Jump to content

sgl_imaging_challenge_2021_4.gif.6a323659519d12fc7cafc409440c9dbf.gif

what telescope (and accessories) to get


Recommended Posts

Hi

I've been interested in astronomy for quite a while and I have been using a vivitel 76700 telescope. I'm looking into upgrading to a better, bigger telescope but Im not sure what to get or what sort of things to look for in a scope. My main questions are:

• how much is reasonable for a first (decent) scope? Is £300 enough?

• apart from size what's the difference between a 5" and 8" scope?

• will I gain anything going for a bigger scope?

• will I need anything extra e.g. lenses, case etc.

• what do you guys suggest I should look at?

Thank you in advance for any help

Jake

Link to post
Share on other sites

Thank you for the reply, I'll have a look at the dobson, I quite like the sound of an 8" mirror, would it be a good idea to replace the mount for a decent tripod?

For £300 i think an 8" dobson would be the best buy. http://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-200p-dobsonian.html

It gives a lot of light gathering for the price.  If you later buy a couple quality eyepieces you have a good setup that enables you to see a lot of deep sky objects.

Link to post
Share on other sites

Thank you for the reply, I'll have a look at the dobson, I quite like the sound of an 8" mirror, would it be a good idea to replace the mount for a decent tripod?

you don't need a tripod with a dobsonion mount it might not look like much but these things are steadier than all but the expensive mounts they really are the most cost effective route into visual astronomy

Link to post
Share on other sites

The main difference between a 5" and an 8" scope is the surface area of the primary mirror. The greater the surface area of the primary, the more photons it can bring to focus. A little maths is useful to understand the difference between 5" and 8". The area of a circle is given by π r², so the area of a 5" diameter circle is π x 2.5², which is 19.63 in², and for an 8", π x 4² = 50.26 in². Doubling the diameter quadruples the surface area.

Link to post
Share on other sites

The main difference between a 5" and an 8" scope is the surface area of the primary mirror. The greater the surface area of the primary, the more photons it can bring to focus. A little maths is useful to understand the difference between 5" and 8". The area of a circle is given by π r², so the area of a 5" diameter circle is π x 2.5², which is 19.63 in², and for an 8", π x 4² = 50.26 in². Doubling the diameter quadruples the surface area.

You can keep it simple and leave PI out of it to get a useful ratio - (2.5²) : (4²) or 6.25 : 16.  It's handy when you're comparing a few different sizes or when ordering pizzas.

Rob.

  • Like 1
Link to post
Share on other sites

You can keep it simple and leave PI out of it to get a useful ratio - (2.5²) : (4²) or 6.25 : 16.  It's handy when you're comparing a few different sizes or when ordering pizzas.

Rob.

But .. all those times I hear folk say they learned things in maths at school and could never find a real-life application for it!

  • Like 2
Link to post
Share on other sites

• how much is reasonable for a first (decent) scope? Is £300 enough?

Yes, plenty.

• apart from size what's the difference between a 5" and 8" scope?

• will I gain anything going for a bigger scope?

The 8 inch scope will have 82/52=2.5 times the light-gathering of the 5 inch scope. Things that are faint in the smaller scope will be brighter in the larger one, and things invisible in the smaller scope may be visible in the larger.

The 8 inch scope will also have 8/5=1.6 times the resolution, increasing the maximum useful magnification for planetary viewing by the same amount, though in Britain you will often be seeing limited anyway.

• will I need anything extra e.g. lenses, case etc.

If you get a reflector, collimation tool. You can use a cap, but a Cheshire is more precise. Cheap lasers are best avoided.

• what do you guys suggest I should look at?

The Moon, Jupiter, and some Messier objects.
Link to post
Share on other sites

you have sort of entered the reflector refractor debate. essentially it comes down to cost, the cost per inch of a good reflector is substantially less than a good refractor and the quality of a good reflector is substantially better than a poor refractor.

As to mounts it is essentially how much do you want to spend and what do you want use it for. if you are just using it for visual all it needs to be is sturdy enough to keep the image from dancing around while you are looking at it goto is nice but its an extra not essential. This is where dobsonion mounted newtonions come into their own good, big, cheap optics on a very steady cheap mount if you just want to observe and portability is not an overriding concern these are the most cost effective way of looking at the universe.

If  you want to do any sort of imaging however than some sort of tracking mount at the very minimum is required, any tracking mount will do you for planetary imaging as long as its stable enough to keep the scope steady, basic long exposure dso astrophotography requires essentially eq tracking on just the ra axis. if you want to do decent quality dso astrophotography then a fairly substantial eq mount  which has goto and is capable of being guided are pretty much essential.

For the price you are looking at the 200p dobson is far and away the best scope there is (My scope and mount  cost over 4 times as much and sees less than a third of what the dobson can) hth

Link to post
Share on other sites

Really transport isn't the issue, its finding somewhere to store it when its not being used. Im more interested in visual use but it might get used for imaging later on. How easy is it to desperate the Dobson from the mount? I did come across this scope, looks nice and the tripod looks decent

http://www.firstlightoptics.com/maksutov/skywatcher-skymax-127-eq3-2.html

  • Like 1
Link to post
Share on other sites

I've been looking at more reviews/videos of the dobsonian and I am leaning more towards it. (Promise its the last time i ask now) I know it costs more and has a smaller focal length but what about the skywatcher explorer 200p? I only ask because it looks easier to transport and store. Would I really notice the difference in length seen as all I have played with is one of maplins specials

Would I need any filters or extra eyepieces?

Link to post
Share on other sites

transport wise its about the same, but the dob has a smaller footprint so is easier to store.  however if you ever want to do any astrophotography the explorer is the way to go although to be fair this isnt the best set up for the discipline.

Filters and eyepieces are best to get after you have your scope. Two reasons for this 1 is that you don't really get an idea of what suits you until after you have used it and 2 it gives you something to look out for once you have received your scope and you are waiting for the weather to improve so that you can use it

Edited by rowan46
  • Like 1
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.