublet Mirrors: 1, 2, 3 Eyepiece: Baader 10mm ortho 1.5m² of 10mm plywood Wooden glue 5m of PLA filament 12 nails Compressed air Isopropyl alcohol Tools I used:
      Jigsaw with a 30° bevel capacity X-Carve 1000 3D printer A laser pointer Clamp Learned modelling basics in:
      LibreCAD Easel TinkerCAD Fusion 360  
      Part 1: Choosing the lens
      The idea of a sunspotter is that the light goes through the lens, travels inside the telescope, bouncing from 3 mirrors, enters an eyepiece and the image gets projected on one of its sides.
      The distance the light travels before entering an eyepiece is the focal length and it determines the size of the telescope.
      I chose a Ø52mm f=750mm achromatic double. Observing the Sun doesn’t require a large aperture, 50mm is more than enough. I wanted a high magnification and went for the longest focal length I could find, which was 750mm. Achromatic doublet design is what people use in refractors. If it is good enough for a refractor, it’s definitely good enough for my project.
       
      With the focal length chosen I could design the wooden parts. A drawing showed that the frame needed to have sides 30cm long, but I wasn’t sure about the placement of the mirrors and went for 31cm sides, planning to shorten the light path as needed by adjusting mirror positions.
      This is the LibreCAD drawing of the layout of parts on a piece of plywood:

      Part 2: Building the base
      Having a drawing of the base in LibreCAD, I printed the drawing 1:1 scale on multiple A4 sheets of paper and glued them together. I transferred the drawing to a piece of cardboard and cut it out.

      Applied this cardboard template to the sheet of plywood, and cut out two parts with a jigsaw.. I’m not an experienced user of jigsaw, and couldn’t manage to cut half-circles accurately enough. Even worse was that the two parts were very different. I didn’t want the frame to randomly tilt left or right when adjusting its altitude, and had to spend a lot of time with sandpaper to make the halves as similar as I could.
       
      Glued the two large parts with three small parts in the middle. Additionally nailed the parts and the base was ready.
       
      Part 3: Frame
      The frame is simply a triangle made of three pieces, with short sides cut at a 30° angle. Most jigsaws can cut at 45°, but not at 30°. Had to buy a new jigsaw with a 30° bevel capacity.
      Cut out three sides, cut short sides at a 30° angle, but didn’t put them together just yet.
      The lens needs to be perfectly aligned with the Sun-facing part of the frame, otherwise the Sun projection isn't circular but elongated.
      My solution was to carve a hole with a little step as shown on the image.

      The inner hole is Ø46.5mm, the outer hole is Ø50.8mm.
      The outer hole is the exact size to let the lens fit, but with a little bit of friction. Had to carve several holes to find the minimal size the lens could fit in.
      The step is just large enough to have enough surface for the glue to keep the lens in place, I didn't want to reduce the aperture too much.
      I used an X-Carve for carving and Easel for modelling.
       
      With all 3 sides ready, I could assemble the frame. It appeared that my 30° angle cuts were not very precise, but after some sandpapering the sides started fitting together alright. Glued the parts together and left them to dry for a day. To apply some pressure on the joints, I wound several twine loops around the frame really tight, made sure all sides fitted well together and left it to dry like that for a day.

      Part 4: Mirrors
      When selecting mirrors I was looking for the smallest mirror that fit the cone of light. Small mirrors are a lot easier to place, and they let me better control the length of the light path. I considered using elliptic mirrors, but they were bulky and really hard to place. All mirrors are first surface mirrors, otherwise planning their locations would be a lot more confusing.
      This was my original plan of placing the mirrors:

      As you can see, all the angles and distances were carefully measured, and I wanted to simply make mirror holders of those exact dimensions. This was clearly a bad idea.
      I 3d-printed some parts like this:

      And only later I realized that the frame angles are not exactly 60°, and that there are drops of glue along the edges that don’t let me fit the pieces deep enough in the joint between the sides.
      I cut angles from all the mirror holders:

      After I put the first mirror in place I realized the angles are all wrong, and that I needed to re-do the holder. Separating the mirror from the holder was a huge pain, which resulted in an accident. The mirror fell off the desk and got damaged.

      Luckily, only the back side got damaged, the front side was still working:

      The final designs of mirror holders looks like this:

      The holes in the front surface let me apply pressure on the back of the mirror if I ever want to separate it from the holder. The recesses collect the excess glue to avoid mirror skewing when gluing them.
      All other holes are simply to save the filament.
       
      Part 5: Placing mirrors
      What I learned is that you can’t plan positions of several pieces with high precision and just hope that it all comes together. I needed a feedback about the precision of mirror positions.
      I used a laser pointer to verify mirror positions at each step.
      In the picture you can see that the laser is firmly set in a hole in another piece of wood, with layers of isolation tape on the tip of the laser pointer to make it stable. A clamp holds the piece of wood in place, ensuring that the laser ray goes in the same direction as a solar ray would. A crosshair of black thread at the center of the lens ensures the laser goes exactly through the center of the lens.


      When placing each mirror, I marked the spot where I expected the laser to end up. While gluing the mirror holder to the frame, I kept the laser as close to that spot as possible. If for some reason, the laser couldn’t hit the expected spot, I did my best with placing the mirror, and recalculated locations of the following mirrors.
      I saw the first sunspots after placing all the mirrors and simply holding an eyepiece in hand.

      Part 6: Eyepiece holder
      I tried eyepieces of different focal length and liked the picture I got with a 10mm eyepiece the most.
      An eyepiece needs to be in a very exact spot to produce a sharp image. At this point it was obvious that my frame doesn’t match the model, and that I didn’t even know what exactly was wrong with the frame. I didn’t want to rely on the model and moved forward with trial-and-error.
      I printed several parts to hold the eyepiece, with different eyepiece locations:

      The part in the photo was a total disaster. It needed quite a lot of filament, at the same didn’t have enough surface area to be glued to the frame, and not enough surface area to hold the eyepiece firmly.
      The next iteration was a lot better:

      This part has a lot more surface area, and needs less filament to be printed. I intentionally printed the hole for the eyepiece too small, and had to sandpaper it a little bit, to make the eyepiece stay firmly fixed.
      Adjusting the focus is done by sliding the eyepiece up and down until the Sun becomes a circle with well defined borders.
       
      Part 7: Dust
      All optical parts should be kept clean. Dust on the mirrors and the lens will make the image darker. Dust on the eyepiece will show up as artifacts on the projected image. Unlike sunspots, the artifacts will not move with the Sun. To clean the eyepiece I used compressed air. To clean the mirrors I used isopropyl alcohol.
       
      Part 8: Fire safety
      Don’t leave devices with magnifying lenses lying around. Once the Sun happened to be in such a spot that its light went right through the lens, burning through the cap of the eyepiece. Luckily, nobody was hurt and no other damage was done.

      Part 9: Future work
      Build quality of the base is very poor. The frame tilts sideways when adjusting its altitude despite all my efforts. I’d like to build a new base, but leave all the work to the machines. I already have a model for an X-Carve to make both base parts, compatible with my current frame:

      A notch along the edge of the half-circle should eliminate the tilt. The precision of the machining should make the base very stable. Maybe next year, when sunspots become a common daily sight, I’ll get to this project.
       
      Thank you for reading this far!
      I hope you enjoyed it.
    • By Dan20
      I'm trying to buy a 10" or 12" dobsonian and I found this website https://www.telescope.com/ 
      Turns out they have free shipping and can ship anywhere.
      Can I trust this website?
       
    • By starcorral
      My club's Atlas is stuck on the date 11/13/2099.   Last night was 6/28/2019.  Every time I reset the date and started the 3 star alignment the scope chose Vega and then pointed to the western sky - sorta wonky.  When I tried a second star it aimed at a totally wrong part of the sky.  I went back to date and it had reset to the11/13/2099 date.  The mount has a working GPS module.   I went through all the menus and there was no place other than the " sub menu to attempt to replace the errant date.  After five tries I gave up.   Apparently the GPS was accurate to withing a stride or two.  What should I try next?   I know my club; they'd rather stuff it in a corner than take the time or money to fix it.  So it will be m time and my money.  I used the mount several times this year and had no problem.
    • By Bellatrix2
      Greetings,
      I'm super happy to have found this forum of night sky enthusiasts and look forward to learning and sharing on this site! I am an amateur stargazer fortunate to live in a rural area with great dark skies. I'm used to using a GoTo Celestron.
      Unfortunately I'm having a problem with a newly purchased Orion SkyQuest XTg 10. 
      I've only used it a couple of times. Recently, when I turn on the power, the hand controller (a SynScan V4 GoTo, version 04.39.04) states a message "Both axes...no response!" which means the motors won't work. 
      I've unplugged all the cords & replugged to no avail. The power comes from a new Orion Dynamo Pro, 12 V, Lithium Power Supply which was recommended.
      Does anyone have any ideas what the problem might be?
      Thank you 🌟
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.