Getting started on stars

[Sprint]

Hello! The past few weeks have been a steep and slippery slope for me, after exhaustive reading and reviews i have gone full swing from merely thinking of high end binoculars with a monopod for stargazing to the realisation i need a scope in my life.

I have always been interested in stars and nebulae not just from a visual point but also navigational, travelling by car/4x4, orienteering, lots of camping etc and am at a point in my life where i can learn some of this vastness.

Anyway enough guff, i have as im sure many have been, going around in circles and i would really appreciate some clarity and advice 👍

I see M81 / M82 as my benchmark, and i think / hope this is not out of reach, am i right in saying;

1. a refractor is capable of seeing these but at great expense, best cooldown & travelling (collimation)
2. a reflector dob/newt is the cheapest way of seeing these, medium cooldown but large and worst travelling
3. a cassegrain is the most compact, medium cost, longest cooldown time, good travelling

Hopefully that is correct from the start lol! I really want to be able to see good detail and contrast, and colour definitely on nebulae, but want it to be able to travel with us on our adventures to see the skies from new vantages. My 4x4 is LWB Patrol so not like im trying to squeeze it in an Aigo 😉

Excited!

[miguel87]

That is roughly correct yes although cool down time isnt usually a big factor for people. More likely to come down to portability if you want to travel with it and cost. Collimation is straight forward after a couple of goes so dont let it put you off completely.

Dont expect to see any colour in nebula, at all. I have seen SLIGHT green in M42 once in more than ten years stargazing.

You can see M81 and 82 in any type of scope over about 3 or 4 inches depending on how dark your sky is.

[miguel87]

If your main interest is deep sky objects like nebula then a DOB or reflector is definitely your best bet for any given budget.

Of course you can get gorgeous images of such objects in a frac but it will cost you.

Do you want a scope that tracks objects or are you happy to keep gently moving a telescope to follow them?

Edited April 18, 2020 by miguel87

[Sprint]

I/we are keen to learn the skies so going for manual, use some books and apps to 'get our eye in' starting out, a decent tripod / mount is a must i think from a manually tracking POV.

Another big factor reading around is user height vs scope type / viewfinder straight or 90deg. I suppose a refractor would be easiest with drum stool - im 6' 4" and my missus is 5' 6" so changing seat height would be easier than scope height right?

I do see that a refractor would be easier to keep clean / no foreigns can get inside of it like a Dob / Newt?

It would seem i was optimistic on the nebulae, obviously the images i have seen are from extremely high power massive scopes - fail 😆🙈

Edited April 18, 2020 by Sprint

[miguel87]

3 minutes ago, Sprint said:

I/we are keen to learn the skies so going for manual, use some books and apps to 'get our eye in' starting out, a decent tripod / mount is a must i think from a manually tracking POV.

Another big factor reading around is user height vs scope type / viewfinder straight or 90deg. I suppose a refractor would be easiest with drum stool - im 6' 4" and my missus is 5' 6" so changing seat height would be easier than scope height right?

I do see that a refractor would be easier to keep clean / no foreigns can get inside of it like a Dob / Newt?

It would seem i was optimistic on the nebulae, obviously the images i have seen are from extremely high power massive scopes - fail 😆🙈

Even basic scopes can track with the additional of a fairly cheap motor.

Yes the lovely long exposure photos are gorgeous a long way from what we see with our eyes. This is my image of what I saw of the black eye galaxy in bortle 4 skies with an 8 inch newtonian reflector after studying the object for 15 minutes or so.

 

I guess cleaning might be easier but best bet is just to never touch or clean optics, just keep them covered when not in use, only take the cap off literally when you are observing. Cleaning regularly is likely to scratch optics. I have never cleaned any of my mirrors.

[carastro]

You are right about transportation,, but it does sound to me as though a dobson Newtonian would suit your needs very well, though it will need collimation after each transportation.

A cassegrain would also do.  Refractors are good but the magnification is much lower unless you can afford a  wacking great expensive one.  

I should ask a question though, whether you have any plans to get into astrophotography as this would greatly influence the choices you need to make and your budget.

Carole  

Edited April 18, 2020 by carastro

[miguel87]

This is a professional photo of exactly the same object,

 

[Sprint]

@miguel87 yes that is what i want to see 🤣 whilst driving along 😁

@carastro yes that was my findings - would need a vastly expensive refractor to reach out deeply. with regard to AP ultimately yes - my partner is into photography and i would love to have some personally captured images and memories at home, however starting out i am happy to miss the photography side to concentrate on learning the scope and skies without the 3rd complication of photography, i would rather purchase an additional specific scope at a later date for that foray.

Am i right in saying that something over 200x and F5-6 is needed for my intended viewing?? This is the point i start contradicting my findings.

[miguel87]

F ratio isnt super important and I wouldnt go any faster than 5 to start with but going over F6 would not be a problem, just that the scope will get larger to handle.

Yhe main thing you want is aperture. In my opinion, if you want to enjoy deep sky objects then get as much aperture as you can afford and move around to wherever you are going to observe from.

Also magnification isnt too important (unless you meant to say 200mm aperture). Magnification for galaxies might be somewhere between 20x and 100x, roughly speaking, depends on the galaxy as some are bigger than others. However, higher magnification always dims an image so if you want to preserve a dim object, keep magnification low.

If you meant 200mm then that is about 8 inches.  You can see galaxies with less, I had a 5 inch for years. But obviously it gets easier with more aperture and darker skies.

Edited April 18, 2020 by miguel87

[Sprint]

By faster do you mean higher or lower F: ? apologies

I did mean 200x not 200mm/8"

8" does seem to be the magic aperture size but hurty on the wallet for sure and large / bulky, definitely tricky to find the balance of all criteria, have not completely ruled out refractors yet, apochromatics seem to get nice images but unsure on magnification required to see M81 82 at a nice size and clarity, i dont want to just ID a dot id love to see their luminescent centre and the swirl.

[Sprint]

For example would it be possible to use a Skywatcher Apo 72 ED DS Pro for observation with the addition of viewfinder etc or just impractical?

[miguel87]

Seeing galaxy arms or swirls as you describe is not wallet friendly.

To see these visually requires a good dark site, I would say bortle 3 or less which is rural. I dont think even good suburban would be enough. And probably 10 or twelve inches of aperture. And good conditions. I have never seen detailed spiral arms. Maybe a hint of shape on andromeda when I was in exmoor with my 8 inch a couple of years ago. I think if you are expecting to see spiral galaxies you might want to try going to try out some scopes at a star party or similar because 99% of the time we dont see this at all. Just the faintest of smudges. I was observing the crab nebula this week but it was so faint in my 8 inch that I could not look directly at it, it would disappear so I had to use averted vision.

As for magnification you underestimate the size of galaxies. Even at 31x mag, the entire andromeda galaxy is too big to fit in my view. However, you would need incredibly dark skies to see the whole structure so we are usually just observing the faint hint of the bright core. I dont think you will find many people observing galaxies at 200x mag

And yes f5 or lower is considered fast.

Edited April 18, 2020 by miguel87

[miguel87]

1 minute ago, Sprint said:

For example would it be possible to use a Skywatcher Apo 72 ED DS Pro for observation with the addition of viewfinder etc or just impractical?

I guarantee you will not see galaxy spiral arms in a 72mm frac. No way.

What do you mean by viewfinder? Like a finder scope?

[Sprint]

Hi yes view finder / finder scope.

Please dont take my inexperience as ignorance, im slowly forming a picture!

If anyone needs any knowledge regarding motorsport engineering, chassis setup, vehicle electrics im a font of knowledge! 😆 So much fun learning something COMPLETELY new!

[miguel87]

3 minutes ago, Sprint said:

Hi yes view finder / finder scope.

Please dont take my inexperience as ignorance, im slowly forming a picture!

If anyone needs any knowledge regarding motorsport engineering, chassis setup, vehicle electrics im a font of knowledge! 😆 So much fun learning something COMPLETELY new!

No not at all. It's good that you are asking the right questions. I dont mean to come across as rude I am just trying to be as honest as possible.

The beauty of looking at galaxies is about WHAT you are looking at, the time and distances involved. Not how they look. Honestly, it is lots of slightly different grey smudges that are VERY faint. If you look at your fully illuminated phone screen whilst observing a galaxy your view will be lost entirely! The brightness of the phone will ruin your night vision and the galaxy will not be visible until your eyes adapt to the darkness again.

The 72mm frac with a finder scope will be a nice beginner scope I think. You could observe the moon, open clusters, venus and its phases, Jupiter's moons, saturn and a very small image of its rings. Bright nebula such as M42 (no colour or sharp detail) and many more things. But, a small frac is not a good telescope for viewing detail in deep sky objects.

 

[miguel87]

Of course a red dot finder or telrad might be easier than a finder scope (personal preference, many would disagree).

Glad you are exploring astronomy!

I have a fair few sketches which show roughly what you might expect under bortle 4 skies with an 8 inch reflector. Depends what information you are after.

Edited April 18, 2020 by miguel87

[Second Time Around]

17 minutes ago, miguel87 said:

I have a fair few sketches which show roughly what you might expect under bortle 4 skies with an 8 inch reflector. Depends what information you are after.

Do you have a link to these by any chance?  I find sketches much more useful than photos.

[miguel87]

They are all stored on my phone so I cant link them but I can share a couple.

 

[Second Time Around]

Many thanks, Miguel!

[John]

M81 and M82 can be seen with very small and low cost scopes. They were the 1st galaxies that I ever saw through a scope - a cheap and old 60mm refractor. I was so thrilled to see them, I kept staring at them for hours !

You can pick them up with 10x50 binoculars but they are defined better as a galaxy pair with a scope at around 25x magnification.

 

[Sprint]

Hi John, thanks for that, I'm trying to acertain visually what aperture focal ratio and mag will get me using M81/82 as a benchmark?

For example at what focal ratio and mag would M81/82 combined both fill the view?

I understand it that for the most part more aperture equals more light and thus contrast?

[John]

A 1 degree true field of view is large enough to see both M81 and M82 with a little bit of room left around them.

The combination that gets a 1 degree true field varies depending on the scope and eyepiece used.

As an example, a 102mm F/10 scope with used with a 20mm focal length plossl eyepiece shows a 1 degree true field of view and 50x magnification - enough to fit both galaxies in the view at the same time.

Larger apertures show the galaxies more clearly but they are visible in quite small scopes.

This sketch was made by Michael Vlasiv using an 205mm aperture newtonian, under a dark sky, and a 25mm eyepiece giving a 1.25 degree true field of view. As you can see, both galaxies fit comfortably within that:

 

[Sprint]

Hi, Thankyou, so if I have it the correct way around, to achieve a similar viewing area to that very nice sketch but with more magnification the scope would also need a faster focal ratio?

Do you know the math?

[miguel87]

With any given telescope you could in theory achieve any magnification that you want. Just change the eyepiece.

The focal length of the telescope is the only other factor in magnification, not the aperture. So for example my telescope has a focal length of 1000mm. So a 20mm eyepiece gives me 50x magnification (1000÷20) if I want to zoom in a bit I could put an 18mm eyepiece in and get 55.5x mag (1000÷18).

So if you are looking to achieve a particular view, you need to to find the right eyepiece for your telescope.

You could frame the two galaxies in almost any telescope. More aperture just means the quality of the picture will be better, no bigger or smaller.

And F number makes little difference visually.

Edited April 18, 2020 by miguel87

[John]

The true field of view is derived, roughly, from the apparent field of the eyepiece divided by the magnification that the eyepiece gives in the scope.

If you want a larger magnification and still to retain the same true field of view, you can use an eyepiece with a larger apparent field and a shorter focal length.

This online tool can be played around with to find what different combinations of scope and eyepiece can show in terms of field of view:

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

M81 and M82 are some of the targets available in the above tool.