SW ED's Top end?

[KP82]

2 hours ago, F15Rules said:

Yes, I saw one of these for sale about 5 years ago on UKABS for £900..A real bargain, but at the time it was just not financially possible for me. If it matches it's 103mm and 81mm smaller siblings it will be a wonderful scope -and lightweight too..?

Dave

Wow, £900 only? That was a real steal.

[SamAndrew]

Great post, not what I was expecting when I opened the thread

6 hours ago, mikeDnight said:

Lesson 6) Over the years I learned that the more portable and user friendly a scope is the more I'll observe with it. Oddly, I found myself using the Equinox 80 ED more and more as time went by, as I was able to carry it out with one hand, it cooled fast and with a binoviewer it gave superb views of the Moon and Jupiter. I'd go out for just a five minute session before bed and often find myself still sat there at the eyepiece of the 80mm an hour later. I really began to appreciate the portability aspect more and more. ....

I totally echo this experience; I haven't yet had the pleasure of owning a larger APO, but my best nights were all with the Equinox 80. I used to just use a cheap camera tripod and it was so easy to plonk it on a table in the garden and grab a glimpse of Venus as the Sun was setting. I took it out to Crete for the Venus transit in 2012 and had some epic nights observing summer DSO's that are a bit low in the UK and those views still stick with me today. I spent hours tracking Saturn at 280x magnification which is far beyond what the aperture should be capable of, but it was always very pleasing.

I've been sorely tempted on the few occasions that Equinox 120s have come up for sale over the last few years. I think I'll have to renew my search after reading this.

[F15Rules]

Yes, £900, and the best of it was it didn't sell first time around!!

[GavStar]

Great post Mike!

I find 90-100mm a sweet point for ease of viewing and portability. Main reason for me is the mount. 100mm and below I can use a light small mount such as an az gti or vixen porta 2. As soon as I go over 100mm then I need something much more sturdy (I hate vibrations) and that increases the set up time etc quite a bit and stops it being grab and go...

Having said that, I’ve done a side by side of a Tak 100 and my TEC 160 and the difference in views is substantial enough to make it worthwhile to setup when time permits ?

[paulastro]

On ‎28‎/‎12‎/‎2018 at 12:33, mikeDnight said:

There's a lot of debate over the value and performance of high end refractors, and how they compare. Somehow though, it seems the SW ED's may be getting overlooked when high end refractors are being considered, viewed by some perhaps as being a poor man's apo. But is that true?

My first experience with an apochromatic refractor was on the 3rd January 2003. Some kind gentleman had donated a 102mm Vixen fluorite refractor, complete with GP mount and pier, 60mm guide scope, motor drives and eyepieces to my local astro club. It was beautiful! When i arrived at the observatory, everyone excitedly showed me this beautiful scope set up on the field along side a 100mm Tal refractor and a 150mm Helios refractor. The trio looked amazing alongside eachother! Saturn was low in the east and looked virtually identical in all three scopes. I openly expressed my confidence that when Saturn rises to 30° the 150mm will give the more detailed view due to its aperture and resolution, and that no matter how good the 102 fluorite was, it would be left standing. 

Lesson 1)  The 102mm fluorite kicked the living daylights out of not only the 100mm Tal and the 150mm Helios, but also every other scope on the field no matter what the aperture or design. Saturn through the Vixen looked as though it was being viewed through a space ship window, and the rings were so detailed they gave the impression of having grooves like those on a vinyl record. That night apertures King had just been dethroned!  I drove home from the observatory in the early hours of the following morning, wondering how on earth I'm going to find a spare £2,200.00 to buy myself one of these amazing scopes?

Lesson 2) Cutting a long story short, I never did get my hands on a Vixen fluorite, as the then sole UK importer was a pretty useless character. Instead, three months after my first encounter with the Vixen FL102 I ended up buying a Takahashi FS128 for considerably more than the cost of the Vixen. It was not only a beautiful scope to look at and to look through, it was big physically, which meant I needed a bigger mount and more expense. Then my friend Gain introduced me to Naglers. More expense! Buying a top end scope is only the beginning of the poverty spiral!

Lesson 3) Years went by and the FS128 never failed to impress. Was it worth the financial pain? For me it was, as I loved every minute under the stars with that scope Then came a proposition! I was offered a Tak FS152 in exchange for my FS128 + £1000. I thought this would be a once in a lifetime chance to own a £10,000.00 Tak, which is what it would have cost had I bought it brand new. I couldn't turn the opportunity down and I became the owner of a superlative 152mm Tak fluorite. Then came further expense,  as the Losmandy GM8 that carried my FS128 was woefully inadequate when it came to carrying my FS152. A new mount was needed and I bought a Losmandy G11. ( I must have the most understanding wife on the planet)! Initially I was thrilled with my acquisition, but very soon I noticed my observing had taken a hit. I was looking for excuses not to observe as setting this heavy beast up, and more importantly dismantling everything and carrying it all back in when tired and frozen, was taking the joy out of the hobby. I missed my FS128, but it had now been sold on to someone in Germany. One night while setting the 152 up on its mount, my back gave way and I slid down the pier in agony while desperately holding on to £10,000 worth of tube assembly. At least thats what it would have cost had it needed to be replaced. It was an expensive lesson and i soon came to realise that bigger isnt always better!

Lesson 4) Don't believe everything you read, especially if its a top end scope manufacturer trying to sell his product. "It Is What You Want It To Be"!  Or at least that is what TeleVue wanted me to believe about their NP101. I read and re-read that advert in Sky & Telescope until I'd convinced myself a small, easy to handle apo was just what I needed. I sold the FS152 and the Losmandy G11 in very short time and bought everything TeleVue.  The 101 when it arrived was a lovely looking scope, and the armoury of Naglers, powermates and Ethos - Ethos's- Ethi, or whatever, were mouth watering. The scopes rich field and deep sky prowess was undeniable and to date I feel the 101 is the best rich field refractor I've ever used. But it made me work hard on the planet's, and when on one night my friends F6.5 Vixen ED gave a far better defined view of Saturn, I knew the NP101's days were numbered, after all the NP101 cost nearly as much as my superlative FS128 and was thrashed by an old Vixen ED costing a fraction of the price.

Lesson 5) ENTER THE DRAGON!   A year after buying the NP101 I sold it on, but things were brought to a head after a side by side showdown with a cheaper Chinese ED. Cheaper in cost only I hasten to add! My friend Paul had managed to get hold of an ex display gold and cream SW 120 ED. One look at the moon through both scopes was enough. Had I not known in advance that it was a SW ED I was looking through, I swear I would have thought it was a Tak! There was essentially zero CA, the moon was almost ice white which was something I loved about the fluorite view through the Tak's and Vixens. By comparison the NP101 gave a rather nicotine view of the moon and it had to go. The SW ED was really something special, and as Tak and Vixen had stopped producing fluorite refractors at this time, I knew I couldn't live without a SW ED. The 101 was sold within 48hrs and in only a couple of days I had my first SW ED120. The only regret I have is that I've wasted thousands of pounds to get to this point. Ive owned five SW ED's -  one DS Pro 120 ED, two Equinox 120 ED's, one DS Pro 100 ED and a fab little Equinox 80 ED. All were stunningly good scopes! 

Lesson 6) Over the years I learned that the more portable and user friendly a scope is the more I'll observe with it. Oddly, I found myself using the Equinox 80 ED more and more as time went by, as I was able to carry it out with one hand, it cooled fast and with a binoviewer it gave superb views of the Moon and Jupiter. I'd go out for just a five minute session before bed and often find myself still sat there at the eyepiece of the 80mm an hour later. I really began to appreciate the portability aspect more and more. When my friend Paul told me Takahashi had begun making Fluorite refractors again I was intrigued. Then one night he phoned me to say he'd ordered one, so I thought if he's having one then so am I. So I put everything I had up for sale and the money came rolling in. Then I got a call from Paul, asking what on earth I was selling all my gear for? I told him that if he's having a Tak then I'm having a Tak! The phone went silent for a while - then he said "I was only kidding just to see how you'd react"! Then he cracked up laughing. What a Git! Still, the 100mm F7.4 Tak has turned out to be virtually everything I loved about all the various refractors I've owned all in one package, so nothing was lost in the venture. 

Lesson 7) Don't trust paulastro!! 

 

Well Mike, what can I say?  It's been a great pleasure to accompany you on your journey through refractor land, it's been a wonderful adventure - though I wouldn't be too sure that your adventure is at an end just yet .

Lesson 7 just concerns me a little - I was just about to post a classified ad - perhaps I'll just wait a while .

[Split Zygote2]

Dear mikeDnight, thank you for taking the time to pen this which I have just read with much interest. Reading between the lines on Roger Vine's site I had deduced some of it but it is good to hear matters first hand as it were.  I totally echo your sentiments in respect of the SkyWatcher 120 EDs. My example shows no discernable colour either in or out of focus a trick my TV85 does not match and there is no perceptible glow of unfocussed light around the moon indicating a good level of polish. Of course mine is a very excellent example but then isn't everybody's? As a visual only scope it compares very well with the best, though  photographically I suspect it would be a slightly different story. Horses for courses. I note your fondness for the AZ4, my Equinox 120 is mounted on one such atop a Berlebach tripod on wheels. Slightly vibration prone at high powers but still very usable and although I suspect the mount is at its limit here it is infinitely preferrable to my Ercole mount which exhibits way too much stiction in azimuth no matter how well balanced.

 

Michael

[jetstream]

On 28/12/2018 at 06:33, mikeDnight said:

There was essentially zero CA

The SW120ED is a very good scope.

Over on CN quite a while back I reported a small amount of CA in my 120ED and many did not take kindly to this. It seems these scope are reputed to have no CA... after a while some came forward to acknowledge that theirs did too. I personally do not believe they are 100% CA free.

Mike, can I get your thoughts on "essentially" zero CA?

[GazOC]

I see CA in my ED120 (which gives a very good star test) on objects such as Jupiter at high power.  

[mikeDnight]

29 minutes ago, jetstream said:

The SW120ED is a very good scope.

Over on CN quite a while back I reported a small amount of CA in my 120ED and many did not take kindly to this. It seems these scope are reputed to have no CA... after a while some came forward to acknowledge that theirs did too. I personally do not believe they are 100% CA free.

Mike, can I get your thoughts on "essentially" zero CA?

Hi Gerry,

I'm with you on this! There's no getting past the fact that SW ED doublets all exhibit some level of CA. It is very well controlled however, so that when in focus, the ED's can be described as apochromatic. If an SW ED doublet is used alongside a quality triplet such as a TSA120, then the difference in colour correction becomes immediately obvious. In fact, my old FS128 and FS152 refractors displayed a very minor level of CA, but there was no doubt about their lunar and planetary prowess. 

I feel my FC 100DC has better colour correction than either of my previous two Tak fluorites, yet I know there is some level of CA in the equation, as as far as I'm aware, no doublet can bring all the colours together completely. Having a small level of CA however in no way impedes these scope from giving truly stunning, essentially colour free views on every kind of object.

There's a lot of debate about CA and also a lot of confusion. Atmospheric dispersion/refraction may cause some to fault an apo, when in reality its not the apo that's causing it. Also today, many use multi element wide angle eyepieces that produce lateral colour. Again, the scope can get the blame when its not the scope at fault. Even reflectors suffer from these two false colour problems!

A few years back, a friend bought a Meade 127 triplet which was an excellent scope exhibiting no discernible CA. In side by side comparison with my then Equinox 120 the 120 did everything the 127 did -  only outside focus did the 120's CA become noticeable. As I observe with the image in focus I remained unconcerned!  Interestingly, my friend desperately tried to talk me into doing a swap, my scope for his. He did this because the Meade was a big scope and he was a little guy. He valued the 120's compact, relatively light weight design. So did I! He soon sold the heavy colour free Meade!!

If CA was something that troubled me greatly, which it isn't, I'd set my sights on a TSA 120 which is not only free of CA, its optics are some of the best available. 

 

[barkis]

2 hours ago, GazOC said:

I see CA in my ED120 (which gives a very good star test) on objects such as Jupiter at high power.  

Nice to see you posting again Gaz. .

Ron.

[Ben the Ignorant]

It's no mystery the Sky-Watcher 120 Equinox or Evostar is a semi-apo, its star test displays the typical pale purple and pale lime green.

(image from Davide Sigillò's blog)

My Astro-Professional 80mm f/7 semi-apo fitted with FPL-51 glass shows the same pattern, allowing for some difference depending on what camera takes the picture. Given that the 120mm has almost the same f/ratio, it has 1.5x the diameter, and chromatism is exponential with diameter increase, the FPL-53 glass did an excellent job.

Interestingly, some older (2009) Equinox refractors spread their diffraction patterns in the reverse way: sharper rings in extrafocal, and softer rings in intrafocal:

(image from Telescope Doctor's blog)

Very close to focus the pattern was more colorful but the focused image had no more chromatism than other 120's. It seems newer 120's don't have the residual spherical (pattern is a little soft in intra) that older ones had with some frequency. Moderately defocused disks have uniform color save for the outermost ring, and that means good semi-apo action.

The 100° Myriad 9mm eyepiece eliminates chromatism in my semi-apo, or other eyepiece designs increase it, and 356astronomy's bottom-price 2" dielectric diagonal absorbs some violet without any other loss of colors or quality. If everyone who operates a semi-apo used that diagonal there would be less complaints about residual chromatism. It is a full-metal unit with no compromise in toughness or stability. The mirror has no aluminum layer so they could taylor its reflective curve to suppress some violet. 

[GazOC]

Cheers Ron ?

[MartinB]

4 hours ago, barkis said:

Nice to see you posting again Gaz. .

Ron.

Ditto!

[John]

6 hours ago, barkis said:

Nice to see you posting again Gaz. .

Ron.

Same for me Gaz !

I see a little CA around the brightest stars with the ED120 (just a slight "spash" of violet), none around the lunar limb or brighter planets. Like all ED doublets it shows a little CA either side of focus (green one side and purple the other).

The Tak FC-100DL fluorite doublet and LZOS 130 triplet show no CA anywhere that I can see so make interesting benchmarks in this respect.

The ED120 shows less CA than some triplets which use an FPL-51 element though. In addition I've found the ED120 objective is a well figured and polished lens which is just as important as the levels of CA IMHO.  They are fine 4.7" refractors

[Moonshane]

I must confess I am now starting to wonder if I could find (and find!) a used TSA120 selling my 120 Equinox and other things plus a small loan. ?

[mikeDnight]

1 hour ago, Moonshane said:

I must confess I am now starting to wonder if I could find (and find!) a used TSA120 selling my 120 Equinox and other things plus a small loan. ?

I'm not one to try and influence anyone as you know, but the TSA120 has the option of being supplied with a feathertouch focuser made specifically engraved for Takahashi direct from Tak. 

[John]

The TSA120 was high up my list when I was looking for a top end refractor a couple of years back. Having read Gerry/Jetstreams reports on his, It's still on my wish list.

I expect the result of a back to back comparison with my ED120 would be reasonably close but with the Tak outperforming the Synta especially at high powers. This brings us back to the questions of how much quantifiable performance difference is there between the two and is that difference worth around £3,000-£3,500 which is I guess what I'd need to find to change my ED120 for a TSA120

I could buy an 18" dob for that and have plenty of change !  

 

 

 

[GazOC]

That's my thinking John when I look at a scopes like the Espirts, you can get a lot of GOTO Dob for the same money. It's an apples and oranges comparison as far as function goes but being happy enough with my ED120 as a grab and go (ish) option I dont think I'd pay for a slightly bigger/ better refractor that would also be harder to mount in place of, say, a 14 inch GOTO Dob.

[Steve]

Welcome back, Gaz ?

[GazOC]

Cheers Steve ?

[mikeDnight]

2 hours ago, John said:

The TSA120 was high up my list when I was looking for a top end refractor a couple of years back. Having read Gerry/Jetstreams reports on his, It's still on my wish list. This brings us back to the questions of how much quantifiable performance difference is there between the two and is that difference worth around £3,000-£3,500 which is I guess what I'd need to find to change my ED120 for a TSA120

 

 

 

 

Is the quantifiable performance difference worth price difference? Almost certainly not! Ive only used a TSA120 a few times, one of which was alongside my Equinox 120. The night was poor so probably not the best true compare, but both scopes gave textbook star images, and the miniscule amount of CA in the ED didn't make me suddenly want to sell my soul and buy the TSA. Having said that, I'm sure the TSA will deliver the goods beyond that of the 120ED on good nights. 

See John, I bet you thought I was going to try and talk you into buying one, but instead I've saved you thousands. I must be losing the plot! 

I'd still buy one if I could afford it though!!

[jetstream]

There are vicious rumors out there that the TOA130 has better optics than the TSA120.....in a heavier package.

[John]

1 minute ago, jetstream said:

There are vicious rumors out there that the TOA130 has better optics than the TSA120.....in a heavier package.

But would the TOA130 match my TMB/LZOS 130 F/9.2 triplet I wonder ?. They cost around the same if bought new. The TMB/LZOS is a little lighter than the TOA at least !

If someone would lend me a Tak TOA130 I'd be glad to compare the two......... over a period of several months

 

[jetstream]

Another rumor is just how good the TEC160FL is, possibly the top of the top?

[barkis]

How would the  analysis of these telescopes by those here comparing them, stand up against any official reviews of the instruments discussed here.

This is fascinating to read, and the practical comparisons made, would certainly give food for thought to anyone considering the purchase of the units discussed in this thread.

Just curiosity on my part, as  I've not ever used any of them myself. My only Apos. are an Ed80, and a WO zs 66.?