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2 Slow Achro Refractors: Why the big cost difference ?


John
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After reading Neil English's piece on the Cloudynights site on slow achro v's fast ED refractors, I've been looking around at high focal ratio achro refractors and come across the Antares 105mm F/15:

Antares 105mm Refractor OTA | Telescopes | Rother Valley Optics

Maybe I'm missing something but the price (£999) seems kind of high to me :icon_salut:

The Antares looks of a similar quality to this 102mm F/11 achro:

Lyra Optic - Telescopes and Mounts

(OK, I know that TS in Germany do it for a bit less than that ;))

The Antares offers an extra 3mm of aperture, a 50mm finder and a dovetail bar but seems otherwise of similar quality to the one Lyra Optics are offering but I'm not sure that those features, plus the longer focal length, justify the additional £700 :(

Or am I missing something ?

Of course the Skylight F/15 achro costs £1,500 but thats much more of a bespoke, low volume instrument as far as I know.

My, rather basic, understanding of optics leads me to think that high focal ratio achromatic objective lenses should be less costly to make than faster ED / apochromats.

Edited by John
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There's something at the back of my head is saying that the Antares has something to do with Vixen John, that might have something to do with that one.

Other than that, I guess it's down to manufacturing. Low volume tends to equal high cost.

Tony..

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Antares refarctors are made by Sky Instruments of Vancouver. They say that the optics are made by the same supplier that make the optics for Vixen. The 105mm has been made in several focal lengths including 1000 and 1500. Look up the Vixen A105M Achromatic Refractor which has more than a passing resemblance to the Antares.

John

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My, rather basic, understanding of optics leads me to think that high focal ratio achromatic objective lenses should be less costly to make than faster ED / apochromats.

Quality, quality, quality ... you pay far more for the surfaces than what they're made of. Then again there's the question of the adjustment mechanism (or lack thereof) on the objective cell ... refractors need collimating just as much as reflectors, if you want to get the ultimate performance from them. And the focuser - which could be £10 for a nasty Chinese tinplate & plastic doodah or near £1000 for a top of the range rack & pinion focuser ...

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The Antares looks of a similar quality to this 102mm F/11 achro.

Hmmm... Does it? :(

I'm not sure what you see.

I just see two shiny white tubes.

Other than them both being telescopes, I see nothing in the descriptions that gives me a reference point for the quality of either. :icon_salut:

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I'm not against the idea of this scope at all. I think it has a charm and a utility of its own. But this bit of adspeak is just silly and does no favours to the idea of an adult discussion of slow achromats; The proliferation of high-element, lower f/ratio, ultra expensive designs may have snob appeal, but for true high power performance, focal length is KING!

It just makes me feel mildly narked, not inspired to give the scope a try. There is a butcher in my old home town of Wirksworth whose sign procalims that his ham is not wet and rubbery. The psychological effect on me is to think of him as the wet and rubbery butcher.

Not too far off-thread, I hope.

Olly

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Good point Olly !.

I'm always vaguely suspicious of anything with the term "Elite" in the title as well :icon_salut:

Mind you Tele Vue's "Majesty Factor" blurb for the Ethos seemed OTT when they launched that but it doesn't seem to have done their popularity any harm :(

Edited by John
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Hopefully barring the BBC Micro classic game?

These scopes could do with a once over though...Olly?

I'm old enough to remember Elite and Elite Plus Nick :(

I've been thinking of getting one of the 102mm F/11's to compare with my Vixen ED102 F/6.5 - though I'm not sure that F/11 is slow enough for the benefits identified by Neil English to be realised :icon_salut:

Can't afford the Antares 105mm F/15 "Elite" at the moment though I'm afraid ;)

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I always wanted a refractor with a high F number and Neil's article made that wish even more so. However, when I looked at the Antares I just felt that it was a little bit pricey so I never ordered one. In the end I bought a Towa 80mm f15 and the stars are pin point.

However, it would be interesting for Astronomy Now to undertake a review so perhaps Nick can pursued them to approach RotherValley etc etc to loan one for a review?

Mark

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I'd rather pass on that to someone else to be honest. After the trauma I went through with the AX103, I really don't want to go through that again without access to a test bench...too much tooing an froing convincing people there was a major problem.. to be fair to Opticron, they were excellent though in dealing with it all...10/10 on that front

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But this bit of adspeak is just silly and does no favours to the idea of an adult discussion of slow achromats; The proliferation of high-element, lower f/ratio, ultra expensive designs may have snob appeal, but for true high power performance, focal length is KING!

It just makes me feel mildly narked, not inspired to give the scope a try.

Ummm. We've been over most of this before, but:

For rich field work, short focal length is a plus point.

For lunar / planetary / solar work, short focal length is a distraction. The only benefit is making the tube shorter / lighter / easier to mount. You want a long focal length anyway; with current cameras with pixel pitch of the order of 5 microns, the ideal focal ratio is f/25 - f/30 and, if possible, it's best to avoid having to use auxilliary optics (barlow, powermate etc) to get there.

But optical quality is superior to design ... a really well built short focal ratio scope will outperform a poor long focus instrument, even though the long focus instrument inherently has much looser construction tolerances.

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Go classic John, much cheaper, my 1979 4" Fullerscopes Deluxe cost a fraction of the Amtares earlier this year and I m sure itd give it a run for its money as the optics are top notch. Also on top of that it is a thing of beauty far more appealing than stock white tubes.

Phil

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  • 4 weeks later...

Hi folks,

In response to the OP's questions, it all boils down to certifiable optical quality. The Antares Elite achromats are very well figured (at least 1/6th wave and better) and deliver the readies. That said, as my research has shown, it's much easier to get good quality from a long focus achromat and those supplied by Lyra Otics are definitely worth a look into IMO. I have talked to a few folk behind the scenes and they tell me good things about these F/11 instruments. For the price, you can't really go wrong. That said, I'd also recommend the Tal 100RS and similar 4" F/10 achromats produced by Skywatcher and Celestron.

Best wishes,

Neil.

Edited by Neil English
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Why can't we have a 150mm refractor, f25, retracts to 500mm or less, weighs only 3kg or less, has 1/10 optics, no false colour, no astigmatism, no spherical or other aberations and costs no more than £200-300???????

I might buy that one...

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Why can't we have a 150mm refractor, f25, retracts to 500mm or less, weighs only 3kg or less, has 1/10 optics, no false colour, no astigmatism, no spherical or other aberations and costs no more than £200-300???????

You forgot the crayford, the illuminated finderscope and a mount to rival a Losmandy Titan with sub arcsecond tracking accuracy - now if that could all be packaged up for say £199 I'm sure there could be a market :)

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You forgot the crayford, the illuminated finderscope and a mount to rival a Losmandy Titan with sub arcsecond tracking accuracy - now if that could all be packaged up for say £199 I'm sure there could be a market :)

I was thinking more like a feathertouch R&P.....

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