New refractor - figure vs flourite?

[Stub Mandrel]

"Skywatcher...........again"

Suggest you are looking for something beyond just optical performance ?

So be honest with yourself and go for something that will give you pure 'joy of ownership' as well as the views.

[Cjg]

Will you be emotionally satisfied with anything other than the Vixen? It’s on your list for a reason, if you purchase anything else, will you always be wondering ‘what if’? 

There’s bound to be deals on the day, tell your SWMBO it’s the last scope you’ll ever buy!

Good luck,

Chris

[parallaxerr]

10 hours ago, Cjg said:

tell your SWMBO it’s the last scope you’ll ever buy!

I think I've already worn that excuse out ?

[John]

If its intented to be a "last scope I'll buy" save up and make it a Tak. While I love my little Vixen ED102SS, the Tak FC-100 is better still optically 

Probably best to avoid that definition to be honest - you never know that the future might bring !

[parallaxerr]

Well a little pre-show enquiry has turned up a result. I have the option to purchase a Vixen ED103S that was used for Pete Lawrences review in Januarys Sky at Night. After the review it was returned to Vixen for a once over and has been passed off as all good and I can have it for £200 off the usual price.

Review here....

http://m.skyatnightmagazine.com/review/telescopes/vixen-sd103s-apochromatic-refractor

It only scored 4/5 but the online review is a shortened version so I dug out the magazine hard copy. Basically it looks like it was scored down slightly on some imaging specific characteristics, which will not affect my visual use.

It appears diffraction spikes around bright stars due to the foil lense spacers appear when imaging. That's how it reads to me. The part about optics states that they're excellent otherwise.

 

[Davey-T]

Budget smudget, you want fluorite get one of these and wait for the divorce papers to arrive ? ? ? ?

"Only" 5000 euros and they throw in some scope rings.

Dave

 

[John]

The SD103S seems to be an F/7.7 version of my ED102SS but using an FPL-53 element. It certainly looks virtually identical apart from the tube length. Vixen didn't specify the ED glass back when mine was made (2000-ish) but it's probably FPL-51. Given that mine is F/6.5 and probably uses an FPL-51 element, the CA control is really rather good, as is the figure and polish of the lens surfaces. An F/7.7 using FPL-53 should be even better. Mine has the same foil spacers and I see no sign of them at all when observing. The focuser is excellent but it is a single speed unit. A dual speed upgrade to the focuser is available though (without needing to change the whole focuser) if you feel that it is needed. 

 

 

 

[parallaxerr]

15 hours ago, John said:

Mine has the same foil spacers and I see no sign of them at all when observing

Thanks John, that's good to know, I guessed the issue was specific to imaging.

Well, the scope is now reserved for me so notwithstanding any mechanical/condition issues, I should be the owner of an SD103S come Saturday!

 

[mikeDnight]

Like nearly every review I've ever read in S@N magazine, it is very superficial and more than a bit limp. The one thing that did jump out at me was that there was NO COLOUR FRINGING around the limb of the moon! That's impressive!! Other than that the review tells very little about the scopes visual performance. Pete did mention it was poor seeing though!

To do the Vixen justice it should have been placed in the hands of a purely visual observer, like John H, who would treat it like a Formula One car, pushing it well past its presumed limits. I would wager that the 103S would, under good conditions, easily show the E & F stars, reveal hints of the Alpine Valleys central rille, reveal the vortex nature of Jupiter's Great Red spot, show Enckes division in the outer anse of Saturn's rings when they are fully open and high in the sky, and reach well beyond Mag 13. It will split equal binaries of 1" arc and still be happy at X100 per inch on a steady night.  If it can't do all those things on a top class night, I'll eat my hat, and I love my hat as I'm a bit thin on the thatch!

 

[parallaxerr]

1 minute ago, mikeDnight said:

NO COLOUR FRINGING

I noticed that too Mike and found it very encouraging.

1 minute ago, mikeDnight said:

I would wager that the 103S would, under good conditions, easily show the E & F stars, reveal hints of the Alpine Valleys central rille

I hope so, these are two of my astro ambtions!

I have a new found interest in the Moon and I'd like to be able to make some high powered observations of it's features. It's here that I feel/hope the Vixen should best a Chinese ED scope.

[mikeDnight]

53 minutes ago, parallaxerr said:

I noticed that too Mike and found it very encouraging.

I hope so, these are two of my astro ambtions!

I have a new found interest in the Moon and I'd like to be able to make some high powered observations of it's features. It's here that I feel/hope the Vixen should best a Chinese ED scope.

I used to avoid the moon Jon, but when I got my first apo back in 2003 I began to see it in a whole new light. I now wish it was there on every clear night. 

[Astro Imp]

I often wonder how much reliance can be put on reviews in the astro press considering the magazines rely on the suppliers for their advertising revenue. I feel it better to read the views of experienced observers on asro fora who are completely independent. Perhaps I'm just an old cynic.

[Stub Mandrel]

58 minutes ago, Astro Imp said:

I often wonder how much reliance can be put on reviews in the astro press considering the magazines rely on the suppliers for their advertising revenue. I feel it better to read the views of experienced observers on asro fora who are completely independent. Perhaps I'm just an old cynic.

As someone who deals with reviews in another field,there tend to be two types - the short 'this is a' of thing sent as samples or just as a press release; these usually avoid doing anything other than quoting manufacturer's specs and should be treated as 'drawing your attention' to something of possible interest. Then there are in-depth reviews; I've avoided any sort of 'rating' although some readers would like to see it.  In my view these should be honest and include any limitations or shortcomings. If something isn't good enough to score a 'notional' four stars then we don't run the review.

I did have an example recently where I tried out a product and just couldn't get satisfactory results compared to a cheap alternative. After much discussion with the supplier's tech department I decided not to run the review - mainly because I know several people who swear by the product and I couldn't be 100% the problem wasn't something to do with the way I was using it. I do have my own theory of what the issue is and when it did work well it was very good, but when it failed it was infuriating!

Another review was a low-end MIG welder; I couldn't get decent results, not even as good as my stick welding. I went to a mate who had (several) high-end MIGs. He taught me how to MIG weld on the good kit and let me practice, then helped me set up the review one properly (I had the gas flow all wrong). I didn't get perfect results, but at the end of the afternoon my welding with the cheap kit was good enough to show it did the job.

[Astro Imp]

^^^^
Interesting Neil, thank you for taking the trouble to recount your experiences but are all reviewers as scrupulous as yourself?
I feel we should finish this discussion as we are going off topic.

[John]

1 hour ago, Astro Imp said:

^^^^
Interesting Neil, thank you for taking the trouble to recount your experiences but are all reviewers as scrupulous as yourself?
I feel we should finish this discussion as we are going off topic.

A number of people who write reviews for astronomy magazines are members here so I think we need to be careful and respectful about their work and the constraints they work under

[parallaxerr]

UPDATE:

PAS has been and gone, I attended and.....I spent some money So what did I spend it on?

Well I went there with the intention of walking away with the Vixen SD103S, however, in the cold light of day after viewing the scope, I needed to do a few laps of the show to mull it over before coughing up the readies. The Vixen looked every bit as nice as I thought it would but I was surprised by the size versus the other 4" ED scopes present at the show. The larger OTA tube diameter , lack of retractable dew shield and longer than average focal length made it appear more like an ED120 than a 100mm scope. It was in as new condition as promised and there really wasn't much to check out, the single speed focuser was smooth enough but appeared to rely on being heavily greased to achieve this.

On my way around the trade stands I bumped into a certain Mr. @mikeDnight, accompanied by @paulastroand their friend Derek (is he an SGL'er?). We just so happened to meet passing the Altair Astro stand where I was headed to look over the 102ED-R. Much deliberation ensued and it became obvious that the general consensus was in favour of the Altair scope, mechanically at least. The Altair scopes at the show all had smooth focusers, far detached from the TS sample I previously returned. Of course, the ED-R has a higher end focuser than the TS and equivalent Ascent 102 do. 

The question then was "are the optics as good as the Vixen"? Well, I spoke to Ian of Altair Astro about this directly. I asked about the FPL-53 objective and he claimed it to be the highest standard coming out of China, with Altair specifying the highest Strehl of any customer. I asked if I were likely to see the small difference between this Chinese glass and that Japanese Vixen equivalent, expecting an answer along the lines of "only on the best nights", for example. However, the response was "there is no difference". Altair Astro are very confident that their FPL-53 objectives are on a par with those coming out of Japan.

One 102ED-R remained for sale at the show with £100 off the listed internet price, so I pulled the trigger! At £650 less than Vixen, I had to try it out with Altair offering to accept a return if I was not happy. I also picked up a Takahashi 1.25" prism diagonal and a new 32mm Plossl with the "spare" change. So here it is, I'm now in the same club as @david_taurus83 with the 102ED-R sitting atop an AZ4, which, appears to handle the scope with ease it must be said. I'm very keen to try it out but the local forecast obviously isn't great for the foreseeable future! Let's hope it delivers!

 

[Chris]

Congratulations  It looks bang on for the AZ4. I'm sure you'll have plenty of fun ahead of you!

[F15Rules]

On 07/03/2019 at 11:42, parallaxerr said:

I would wager that the 103S would, under good conditions, easily show the E & F stars, reveal hints of the Alpine Valleys central rille

Both my ED103s scopes showed the E & F stars without difficulty on good (transparent) nights. I don't know the lunar feature you mentioned as I'm not a serious observer of the Moon.

The first ED103s also gave me my first view of the Pup (I haven't yet tried it with my current one).

I've just noticed that you changed your mind and went for the Chinese Altair scope. So you have your first benchmarks to test it against - to match the Vixen , as claimed by Altair, it needs to show E & F and if conditions allow, the Pup.

Here's hoping you get good enough, transparent conditions to find out before the clocks go forward and we lose Orion for the summer ☺.

Dave

[Saganite]

I may have witnessed the deal Jon, as I was aware that Mike and Paul were deep in discussion at the Altair stand with someone, and I managed to grab Mike's attention at a convenient point. I have to say that I was very impressed with the 102ED-R, and you got a cracking deal. Look forward to your first light with it.

[John]

To be honest I'm not at all surprised by the Altair Astro reps response (what else was he going to say ?) but I hope you enjoy the scope and that it meets your expectations. I also hope that the AZ-4 is up to the job. I used my F/9 Tak 100 on mine the other night (on a nice stable wooden tripod as well) but at the high powers that a quality frac is capable of, the AZ-4 showed too many vibrations for my liking. Back to the Skytee II for the Tak !

BTW FPL-53 is from Japan (at least the blanks are) but I expect you know that.

£650 is a massive price difference though, I can appreciate that.

Look forward to your reports on your nice new Altair 4 inch !

 

[mikeDnight]

It really does look like a fabulous scope Jon. Taking a close look at it myself yesterday, I was very impressed by its quality and feel. I'm fairly confident it will do everything a top apo doublet should do, and would be very surprised if it failed in any respect.  It was a massive saving you made also, so doubly impressive! 

Looking at all the wonderful refractors that were on display at the show yesterday, it impressed on me how fortunate we all are. Any one of us could have been lead into that show blindfolded and made to choose a refractor, and not one of us would come out without an impressive scope in our possession. 

I'm looking forward to your first light impressions! The Moon looked amazing this evening through a gap in the clouds, so you may get chance to see it over the next few days.

[parallaxerr]

I got my first look through the scope this afternoon. Sadly, not under the stars but enough to get an initial impression. 

I have a few targets visible from the front of the house that I've used to evaluate scopes before:

1. TV aerial against the sky across the street - Very high contrast target which brings out CA if present. It has brought CA in all my scopes so far including a WO ED and the Equinox 120ED (albeit unfocussed). I'm happy to say that I could not detect a jot of CA in the 102ED-R, despite trying very hard. This includes inside and outside of focus, which I did not expect. The edges of the aerial simply softened when out of focus, the metal grey/sky blue colours simply met with no sign of blue/violet or green in between.

2. Distant high rise tower block on high ridge line - I use this to check for edge correction and it has, in the past, highlighted issues such as spherical aberration or maybe pincushion with the vertical edges of the tower block bowing in or outwards when approaching the edge of the FoV. No such aberrations with the 102ED-R, the walls remained straight as a die as close to the edge of the FoV as was comfortable to view.

3. Top of metal footbridge tower in far distance - I use this to test high mags. At x100mag, the 102 ED-R pulled out the individual rivets on the metal work despite warm, turbulent air. I didn't get a chance to barlow the EP so will try higher powers again, when I get the time. But, the focus snap at x100 was so pronounced and the view so sharp, I have confidence of hitting higher powers with relative ease.

So, good first impressions, under the stars is where it counts though but the forecast is terrible for the next 7 days ?

[david_taurus83]

23 hours ago, John said:

 I also hope that the AZ-4 is up to the job. I used my F/9 Tak 100 on mine the other night (on a nice stable wooden tripod as well) but at the high powers that a quality frac is capable of, the AZ-4 showed too many vibrations for my liking. Back to the Skytee II for the Tak !

 

 

I've used mine twice now and its absolutely fine on the AZ4. Very minimal vibrations and I'm using mine without the leg spreader for ease of packing away. My only gripe with the AZ4 so far is the stiction in the altitude direction. Azimuth is really smooth. Can move it all with a finger and it stops where I want. But the altitude, I have to go past where I'm viewing for the fov to fall back to where I need it. I added more grease to both axis when I recieved as I seen your comment about the factory application being somewhat lacking. Is there a certain grease best to use? I take it the roller bearing is to stay dry as both on mine have no grease on that side of the PTFE discs?

[John]

I'm not sure on the grease type - maybe lithium ?.

The AZ-4 I have just acquired (pre-owned) seems quite smooth so I'm not going to mess with it. Like the other AZ-4's I've had, it's just not composed at higher power when the scope tube length goes above 75-80 cm or so. My Vixen and Tak weigh around the same but the Tak is 20cm longer and that seems to tip the balance for the AZ-4.

Personally I like a little bit of "sticktion" in the altitude axis because it helps when switching between eyepieces where the weight varies. There is a "just right" level and also "just too sticky / too loose" level for me though and sometimes adjustments / tweaks are needed to achieve the right movement.

There is an old thread on re-greasing mounts which might be of interest:

https://stargazerslounge.com/topic/170018-re-greasing-mount-grease/

I'm pleased that your scope matches the AZ-4 well. A well mounted scope can really show off it's performance potential

[dweller25]

On 10/03/2019 at 19:07, parallaxerr said:

UPDATE:

PAS has been and gone, I attended and.....I spent some money So what did I spend it on?

Well I went there with the intention of walking away with the Vixen SD103S, however, in the cold light of day after viewing the scope, I needed to do a few laps of the show to mull it over before coughing up the readies. The Vixen looked every bit as nice as I thought it would but I was surprised by the size versus the other 4" ED scopes present at the show. The larger OTA tube diameter , lack of retractable dew shield and longer than average focal length made it appear more like an ED120 than a 100mm scope. It was in as new condition as promised and there really wasn't much to check out, the single speed focuser was smooth enough but appeared to rely on being heavily greased to achieve this.

On my way around the trade stands I bumped into a certain Mr. @mikeDnight, accompanied by @paulastroand their friend Derek (is he an SGL'er?). We just so happened to meet passing the Altair Astro stand where I was headed to look over the 102ED-R. Much deliberation ensued and it became obvious that the general consensus was in favour of the Altair scope, mechanically at least. The Altair scopes at the show all had smooth focusers, far detached from the TS sample I previously returned. Of course, the ED-R has a higher end focuser than the TS and equivalent Ascent 102 do. 

The question then was "are the optics as good as the Vixen"? Well, I spoke to Ian of Altair Astro about this directly. I asked about the FPL-53 objective and he claimed it to be the highest standard coming out of China, with Altair specifying the highest Strehl of any customer. I asked if I were likely to see the small difference between this Chinese glass and that Japanese Vixen equivalent, expecting an answer along the lines of "only on the best nights", for example. However, the response was "there is no difference". Altair Astro are very confident that their FPL-53 objectives are on a par with those coming out of Japan.

One 102ED-R remained for sale at the show with £100 off the listed internet price, so I pulled the trigger! At £650 less than Vixen, I had to try it out with Altair offering to accept a return if I was not happy. I also picked up a Takahashi 1.25" prism diagonal and a new 32mm Plossl with the "spare" change. So here it is, I'm now in the same club as @david_taurus83 with the 102ED-R sitting atop an AZ4, which, appears to handle the scope with ease it must be said. I'm very keen to try it out but the local forecast obviously isn't great for the foreseeable future! Let's hope it delivers!

 

Thats a nice looking scope ?