Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Altair ASCENT 102mm F11ED Refractor vs Skywatcher 120ED for Visual Astronomy

  • Please log in to reply
41 replies to this topic

#26 barbie

barbie

    Apollo

  • *****
  • Posts: 1,050
  • Joined: 28 Jan 2013
  • Loc: Northeast Ohio

Posted 29 December 2019 - 03:07 PM

Polychromatic Strehl, mating element glass and other properties aside, the 4" F11 will be a better planetary and double star instrument.  The build quality of the Altair Starwave 4" F11 ED is also much better, by a fair margin.  It has a much better focuser(I never really liked Crayford type focusers) and it has many other attributes which make it the better option for this type of observing.  The Skywatcher, while excellent, would be my second choice.  After having owned the Skywatcher 100 ED F9 and the 120 ED F7.5, I've found that the 4" F11 has the superior optical figure and virtually no spherical aberration( at least not detectable visually) on my sample.  It splits close doubles far better with tighter, more pinpoint stars than the Skywatcher and the color correction is better at F11. It is an excellently corrected ED doublet and the longer focal length is more forgiving of simpler eyepiece designs.  I recently tested my Altair 4" f11 against my Takahashi FC100 and the F11 at $775.00 easily approaches the same textbook star test as the FC100, virtually identical results on every double I've compared the two scopes on.   If that seems like high praise for the Starwave ED F11, it is well earned.  Whomever makes the scope for Altair Astro knows what they are doing and takes the time to do a well thought-out Q.C. on their products!!  Of course, you don't get all the little extras like you do with the Skywatcher, but those can be easily obtained for little extra expense.  IMO, the Starwave 4" f11 is the better scope.


  • Uwe Pilz, beanerds, eros312 and 2 others like this

#27 BillP

BillP

    Hubble

  • *****
  • Posts: 19,080
  • Joined: 26 Nov 2006
  • Loc: Spotsylvania, VA

Posted 29 December 2019 - 07:26 PM

This is absolutely wrong. Visual estimates of variable stars are STILL HIGHLY SCIENTIFICALLY USEFUL. ...

Ahhh...I knew someone would crawl out of the woodwork to find the very few esoteric examples that exist.  But let's be real, so you have some examples of variable study, and transit timings, and the like, and those all of a sudden make getting larger apertures preferred because of their better scientific benefit to those viewing....various faint fuzzies to knock off the Herschel 400 list, or Messier Marathons, or being able to split very tight doubles.  Sorry...but those few endeavors that can still be accomplished via visual observation with amateur level instruments are far, few, and while somewhat useful in a general way really not relevant to mainstream astronomical research today. 

 

So let's not blow things way out of proportion beyond what they really are.  No professional astronomer is going to make it in their career by observing variables to determine periods and approximate magnitudes visually as their mainstay.  What contributions amateurs do make to mainstream science is probably no more than a fraction of a percent of professional research, and it is mostly in areas professionals do not want to cover as there is no opportunity for funding for that kind of stuff as it is low interest.  99% of amateurs and amateur equipment is used for enjoyment, fun, elementary learning/outreach, and edification.  It's not for any direct furthering of some line of scientific inquiry and they are not doing professional science.  Thinking that amateurs looking at DSO with their big obs are somehow now being scientists is like thinking that geeks using Microsoft Flight Simulator are now somehow piloting lol.gif  I know how everyone wants to be thought of as a scientist in some way, but let's face it for the most part we are all just out in the field at night having fun under a dark sky, nothing more.  And not that that is bad, just not doing science or being a scientist.  Just being a lay person whole likes to look at the stars and other celestial objects as a passtime for enjoyment and relaxation.


Edited by BillP, 29 December 2019 - 07:39 PM.


#28 Astrojensen

Astrojensen

    Voyager 1

  • *****
  • Posts: 12,531
  • Joined: 05 Oct 2008
  • Loc: Bornholm, Denmark

Posted 30 December 2019 - 03:40 AM

Ahhh...I knew someone would crawl out of the woodwork to find the very few esoteric examples that exist. 

Bill, did you even bother to read the link from AAVSO? The area of variable stars is so criminally underobserved, that professionals that study some of these stars are HIGHLY dependant on amateur work, including visual. Some stars are so poorly observed professionally, that they don't dare to point a multimillion telescope or spacecraft at them, before an amateur has checked their brightness beforehand, lest they destroy a sensitive detector by flux overload. A lot of variable stars are in a magnitude gap, where they are ONLY regularly observed by amateurs, including visual. And there are so many of them, that in many cases, the last observation was weeks or even months ago. Anything could have happened in those gaps, but no one knows, because no one was looking.  

 

 

No professional astronomer is going to make it in their career by observing variables to determine periods and approximate magnitudes visually as their mainstay.

No, but they rely on amateurs doing that for them. That is what I mean by doing "professional work" visually. You accumulate data, that the professionals can use. Professionals simply can't get the decade-long uninterrupted telescope time that amateurs can (most can barely get any telescope time at all), and it's precisely the very long timelines that make amateur observations highly useful. For some stars, observations go back uninterrupted for hundreds of years, all made with roughly similar size equipment and identical method, which makes it uniquely constant and statistically reliable. It is of the utmost importance for calibration, that these observations continue in the future.  

 

 

What contributions amateurs do make to mainstream science is probably no more than a fraction of a percent of professional research, and it is mostly in areas professionals do not want to cover as there is no opportunity for funding for that kind of stuff as it is low interest.

I think stellar evolution is not an area of low interest. It's pretty much key to understanding how a lot of things work in the universe.

 

I am well aware that most amateurs, visual or otherwise, aren't doing scientifically useful work and never will, nor should they feel forced to do so, but that is no reason to ridicule what scientifically useful work they can actually still do, if they choose to. 

 

 

Thinking that amateurs looking at DSO with their big obs are somehow now being scientists is like thinking that geeks using Microsoft Flight Simulator are now somehow piloting

Where the heck did that even come from? I never mentioned deep-sky observing as an area where visual amateur astronomers could do useful work.

 

And I think there's a great misunderstanding in the idea that just because one telescope is larger than another, then it's automatically more suitable for scientific work. It doesn't work that way. It's more suitable than the smaller one for some areas of research, but the small one is perfect for others. A carefully chosen and executed observing program with a small telescope can be just as uniquely scientifically useful, as one from a large telescope. Telescopes are tools and you choose the right tool for the job or the right job for the tool. You don't repot bonsai with the world's largest excavator, nor do you remove overburden in an open pit coal mine with a potting shovel. 

 

 

Clear skies!
Thomas, Denmark 


  • daquad, Uwe Pilz and Bean614 like this

#29 barbie

barbie

    Apollo

  • *****
  • Posts: 1,050
  • Joined: 28 Jan 2013
  • Loc: Northeast Ohio

Posted 30 December 2019 - 06:29 PM

I agree! I used to do variable star observing and spectroscopy and they are very scientifically valuable areas of research, both to the amateur and professional astronomers.


  • daquad, Astrojensen, mikeDnight and 1 other like this

#30 John Huntley

John Huntley

    Vanguard

  • *****
  • Posts: 2,332
  • Joined: 16 Jul 2006
  • Loc: Portishead, SW England - mentioned in the Domesday Book.

Posted 30 December 2019 - 07:29 PM

I hope the OP gets the F/11 ED 102 and is able to actually compare the views over a range of targets and under different conditions with both scopes and then shares the experience in some detail with us smile.gif

 

As the current owner of a Tak FC-100DL F/9 and a very fine Skywatcher ED120 I'd like to know if I can sell both off, buy one of the F/11 102 ED doublets and bank a tidy sum for other astro investments grin.gif


Edited by John Huntley, 30 December 2019 - 07:51 PM.

  • Tyson M, mikeDnight and Steve Allison like this

#31 daquad

daquad

    Apollo

  • *****
  • Posts: 1,412
  • Joined: 14 May 2008

Posted 30 December 2019 - 07:32 PM

As is solar work (sunspot numbers, e.g.)  and comet hunting.

 

Dom Q.


  • Astrojensen and Bean614 like this

#32 aa6ww

aa6ww

    Vanguard

  • *****
  • topic starter
  • Posts: 2,285
  • Joined: 23 Oct 2011
  • Loc: Sacramento, Calif.

Posted 09 January 2020 - 03:50 PM

More proof that refractor optical quality is leveling off or has leveled off and no one is clearly superior to anyone else optically any more.

I still have yet to find a single flaw in the optics of my SW-120ED. Once the weather clears, I'll be anxious to get this scope out for double stars. I'll probably put my Big Barlow in front of my diagonal so the focal length will be large enough so my scope can loft alone in the + 250x range with my large 100 deg eyepieces.

...Ralph



 

Polychromatic Strehl, mating element glass and other properties aside, the 4" F11 will be a better planetary and double star instrument. The build quality of the Altair Starwave 4" F11 ED is also much better, by a fair margin. It has a much better focuser(I never really liked Crayford type focusers) and it has many other attributes which make it the better option for this type of observing. The Skywatcher, while excellent, would be my second choice. After having owned the Skywatcher 100 ED F9 and the 120 ED F7.5, I've found that the 4" F11 has the superior optical figure and virtually no spherical aberration( at least not detectable visually) on my sample. It splits close doubles far better with tighter, more pinpoint stars than the Skywatcher and the color correction is better at F11. It is an excellently corrected ED doublet and the longer focal length is more forgiving of simpler eyepiece designs. I recently tested my Altair 4" f11 against my Takahashi FC100 and the F11 at $775.00 easily approaches the same textbook star test as the FC100, virtually identical results on every double I've compared the two scopes on. If that seems like high praise for the Starwave ED F11, it is well earned. Whomever makes the scope for Altair Astro knows what they are doing and takes the time to do a well thought-out Q.C. on their products!! Of course, you don't get all the little extras like you do with the Skywatcher, but those can be easily obtained for little extra expense. IMO, the Starwave 4" f11 is the better scope.


Edited by aa6ww, 09 January 2020 - 04:34 PM.


#33 Steve Allison

Steve Allison

    Apollo

  • *****
  • Posts: 1,181
  • Joined: 25 Nov 2016
  • Loc: Olympia, Wash. 98502

Posted 09 January 2020 - 06:46 PM

More proof that refractor optical quality is leveling off or has leveled off and no one is clearly superior to anyone else optically any more.

[....] 

I'd still take a Zeiss...


  • mikeDnight likes this

#34 barbie

barbie

    Apollo

  • *****
  • Posts: 1,050
  • Joined: 28 Jan 2013
  • Loc: Northeast Ohio

Posted 09 January 2020 - 07:56 PM

I'll still keep my Taks!
  • mikeDnight and Steve Allison like this

#35 coopman

coopman

    Fly Me to the Moon

  • *****
  • Posts: 5,815
  • Joined: 23 Apr 2006
  • Loc: South Louisiana

Posted 09 January 2020 - 08:10 PM

Barbie,

Didn't I see your DF in the classifieds for a short period of time earlier this week?  You must have decided to keep it.


  • Tyson M likes this

#36 barbie

barbie

    Apollo

  • *****
  • Posts: 1,050
  • Joined: 28 Jan 2013
  • Loc: Northeast Ohio

Posted 09 January 2020 - 10:39 PM

I did!!
  • Erik Bakker likes this

#37 mikeDnight

mikeDnight

    Viking 1

  • -----
  • Posts: 869
  • Joined: 19 Apr 2015
  • Loc: Lancashire, UK

Posted 10 January 2020 - 06:37 PM

I hope the OP gets the F/11 ED 102 and is able to actually compare the views over a range of targets and under different conditions with both scopes and then shares the experience in some detail with us smile.gif

 

As the current owner of a Tak FC-100DL F/9 and a very fine Skywatcher ED120 I'd like to know if I can sell both off, buy one of the F/11 102 ED doublets and bank a tidy sum for other astro investments grin.gif

I'll be happy to buy you a brand new 102mm F11 ED John, and take your FC100DL and ED120 off your hands at no extra cost. grin.gif


  • John Huntley likes this

#38 mikeDnight

mikeDnight

    Viking 1

  • -----
  • Posts: 869
  • Joined: 19 Apr 2015
  • Loc: Lancashire, UK

Posted 10 January 2020 - 06:51 PM

I really love the SW 120ED's - I've had three of them and they were all terrific scopes. But when I bought my Tak FC100DC, its planetary definition was clearly better than the 120ED I had alongside it. I was looking through an old note book earlier today and stumbled across the observation I recorded on that comparison night. Jupiter in the FC 100DC I described as being "terrifyingly complex". The 120ED was good but not in the same league, so i can kind of go along with the reports that the 102 F11 ED was a better lunar, planetary & double star scope. And although it may not have the same wide field, it will doubtless give high contrast views of dso's. I used to own a Vixen 102 F13 back in the 1980's and that gave stunning views of the deep sky.


  • John Huntley and Steve Allison like this

#39 aa6ww

aa6ww

    Vanguard

  • *****
  • topic starter
  • Posts: 2,285
  • Joined: 23 Oct 2011
  • Loc: Sacramento, Calif.

Posted 12 January 2020 - 06:04 AM

I sold my TSA-102 after buying my SW-120ED. They were physically the same size but the extra 18mm of aperture made a significant difference on everything I observed with it. Mostly deep space, but even Jupiter, the most difficult object to observe visually, just showed more. As an example, I would always struggle on the rare nights of perfect seeing to see the festoons on Jupiter in any 4" refractor, the TSA-102 was no exception. I could see them, in that I knew they were there, but there were no details. The SW-120 would clearly see the swirls and even the gap between the GRS and its bands. It wasn't like I think I could see a difference, it was an obvious difference.

Same with the moon transits across the surface. I could make out the dark dots on Jupiters surface, but there wasn't enough resolution to make out a round disc. The bands are darker on Jupiter with the 120ED. They should be, more aperture means more contrast. This is no surprise.

 

I sold my TOA-130 also, and wanted to get a TSA-120 to replace both the TSA and TOA. A few TSA-120's came up for sale but none were pristine, so I passed over all of them.

 

 In the interim, I found an excellent used SW-120 for sale and thought keep it for a while. To this day, I still have yet to find a flaw in the optics of my SW-120ED. I know some aren't into the Skywatchers focuser? Mine was horribly out of alignment when I got mine but it only took a few minutes to make it glassy smooth. I tried it once, after the adjustments, but I already had a nice William Optics Digital focuser which matched the white focuser on the Skywatcher perfectly.

The Skywatcher is a big enough scope to handle the large 2" 100 deg and 110 degree eyepieces easily. Maybe not with the stock focuser but no problem with  the W/O Digital focuser.

 

On the messier objects, every one I've observed just naturally shows more details in the 120. No surprise there. Even an Achromat 120 will present deep space deeper then a Fluorite 102. Clear aperture is still clear aperture. You just see deeper when you have more glass.

When I read that the Optician  who designed the Fluorite doublets for Takahashi's moved over to Skywatcher, I  knew the SkyWatcher ED's were going to be good. Myself, like others, just didn't realize how nice these optics really are till we own them and use them. 

 

 

...Ralph

 

 

 

 

 

I really love the SW 120ED's - I've had three of them and they were all terrific scopes. But when I bought my Tak FC100DC, its planetary definition was clearly better than the 120ED I had alongside it. I was looking through an old note book earlier today and stumbled across the observation I recorded on that comparison night. Jupiter in the FC 100DC I described as being "terrifyingly complex". The 120ED was good but not in the same league, so i can kind of go along with the reports that the 102 F11 ED was a better lunar, planetary & double star scope. And although it may not have the same wide field, it will doubtless give high contrast views of dso's. I used to own a Vixen 102 F13 back in the 1980's and that gave stunning views of the deep sky.


Edited by aa6ww, 12 January 2020 - 06:04 AM.


#40 coopman

coopman

    Fly Me to the Moon

  • *****
  • Posts: 5,815
  • Joined: 23 Apr 2006
  • Loc: South Louisiana

Posted 12 January 2020 - 11:53 AM

I'm torn between the FS102 and the SW120ED whenever I decide to use a refractor for the evening.  It's a tough choice and I'm very thankful to have such nice equipment in my possession.      


  • jeremiah2229 likes this

#41 aa6ww

aa6ww

    Vanguard

  • *****
  • topic starter
  • Posts: 2,285
  • Joined: 23 Oct 2011
  • Loc: Sacramento, Calif.

Posted 13 January 2020 - 04:58 AM

7 years later and you still have them both. That's nice.

 

https://www.cloudyni...0mm-telescopes/

 

 

I've had my SW-120 since 2014.  The 120mm size is the perfect size for me.

 

...Ralph

 

 

 

 

I'm torn between the FS102 and the SW120ED whenever I decide to use a refractor for the evening.  It's a tough choice and I'm very thankful to have such nice equipment in my possession.      



#42 beanerds

beanerds

    Apollo

  • -----
  • Posts: 1,027
  • Joined: 15 Jul 2008
  • Loc: Darwin Australia

Posted 13 January 2020 - 08:22 AM

Bill, did you even bother to read the link from AAVSO? The area of variable stars is so criminally underobserved, that professionals that study some of these stars are HIGHLY dependant on amateur work, including visual. Some stars are so poorly observed professionally, that they don't dare to point a multimillion telescope or spacecraft at them, before an amateur has checked their brightness beforehand, lest they destroy a sensitive detector by flux overload. A lot of variable stars are in a magnitude gap, where they are ONLY regularly observed by amateurs, including visual. And there are so many of them, that in many cases, the last observation was weeks or even months ago. Anything could have happened in those gaps, but no one knows, because no one was looking.  

 

No, but they rely on amateurs doing that for them. That is what I mean by doing "professional work" visually. You accumulate data, that the professionals can use. Professionals simply can't get the decade-long uninterrupted telescope time that amateurs can (most can barely get any telescope time at all), and it's precisely the very long timelines that make amateur observations highly useful. For some stars, observations go back uninterrupted for hundreds of years, all made with roughly similar size equipment and identical method, which makes it uniquely constant and statistically reliable. It is of the utmost importance for calibration, that these observations continue in the future.  

 

I think stellar evolution is not an area of low interest. It's pretty much key to understanding how a lot of things work in the universe.

 

I am well aware that most amateurs, visual or otherwise, aren't doing scientifically useful work and never will, nor should they feel forced to do so, but that is no reason to ridicule what scientifically useful work they can actually still do, if they choose to. 

 

Where the heck did that even come from? I never mentioned deep-sky observing as an area where visual amateur astronomers could do useful work.

 

And I think there's a great misunderstanding in the idea that just because one telescope is larger than another, then it's automatically more suitable for scientific work. It doesn't work that way. It's more suitable than the smaller one for some areas of research, but the small one is perfect for others. A carefully chosen and executed observing program with a small telescope can be just as uniquely scientifically useful, as one from a large telescope. Telescopes are tools and you choose the right tool for the job or the right job for the tool. You don't repot bonsai with the world's largest excavator, nor do you remove overburden in an open pit coal mine with a potting shovel. 

 

 

Clear skies!
Thomas, Denmark 

Yep , except the amateur astronomers from down under that seen SN 1987A before any professional ,, oh lets not forget S/L9 ? ,,, Beteleguese is ,, and was found to be becoming very variable over the last 6 months ,,, guess what ? you guessed it Aussie amateur's again ,,, don't get me started on comets .

 

Beanerds.


Edited by beanerds, 13 January 2020 - 08:23 AM.

  • Astrojensen and eros312 like this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics