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Best scope for planetary / star cluster observing?

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#26 Keith Rivich

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Posted 22 August 2018 - 03:51 PM

This can be very true!  Just depends on your perspective.  I was recently at a dark site in New Mexico for a week observing.  I was using substantially a 6" Apo but would wonder over to the 16", 18", and 20" Dobs that friends had there.  The larger apertures obviously could view targets showing more detail/structure and at higher magnifications.  But even so, their views were limited in terms of what we know the structures of the objects to be from ground-based and space-based imaging.  In the end some of the extra details were casually "interesting" to see, but nothing that I felt was overwhelmingly over the top.  One exception was glob cores with the 20" as this aperture had enough pull that when close up in the core there was still enough light to let all the individual star colors come through which was quite enthralling.  However, I'm sure glad I didn't have to manage the setup, acclimation, collimation and re-collimation, operation, precarious ladder observing, and breakdown of that monster.  So view was nice, but operationally I considered it a complete nightmare.  All that being so, went back to and spent the majority of my time with the 6" Apo as its views were beautiful, had greater context since generally worked at lower magnifications to keep the targets bright like the bigger apertures, and operationally it was completely easy-peasy with zero hassles over the course of each evening's observing.  I generally stopped observing with a telescope at around 2-3am each evening, then spent the last hour in a lounge chair observing the Milky Way in detail naked eye.  In many ways that end of evening observing at the dark site was the most memorable over what any telescope could provide, even the 20".  A lot of magic to observe in the sky...more when you have studied up on what you are looking at...and aperture is largely irrelevant IMO to the reward of the experience as any aperture will do.  So your best "scopes" for planetary and cluster observing are really your "brain" to know the details of what you are observing before you observe it and your "eyes" to take in all the context of the object.  Any aperture scope will due after those two grin.gif

I don't think you give the human brain enough credit to paint a picture with minimal information. The differences are subtle, yes, but the actual experience is much more then that. Kind of like seeing Star Wars on a 5" black and white compared to IMAX. 


Edited by Keith Rivich, 22 August 2018 - 04:33 PM.


#27 Jon Isaacs

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Posted 22 August 2018 - 04:55 PM

The larger apertures obviously could view targets showing more detail/structure and at higher magnifications.  But even so, their views were limited in terms of what we know the structures of the objects to be from ground-based and space-based imaging.  In the end some of the extra details were casually "interesting" to see, but nothing that I felt was overwhelmingly over the top.

 

 

To each his/her own.  I spend a week to two weeks a month observing under reasonably dark skies.  There's a lot to see in a 16 inch or 22 inch scope that's simply beyond the reach of a 6 inch.  The number of objects visible is dramatically increased as it the detail visible in existing objects .

 

This is not to say , there's not room for a smaller scope but a 6 inch F/8 apo/ed would not be my choice.  My 12.5 inch F/4.06 operates at a 1482 mm focal length with a Paracorr so the maximum field of view is only about 19% narrower but it shows much more and is an easy scope. 

 

When i go small,  I want something in return , a wide field of view with a bright image to see those objects between binos and a 10 inch F/5 or a 12.5 inch F/4.

 

Sure a 12.5 inch or 25 inch doesn't show everything one might see in the photos but there is still plenty to see.  It takes me about 10 minutes to setup the 16 inch when we're camping in the motor home and it might be a week or so until it's time to tear it down,  not much trouble at all. 

 

Joshua Tree March 2017 1.jpg

 

Jon


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#28 OleCuss

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Posted 22 August 2018 - 07:35 PM

In my opinion, nope.

 

I have access to 6" and 11" refractors of very good quality and they do not come close to equaling or surpassing my 18" Obsession. 

Nicely stated and I'd probably both agree and disagree.  How's that for being decisive!

 

I've a number of scopes of a variety of sizes.  When my eyes were working well enough for eyepieces (as they will again some day I believe) my most used telescope was my ED-Doublet 80mm spotting scope.

 

Now that isn't because my little 80mm spotter will show more than will/would any of my other scopes (it won't) but because it can be quickly taken outside and set up even if I have only 2-3 minutes for observing.  No alignment, no cool-down, no fuss, and nearly no time.  It has also given me the most esthetically pleasing view of M31 that I've ever had with any scope - framed it just right and was gorgeous.

 

I actually got that 80mm spotter when my wife and I went to a star party (well, the star party wasn't the point but we were still there when a club showed up).

 

We watched the club set up and then do a bit of a cool-down.

 

We then viewed Mars through a 6" Dobsonian, an 8" Dobsonian, and a Dobsonian in the 16-18" range (don't remember exactly which after all these years) - the owners were kind and were proud to show us the view through their scopes.  The views were, in fact, horrible.  Lots of distortion and no detail could be seen at all.

 

I then went to view Saturn through an 80mm spotting scope and while the view was smaller than I prefer it was nice and crisp and beautiful!  We also viewed through an A-P Starfire (I think it was 130mm) and Mars was showing some detail and there was no distortion at all.

 

Now I'm no enemy of the Dobsonians (I own 3), and I'd certainly not bad-mouth an Obsession (I've gotten to view through a 24" and it was excellent), but that evening the little refractors were beating the pants off the far bigger Dobsonians.

 

Later that night I don't doubt that the Dobsonians would have been far better to my eyes for most targets.

 

I've also been at a star party where we did some comparison views between my el cheapo 8" Dobsonian against another gorgeous Starfire and IMHO the 8" Dobsonian did much better on those particular targets than did that refractor.  But the comparison was late at night after plenty of cool-down and such.

 

I won't buy a Newtonian on a GEM for visual use.  Viewing with such is all too often an unpleasant experience for me even if the views are technically excellent.

 

I've been known to bring the 80mm spotter to public viewing star parties because I can put it and its camera tripod at the right height for little kids and the FOV is right for the Moon.  Those little kids who don't seem to be able to organize/recognize an amazing nebula or even Saturn can recognize the Moon because it looks similar to what they see in the sky - only a little bigger and more detailed.  Point a big Dobsonian at the Moon and they won't generally be impressed but, rather, disinterested.

 

At the moment I've some eye problems which make the eyepiece generally not useful.  I do expect resolution in the future but for at least several months I'll be observing with a scope and camera.  If someone tells me that their awesome scope and maybe even more incredible eyepiece are better than mine I'll happily agree but I won't use them because for me right now they're pretty useless.  A greatly inferior scope with a camera and screen I can enjoy whereas your awesome scope and incredible eyepiece will provide me with an unpleasant experience.

 

There are a bunch of reasons why one person might find one scope to be inferior to another while a different person will have a different opinion which is equally valid.  The perspectives, goals, time frames, observing methods, budgets, etc. vary greatly and it makes it so that there just isn't one scope which is just plain better than another.  What's more, what is better can change over time, and even several times in a single observing night.



#29 Keith Rivich

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Posted 22 August 2018 - 10:03 PM

Nicely stated and I'd probably both agree and disagree.  How's that for being decisive!

 

I've a number of scopes of a variety of sizes.  When my eyes were working well enough for eyepieces (as they will again some day I believe) my most used telescope was my ED-Doublet 80mm spotting scope.

 

Now that isn't because my little 80mm spotter will show more than will/would any of my other scopes (it won't) but because it can be quickly taken outside and set up even if I have only 2-3 minutes for observing.  No alignment, no cool-down, no fuss, and nearly no time.  It has also given me the most esthetically pleasing view of M31 that I've ever had with any scope - framed it just right and was gorgeous.

 

I actually got that 80mm spotter when my wife and I went to a star party (well, the star party wasn't the point but we were still there when a club showed up).

 

We watched the club set up and then do a bit of a cool-down.

 

We then viewed Mars through a 6" Dobsonian, an 8" Dobsonian, and a Dobsonian in the 16-18" range (don't remember exactly which after all these years) - the owners were kind and were proud to show us the view through their scopes.  The views were, in fact, horrible.  Lots of distortion and no detail could be seen at all.

 

I then went to view Saturn through an 80mm spotting scope and while the view was smaller than I prefer it was nice and crisp and beautiful!  We also viewed through an A-P Starfire (I think it was 130mm) and Mars was showing some detail and there was no distortion at all.

 

Now I'm no enemy of the Dobsonians (I own 3), and I'd certainly not bad-mouth an Obsession (I've gotten to view through a 24" and it was excellent), but that evening the little refractors were beating the pants off the far bigger Dobsonians.

 

Later that night I don't doubt that the Dobsonians would have been far better to my eyes for most targets.

 

I've also been at a star party where we did some comparison views between my el cheapo 8" Dobsonian against another gorgeous Starfire and IMHO the 8" Dobsonian did much better on those particular targets than did that refractor.  But the comparison was late at night after plenty of cool-down and such.

 

I won't buy a Newtonian on a GEM for visual use.  Viewing with such is all too often an unpleasant experience for me even if the views are technically excellent.

 

I've been known to bring the 80mm spotter to public viewing star parties because I can put it and its camera tripod at the right height for little kids and the FOV is right for the Moon.  Those little kids who don't seem to be able to organize/recognize an amazing nebula or even Saturn can recognize the Moon because it looks similar to what they see in the sky - only a little bigger and more detailed.  Point a big Dobsonian at the Moon and they won't generally be impressed but, rather, disinterested.

 

At the moment I've some eye problems which make the eyepiece generally not useful.  I do expect resolution in the future but for at least several months I'll be observing with a scope and camera.  If someone tells me that their awesome scope and maybe even more incredible eyepiece are better than mine I'll happily agree but I won't use them because for me right now they're pretty useless.  A greatly inferior scope with a camera and screen I can enjoy whereas your awesome scope and incredible eyepiece will provide me with an unpleasant experience.

 

There are a bunch of reasons why one person might find one scope to be inferior to another while a different person will have a different opinion which is equally valid.  The perspectives, goals, time frames, observing methods, budgets, etc. vary greatly and it makes it so that there just isn't one scope which is just plain better than another.  What's more, what is better can change over time, and even several times in a single observing night.

Hopefully your eye issues get handled. I have actually started to use my left eye more (I observe right eyed) to train it just in case I should ever start to lose my right eye. Its amazing how much more I can see right eyed over left eyed. But its coming along.

 

Its to bad you had such a bad experience with the clubs scope on that particular night. Sounds like a collimation issue more then anything else. 

 

As a note I use a 102mm f/5 refractor as a finder on my 25" and the 80mm version on my 18". I can honestly say I have never, ever thought my finders were outperforming the mains. I think collimation is the main killer of newt performance with "cooling issues" a far distant second. 

 

One thing about refractor's...they have also have to be collimated from time to time or they to will suffer from sub par performance.

 

I agree on the GEM. Unless equipped with rotating rings they stink for visual work.




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