Refractor people - unbiased opinion please

[FlashDrive (Poppy)]

Just spoke to a Vixen Representative in Sydney... ' ALL ' Vixen NA140SS are made solely in Japan

The previous models which has the ' f ' on the end of the ' SS ' as this SSf were conjointly manufactured in Japan and China.

' ALL ' manufacturing of the newer NA1400SS is Japan made......period.

These were his words....Not mine....Phone him if you want.... his name is Warren
PHONE: (02) 9436 4360 .....

By the Way ...all the NA140SS that were imported at the time I got mine were 'SOLD'
Plenty of other people consider these as a worth while purchase....that speaks for itself.

and of course it won't be as good on Planets .....it's focal length is predominately for ' wide field ' deep sky viewing...which it excels at and with a flatter field and very sharp. I use low mag' eyepieces most of the time....17mm down to 40mm

As one owner of a NA140SS has said ..... Doesn't excel at everything, but does nothing badly, and in a small, lightweight package that is easy on the mount.....In fact, the Vixen 140 is a really superb all around telescope.....information from CN

http://www.vixenoptics.com.au/details.asp?id=MAS-046C2


Flash.....

[Profiler (Profiler)]

I had one of these Vixen NA140 as well but I wouldn't have a clue whether it was made in Japan or China or Timbuktu!

I think everyone has gone way off track as I do agree what counts is how the mechanism performs. In this context there are some big benefits about the Vixen which have been under-estimated and some disadvantages which - irrespective of whether it is made by Merlin himself - won't change.

The huge plus I found about the Vixen was its weight - absolutely amazing that something so large can weigh so little. It is probably the only 5 inch + refractor that you can easily pick-up with one arm - this has huge benefits in getting your backside and the scope easily outside in dark locations and on a relatively small mount - do not underestimate this factor - it is very significant

The bad side which everyone seems to gloss past except for Flash that you have to keep in mind is the optical design of the Vixen as a very fast Neo Achro - thus it is optimally designed for exactly what Colin wants which is widefield observing with refractor quality optics. There is no fluoro element in the optical design and instead uses a 4 lens design.

So planetary observing is not its forte and never will be. This is not a weakness of whether it is made in China or Japan but fundamental to optical principles in how optics perform.

Finally, trying to compare the Vixen to the Istar is an apples and oranges comparison as they are very different telescopes designed to do very different things and have different strengths. For what Colin likes observing the Vixen sounds perfect. However, if I were after something for planetary observing I would probably pick something with a longer fl

If you want excellent bang for your buck in terms of planetary observing a whole bunch of beautiful f11 4 inch achros are now available - I think you can pick one up brand new for $500 (OTA)

If one of these appeals you will however have to come to grips with owning a telescope exclusively made in China - and good product too boot as well in my humble opinion.

[Kunama]

Couldn't agree with you more Richard, horses for courses!!!!

Oh and there is no telescope making facility in Timbuktu, I've been there!! In fact you would be hard pressed to find a telescope anywhere in Mali ...... but I digress.

[Profiler (Profiler)]

It sounds like potentially a wonderful dark sky site

[glend (Glen)]

Thanks to everyone for their ideas and comments. I have had a talk with Istar and based on that I have decided to buy the objective lens set from iStar and build a scope for it over the coming months. This will bring my costs way down, teach me alot about optics, and utilise my dormant boat building skills to create a platform for the objective.

[brian nordstrom (As avatar)]

Good choice Glen , but either way both scops rock .
Will you be joining Istar scope club ? hope so its small but like IIS here very friendly and helpful , ask MattT .

Do you mind telling us what you are getting ? and please , please keep us all up to date as this project progresses , I am sure I ain't the only one interested in this ,,,,
Refractors rule even my lowely Achromat ( by Istar ) . I hope to get east within the next couple of years and I will show what mine is capable of to any who are interested ,,, I will never sell it , like a few Perthites have seen receintly .. .

Brian.

[Satchmo]

2c on the subject of planets through refractors , from an owner of both a good reflector and an ED refractor who has been observing the planets for over 40 years .

I would recommend also putting a 6" off-axis stop on your 16" to give you effectively an unobstructed `apo' equivalent ( colour free ) to see how well a small aperture works on the planets compared to larger

I do like observing the planets and own an excellent 120mm ED refractor that is well colour corrected, but I wouldn't use it instead of my 14" Newt if the seeing is reasonable and I want to see loads of detail on the planets. 5" or 6" is just not enough light to get high enough magnification to see fine detail. A 6" will show you the red spot on Jupiter but a 12" to 16" will show swirls inside the spot and colour differentiation amongst the features.

There is more to the issue of the appeal of apparently sharper planetary views in refractors ( due to their not resolving the finer turbulence that a larger scope `sees' and marginally better contrast ) . They are not good at showing complex smaller scale and larger scale band detail due to inability to supply colour differentiation of features in the disc view.

The ability to show colour differentiation needs a larger exit pupil and this is where the extra aperture comes in. If you are using ( maximum ) 2mm pupil for this ability on a 6" you only have 75X ( too low mag for resolving detail ) but on a 16" it is 200X which is at the lower end of useful magnification for planetary observing . A 1mm pupil will be too small to show clear colour differentiation with any size scope - but it is more likely going to be needed with a refractor to get the magnification high enough ( ie 150X on a 6" refracator) .

Even when the seeing is not so good colour differentiation will show you a mass of features that are invisible in a smaller aperture which is operating at a small pupil showing essentially only shades of grey on the disc features and that is even on nights where the seeing is soft - the small telescope will show a soft disc with mimimal detail but the larger scope operating at a larger pupil ( which activates the cones in the eye ) may show a wealth of detail ( albeit soft ) due to colour differentiation of the features .

I hope I explained this point clearly enough .

[glend (Glen)]

This thread started as a request for input on a choice of two possible refractors (neo achro doublet designs) and simply invited comment on those two, re a purchase decision. I had hoped to limit it so that it did not drift off or get highjacked (as they seem to do) into theory discussions on Achro vs APOs, or the other - and certainly the merits (or not) of reflectors was not a consideration.

Both the scopes were 'fit for my purpose' and I subsequently made a decision to go with iStar (well to buy the iStar objective and build the rest myself).

The rational for a refractor is mine, and no amount of masking a 16" dob is going to make it weigh less than 15kg, regardless of what might be done to make it a better choice. I love my 16" dob but it is big, heavy, and not easy to transport - all advantages that those two refractors offered.

[Satchmo]

It doesn't look like any one here has experience with the 5" F12 I30 objective and there are no spot diagrams on the site but I dont think you could go wrong as long as you accept that all achros will have some degree of false colour.

[PlanetMan]

It is good to see so much diverse input