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Update on my SW ED150 order...

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#626 starman876

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Posted 13 August 2018 - 01:51 PM

Oh, to add, I'm kicking around an idea for this scope.  It's got nice light grasp, fair-good (rather than great) optics, doesn't weigh that much (as an OTA) and didn't break the bank.  From home my darkest skies and stablest seeing tend to be in the early morning hours starting about 3 hours before sunrise.  I've toyed for years with the idea of a scope left set-up, covered, for on-demand use.  I've even done trial runs with a variety of instruments (e.g., left 12x50 binoculars on a p-mount set up, covered, for several months, left a C90 MCT on a Nexstar SE mount similarly deployed for a couple of months, though I would deploy the battery each session with this setup, and more recently for several weeks, a LOMO 80/480 APO on a manual alt-az mount and cheap surveyor's tripod), but think it requires some aperture to make truly engaging and viable.  I thought about a C8 - big, cheap, capable - but prefer my SCTs on driven mounts and really prefer a manual no-electronics needed mount for an exposed setup.

 

This OTA seems pretty perfect for such a deployment.  In addition to its Milky Way sweeping and binocular tour guiding role, hour long early morning sessions and maybe a little pre-dawn comet sweeping several times a month courtesy of having it ready on a whim would be a good use of this scope I think.  I will need a sturdy weather proof cover (Telegizmos 365 or is there a better option?).  The cover will need to cover the scope mount and tripod so I am thinking a big Dob cover would be best (and have additional utility for use with my Dobs).  I have plenty of low cost accessories with which to dress the OTA as well as cheap eyepieces (probably will dedicate the set of Sterling Plossls for this duty) that I don't mind leaving out under the cover.  The Tak tripod I use (an SE-L made for the EM-200) has a traditional triangular tray to hold the eyepieces.  I have a spare older Sky Commander mothballed so I can update and attach that to the AYO Master.  I don't think the AYO Master will suffer much being outside under cover - it is well sealed and made of aluminum on the exterior.

 

Of course I'm not going to do much of anything with it beyond occasional use unless and until the focuser mess gets resolved.  The damaged focuser much more than the optics makes this scope less than pleasant to use.

 

Whacha think?

 

Best,

 

Jim 

Find it so hard to  believe that they cannot send you a replacement focuser.  You would think the customer support at this time would be hand delivering one to your front door.  I cannot imagine that reviews like this is going to help sales.   You have been more than fair with keeping the scope.   If I were running the place I would have ordered whatever you need from China overnight express and would have taken the hit on the cost of it all to ensure customer relations.  You only get one chance to make a first impression.  


 

#627 daquad

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Posted 13 August 2018 - 01:54 PM

For getting rid of bugs I use this. Works like magic

 

https://www.rei.com/...ASABEgKejPD_BwE

Jeff, I was wondering more about bugs getting into the equipment.

 

Dom Q.


 

#628 Rutilus

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Posted 13 August 2018 - 02:01 PM

No focuser cap which might have been a problem.  My scope may have been a demo/dealer sample for all I know.  And my dealer worked on it before shipping it (recentered the objective elements using instructions from Skywatcher Europe).  Anything is possible.  Mine came with a few miscellaneous imaging adapters too (Canon adapter ring, some kind of extension tube, etc.  Is that normal?

 

This is likely a very early unit.  I've heard rumors that they are going to revise the prescription/glass types to shave costs in the not too distant future, too.  It will be interesting to watch how the scope's optical group evolves.  Another interesting thing is that this scope like a few of the very earliest dealer samples (such as at NEAF) has non-typical multi-coatings.  Every Synta refractor I've ever owned (and every Long Perng who I believe to have a corporate relationship - interlocking directorates - with Synta) has used what we call "China Green" multicoatings.  These are thickly applied, deep green hued coatings.  This scope uses the more typical dual-hued formulation that you find on fancier scopes.  Perhaps the Esprits also use something other than China Green?  I've never looked down the business end of an Esprit.

 

Best,

 

Jim

Jim - Both of my ten year old  Synta Achromat scopes 120mm & 150mm use the dual-hued coatings. Certainly not the

China Green coatings found on the Synta ED scopes. 


 

#629 Jeff B

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Posted 13 August 2018 - 02:11 PM

Jeff, I was wondering more about bugs getting into the equipment.

 

Dom Q.

And that is a real concern around here, in particular Asian Lady and Stink bugs and in particular the late spring and mid-fall.  Those bugs do get up under the cover but they seem to hang out on the equipment and not the interior surface of the cover for some reason.  Both will find their way into the smallest openings.  That's why I use duct tape to cover open holes in the mounts.  The TEC 200ED is sealed at both ends, so invasion of the OTA is not a problem.  With the newt, I also have inner regular Telegizmos covers that slide over the front and back to seal up the OTA.  I suspect the critters will get in between the gap between the newt's static and rotating tube rings too but I shall see.  

 

Jeff


 

#630 Bomber Bob

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Posted 13 August 2018 - 03:27 PM

If you are referring to damage during shipping that is, of course, a different matter.

 

Yes, and by SPEC, I mean it arrives at my home exactly as it was when finished at the factory -- not as "corrected" or "improved" en-route by the vendor, which should be unnecessary.


 

#631 BarrySimon615

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Posted 13 August 2018 - 04:46 PM

I would say the NA 140, which is still very much achromatic in its performance, is no where near to be considered an alternative to the 150 class ED doublet Apos.  Getting to higher magnifications well, particularly for planetary without any filtration, is more about color correction across the visual spectrum.  With my 152 ED Apo I get zero halo around any planet in focus, including Venus.  About the only object I can reliably  coax a faint bit of very dim blue around in focus is Sirius.  Vega, nada. 

Bill, maybe yours.....a Lunt, isn't it?  However maybe not all 150 class ED refractors.  Being that you are happy with yours and can push beyond 30x per inch I would venture to guess that if you have tested or can test, it will yield better than 1/4 wave results.

 

Barry Simon


 

#632 CHASLX200

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Posted 13 August 2018 - 05:51 PM

Mine certainly has zero issue at producing a nice crisp and detailed view at 60x/in and more.  A tour of Venus, Mars, Jupiter, and Saturn two days ago was simply spectacularly detailed at about that magnification level. Then backed her way down for some really pretty views of the Swan Nebula and others around that portion of the Milky Way.

My AT102ED sure does 60x per inch and keeps going.  I would expect the SW150 ED to do 60x per inch without breaking a sweat if done right.


 

#633 CHASLX200

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Posted 13 August 2018 - 05:55 PM

Here is a trio.

 

Jeff

Could never do that in my back yard. The insane salt air and dew points 75f to 83f and humididty at 80%+ would turn all them scopes to rust in no time.


 

#634 daquad

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Posted 13 August 2018 - 06:38 PM

And that is a real concern around here, in particular Asian Lady and Stink bugs and in particular the late spring and mid-fall.  Those bugs do get up under the cover but they seem to hang out on the equipment and not the interior surface of the cover for some reason.  Both will find their way into the smallest openings.  That's why I use duct tape to cover open holes in the mounts.  The TEC 200ED is sealed at both ends, so invasion of the OTA is not a problem.  With the newt, I also have inner regular Telegizmos covers that slide over the front and back to seal up the OTA.  I suspect the critters will get in between the gap between the newt's static and rotating tube rings too but I shall see.  

 

Jeff

I use the Telegizmos to cover my GM 100, which stays out all year.  I carry the scopes and electronics to the mount.  Only a few spiders and an occasional hornet trying to make a nest every so often. But if used regularly they are not a real problem.  I thought of spraying the cover with Deep Woods Off, to discourage the critters, but haven't tried that yet, since it has not been a real concern.

 

Dom Q.


 

#635 noisejammer

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Posted 13 August 2018 - 06:45 PM

Jim - I'll offer another vote for the Telegizmos 365 covers. My TOA150, APM15/805 and LX200/12 all live outside under them. I bring them in for February (when we often get -30C or colder) or if I'm away but most of the time, they live outside.

 

I'm leery of dew so I use desiccant caps in the diagonals and have taped desiccant packs like these under the lens covers. I also use a 12" gun-safe heater to keep everything above dew point.


 

#636 Daniel Mounsey

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Posted 14 August 2018 - 04:52 AM

I would say the NA 140, which is still very much achromatic in its performance, is no where near to be considered an alternative to the 150 class ED doublet Apos.  Getting to higher magnifications well, particularly for planetary without any filtration, is more about color correction across the visual spectrum.  With my 152 ED Apo I get zero halo around any planet in focus, including Venus.  About the only object I can reliably  coax a faint bit of very dim blue around in focus is Sirius.  Vega, nada. 

 

100% correct here Bill. Barry, there are just so many mixed ideas people have here. If I was a beginner, I’d be confused with all this. 


 

#637 Daniel Mounsey

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Posted 14 August 2018 - 05:41 AM

SW only offers a “diffraction limited” optical quality guarantee. So Jim’s SW 150 ED meets SW’s optical quality guarantee and it is made exactly to spec.

 

If the scope is returned, it will most likely be sold to someone else. The optics will not be stripped and refigured, why should they be, they meet spec. If you want another one of these scopes, the chances are you will get something similar. If one of these scopes comes off the line at ¼ wave it goes out the door. Why would it not?

 

If SW could produce better 6” refractor optics consistently and profitably and at this price they would offer a better optical quality guarantee – they do not.

 

Bob

 

Bob, in the end, a number of reviews will be needed to finally determine if and how observers like the Evostar. I really think this is all very premature to assume that Jim’s sample is acceptable by SW. Also, there is so much misinformation getting tossed around in these threads. There are so many countless factors that affect the views different observers see and people have too many incorrect, preconceived notions about how all these scopes should perform. People with none or hardly any experience using these telescopes are using Strehl ratios to determine optical performance, yet there’s really no way to put that into an observation. How would people understand how to describe how the images will look with these numbers. Some of the things I get from the comments in these threads are just so preposterous. It merely illustrates the lack of time and effort people have spent behind an eyepiece laboring under the stars and learning for themselves what real challenges reside ahead. It’s as if people think they can just learn to play a guitar over night without ever having played a guitar. Not an ounce of humility, it amazes me. 


 

#638 CHASLX200

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Posted 14 August 2018 - 06:04 AM

Well if SW would have sent me one the truth would have been out there. Now i may sell my mount and thin down all my stuff.


 

#639 Daniel Mounsey

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Posted 14 August 2018 - 06:05 AM

Hi Daniel.  I see overcorrection because it's a simple doublet the Fresnel rings on the inside of focus, filtered or au naturel, are mushier and less distinct than the rings on the outside of focus, which is the opposite of other Synta ED doublets I've owned.

 

As for acclimation, the scope was out in stable temperatures last night (high pressure system built in) and is stored in an unheated shed.  No change in performance over the course of the 3.5 hour session.

 

I agree that there are qualitative differences to be seen scope to scope on the Moon.  However it's rare that a truly bad optic does not look, well, pretty good, on Luna if you are not being critical.  That is, the same scope that starts to put graininess in the image at 170x on Jupiter nonetheless puts up a seemingly sharp, contrasty view of the Moon at 275-300x.  Chalk it up to limitless light and lots of high contrast features (brilliant highlands and inky shadows).

 

My point about Luna is that it can mislead one into thinking the scope is better than it is.  Terestrial use is similar.  This scope was putting up wonderful views of bricks on the facade of a Target store 2 miles away.

 

Best,

 

Jim  

 

Jim,

I just wanna follow up with you here. These refractors should not display the over-correction you describe. The other factor is that we don’t really know if you saw over-correction after it was acclimated properly or not. If it wasn’t acclimated, then I’d hate to think of the direction the spherical correction is headed. Theoretically, the telescope would perform worse as it acclimates. It will sway further away from proper spherical correction. If this doesn’t bother you, then I suppose you could just enjoy the scope for the casual purposes you described. For me personally, it contradicts all these concerns about optical quality. 


Edited by Daniel Mounsey, 14 August 2018 - 10:06 AM.

 

#640 CHASLX200

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Posted 14 August 2018 - 06:15 AM

I just hope the cells can take the banging around of shipping. This is where Meade failed us with the 7" ED.


 

#641 JKAstro

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Posted 14 August 2018 - 06:27 AM

Bob, in the end, a number of reviews will be needed to finally determine if and how observers like the Evostar. I really think this is all very premature to assume that Jim’s sample is acceptable by SW. Also, there is so much misinformation getting tossed around in these threads. There are so many countless factors that affect the views different observers see and people have too many incorrect, preconceived notions about how all these scopes should perform. People with none or hardly any experience using these telescopes are using Strehl ratios to determine optical performance, yet there’s really no way to put that into an observation. How would people understand how to describe how the images will look with these numbers. Some of the things I get from the comments in these threads are just so preposterous. It merely illustrates the lack of time and effort people have spent behind an eyepiece laboring under the stars and learning for themselves what real challenges reside ahead. It’s as if people think they can just learn to play a guitar over night without ever having played a guitar. Not an ounce of humility, it amazes me. 

The question isn't whether or not the scope is acceptable to Skywatcher, the question is whether or not an amateur would know the scope they received was an underperformer and should be sent back, even if it was purchased from a trusted dealer who has labored endlessly under the stars.

 

At the start of the discussion for the Evostar 150 we were told to ignore everything and just look through the scope.  Now someone who actually has the experience to judge has looked through it and given his impression.  True, it is only one sample, buts lots of people look through one sample of a scope and give it their blessing, so we see the first hand review theory also has its limitations.  How many Evostar 150 scopes would one need to look through and compare to give an accurate representation of its overall quality?  

 

At least discussing Strehl is an attempt to quantify quality.  Even if it is known to be imperfect, it doesn't come across as lacking humility any more than when a salesperson who sells scopes without test reports criticizes people who find them useful or interesting.


 

#642 starman876

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Posted 14 August 2018 - 07:04 AM

There should be locations around the country where one could take their new scope and have it tested before they use it.  That way one would know if they got good optics or not.  At least it would eliminate the guesswork of not knowing if I need to let the scope temperature equalize to its surroundings.  Is the atmosphere not steady enough for a good star test.  Did the scope get bounced around too much during shipping and is it out of alignment.  We would have a written report after the scope was shipped that everything was still aligned properly and we would know what to expect in regards to performance.   I think Company Seven provides this service only on scopes you buy from them.  Cumberland Optics (they make Questar optics) in MD I know have the ability to do this, but do not know the cost.  


Edited by starman876, 14 August 2018 - 07:13 AM.

 

#643 Bomber Bob

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Posted 14 August 2018 - 07:18 AM

Bob, in the end, a number of reviews will be needed to finally determine if and how observers like the Evostar. I really think this is all very premature to assume that Jim’s sample is acceptable by SW.

 

Jim's 150 is not a representative sample -- unless the majority of these are delivered with damages.

 

I hope his report gets Sky-Watcher to properly pack these scopes.  In the end, shoddy work saves no money, and sours buyers for a product, no matter how "cheap" it is (and IMO, $2500 for an OTA used in a hobby isn't cheap!).

 

I just hope the cells can take the banging around of shipping.

 

With a decent packing job it should do okay.  I've bought vintage scopes from Goodwill on-line that were packed better.


Edited by Bomber Bob, 14 August 2018 - 09:07 AM.

 

#644 bobhen

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Posted 14 August 2018 - 07:38 AM

Bob, in the end, a number of reviews will be needed to finally determine if and how observers like the Evostar. I really think this is all very premature to assume that Jim’s sample is acceptable by SW. Also, there is so much misinformation getting tossed around in these threads. There are so many countless factors that affect the views different observers see and people have too many incorrect, preconceived notions about how all these scopes should perform. People with none or hardly any experience using these telescopes are using Strehl ratios to determine optical performance, yet there’s really no way to put that into an observation. How would people understand how to describe how the images will look with these numbers. Some of the things I get from the comments in these threads are just so preposterous. It merely illustrates the lack of time and effort people have spent behind an eyepiece laboring under the stars and learning for themselves what real challenges reside ahead. It’s as if people think they can just learn to play a guitar over night without ever having played a guitar. Not an ounce of humility, it amazes me. 

Whether observers like the SW 150 ED is completely irrelevant as to how it performs.

 

I can find reviews where people “like” the lunar/planetary views in a ¼ wave 6” F8 achromat. I can find reviews where people “like” anything. However, when it comes to quantifying performance, optical theory is well established.

 

These scopes will all come in between ¼ and 1/6 wave: 1/5 wave is .88 Strehl. 1/6 wave is .92 Strehl. If they could be made to ALL come in at 1/8 wave and at this price point, then SW should guarantee 1/8th wave as an optical quality minimum. Then these scopes would actually be a good value and a good choice. SW will never do that.

 

Here is quote from R F Royce…

 

“From this optician's viewpoint a reasonable standard for telescopic objectives of high-quality would be those producing a Strehl ratio from at least .95 upwards…and preferably .96 Strehl (which is 1/9 wave) or better.”

 

This scope is designed for visual, high power lunar/planetary viewing. Sure you can use it for deep sky observing and even imaging but there are better (even better refractor) choices for those pursuits. But as a lunar/planetary refractor, those numbers are mediocre at best.

 

Those radial lens element adjustment screws alone would keep me on the sidelines. At no point do I want to have to (or even think about) adjusting individual lens elements in a refractor.

 

Sure, some might like the views (as some like the views in those 6” F8 achromats) but that does not change the optical quality or make this scope a good choice, or even a good value, for the lunar/planetary observer. There are better values and choices out there.

 

 

All respectfully IMO of course.

 

Bob


Edited by bobhen, 14 August 2018 - 07:41 AM.

 

#645 peleuba

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Posted 14 August 2018 - 10:52 AM

Admittedly, I have not read all 26 pages of posts in this thread...   And, as someone who has an optical bench with DPAC and a collimator (not newt colimator, but a device that generates parallel wave of light for indoor star testing) and is a pretty good star tester, I have to agree with Bob (bobhen).  Some random thoughts:

 

(1) SW only guarantees diffraction limited performance. 

 

(2) Daniel's contention that "a number of reviews will determine how observers like the Evostar.."  is curious to me and practically irrelevant to the discussion.  I don't "like" a telescope because of a review.    One's emotional response to "like" something has little to do with reviews or even absolute optical performance.  Though its easier for me to "like" a telescope that performs well.  Perhaps Daniel meant that once the telescope got into more peoples hands, and reviews starting coming out, and a consensus started to build, and owners' opinions were socialized genralities could be made.   But, dont hold your breath - you almost NEVER hear of critical reviews of telescopes people bought with their own money.  I can only think of a few:  Jim's experience with this SW150; a recent review of a CFF92; and the other was my own a few years back of a TEC110FL.   To this end, I don't always put a lot of stock in "reviews" I see/read.  I trust myself and my ability to discern good from bad.  I am ALWAYS willing to help someone do this for their own telescope.

 

(3) This talk about overcorrection/undercorrection is amusing because it means little without additional information.  Hard to say if its brought on by environmental conditions like temperature swings. Star testing is easy to do and hard to interpret especially when Spherochromatism - spherical aberration as a function of wavelength can cause Fresnel patterns to be "mushy" on one side.  

 

(4)  Jim, whether he knew it or not is trying to eliminate the effects of Spherochromatism, by testing using filters.  He mentioned that even with a green filter the pattern is mushy on one side.  I've seen this myself, and, best advice I can give is to stack a Wratten 56, Wratten 58 and Wratten 11 then test again.  The lens WILL be nulled at some wavelength.    Sometimes, you have to figure out with trial and error.

 

(5)  At this price point, these lenses come off a machine, tested in a pass/fail manner then placed into telescope.  Some will be better then others.  Almost all of them will meet the "diffraction limit" promise.  If you want more then diffraction limited performance, buy from a manufacturer that guarantees it, or be prepared to spend time and money searching for the best sample available.    


 

#646 roadi

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Posted 14 August 2018 - 11:13 AM

Bob, in the end, a number of reviews will be needed to finally determine if and how observers like the Evostar. I really think this is all very premature to assume that Jim’s sample is acceptable by SW. Also, there is so much misinformation getting tossed around in these threads. There are so many countless factors that affect the views different observers see and people have too many incorrect, preconceived notions about how all these scopes should perform. People with none or hardly any experience using these telescopes are using Strehl ratios to determine optical performance, yet there’s really no way to put that into an observation. How would people understand how to describe how the images will look with these numbers. Some of the things I get from the comments in these threads are just so preposterous. It merely illustrates the lack of time and effort people have spent behind an eyepiece laboring under the stars and learning for themselves what real challenges reside ahead. It’s as if people think they can just learn to play a guitar over night without ever having played a guitar. Not an ounce of humility, it amazes me. 

But isn't the strehl value about where the light is distributed? etc. if the strehl test says 0.90 then 90% of the light is going to the exact point. So it must very accurate to determine the optics value.


Edited by roadi, 14 August 2018 - 11:22 AM.

 

#647 jrbarnett

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Posted 14 August 2018 - 11:48 AM

Jim,

I just wanna follow up with you here. These refractors should not display the over-correction you describe. The other factor is that we don’t really know if you saw over-correction after it was acclimated properly or not. If it wasn’t acclimated, then I’d hate to think of the direction the spherical correction is headed. Theoretically, the telescope would perform worse as it acclimates. It will sway further away from proper spherical correction. If this doesn’t bother you, then I suppose you could just enjoy the scope for the casual purposes you described. For me personally, it contradicts all these concerns about optical quality. 

You may not really know since you weren't there.  :grin:  I however was there and do know.  And yeah, I know how lenses change when they cool down or heat up.

 

As I stated in my response to your original question the telescope was acclimated.  It is stored at ambient, a high pressure system had settled over the area the day before such that day-night temperatures did not vary as much as is typical for the area, and this particular scope was deployed, given a half hour to cool before use and used continuously for several hours after that.  Yet at no time did it's figure improve - the unfiltered star test using Altair and magnifications in the 200x range did not change noticeably from earlier in the session to later, planetary performance likewise didn't markedly improve through time.  The only real variance detected were changes in seeing and in transparency (variable smoke density overhead throughout the session).

 

I'll relegate this one to "casual use" by necessity, not preference.   And whatever my perspective on optical quality (I have lots of scopes; one that underperforms expectations isn't such a big deal - it will have a home and a role while I own it and at some point I may send it on to a new home with full disclosure as I've done with many prior "fair to middling" scopes), the reality is others considering buying this scope or a competitive offering as a main or only scope do understandably care about and have asked about optical quality.  Ergo it's relevant for assessment and discussion. 

 

For me, this scope replaces a casual use 6" refractor whose poor color correction relegated it to that specific role.  I purchased this scope hoping that it would be more versatile than the last on account of its better color correction.  While it satisfactorily fills the same role as its predecessor the indifferent figure of the optic and damaged focuser caused by the manufacture's woefully sloppy packaging decisions hold it back from doing much more.

 

You win some and you lose some.  On this one, I feel like I kind of broke even.  Am I delighted?  No, not really or at least not yet.  Am I understanding?  To a point - it's a new large refractor with a heavy OG and teething pains in the centering and alignment department aren't entirely unexpected.  Tak blew it with the TOA-150.  If Tak can blow it in this regard with a then $9k scope, anyone can blow it.  Though the focuser thingy really does kind of tick me off.  There apparently are none to be had from Synta at the moment, which is a little lame given the lousy packaging.  But what are you going to do? :shrug:

 

Well I know what I am going to do - use it just like I did its predecessor for the foreseeable future.  I'm also going to spend more time getting to know the scope.  I have a total of about 5 hours of active use with it this far.  I'll also do some more deliberate side by side comparisons with this scope versus the TEC 140ED (folks have asked for this) but some of the suggested tests are off the table.  This is not a 1 arc second double scope.  It's okay on Epsilon Lyra, as you'd expect, though less "tidy" than some better figured much smaller scopes I've used recently (LOMO 80/600 for example).

 

I'm hoping that with better transparency, a functional focuser, much more deliberate star testing using real and artificial stars, etc., I'll discover that something is wrong with the optic like slight decentering that I missed on my initial datytime inspection using the artificial star.  If so, I'll correct it and report back.  If not, it's no worse than the scope it replaced in the intended main role and much better in one regard - bright field stars don't have big maroon halos.

 

Out of curiosity have you or your crew performed a star test on the unit you have been sharing around?  I may have missed it if you've already reported it, but if you have done a star test and haven't yet shared or would consider doing one next time you're out, I'd love to read about it and all of the particulars (star, magnification, filtered or not, what did you see inside and outside of focus, where would you estimate the spherical correction to fall, etc.).   

 

Best,

 

Jim


 

#648 CounterWeight

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Posted 14 August 2018 - 11:49 AM

Though Strehl is a number it is not standardized therefore it is also irrelevant in ways.  Along that line I also have to ask if the difference in using an LED and a coherent source should be qualified... ?  there is a very important difference in the behavior of the two different type sources...  anyone care to speculate on speckling(sp?) here?  As I've mentioned before there too is the geometric graph theory of number of points and locations, are we talking thousands? hundreds? 10? Still a huge digression as we are talking about something that is not a standard.  Metrology is a science and unless using accepted standards and units of measure it is only measurement and in ways can be considered scientifically arbitrary. I am in no way way taking issue with any of the optical science behind Strehl.

 

A little patience in setting things right will go a very long way, it is one of those things IMO early adopters volunteer to do.  If I recall this purchase was an end run around SW USA?

 

As a lifetime guitarist, I second what Daniel mentioned.  Many thousands of times folks have said they are a musician or play guitar or base (or whatever) and they cannot play anything at all. There is absolutely no replacement for practice, never will be.  That takes time, and loads of it, not always fun or entertaining and usually resembles 'work'. 


Edited by CounterWeight, 14 August 2018 - 11:49 AM.

 

#649 BillP

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Posted 14 August 2018 - 11:53 AM

Bill, maybe yours.....a Lunt, isn't it?  However maybe not all 150 class ED refractors.  Being that you are happy with yours and can push beyond 30x per inch I would venture to guess that if you have tested or can test, it will yield better than 1/4 wave results.

 

Barry Simon

 

A few rhetorical questions... How many 150 ED refractors are there out there?  How routine is it for there to be a prevalence of telescopes sold from mainstream vendors that are less than 1/4 wave or diffraction limited? 

 

It just seems kind of silly to me for anyone to suggest that there is any prevalence for any ED-level scope from mainstream vendors, triplet or doublet, to be so sub-par that it cannot even hold 30x/in (which I would call defective unless for an uber-fast f/4-f/6 achromat).  The 150 EDs we are talking about here are the new SW, Lunt, APMs.  For the latter two at least finding CA is something you really need to hunt for so they are very much visually color free in operational use for lunar, planetary, and DSO.  Should never be an issue for these to get to 50x/in without breaking a sweat -- with mine, it's not like it is struggling in the slightest to do 50x/in with anything other than a pristine view.

 

At any rate, if the discussion is about 150 class ED Apo refractors that cannot achieve 30x/in then the discussion is really about IMO defective equipment or equipment not properly managed by the observer (i.e., out of collimation or a thermal mess).  So not sure how meaningful that is really...other than letting others know they have a defective scope.  I've only had one scope in my life that could not easily achieve 50x/in and it was an 80mm f/5 achromat...but that was expected as it is a crazy fast achromat with a color blur over 7.0!  Color blurs on these 150 EDs should be around 2 (1 is fully Apocromatic), which is a lot less than even an 80mm f/11.4.


Edited by BillP, 14 August 2018 - 12:00 PM.

 

#650 jay.i

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Posted 14 August 2018 - 12:07 PM

Honestly Jim, as much of a hassle as it might be, I really think you should ship that scope back. Even if you decide not to get a replacement. It seems it is not a representative example of this scope nor a representative example of what to expect for this size and cost, and you deserve better; every buyer of it does.


 


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