Join for FREE
It only takes a minute!
Zeiss - Always on the lookout for something special – Shop now

Welcome to BirdForum.
BirdForum is the net's largest birding community, dedicated to wild birds and birding, and is absolutely FREE! You are most welcome to register for an account, which allows you to take part in lively discussions in the forum, post your pictures in the gallery and more.

Opinion on one good astro-spotting

Reply
 
Thread Tools Rate Thread
Old Wednesday 14th August 2019, 21:37   #1
pluton
Registered User

 
Join Date: Jul 2019
Location: spain
Posts: 12
Opinion on one good astro-spotting

Hello,
I am looking for information on some good spotting scope that works well also for astronomical observation.
Thanks for your comments.
Pluto
pluton is offline  
Reply With Quote
Old Thursday 15th August 2019, 15:26   #2
Binastro
Registered User

 
Join Date: Aug 2012
Location: S.England
Posts: 4,455
Pluto (still a planet to me).

It depends what kind of astro observation.

Much more important is a dark clear sky.

For planets, to see any detail, one needs 100x.
For deep sky, clusters, nebulae anything will do.

However, maybe 80mm or bigger.
I suppose a Nikon Monarch 82ED as reviewed by Henry would be the best.

Generally spotting scopes aren't great for astro work.
If one has a car then a spotting scope and a separate astro scope would be my choice.
Say a 6 inch or 8 inch good quality Dobsonian, and a spotting scope for birds.

Regards,
B.
Binastro is offline  
Reply With Quote
Old Friday 16th August 2019, 12:19   #3
slingworks
Registered User

 
Join Date: Jul 2015
Location: OH
Posts: 80
That's really a tough challenge to combine both....

I'd say you might want to look for a spotter with a longer focal length to start with. What are you looking to spend? I've looked up with both angled and straight scopes and suggest a straight if you want it to cover everything.
slingworks is offline  
Reply With Quote
Old Friday 16th August 2019, 14:28   #4
opisska
Jan Ebr
 
opisska's Avatar

 
Join Date: Mar 2012
Location: Warszawa
Posts: 1,156
Honestly, at the diameters that make sense for a spotting scope in terms of practicality, astronomical viewing will always be mediocre, so it almost doesn't matter. Yeah, when you find yourself with a spotting scope under clear dark sky, it's fun to have a look once in a while, but there is simply so much more the night sky has to offer with a proper telescope. It doesn't even have to be expensive, just bulky, because diameter is what matters.
__________________
Birds: world 2002, WP 561 (#1 Czech WP birder!*)
Mammals: 238
* and my wife is #3
opisska is offline  
Reply With Quote
Old Friday 16th August 2019, 17:54   #5
henry link
Registered User

 
Join Date: Feb 2004
Location: north carolina
Posts: 4,386
The Nikon Monarch 82ED specimen I reviewed was optically equal to a very high quality astronomical APO refractor of the same aperture, but it has two disadvantages for astronomy. Firstly, the 45º angled prism is IMO much less comfortable for viewing objects near the zenith than a 90º star-diagonal and secondly at the moment there is no easy way to achieve magnifications above 60X, which means the full potential of the scope's resolution of lunar and planetary detail can't be realized.

A cherry specimen of the Kowa TSN-883 is also a high quality APO and combined with the Kowa 1.6x extender or either the Kowa or Baader 1.25" eyepiece adapters with short FL eyepieces for higher magnifications would be be more useful.

Small high quality refractors in the 80-100mm range can be very effective portable astronomical telescopes, especially for lunar and planetary observing, sometimes outperforming much larger mirror scopes with image quality degraded by large central obstructions, slower cool down times and higher wavefront errors.

Last edited by henry link : Friday 16th August 2019 at 18:51.
henry link is offline  
Reply With Quote
Old Friday 16th August 2019, 19:03   #6
wllmspd
Registered User

 
Join Date: Feb 2008
Location: Hampton
Posts: 239
I’d go for a skywatcher, APM or William Optics refractor and then use Astro eyepieces (wide choice of wide angle) with an erecting diagonal. Optically great(as long as you get an apo), but heavy and less portable that spotter. Depends what your priority is... I use a 66mm refractor as a spotter and its great.

Peter
wllmspd is offline  
Reply With Quote
Old Friday 16th August 2019, 19:27   #7
Tringa45
Registered User

 
Join Date: Dec 2017
Location: Cologne, Germany
Posts: 273
Pluto,

Although I would not describe myself as a hobby astronomer, I think I can say that a good birding scope will open up possibilities for astronomical obsevations that no birding binocular can.
With standard eyepieces above about 25x you are going to be able to see Saturn's rings, cloud bands on Jupiter and its Galilean moons, impressive views of craters on the moon and, with an appropriate filter, sunspots.
I made up a filter using Baader Astro-Solar film for mv Swarovski ATM 65HD and unfortunately missed the Venus transit in 2012 due to bad weather (don't think I'm going to make it to the next one ) but did see the Mercury transit in 2016.

Many good birding scopes will cope with more magnification than with the standard eyepieces and I have used a 3,5 mm Televue Nagler with astro adapters on the Swaro (130x) and on my Kowa 883 (140x) to measure resolution. For observation though, it is important that the astro adapter attaches to the scope body and not the eyepiece, allowing a rapid change. I usually plop in a 28 mm RKE as a finder and then change to a shorter focal length for detailed observation. The Swaro has lots of in-focus but with some eyepieces I cannot achieve infinity focus on the Kowa.

Finally, the only possible disadvantage I see compared to similar sized astronomical refractors is some flare on bright objects. However, if you are looking for dual usage, the disadvantages of the latter for birding (weight, 90° reversed image viewing and lack of waterproofing) far outweigh this.

John
Tringa45 is offline  
Reply With Quote
Old Friday 16th August 2019, 20:25   #8
opisska
Jan Ebr
 
opisska's Avatar

 
Join Date: Mar 2012
Location: Warszawa
Posts: 1,156
Quote:
Originally Posted by henry link View Post
Small high quality refractors in the 80-100mm range can be very effective portable astronomical telescopes, especially for lunar and planetary observing, sometimes outperforming much larger mirror scopes with image quality degraded by large central obstructions, slower cool down times and higher wavefront errors.
There is indeed a group of die hard fans of small refractors who happily spread this kind of rumors, but not once were they able to show me this to be true in direct comparison. The horror tales of central obstruction and wavefront errors perpetuated by refractor enthusiasts exist mostly due to the ubiquity of poorly colimated Newtonians around, giving this design a bad rep that is completely unwarranted.

If you are able to follow a simple, five-minute procedure with your Newtonian to achieve proper collimation, a parabolic mirror on axis shows a perfect, error-free image. No amount of optical coolness will overcome the physical limitations that come with diffraction on a small aperture. I am not saying that watching planets with small apochromates can't be fun, but the bit about outperforming much larger apertutes is nothing but wishful thinking started by people who don't want to accept that there is no way to avoid lugging around freakishly large optics.

Again, if you are limited in what you can pack, for example travelling by airplanes, then most of this advice given here is sane. If you want to enjoy stargazing and can afford to transport large mirrors, then the best solution is to get a separate telescope for it. One thing to note is that compared to high-end spotting scopes and apochromates, large reflectors (on Dobsonian mount) are almost unbelievably cheap, with complete 30cm telescopes being available for 700 euro or so.
__________________
Birds: world 2002, WP 561 (#1 Czech WP birder!*)
Mammals: 238
* and my wife is #3
opisska is offline  
Reply With Quote
Old Saturday 17th August 2019, 12:39   #9
henry link
Registered User

 
Join Date: Feb 2004
Location: north carolina
Posts: 4,386
opisska,

I was thinking of commercial quality SCTs with obstructions above 30% and corrections no better than the usual 1/4 wave specification. A Newtonian with a really good mirror and a 20% or smaller obstruction would certainly be a different animal for planetary viewing.

I recall taking my 92mm Astro-Physics Stowaway to a public viewing of Mars during the 2003 opposition. The other telescopes available were Celestron C-8s. Pretty soon a line formed behind the Stowaway as word spread that the best view was through "the little one". If there had been an 8" 1/10 wave Newtonian with a 15% obstruction available I'm sure that would have been the scope with the line.

Henry
henry link is offline  
Reply With Quote
Old Saturday 17th August 2019, 16:59   #10
Binastro
Registered User

 
Join Date: Aug 2012
Location: S.England
Posts: 4,455
Hi,
I agree with opisska.

The great observer George Alcock used a 4 inch f/12 Ross triplet refractor to observe Mars.
Nobody believed his drawings or observations, as he was seeing as much as experienced observers using 16 inch Newtonians.

So he gave up the planets and learnt 30,000 stars by sight, and discovered 5 novae and 5 comets, sometimes through double glazing with perhaps a 20x60 Soviet binocular.
He generally used a Schneider 25x105 triplet binocular.

However, looking at actual observations by dedicated planetary observers about 85% use reflectors and 10% to 15% refractors.
The refractors were the 12 inch Northumberland at Cambridge, and the approx 30 inch at Meudon France. Perhaps one smaller one.

Dawes used a 6.5 inch refractor.

I had essentially perfect 4 inch refractors, but my 8.5 inch Newtonian showed more. It also showed more than the observatory 135mm refractor.

My 12.5 inch Dall Kirkham was in a different league to these refractors, as was Dall's 8 inch Maksutov.

Incidentally, I clearly saw and followed the Mercury transit with a filtered 3x opera glass costing about £5 or less. These were also given away free by a British bank.
The Venus transit was an easy unaided object with a large welders glass shade 14.

Regards,
B.
Binastro is offline  
Reply With Quote
Old Saturday 17th August 2019, 17:16   #11
Binastro
Registered User

 
Join Date: Aug 2012
Location: S.England
Posts: 4,455
My friend has both a superb 7 inch Astrophysics refractor and an excellent Celestron C14.
The C14 is clearly better both visually and for world class planetary images.

Another planetary observer uses his 8 inch Newtonian for the most beautiful high resolution drawings.
He also uses a 20 inch Planewave Dall Kirkham.

I nearly always chose to use my 6 inch Maksutov rather than the superb Pentax 4 inch refractor.

B.
Binastro is offline  
Reply With Quote
Old Saturday 17th August 2019, 20:15   #12
Binastro
Registered User

 
Join Date: Aug 2012
Location: S.England
Posts: 4,455
In the 1980s I bought a used 6 inch f/8 Newtonian for £40.
The mirrors needed recoating as they were dull.

On looking through this telescope for the first time I was staggered by the quality of the view on the moon and planets. It was a complete shock.

What I had got was an AE Engineering heavy scope with optics made by Jim Hysom. His brother was the proprietor of AE.

The diagonal was 25% obstruction.
In my opinion this telescope is the equal of a top quality 4 inch refractor. In fact I think that it equals a top quality 4.5 inch refractor.

I was brought up on refractors, but later realised how good reflectors could be.

My 20.5 inch Newtonian mirror made by Jim Hysom's friend was 1/20th wave. I think that the 6 inch f/8 optics are exceedingly good as were most of Jim Hysom's optics. His B grade optics usually were better than others A grade.

There is nothing wrong with people who value and use apochromatic refractors.
But a good reflector can be mind blowingly good if made with skill, and even with a 25% obstruction.

I appreciate any scope if well made.

Regards,
B.
Binastro is offline  
Reply With Quote
Old Saturday 17th August 2019, 22:56   #13
Tringa45
Registered User

 
Join Date: Dec 2017
Location: Cologne, Germany
Posts: 273
Quote:
Originally Posted by Binastro View Post
Hi,
Incidentally, I clearly saw and followed the Mercury transit with a filtered 3x opera glass costing about £5 or less.
On my filtered and tripod-mounted 65 mm birding scope at 30x it was a comfortable view, but with an angular diameter of 13" at 3x would be beyond the visual capabilities of most of us.
https://commons.wikimedia.org/wiki/F..._9th,_2016.png

John
Tringa45 is offline  
Reply With Quote
Old Sunday 18th August 2019, 14:29   #14
Binastro
Registered User

 
Join Date: Aug 2012
Location: S.England
Posts: 4,455
Hi John,
I thought so too.
But this wasn't the case.

I think that Mercury was nearer 12 arcseconds diameter.

I first tried a filtered 7x binocular. It was easy.

Then the filtered 5x25 Foton. Surprisingly easy.

So I thought. Can I go to something smaller.

I had this exactly 3x part coated opera glass.
Much to my surprise Mercury was a tiny dot using an optimum filter.
I was able to follow Mercury across the Sun.

I could see sunspots with a penumbral diameter of 38 arcseconds with a tilted large welders glass 13 to optimum density. Unaided eyes but distance glasses.
Or 34 arcseconds with my head resting against a lamp post for stability.

However, Mercury is darker and black whereas sunspots have fuzzy grey edges.

People with very fine acuity have no problem seeing 20 arcsecond sunspots on a regular basis. Unaided eyes optimum filtering.

So I always wondered if a Mercury transit could be seen by human eyes.
I think the answer is yes. Young Aboriginal Australians have 20/6.7 vision with a best measured at 20/4.7.
So with optimum density safe filtering, I think Mercury would be seen crossing the Sun.

Regards,
B.

P.S.
For May transits the diameter of Mercury is 12 arcseconds.
For November transits the diameter of Mercury is 10 arcseconds.

The 2019 November 11 Mercury transit is only partly visible in Europe.
The full transit is visible from central and south America.
Japan and Australia will not see the transit.

For the U.K.
The solar diameter is 32'18.6"
Mercury diameter 10.0"

Last edited by Binastro : Sunday 18th August 2019 at 15:37.
Binastro is offline  
Reply With Quote
Old Sunday 18th August 2019, 16:02   #15
henry link
Registered User

 
Join Date: Feb 2004
Location: north carolina
Posts: 4,386
I'm not at all surprised by this since a single dark spot or line on a light background can be detected at a much smaller angular size than what is required to resolve two spots or lines separated by a space of the same width as the spot or line. With a filter detecting a dark Mercury against the face of the sun shouldn't be much harder than detecting a bright Mercury against a twilight sky.
henry link is offline  
Reply With Quote
Old Sunday 18th August 2019, 16:27   #16
Binastro
Registered User

 
Join Date: Aug 2012
Location: S.England
Posts: 4,455
As to the original post.

I doubt that a birdwatcher wants to fill his car with a 30cm Dobsonian.
That is why I suggested a 6 inch or 8 inch.

One of my colleagues transports his 20 inch Dobsonian in an old Volvo estate car or station wagon.

One of the best astro observers I know only uses binoculars, monoculars and small spotting scopes up to 65mm on photo tripods.

We are all different.
It is up to the observer to choose the form of observing and equipment.

Regards,
B.
Binastro is offline  
Reply With Quote
Advertisement
Reply


Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Astro Eyepieces on spotting scopes? giosblue Spotting Scopes & tripod/heads 47 Wednesday 17th February 2016 13:50
Astro Eyepieces id spotting scopes? giosblue Spotting Scopes & tripod/heads 1 Monday 9th November 2015 21:50
Astro eyepieces in spotting scopes michaelmorris Spotting Scopes & tripod/heads 17 Wednesday 27th January 2010 17:27
Difference? Spotting vs Astro Scopes Paul Godolphin Spotting Scopes & tripod/heads 38 Friday 11th September 2009 12:30
Zennox spotting scope opinion please oldbaldman Spotting Scopes & tripod/heads 0 Tuesday 24th April 2007 21:42

{googleads}

Fatbirder's Top 1000 Birding Websites

Help support BirdForum

Page generated in 0.19329405 seconds with 28 queries
All times are GMT. The time now is 09:22.