John

I've not used one but here is a German optical test of the AX103S which seems very positive (might want to run it through Google translate or similar): http://astro-foren.de/index.php?thread/13357-refraktor-als-fotomaschine/&postID=57253&l=2

Many chinese achromats have a noticable degree of SA as I discovered when I was playing around with Chromacor's a few years back. I think the chart is accurate from my experiences with various achromats but I agree that terming the CA as "unnacceptable" is not helpful. Thats down to personal preference I think. Personally I prefer as little CA and SA as possible which is why I was exploring Chromacor's back then. The difference in performance, particularly at higher magnifications, of a chinese 6" F/8, when the CA and SA were reduced around 80% was quite dramatic !

Interesting link. The table below is quite a useful guide to the relative amounts of chromatic aberration that achromats of different specifications should show. It's a normal feature of the optical design though, in the same way that coma is to the newtonian design so we should not be overly concerned by it. Spherical aberration is present in many refractors and has more of an impact on performance than CA does.

I found the Radian's and Nagler T4's quite straightforward to use without needing to use the pupil guide. The 22mm T4 was a lovely eyepiece - my favourite Nagler I think. I'd steer clear of Tele Vue eyepeices if they don't suit you though. There are other decent options around

But they do provide pupil guides with the models that are most sensitive to this.

I think it's a standard F/5 achromat. Similar performance to the Skywatcher ST80 probably (which are not too bad for CA) but a more individual looking scope. Vixen also produced some small refractors for Tasco during that era. Good Tasco's to watch out for

Yay ! - I've still got that brochure somewhere I ended up with one of their 6" F/6 newts instead 1st "proper" scope and a huge upgrade over my Tasco 60mm frac.

What happened to the Giro mount Jules ?

Indeed. My TMB / LZOS 130 uses neither Ohara FPL or Fluorite. LZOS use their own proprietary glass types (OK4 and OF-1) in their objectives and I believe don't make this available to any other optical manufacturer. The results judging from my example are very, very good

I was a doubter until last year. They are.

My ED102SS replaced a Skywatcher ED100. I was expecting a slight drop in CA control and possibly sharpness but I didn't see it to be honest. The lens is well figured in the F/6.5 Vixen but the Tak is even better. FrT Telescopes do an F/12.5 120mm ED doublet refractor. Quite expensive though: http://www.frtelescopes.com/frt120ded.html

Here is a short post I made on the CN forum comparing the two: https://www.cloudynights.com/topic/541112-vixen-ed102ss-and-takahashi-fc100dl-brief-comparison/

I think the Deepview eyepieces are a modified 3 element kellner type design.

I have to say that I feel the prices for the 35mm Eudiascopic are a little on the steep side if they are the same as the old Celestron Ultima 35 and Orion Ultrascopic 35 Last time I bought a used Ultima 35 (which was a few years back admittedly) I think I paid around £45 for it, delivered

I had one for a short while. I ended up using the 32mm much more because I didn't like the 43 degree AFoV of the 40mm as much and the 40mm is not par focal (by quite a few mm) with the other TV plossls. It's a very nicely put together 40mm plossl though.

I can recall a few years back there were rarely any posts on this forum about Takahashi products but quite a few folks had Vixen's of one type or another. Today Tak's seem to be much more frequently discussed so I'm assuming that the ownership levels are higher now. Or maybe my memory is playing tricks on me

Your Skysensor looks so modern compared to the "shoebox size" that my late 1980's one was Jeremy. My old brick had a red LED display just like the old Sinclair calculators and digital watches - very 80's I'll be the modern units are much more user friendly as well. The old ones took seemingly forever to set up

Can't see the pics of yours Dave (edit: oh yes I can now - very nice ! ) Here are pics of my old (I owned this around 1990) Bresser Uranus which was really a Vixen SP102M in a black colour scheme (complete with early Skysensor GOTO) and a couple of my current Vixen ED102SS toting it's Vixen handle and rings, care of your good self Dave plus Moonlite focuser. I've owned the ED102 for over a decade now

So because you can't tell any difference thats it is it ? They are expensive so if you try them and they don't make any difference to you, don't buy them. Oh and by the way, the Nagler T5 16mm is made in Taiwan, not Japan. Most of the larger and more complex Tele Vue designs are made in Taiwan now. There are many very experienced observers around this planet who do use and value Tele Vue's products and other premium brands such as Pentax, Leica, Zeiss etc. This is not an accident and these folks are not just about showing off or throwing money away. They have found over years of comparisons that these brands do have a performance edge and they are prepared to invest as needed to obtain that.

Presumably the people you need to convince are the retailer from whom you purchased the mount from, rather than us ? Probably best to get a refund then pick an alternative mount. Good luck

Here is my Takahashi FC-100DL in white light solar mode:

Thanks Dave I'm still standing when viewing through the 12" dob. It's F/5.3 so I'd need a tennis umpires chair to sit at the eyepiece quite a lot of the time ! My knees are starting to play up though so my habits may well change. Last night was too cold to stay at the eyepiece for long though.

I think the £ sign should be an epsilon symbol ie: ε-130D Ian King have this optical tube at £2,251 - £130 = too good to be true

That sounds like the way I'm seeing it Paul. It does get a little clearer with subsequent viewings but I think I'd need to go to darker skies to take the definition up a notch (apt word !) further. The skies don't get much better for DSO's here than they were last night and on the previous sighting. I'm still very pleased to be able to detect this target at all from my back garden. I'd almost written it off last year

The cold and windy conditions made it less comfortable (ie: harder to stay at the eyepiece and concentrating !) but having found it before helped in terms of realising that it might be "on" tonight and zeroing in on the right patch of sky. So thats a "yes and no" answer !