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FIRST LIGHT with Stellarvue SV-ED80. Bella!!

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#1 Rainguy

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Posted 18 August 2013 - 11:10 AM

Last night I intended to set up my C90 Mak and do some afocal lunar photogging. But I never even saw the moon. Too low, too "east", too hidden behind the massive trees to the southeast of our patio.

So I instead hauled out my shiny new high gloss piano black finish SV-ED80 for its maiden voyage, though the skies were never darker than a medium charcoal gray, pretty washed out.

That said: W.O.W.

The SV80 was superb! Absolutely PINPOINT stars, no CA at all that I could see. No blue, no red, no purple. Nada. The dual speed focuser was flawless and incredibly precise——and the optics, well, magnificent. It's now official: I am a refractor guy.

Couple of first time observations next——comments and suggestions from you refractor vets out there much appreciated!

1) My 1.25" EPs in the 2" focuser adapter gave me really sharp, crisp images. The only 2" EP I currently own is the Zhumell 30mm and it, too, served up splendid images——and what appeared to be a bigger chunk of sky. Also barlowed the 30mm and there was no fall off at all in resolution. But, man, that 2" GSO barlow is massive. What a chunk of metal. I also used it with several 1.25" EPs via the adapter and thought that the views were noticeably superior to those through the 1.25" barlow. But I need to do more extensive a-b comparisons here. And will. I intend to pick up 1 or 2 more 2" EPs, but was happy, and relieved, that my current stable of 1.25" adapters performed so admirably.

2) Based on last night, I'm not sure I am going to need a finder. I used my Meade 1.25" 8-24 zoom a lot and, along with the 2" Zhumell, seemed to find my way around pretty well. I think maybe I will get a 2" EP in the 40-50mm range for super low power/wide FOV viewing, and think/hope that this will also serve as a de facto finder. The SV 80 OTA is just so darn gorgeous that I'd prefer not to clutter it up with a Rigel QF or SV rdf. But it will take more nights out to make this call.

3) So what did I see?

a) Well, I re-visited the 3 open clusters in and around Cebalrai I have been using as "test" objects (with my other scopes) over the past week: IC 4665, NGC 6613, and IC 4756. Wonderful! I used both the Zhumell 30 and two 1.25" EPs: a flat field 19mm GSO and 15mm SWA Agena. All 3 gave me uber sharp, beautifully resolved stars, all laid out in these lacy, brilliantly-dotted spider webs. I would run through the EP trio, then go back again for 2nd and 3rd looks. Just awesome.

B) Then I swung up to the north and east and——bam, bam, bam!——quickly found Cr 399 (the coathanger: brilliantly bright) and NGCs 6802, 6830, 6800 and Stock 1. All looked sharp and bright in all 3 EPs. Then I faffed around a bit until I found Alberio——breathtaking at every magnification: both surrounded by a sparkling starfield at lower mags (they are just scattered about everywhere) and more isolated but much larger and more impressive at higher mag, in this case my 1.25" Zhumell 9mm planetary and, better yet, Orion Expanse 6. A pair of bright, impeccably-resolved orbs, one bright yellow, the other French blue and, at high mag, well-separated and defined. I stayed on Alberio for a long time, just drinking it in.

So, all in all, a heck of a good night. More to come, I'm sure, even better once I become more adapted to the Refractor Way.

Once more, guys, I will be grateful for any suggestions or advice that might enhance my enjoyment of this sublime instrument.

Doug

#2 pdxmoon

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Posted 18 August 2013 - 11:54 AM

Just one piece of advice, Doug: cut down all those trees! :watching:

#3 Scott in NC

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Posted 18 August 2013 - 12:32 PM

Nice report, Doug, and congrats on the new scope! :grin:

#4 Rainguy

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Posted 18 August 2013 - 01:19 PM

Thanks, Scott, for all the good information you sent me previously. It helped me out a lot. And you sure were right about just how outstanding the SV ED80 is. Better even than I expected.

Doug

#5 Scott in NC

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Posted 18 August 2013 - 01:29 PM

My pleasure! :waytogo:

#6 T1R2

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Posted 19 August 2013 - 12:46 AM

Is your scope the F/7 80mm ED doublet, the black one I seen a while back with CF tube, that they don't make anymore? I always thought that was a good lookin scope, nice read on that scope.

#7 Rainguy

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Posted 19 August 2013 - 10:04 AM

T1R2:

Yes, that's my scope: 80mm f/7 doublet. All black. I spoke with a really nice woman at Stellarvue who looked up my scope's serial # and told me that it was made in Dec, 2010 and part of a limited run of SV ED80s that had the integrated Vixen dovetail foot.

It is just beautiful, like something that should be sitting in the sculpture wing of an art museum. Right now, I enjoy looking AT it almost as much as looking through it.

Doug

#8 jrbarnett

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Posted 19 August 2013 - 10:49 AM

Try higher magnification (around 100x) on a very bright target (like Vega) and see if you can spot any false color. Even in large fast achromats using ordinary crown and flint glass types lower magnification views of targets and even higher magnification views of dimmer targets are relatively color free visually.

The magic of refractors is more in the nature of their lack of light scattering obstructions and how conducive the unobstructed design is to superior tube baffling. Your exercise under Moon-washed skies illustrates these strengths. I'd reserve judgement on the relative efficacy of color correction, though, until I'd pushed the scope on targets and at magnifications where you'd expect to encounter visual false color.

Achromat, ED or apochromat - refractors may not be the *only* way to fly, but they are by far the *best* way to fly inch-per-inch. Happy piloting. Stellarvue builds some nice tube assemblies.

- Jim

#9 Rainguy

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Posted 20 August 2013 - 11:11 AM

Thanks for the advice, Jim. I will home in on Vega next time out, though I have already had Altair in the crosshairs and don't recall seeing any false color at all.

What I did notice immediately during my initial test drive of my SV ED80 was the difference between reflector and refractor optics. Keeping in mind that this observation is from someone who has been at this for just over a year.

Two night ago I was observing with my 6" dob and having a good time, thinking, as I observed, how sharp and clean the stars were in the various open clusters I was sailing through. But when I used the SV ED80 the next night, I instantly understood just how superior refractors are when it comes to serving up absolute pinpoint stars, brilliant clean dots. As I said in an earlier post, the first few minutes with the ED80 converted me into a refractor guy.

Thanks for your suggestion here. I always find both information and inspiration in your posts.

Doug

#10 Kfrank

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Posted 20 August 2013 - 11:21 AM

I have this exact scope. Bought it new about 3 years ago and agree wholeheartedly with the OP.

It's a great scope, well made, and, among my other scopes, it's my only "keeper".

#11 jrbarnett

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Posted 20 August 2013 - 12:11 PM

"Two night ago I was observing with my 6" dob and having a good time, thinking, as I observed, how sharp and clean the stars were in the various open clusters I was sailing through. But when I used the SV ED80 the next night, I instantly understood just how superior refractors are when it comes to serving up absolute pinpoint stars, brilliant clean dots."

Be very careful drawing such generalizations from comparisons on different nights and using different magnifications. To be valid, you must make everything as much apples-apples as possible. If, for example, seeing was better or worse on a night when you used one of the scopes but not the other, or if one of the scopes was operating at much higher magnification than the other, those factors may have played a far more significant role in what you saw comparatively than any difference between the design or other specifications of the two telescopes.

At low magnification everything looks sharp, even in a relatively poor optic. As magnification increases, the wheat is separated from the chaff in terms of image quality. Lots of factors affect image quality, including telescope acclimation, collimation, atmospheric seeing, etc.

I'm definitely a "refractor guy" as well, but note that if two scopes - a Dob and a refractor - operate at the same low magnification level, assuming the Dob is collimated and cooled, they tend to produce equally sharp and crispy stellar images. A common mis-perception of the "superiority" of refractor star images is caused by the user using extremely low magnification in the refractor; a common occurrence in small fast refractors with very short focal lengths.

For example, let's say you used a 20mm Plossl in your SV80ED. 560mm of focal length divided by 20mm of eyepiece focal length would put you at 28x. Let's say your other scope is a 6" f/8 Dob. 1200mm of focal length divided by 20mm puts you at 60x or more than twice the magnification you have when using the same eyepiece with the 80mm scope. To make it apples-apples, you'd need to use a 9mm eyepiece in the 80mm refractor and the 20mm in the 6" reflector.

Here's another tidbit. The star image (the airy disc) is actually smaller in diameter in a larger instrument than in a smaller.

And I am not being critical in the least - I'm just reliving my own reactions when switching from a 6" Newtonian to a 4" refractor many, many years ago. I was in exactly your shoes. It was only after I started picking at the details (i.e., experimenting with matched magnification, matched exit pupils, etc.) that I found the superiority of the refractor not to be quite so categorical or unqualified.

The reason I recommended Vega for looking for false color is that it is extremely bright and also blue-white in color. Be sure that you bump up the magnification too. Try at least 100x. These scopes do a great job suppressing false color at lower magnification but in my experience if you pick "trouble cases" like Vega at higher magnification, you can start to probe the limits of the color correction of the scope.

In any case, I'm not dampening your enthusiasm. Just trying to coach your experimentation with the "refractor uber alles" theme. :grin:

To me the real inspiration isn't in what old timers write. It's in the expressions of delight that comes from users like you sharing their first adventures with different kinds of telescopes. :waytogo:

- Jim

#12 Rainguy

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Posted 20 August 2013 - 04:42 PM

Excellent points all, Jim. Thank you.

The two "comparison" nights were back to back and seemed about as similar as possible, though there were obviously some nuanced differences. When I made the comment about the superior sharpness of the ED80 images vis a viz those in the 6" dob (StarBlast 6, not the XT), I should have added that the differences became so apparent only after going up to higher magnification in both scopes. At lower mag, as you point out, the differences were all but negligible. But the more I increased the magnification, the softer and more spikey the images became in the dob. Not bad even then, not bad at all, even pretty good I thought at the time, but in retrospect once I ran through the same mag range with the ED80 the next night, well, not quite as sharp/clean as I had thought at the time.

That said, I still find my SB 6 a delightful scope, one that shows me more stars in a given window and probably brighter images as well because of its much larger aperture. I don't see myself abandoning it, rather I now regard it as a complement to my new refractors, and an instrument that provides a qualitatively different kind of observing experience.

But I can see those scalpel-sharp, contrasty views in a refractor becoming addictive.

Thanks once more for taking the time to reply in such depth.

Doug

#13 dvb

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Posted 21 August 2013 - 07:18 PM

Congratulations on the scope! Mine just arrived yesterday, and it is a beautiful piece of equipment. I assume it is the same optics - mine is the 80mm doublet, with, I believe, the FPL-51 ED element.

I haven't used it at night yet, but it is putting up extremely clear daytime views - I'll be getting a 45º correct image prism for daylight use - although an extension tube is needed for use at less than infinity (except with a few eyepieces with lots of in-focus, like the Speers-WALERs).

I did get the optional bag, which is very nice, but twice as wide as I need, since I don't want to pack anything in it but the telescope.

It seems to ride quite well on a fairly light-weight Olivon tripod, but I need to give that more of a work-out.

Full Moon tonight, but clear, so I'll check it out on the Double-Double for resolution and on Vega for chromatic aberration. I'm looking forward to trying it on the Ring, but that wouldn't be a fair test tonight.

This will be a great travel scope. An exceptional value for $499.00!

#14 Rainguy

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Posted 21 August 2013 - 09:05 PM

Congrats back at you, dvb! Yes, it is a beauty. And, as you are about to discover, the optics are just superb. Which Olivon tripod are you using?
Be sure to post your First Light results.

Clear skies,

Doug

#15 dvb

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Posted 21 August 2013 - 11:24 PM

Hi Doug,

I'm using the Olivon TR154-11 (although tonight it will be on the AZ4)

http://www.binocular...15411tripod.cfm

#16 jrbarnett

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Posted 21 August 2013 - 11:26 PM

Doug, I know what you mean. My own "conversion" was at the hands of a 4" f/9.8 Vixen achromat used head to head with a 13.1" Dob same night, same targets, similar magnifications. The Dob was brighter but the refractor was oh-so-much-more delectable. Previously I'd used a 6" f/8 Newtonian for almost 20 years.

Every inch of refractor aperture from 3" to 6" adds a new dimension to the "refractorness" experience. Each has its advantages and disadvantages and different aperture refractors, unlike any other design, complement one another. You also don't need as much refractor aperture to deliver a given observing experience as you do for other designs. Obstruction matters, lower throughput/efficiency matters, lesser contrast due to less efficient baffling matters. Refractors are the sports cars of the telescope world. :grin:

Regards,

Jim

#17 beanerds

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Posted 22 August 2013 - 02:03 AM

That's exactly why my 127mm Istar f8 Jim , it is my most used scope , perfect star images that no reflector can quite copy .
And Doug congrats on a beautiful scope , Stellarvue know how to make them alright , hope the weather co-operates and lets you enjoy it a while .

I had a lovely pearl white SV 80mm Aplanet with Lanthium glass that was so nice , I regret selling that scope .

Brian.

#18 Jon Isaacs

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Posted 22 August 2013 - 02:55 AM

At lower mag, as you point out, the differences were all but negligible. But the more I increased the magnification, the softer and more spikey the images became in the dob.



I enjoy my refractors and the pristine images they can provide but I also enjoy my reflectors and I find that while they are more finicky and require more care, they too can provide pristine, picture perfect views of their own. A few thoughts:

- Comparing scopes of different apertures is difficult, in part because the exit pupil and the eye's response are important. Does one test at equal magnifications or equal exit pupils? Both are problematic. Optically, the test should be done at equal exit pupils, this eliminates the largest variable, the eye, but since it results in double the magnification, it means a larger scope is more likely to suffer from seeing issues.

In this situation, I am wondering if there are thermal or collimation issues with your reflector. One of the real advantages of an 80mm refractor is that it is essentially free of thermal/cool-down problems, it's great right out of the box. Your 6 inch Newtonian will require time to cool and some attention to managing your own body heat. The other question is collimation, Newtonians do require careful collimation.

If the seeing is good, if your 6 inch Newtonian is well cooled and collimated, then at higher magnifications, it should show greater resolution than your 80mm refractor, you should split double stars that are beyond the reach of an 80mm, see planetary details unseen in the 80mm.

There are other issues too, the F/5 focal ratio of the Starblast means there is off-axis coma from the mirror and off-axis eyepiece astigmatism unless one is fancy eyepieces. Both these can be addressed, the coma can be corrected, eyepieces free of astigmatism at F/5 are available..

One of the reasons I enjoy my refractors is that they are less hassle, they are pretty much ready to go as soon as they are out the door, simple and easy. But, I do enjoy my reflectors, more effort, more understanding is require but also more capability.. Both are good.

Jon

#19 beanerds

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Posted 22 August 2013 - 03:05 AM

Yes , refractors are real telescopes .
In my view .
Brian.

#20 Jon Isaacs

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Posted 22 August 2013 - 03:47 AM

Yes , refractors are real telescopes .
In my view .
Brian.


Refractors are real telescopes, reflectors are real telescopes. Both are good, both have their place. That's why I have both refractors and reflectors.

In general, refractors make the best small telescopes, this is where the lack of a Central obstruction, the high throughput are most valuable and where the difficulties with chromatic aberration are the least. Reflectors make the best larger telescopes, as you scale up a reflector, the disadvantages such as the throughput and central obstruction become less important and the fact that they are inherently free from chromatic aberration and that their aberrations are only a function of focal ratio and not aperture/focal ratio mean that large Newtonians with reasonable focal ratios are realistic and affordable.

Jon

#21 David E

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Posted 23 August 2013 - 06:16 PM

Thanks for the advice, Jim. I will home in on Vega next time out, though I have already had Altair in the crosshairs and don't recall seeing any false color at all.

What I did notice immediately during my initial test drive of my SV ED80 was the difference between reflector and refractor optics. Keeping in mind that this observation is from someone who has been at this for just over a year.

Two night ago I was observing with my 6" dob and having a good time, thinking, as I observed, how sharp and clean the stars were in the various open clusters I was sailing through. But when I used the SV ED80 the next night, I instantly understood just how superior refractors are when it comes to serving up absolute pinpoint stars, brilliant clean dots. As I said in an earlier post, the first few minutes with the ED80 converted me into a refractor guy.

Thanks for your suggestion here. I always find both information and inspiration in your posts.

Doug


It can be really fun stuff, having two scopes out in the same night, especially with two very different ones. I often pair one of my Stellarvue refractors with my 8" Zhumell Dob. Each one gives different views, and both can contribute to the viewing session in a positive way. I called Vic a few weeks back checking on the progress with my SV85S makeover. The conversation gravitated to the SV80ED models he currently has for sale. He told me he had one Stardust Blue tube left, the split tube that can be made bino-ready, and he could have this scope assembled and shipped in a few days, so I took the bait hook line and sinker. :foreheadslap: Lately it's like I've been living in a Venus Nova colony, with never ending clouds, but I've managed to get some great lunar views and a little bit of deep space. I've been wanting one of these SV80ED doublets when they were first introduced and I'm glad I pulled the trigger on this one. :jump:

#22 Rainguy

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Posted 23 August 2013 - 06:53 PM

Hey David.

Happy to hear that you have scored your own SV80ED. I'm sure you are going to love it as do the rest of us. And, yes, going back and forth between two different kinds of scopes is great fun, in my case the ED80 and Orion Starblast 6 reflector (which is a fine little scope with sharp bright images, and one I'll not abandon even in the throes of my new refractor infatuation). As Jim and others have posited, different scopes for different purposes and different experiences. Enjoyed your post. Thanks.

Doug

#23 Rainguy

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Posted 23 August 2013 - 06:57 PM

"One of the reasons I enjoy my refractors is that they are less hassle, they are pretty much ready to go as soon as they are out the door, simple and easy. But, I do enjoy my reflectors, more effort, more understanding is require but also more capability.. Both are good."

Jon,

Exactly. Well and succinctly put. Infatuated as I am with my refractors, I still can see more (and larger) with my SB6. I always try to put it outside for a good hour before I intend to observe. With the ED80, I can take it out any time I want, so a far better spur of the moment instrument. But, as you say, they're all good scopes, each with its strengths, each its limitations.

Doug






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