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Equipment Discussions >> Refractors

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astroneil
Pooh-Bah
*****

Reged: 07/28/09

Loc: res publica caledoniae
Re: Are achromats enjoying a come back? new [Re: Astrojensen]
      #5535652 - 11/23/12 02:37 PM

I don't know why I waste my time Thomas.

It's a lost cause anyway.

Regards,

Neil.


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7331Peg
Sirius Observer
*****

Reged: 09/01/08

Loc: North coast of Oregon
Re: Are achromats enjoying a come back? new [Re: Jon Isaacs]
      #5535722 - 11/23/12 03:22 PM

Quote:


I imagine there are those who choose their scopes based on fashion but I am certainly not one of them... I base my choices on what I see at the eyepiece and I assume that the rest of the members of this forum do likewise. To assume otherwise is disrespectful.

When it comes to a discussion between apochromats and achromats, costs somehow always seems to enter into the equation. Achromats are better deals, apochromats are better telescopes... I like them both.

Jon Isaacs





Of course cost enters into the equation. Depending on the aperture a person is considering, as well as the particular brand of the scope, the cost differential is usually very significant. And that difference in cost has kept more than one person out of this hobby.

A few years ago, someone new to astronomy and refractors would have read one comment after another about the "dreaded color" in an achromat. Fortunately that's changed, especially in the last year, thanks to the efforts of Neil and many other people to draw attention to the positive aspects of achromats. No doubt the slow economic recovery in most countries is responsible for some of that as well.

It's good to see the healthy debate. Both types of scopes work quite well when used to their strengths. But you certainly can't expect cost to not be part of the discussion -- in many ways, it represents the greatest difference between the two kinds of lenses.


John


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ken hubal
Pooh-Bah
*****

Reged: 05/01/07

Re: Are achromats enjoying a come back? new [Re: 7331Peg]
      #5535882 - 11/23/12 05:14 PM

After owning several apochromats in the 80mm-127mm range, the long focus achromat has made a comeback in MY collection of refractors beacause I have simply learned to see beyond the rediculous marketing hype perpetrated by individuals here and on other internet forums, glossy ads in S&T(which is no longer the definitve astronomical journal it was years ago), and the continuing praddle that drives irrational people to spend thousands of dollars on small apos when FAR better views may be enjoyed by larger reflectors, which by the way are color free AT ANY FOCAL RATIO!!

One could always build a Newtonian of F8 or longer focal ratio with a smaller secondary, obtain a Mak-Cass, or build a 5 inch achro around one of D&G optical's lenses, which are outstanding performers at F12 or longer to obtain well color corrected performance rather than spending a fortune on a small apo which will simply not perform as well as longer focus achros, Maks, or long focus Newtonians.

CLEAR SKIES!


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Are achromats enjoying a come back? new [Re: ken hubal]
      #5535920 - 11/23/12 05:33 PM

Ken, has your perception of this fast apochromat changed from when you provided the report that follows?

http://www.cloudynights.com/item.php?item_id=1477



- Jim


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ukcanuck
Vendor (Skylight Telescopes)
*****

Reged: 11/07/06

Loc: London, UK
Re: Are achromats enjoying a come back? new [Re: Sky Muse]
      #5535923 - 11/23/12 05:35 PM

Wow this thread has some legs...

Ultimately, to me the quality of the optics are key...and if it happens to be a long achromat tube, then so be it. It never ceases to amaze me when I get reactions from people who are stunned when they look through a long refractor as if they had no idea an 'achromat' (said with some scorn for full effect) was capable of such good views.

As long as the sight of that graceful long tube captures the imagination and calls to people, and the views from within are there to back it up...reports of the demise of the long achromat will continue to be exaggerated.

Quote:

I'd love another achromat, the Skylight 4" f/15 in particular... Alan




I'm working on that...


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ken hubal
Pooh-Bah
*****

Reged: 05/01/07

Re: Are achromats enjoying a come back? new [Re: ukcanuck]
      #5535936 - 11/23/12 05:43 PM

Jimmy...YES!! Your perception doesn't seem to have changed however since you continue to profess the same exact findings about apos as you did two years ago when we last exchanged pleasantries!! I have been reading(with much laughter) your posts concerning optics, optical performance, and other comments. My conclusions are still the same now as they were then! I've also seen others review your comments with much skepticism. Perhaps a re-read of Neil English's excellent work is in order for you!! I also find it interesting(and quite obsurd) that you must quote from a review that was done more than 6 years ago!! I KNOW you can do better than that my old friend!! By the way, have YOU written a book like Neil's yet?
Seidel Aberrations!!



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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Are achromats enjoying a come back? new [Re: ken hubal]
      #5535967 - 11/23/12 06:05 PM

Now that's just odd, Ken. I mean we have a guy like you that tends to preface his comments with a recitation of his (alleged) decades of experience, who a few years ago was raving (literally) about a cheap, fast, apochromat, yet when interest in slow achromats came back into vogue in the couple of years, you shift your raving to that design instead, contradicting your prior statements about fast apochromats like the one you reviewed here on CN. If you could be that badly and easily fooled by that speedy little Astro-Tech, Ken, what are your (claimed) multiple decades of experience actually worth?

If one's perceptions are accurate and factual, and one actually does own and use the scopes one claims to own, those perceptions should *not* change with fashion. It's only when you make stuff up, Walter Mitty style, that you tend to contradict yourself.

Say, any pictures of your with your D&G long focus achromat? We've been waiting for those for four years now.

- Jim


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ken hubal
Pooh-Bah
*****

Reged: 05/01/07

Re: Are achromats enjoying a come back? new [Re: jrbarnett]
      #5535975 - 11/23/12 06:11 PM

Jimmy.. Walter Mitty is a person you should be able to identify with quite easily! You have, and continue to contradict yourself repeatedly in every one of your posts!! BTW, how's the oil in your triplet holding up?

As for fashion, apos are simply that, fashion. Only through years of owning and testing have I gained more up to date knowledge about their advantages(few to none) and disadvantages(many). When you show me YOUR BOOK, I'll show you my pictures of the D&G!!
So long, OLD FRIEND!!



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The Ardent
scholastic sledgehammer
*****

Reged: 10/24/08

Loc: Virginia
Re: Are achromats enjoying a come back? new [Re: ukcanuck]
      #5535987 - 11/23/12 06:18 PM

Skylight Telescopes:

This somewhat answers my previous question about refractors make in the UK, but there are more questions.

From reading the Skylight description, it looks very nice, but why are the lenses imported? Why is no one making objective lenses in the UK?

Last month I viewed thru a 6" f/15 refractor made by an amateur from North Carolina. Very nice views. It seems that all the American "boutique" refractors originated from an enthusiastic amateur telescope maker.

Having owned a 6" D&G, I remember the optics, build, and appearance highly pleasing. And its just a lowly achromat.

Quote:

Ultimately, to me the quality of the optics are key...and if it happens to be a long achromat tube, then so be it. It never ceases to amaze me when I get reactions from people who are stunned when they look through a long refractor as if they had no idea an 'achromat' (said with some scorn for full effect) was capable of such good views.






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la200o
Carpal Tunnel


Reged: 09/09/08

Loc: SE Michigan, USA
Re: Are achromats enjoying a come back? new [Re: Astrojensen]
      #5535998 - 11/23/12 06:23 PM

Quote:

Quote:

the US have a stranglehold on telescope trade... the market is dominated by US products.




Hmmm. Last time I checked, there were four major players in the apo refractor market: TEC, AP, APM and Takahashi. Two are US based and do their own optics, APM is located in Germany and use Russian or Chinese optics, and Takahashi is in Japan and do their own optics. APM and Takahashi outsell the two US based companies by a wide margin.

A US stranglehold on telescope trade? Come on...


Clear skies!
Thomas, Denmark




Thomas,

Aren't you forgetting Tele Vue? Or are you only considering triplets? (TV makes only ED doublets and Petzvals, as I'm sure you know). Also, it's my understanding that Canon provides the optics for Takahashi.

Regards,

Bill


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Are achromats enjoying a come back? new [Re: ukcanuck]
      #5536051 - 11/23/12 06:49 PM

"Ultimately, to me the quality of the optics are key...and if it happens to be a long achromat tube, then so be it."

Richard, I couldn't agree more. At a given aperture, assuming rational design and choice of glasses, the refractor with the better optics will be the one that shows you more, fast or slow, apochromat or achromat. You can't go wrong with quality.

I'm looking forward to your upcoming offerings.

Regards,

Jim


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Deep13
Carpal Tunnel
*****

Reged: 01/25/05

Loc: NE Ohio
Re: Are achromats enjoying a come back? new [Re: jrbarnett]
      #5536103 - 11/23/12 07:07 PM

Well, I certainly like the views in my DIY (not by me) 5" f/12 w/ D&G lenses. Unfortunately, it is huge for its size. And it exhibits false color around Jupiter. Plus, under magnification, the image gets dark pretty quickly. My TV 101 has no false color, of course, so fewer of its photons are wasted. It gives sharp, high contrast images, as does the 5". Still, the second set of lenses in the 101 takes a long time to cool off. What could provide a better image than either of these fine instruments? My garden variety 8" f/6 Dob at 1/5 the price of the TV101 (without the $600 mount). It shows diffraction spikes, of course. But even with that, I get more detail out of the 8" than either refractor. Aperture rules. Period.

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Are achromats enjoying a come back? new [Re: Astrojensen]
      #5536113 - 11/23/12 07:17 PM

"APM and Takahashi outsell the two US based companies by a wide margin."

That might be correct in the case of Takahashi, but it might not be in the case of APM. I'm not sure how many refractors APM sells a year under its own brand, but for a given aperture, the production numbers seem to be pretty small.

But Takahashi and APM are not like TEC or Astro-Physics. Neither firm makes their own refractor optics. Takahashi uses Optron, a Canon subsidiary, for lenses, but makes its own tube assemblies and focusers. APM, though, is really no different than Stellarvue, Astro-Tech or the other branders. They take bits and pieces from various sources and assemble them into complete telescopes.

TEC and Astro-Physics pretty much make everything in the scope, nose to tail. This is more akin to the 19th century artisanal model. This is what Alvan Clark & Sons did, for example. So for entirely in-house refractors, I'd say the US does almost have a stranglehold on that tiny niche. As for telescopes in general, US brands are dominant, but most of the scopes sold under those brands (Meade, Celestron) are not made in the US.

Regards,

Jim


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Sky Muse
sage


Reged: 10/26/12

Loc: De Soto County, MS
Re: Are achromats enjoying a come back? new [Re: ukcanuck]
      #5536264 - 11/23/12 09:03 PM

"Wow this thread has some legs..."

...yes, especially the "chart phase".

"...reports of the demise of the long achromat will continue to be exaggerated."

...rather, for as long as the objectives do not come out of Japan; or arise from native soil, decidedly during a collective, nationalistic shout, the present lack of which I've read bemoaned?

"I'm working on that..."

Yes, I noticed, as it's sold out. It will require an equatorial, perhaps a Losmandy G-11 later in the coming year. It's to be given very serious consideration.

Cheers,

Alan


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ThomasWos
super member


Reged: 02/10/07

Loc: Bellingham WA
Re: Are achromats enjoying a come back? new [Re: ken hubal]
      #5536273 - 11/23/12 09:09 PM

Quote:

As for fashion, apos are simply that, fashion. Only through years of owning and testing have I gained more up to date knowledge about their advantages(few to none) and disadvantages(many).






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coopman
Post Laureate
*****

Reged: 04/23/06

Loc: South Louisiana
Re: Are achromats enjoying a come back? new [Re: ThomasWos]
      #5536349 - 11/23/12 10:01 PM

I've seen a lot of discussion about the various 6" f/6.5 models in the last year or so. I also see that a lot of their owners put them up for sale a few months later. I think that maybe this is due to the large size & weight of the OTAs. These scopes can really be a severe test for many mounts.

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Scott in NCModerator
Mad Hatter
*****

Reged: 03/05/05

Loc: NC
Re: Are achromats enjoying a come back? new [Re: coopman]
      #5536383 - 11/23/12 10:32 PM

Hmm...right now my achromat to apochromat count is tied at 3-3. Although I just sold one of my apos, so once I mail it off the score will be 3-2 in favor of achromats. So in my household, yes, the achromats are enjoying a comeback!

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Kentuckystars
member
*****

Reged: 03/17/08

Loc: Northern Kentucky
Re: Are achromats enjoying a come back? new [Re: Scott in NC]
      #5536582 - 11/24/12 02:04 AM

Fact One: An apo will put up a better image than a fast (short-tube) achromat. Much less color, more detail. WE ALL KNOW THIS. It's simple physics.

Fact Two: Though a subject of much debate, the image of an apo will be slightly better then the image of a long focus achro. If SLIGHTLY more detail is seen in the apo it is probably due to more time and expense in perfecting the optical figure while it is being made. We all should expect as much for the price of entry.

Fact Three: Apo's are expensive, sometimes very expensive. Achro's much less so.

Fact Four: I am not a doctor or lawyer, and it would be fair to say the same for many of us. In fact, I would say many of us have to watch our budgets in these times. Taking out a second mortgage to buy a scope does not make sense if you are on a budget, and maybe you do not want to save in the piggy bank for 5 years to get a scope. Then for average working folks like us that want a refractor (before we die) an achro fits the bill. And it will show us AT LEAST 90% of what an apo of the same aperture will show with decent quality optics on both sides.

Fact Five: Achro's are what people wanting a refractor in the days before the development of the apo used. It is safe to say they were plenty happy with them.

Fact Six: If you are on here debating over known facts then you are not using the scope you have. No wonder your not happy. Use the scope you have no matter what it is, it's the best scope in the Universe when your eye is to the eyepiece. Use Scope=Happy Astronomers

Hey, some of us can't afford the best of the best in refractor technology but still want a refractor for various reasons of our own. We ARE aware that better scopes exist, you don't need to keep reminding us. Really......WE KNOW.


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Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Are achromats enjoying a come back? new [Re: Kentuckystars]
      #5536626 - 11/24/12 04:04 AM

Ken, it is refreshing to see that there is another ATM on the forum who has the same views as myself, another little boy who sees that the king is stark naked. You are righr there is a helluva lot of praddle guffed about the merits of APOs, why use em when you have reflectors? I will give a bit of practical information here for those who love to step out of the rut and experiment,try using a small short focus achromat ( A bino OG), or a well corrected reducer just inside the focus, you will find that the very small amount of secondary colour will be supressed significantly in fact you will practically have an apo. I have done this and boy does it work!.

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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Are achromats enjoying a come back? [Re: Crayfordjon]
      #5536639 - 11/24/12 04:35 AM

Question to those in the know: Increasing focal ratio of an APO with a Barlow for example from 7.5 to f/15 - will this give at least some of the discussed benefits of long Achros like increased focal depth besides the side effect of loosing some light due to the additional optical element?
Wilfried


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