Spotting scope for casual astronomy, or something else? (1 Viewer)

[BoldenEagle]

I currently have Kowa Prominar Tsn-883 spotting scope which I use for moon and planets. Often with 1.6x extender with 25-60x TE-11WZ zoom but sometimes also APM 3.5 mm 1.25" eyepiece. In good seeing these can give very pleasing image quality and details (in my opinion), even the 3.5mm @about 145x magnification with 883. Couple of times I tried the 3.5mm eyepiece with the 1.6x extender resulting to about 230x but image quality was quite bad and no more details were showing.

I'm wondering which would be more reasonable; upgrade to a bigger aperture spotting scope (probaly through exhausting journey to find a low aberration sample...) which I can still use for birds also, or buy a specific astro telescope? I don't want to spend thousands of euros, so refractors are(?) out of question but as I understand, some dobsonian reflectors have good quality/price ratio and they would cost only some hundred euros? I have a place with quite low light pollution and I don't have to carry the scope far away from my house.

Any advice appreciated.

Regards, Juhani

 

[opisska]

The benefit of a larger spotting scope for astronomy will be marginal - you already have 88 mm aperture, they don't make them much larger than that anyway - and the spotters aren't optimal for very high magnifications (relative to their aperture) anyway, considering that they are fast (short).

Now there are obviously two separate reasons to get a bigger scope for astronomy - magnification (for Moon/planets) and light gain (for distant objects like nebulae, galaxies, star clusters). A 10" Dobsonian (which I got 15 years ago for 400 EUR, today it is surprisingly a bit more expensive) will provide a marked improvement in both aspects - however you also need appropriate eyepieces, which may add to the cost. The gain in magnification is typically less than one would expect, because above 200x, the atmosphere is often the limit, not the telescope - but when conditions are good, the larger telescopes really shine. A Dobsonian is, by a long stretch, unbeatable in value for money for astronomy - but requires some skills in handling.

 

[Binastro]

I would suggest a 200mm or 8 inch Dobsonian or 10 inch if you are strong.

Maybe a Skywatcher.

You have to carry the base and tube probably separately.

If it is moved often it may need recollimating sometimes. This isn't difficult assuming it has the necessary screws.

I have done a lot of astro observing in Finland with my 8.5 inch f/6 Newtonian, 6 inch Maksutov and 100mm f/12 Pentax refractor.
Also observatory refractor and poor 8 inch C8.

The Seeing can be exceptional in autumn but in winter at minus 20C or minus 25C I had trouble with icing on the eyepieces.

The 8.5 inch mirror I kept separately, but it survived minus 30C and my friend's 20cm mirror about minus 35C.

My cameras worked at minus 35C.
Other cameras worked well at minus 37C and I think the Nikon FM2n works at minus 50C.
I don't know about digital cameras.

In summer it can be too light.

The planets are lower than in the U.K. but Jupiter is high now.

If you don't need to move then a 12 inch or 14 inch Dobsonian is nice.

In the U.K. I used a 14.5 inch tubeless Newtonian, just a thick post holding the secondary and a 20.5 inch Newtonian, which was too big for me.
Also 120mm refractors.

You don't need expensive eyepieces but 82 degree ones do provide wider fields and less moving the scope.

My friend tracks well at 650x with his 14 inch Skywatcher Dobsonian.

Regards,
B.

 

[BoldenEagle]

Thanks opisska and Binastro.

Yes I have already noticed how detrimental effect poor seeing can have when birding but I was a bit suprised how strong the effect is with celestial targets also. First times watching Jupiter with 3.5mm eyepiece I thought my scope was the reason for the minimal details showing but after that in better seeing it was obvious that it was just bad seeing/planet quite low on the horizon. I had very good views yesterday with 3.5mm eyepiece for Jupiter and I felt that my scope could handle even some more than 145x magnification. Moon being high on the sky I have had very good views couple of times @145x and there has definitely been more details than using the 25-60x zoom with the 1.6x extender @96x. Sometimes the view is just soft already @96x and @145x it just gets even worse.

I currently have 3.5mm and 12.5mm eyepieces to begin with if I decide to get a Dobsonian. Maybe get one or two more later. So I guess a Maksutov makes no sense if I don't have to carry the scope a lot? I do have Berlebach UNI tripod, which could support several kilograms and I could use it with Maksutov type telescope?

Regards, Juhani

 

[Binastro]

The Skywatcher 8 inch Dobsonian is 1200mm fl as is the 10 inch.
So for planets there is much to be said for the 8 inch at f/6 compared to f/4.8. for the 10 inch.
Both have parabolic mirrors.
The scopes cost about £400 and £ 600 new.

For deep sky work the 10 inch is probably better.

For the 10 inch, eyepieces giving 40x, 80x, 140x, 200x, 250x, 300x and 400x covers most possibilities.
200x and upwards for planets, planetary nebulae and double stars.

Pretty similar for the 8 inch.

A 2x Barlow can be used to reduce the number of eyepieces. Preferably a good quality Barlow.

At 1200mm fl the 3.5mm gives 340x which is usable on the better nights.
It is always better when the planet is higher and the really good Seeing comes at 3 a.m.

The 12.5mm gives 96x, say 100x as eyepieces are usually a bit different to marked values.

If the scope comes with a Barlow you have 200x, but the field may be narrow.

Personally,I am quite happy using older Japanese Kelners, orthos, Plossls and Erfles.
Secondhand ones might need cleaning.
Also the RKE original version is very good.

If it has a 2 inch eyepiece tube the 32mm Erfle is good.

The old eyepieces have small eye relief, so if you wear glasses, more modern eyepieces are better.

Regards,
B.

 

[Binastro]

The Berlebach could support a 5 inch or maybe 6 inch Maksutov.
The Russian Maksutovs are good but heavy.
The Skywatchers lighter.
My 127mm Skywatcher Maksutov is poor optically, but some are good.
It is actually only about 118mm aperture.

The problems with Maksutovs are the front corrector takes long to cool and can get dewing on the front.
The Dobsonians have the primary at the bottom.

For my windowed 12.5 inch Dall Kirkham I used a small hair dryer not too hot as I didn't want to crack the optical window.

Regards,
B.

 

[albie...]

I made the mistake of downsizing my 10 inch dob to a 6 inch dob because of the hastle of lugging the 10 inch out of the basement . I rarely use the 6 inch because the views are a bit disappointing compared to my memory of the views through the 10 inch .
With the 10 inch I've watched the shadow of a moon transit on Jupiter and seen the big eye . I saw the gas clouds of the Orion Nebula . I actually thought they were Earth's clouds until I realized that it was a perfect cloudless night . I had a friend view Saturn with the 10 inch dob and she had a WOW moment and asked me if what she was seeing was real . I said "no it's a photograph taped to the other end of the scope" . That night I was able to see three splits in the rings . Very little turbulence in the upper atmosphere that night .
Suffice to say a f/4.7 ten inch dob is a great place to start to see decent detail . The dob in the picture is a 10" Skywatcher with some upgrades . Being an f/4.7 it's a bit fast so better ep's are needed . I had a nice set of Naglers at the time .

 

[Scott98]

I'm a big refractor lover, to the point where I haven't owned a mirror scope since the late 80's when I gave up on them. I wouldn't give up on a larger refractor. The lower-cost apos (usually w/ lens and/or tube made in China under a European brand like APM or American brand like Astro-Tech) can be machine-made with excellent quality these days.

Even a 102mm refractor will give a nice improvement on planets and deep-sky over an 88mm. And these apos will typically have better lens quality for high power.

The thing about spotting scopes that always bothered me is the 45-degree angle diagonal (or even worse, straight-through). I like using a 90 degree angle for astronomy, otherwise you're torquing your neck at zenith. I don't mind using a 90 degree angle for birds either, it seems fine. So I cover this area with a 92mm f/7 astronomy refractor. It's good for quick astro session or a really nice bird session. But I've used 102mm and 110mm refractors for birding too.

 

[MiddleRiver]

...
With the 10 inch I've watched the shadow of a moon transit on Jupiter and seen the big eye . I saw the gas clouds of the Orion Nebula . I actually thought they were Earth's clouds until I realized that it was a perfect cloudless night . I had a friend view Saturn with the 10 inch dob and she had a WOW moment and asked me if what she was seeing was real . ...

 

[Scott98]

These telesopes are the closest any of us are going to get to flying a spaceship around the galaxy! I love astronomy

You can see shadow transits on Jupiter in small scopes - for many years I used a 3.25" Jaegers f/15 refractor from my balcony in the city - mostly I would watch Jupiter every clear night and observe the moons. You can look up transit events on the computer beforehand and mark your calendar to catch them.

We have to talk to these birders more! The Orion nebula, M31, Pleaides, Hyades, are stunning in 42mm binoculars in dark winter skies. Many people here confess to never pointing their binos at the night sky! Tragic. I try to slip in a plug for astronomy whenever I can

 

[opisska]

I'm a big refractor lover, to the point where I haven't owned a mirror scope since the late 80's when I gave up on them. I wouldn't give up on a larger refractor. The lower-cost apos (usually w/ lens and/or tube made in China under a European brand like APM or American brand like Astro-Tech) can be machine-made with excellent quality these days.

Even a 102mm refractor will give a nice improvement on planets and deep-sky over an 88mm. And these apos will typically have better lens quality for high power.

This is something that refractor people often say, but I was never really able to see it. I acknowledge that there is a group of people who get a lot of enjoyment from small telescopes in astronomy and for whom the view through a refractor tickles some feeling that's hard to replace with other systems, but most people have a different experience.

 

[Maljunulo]

I spent quite a bit of time using my little Nikon Fieldscope ED for double stars.

It did quite well, I thought, and provided many hours of entertainment.

 

[Scott98]

I spent quite a bit of time using my little Nikon Fieldscope ED for double stars.

It did quite well, I thought, and provided many hours of entertainment.

I have commandeered Swaro spotting scopes a few times for quick looks Venus & the Moon during evening birding and it's always been a good view, the better scopes have great lenses for astronomy

 

[Maljunulo]

I have commandeered Swaro spotting scopes a few times for quick looks Venus & the Moon during evening birding and it's always been a good view, the better scopes have great lenses for astronomy

Double stars are an interesting challenge, and I very much enjoyed “chasing” them.

 

[Ignatius]

Could a binoviewer be fitted to a Dobsonian? I am better with two eyes than with one.

 

[William Lewis]

I'm by no means an expert on astronomy but I do dabble in it when the nights draw in.

I usually have 2 scopes set up, a Nikon monarch 82 with the 20-60 zoom and an 8" dobsonian that I have a few eye pieces for.

The dobsonian delivers much (really significantly) better views of the stars and planets, far more detailed views of Jupiter's storms, Saturns rings or various dso's for less than a third of the cost of the monarch and it's tripod etc - I don't have fancy eye pieces for it.

The spotting scope is useful though, I move it around the garden to see if something's worthwhile observing before moving the Dob.

There are 2 main downsides with a spotting scope for me. Firstly even in a well corrected spotting scope eye position is absolutely crucial to getting a good c.a free view compared to a reflector like a dob. Secondly finding your target object without a finder or a telrad or red dot etc is a right pain with a spotting scope.

 

[Scott98]

Could a binoviewer be fitted to a Dobsonian? I am better with two eyes than with one.

Yes, one of my friends with a 12" dob uses a BV all the time. He greatly prefers it to one-eye viewing.

 

[wllmspd]

Was out checking the collimation on a 127mm Maksutov last night on the moon and Jupiter. Lovely, colour free detailed views at 120x of fine rilles. Looks like it’ll be just fine running around 70x when I take it birding in January.

Peter