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Equipment Discussions >> Refractors

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opticsguy
sage


Reged: 02/02/09

Loc: Washington State
Re: Astro-Physics the Best Brand? new [Re: orion69]
      #6067551 - 09/07/13 10:36 AM

Many years ago, I had the opportunity to share some observing time with Roland. Asked him about searching out pluto with his 6". Roland aimed the scope at the field of Pluto and a check with my hand held deep sky map we easily identified Pluto, not a scintillation but a solid star!! Much easier to see and identify than in other larger scopes.

Yes, AP is as good as it gets.


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Eddgie
Postmaster
*****

Reged: 02/01/06

Re: Astro-Physics the Best Brand? new [Re: Bill McNeal]
      #6067560 - 09/07/13 10:42 AM

To answer your quesiton, I am going to narrow in somewhat on what an AP telescope is and is not.

The AP is sold as a telescope, but it would be a waste of money to buy a large AP and stick an eyepeice in it. For less money, you can get a telescope from a variety of manufacturers that will give you the same visual image. The value of the modern large AP refractor is not to be found when it is used as a visul instrument.

What the larger AP scopes really are though is that they are high quality astrograph instruments. Where they still perhaps hold the high ground is when they are used as imaging lenses.

The AP scopes are perhaps still correctoted over the widest range of wavelengths than any other refractor of similar apeture made (funny though, even a cheap reflector is CA free..)

Not only that, but the aspherizing and design of these intruments often produce results that are capable of producing pinpoint and color free star images right to the corners of the biggest CCD cameras normally used by amateurs.

And since astro-imaging is far more demanding than visual use (the eye is simply not a very good detector) and the APs still produce the finest wide field images, with color free stars that are aberattion free and pintpoint right to the corner of the biggest chips, I would argue that the AP is still the best brand money can buy.

There are no other similar sized amateur instruments I think that can approach the wide field imaging capabilities of the latest generation of large AP refractors.


The off axis performacne of the large AP refractor is peerless. No one makes a better similar size astrograph.

Is AP the best brand? Well, if you are discerning and have a honking big CCD camera, and you want wide field with a big image scale and pinpoint and color free stars right to the edge corner of the frame, it is I think still the very best game in town.

If you just want to dork around with an eyepeice, it is a waste of a high quality astrograpich lens, You can do far better visual observing with any number of different telescopes.

Measured for what it is not (not the best planetary scope on the planet for example) is unfair.

Measured for what it is, I think it is the best brand.


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PeterR280
Pooh-Bah
*****

Reged: 05/27/13

Re: Astro-Physics the Best Brand? new [Re: Eddgie]
      #6067653 - 09/07/13 11:40 AM

The telescope is not sold as an astrograph. I happens to excel in all areas including visual and photography but that is because all the fundamentals are there. There are better telescopes for astrophotography like the RCs that AP sells. A C14 will produce incredible planetary images.

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Paul G
Post Laureate
*****

Reged: 05/08/03

Loc: Freedonia
Re: Astro-Physics the Best Brand? new [Re: Bill McNeal]
      #6067750 - 09/07/13 12:43 PM

AP has the highest minimum guaranteed optical quality (Strehl .984). Superb astrographs, and the optics are nulled at the wavelength of maximum visual sensitivity so they are top notch for visual as well.

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John Anthony
sage
*****

Reged: 04/27/13

Re: Astro-Physics the Best Brand? new [Re: Paul G]
      #6067781 - 09/07/13 01:06 PM

Best ??? Maybe but I have never noticed a big enough visual difference with apertures smaller then 140mm to really talk about, it's splitting hairs, Tec, Takahashi, Tele Vue, Stellarvue and TMB all included.

I will say this, the absolute finest views I have ever had bar none all telescope designs and apertures included have been thru 6 inch or larger refractors from AP.


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orion69
scholastic sledgehammer


Reged: 05/09/10

Loc: Croatia
Re: Astro-Physics the Best Brand? new [Re: Eddgie]
      #6067818 - 09/07/13 01:29 PM

Quote:

Not only that, but the aspherizing and design of these intruments often produce results that are capable of producing pinpoint and color free star images right to the corners of the biggest CCD cameras normally used by amateurs.

And since astro-imaging is far more demanding than visual use (the eye is simply not a very good detector) and the APs still produce the finest wide field images, with color free stars that are aberattion free and pintpoint right to the corner of the biggest chips, I would argue that the AP is still the best brand money can buy.




With or without FF?
Is there any refractor with completely flat field except Petzvals? Even for them I'm not so sure...

Of course, I never imaged with AP scope but I imagine they still need FF for completely flat field and pinpoint stars...

Edited by orion69 (09/07/13 01:30 PM)


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mikey cee
Postmaster
*****

Reged: 01/18/07

Loc: bellevue ne.
Re: Astro-Physics the Best Brand? new [Re: orion69]
      #6068356 - 09/07/13 06:53 PM

Not in my play book. Way too much money. The best brand is the "generic" one with an Istar R30 lens. Mike

Edited by mikey cee (09/07/13 10:31 PM)


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Aquatone
sage


Reged: 03/23/06

Loc: Moraga, CA (Bay Area)
Re: Astro-Physics the Best Brand? new [Re: mikey cee]
      #6068734 - 09/08/13 12:06 AM

Yes. Other vendors do not generate threads like this with such frequency, and that speaks for itself. Astro-Physics is the standard other refractors are measured by.

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PeterR280
Pooh-Bah
*****

Reged: 05/27/13

Re: Astro-Physics the Best Brand? new [Re: Aquatone]
      #6068739 - 09/08/13 12:08 AM

Celestron has the longest thread in a while with their $59 4" refractor.

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Eddgie
Postmaster
*****

Reged: 02/01/06

Re: Astro-Physics the Best Brand? new [Re: PeterR280]
      #6068760 - 09/08/13 12:40 AM

Well, I think if you asked Roland Christen, he would tell you that the real strength of his telecopes is only realized when they are used as astrographs.

This was his message to me personally about 8 years ago when I complained to him about the wait list.

He pretty much told me that if I was just interested in visual, I should get something else.

And I have not yet seen a reflector that can match the wide field imaging capabilities of a big AP refractor. They simply can't come close.

If you are content with a narrow field, you can get some reasonable performance out of many large reflectors.

If you want wide field images that are color corrected, coma free, and pinpoint the corners of the biggest CCD cameras out there, you will struggle to come close to the AP with any reflector you can find.

The APs are simply among the finest astrographs money can buy.

To buy an AP and use it visually is kind of a waste of money. You simply are not getting at the true value of the instrument, and there are many other large refractors that can equal it in visual performance.

If you put a camera back there though, good luck in getting the same wide, brilliant field that you can get from the APs. They are amazing astrograph lenses.


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Erik Bakker
Carpal Tunnel
*****

Reged: 08/10/06

Loc: The Netherlands, Europe
Re: Astro-Physics the Best Brand? new [Re: Bill McNeal]
      #6068952 - 09/08/13 06:17 AM

A-P is very good at resale value, but faces stiff competition from the NLA Zeiss APQ's

For sure, they make very fine telescopes. I am not an astro-photographer, so I will only comment on their visual quality. They are not the best visual, but top-tier with others. For visual performance over a wide range of conditions, it is hard to beat a top quality fluorite doublet. But beyond 5" these are rare and the largest seems to be a 7" f/8 from Aries. That may very well be the finest visual APO currently available in sizes up to 7".

But all these refractors are limited by their aperture. A good 12.5-18" dob with Zambuto-quality optics, small CO (<18%) and good thermal properties will open up a new world on the planets beyond even the finest 7" refractor.

Just my 2 cents.


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vahe
professor emeritus


Reged: 08/27/05

Loc: Houston, Texas
Re: Astro-Physics the Best Brand? new [Re: Erik Bakker]
      #6069140 - 09/08/13 09:40 AM

APQs are optimized for visual, the current crop of AP refractors are optimized for imaging. AP abandoned visual refractor design in mid 90s, those were 130, 155 and 180 EDT series, I have 155 F/9EDT from that period and I can safely claim that it is one of the finest visual apos in 6 class.

To me TEC fluorites are the natural successors to APQ series, I really dreamed of having a TEC 160 F/9 fluorite and even asked Yuri if he would build me one, the answer was NO, so I am out of luck, to me the current F/7 is not the best choice for visual.

Are APs the finest? That depends who you ask, to me no matter how good AP optics are there is definitely room for an improvement by using fluorite instead of ED.
By definition the very best must use the very best materials and the fluorite is the best.

Vahe


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PeterR280
Pooh-Bah
*****

Reged: 05/27/13

Re: Astro-Physics the Best Brand? new [Re: vahe]
      #6069145 - 09/08/13 09:43 AM

I think the short focal lengths are much more challenging for the design.

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vahe
professor emeritus


Reged: 08/27/05

Loc: Houston, Texas
Re: Astro-Physics the Best Brand? new [Re: PeterR280]
      #6069260 - 09/08/13 10:45 AM

The design is on the computer screen, computer will do all the work for you, all you need to do is to enter glass data and the computer will do the rest for you.

As for the challenge it is all in the construction of the lens, as long as the objective remains all spherical the challenge is about the same, once the design reaches the limit of what is possible with a given set of glasses and requires aspherics then you are faced with a real challenge.

All recent oil spaced FPL-53 AP lenses required aspherics, both 130 and 155mm fast apos, in a recent post Roland explained his line of reasoning for going air spaced in his 160 F/7.5, air spaced allowed all spherical design and less exotic mating elements, so the bottom line from production standpoint is to simplify the design and make it less costly and more practical to produce, this is where air spaced design begins to make sense.

Vahe


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PeterR280
Pooh-Bah
*****

Reged: 05/27/13

Re: Astro-Physics the Best Brand? new [Re: vahe]
      #6069287 - 09/08/13 10:59 AM

Of course the computer will do the design work but manufacturing becomes an issue. I look at mass production for the high end camera makers and they incorporate aspherical as well as exotic glasses in automated processes. Some of the lenses can have more than 10 elements and the image quality is far superior to older production. I think you are seeing automated manufacturing being introduced with some of the newer high end telescopes coming out of China. If the volume is there, there is no reason why the manual process cannot be automated to reduce cost.

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ManuelJ
professor emeritus


Reged: 12/19/05

Loc: Madrid, Spain
Re: Astro-Physics the Best Brand? new [Re: PeterR280]
      #6069356 - 09/08/13 11:44 AM

I have dreamed of owning an AP for a long time. Once I did, I only want to get rid of it and never buy one again.

Yes, they are good, but they are not worth the money people are paying second hand, I just can't understand that.


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PowellAstro
scholastic sledgehammer
*****

Reged: 10/14/09

Loc: Tennessee
Re: Astro-Physics the Best Brand? new [Re: ManuelJ]
      #6069431 - 09/08/13 12:33 PM

If you ever hand build a large refractor yourself and grind all the lenses and do the machine work to the level of the AP units. You would most likely want to charge more for it than what they are currently selling for. I have produced/ground many in my time in the hobby and it gives one a new level of appreciation for the work that some of these companies are doing, IMHO. Yes it is a lot of money but it is also a lot of hard work.

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M13 Observer
scholastic sledgehammer


Reged: 12/09/06

Re: Astro-Physics the Best Brand? new [Re: ManuelJ]
      #6069451 - 09/08/13 12:48 PM

Quote:

I have dreamed of owning an AP for a long time. Once I did, I only want to get rid of it and never buy one again.

Yes, they are good, but they are not worth the money people are paying second hand, I just can't understand that.




You purchased one second hand that may have a problem because someone or something happened to it. Telephone Astro-Physics, get an RMA number, package it up and ship it to Roland to get it fixed. If it is a problem in the original design and building of this telescope I am sure he will fix it at little or no cost other than shipping. If it is a problem which is not a design or build problem and has happened due to use, misuse or abuse, then you will have to pay to get it repaired. It is really quite simple. Count yourself extremely lucky that he is around and available to do this for you. I have used and still use a number of Astro-Physics scopes in very cold weather, including a Traveler and have never had a problem. All of my AP scopes except one have been purchased second hand.

Whining about yours will get you nowhere and, at some point in the future will likely result in the loss of a very nice telescope because Roland will no longer be physically able to repair it.

Edited by M13 Observer (09/08/13 12:50 PM)


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Astro-Physics the Best Brand? [Re: M13 Observer]
      #6069468 - 09/08/13 12:57 PM

A caveat to that is get something with good coatings and the glass intact. Heck, just get a lens cell. The rest of the OTA can be reconstituted or replaced if that part is good. If it isn't, then it's new telescope time.

When facing that exact question, I asked Roland if an old AP with munged coatings would be worth getting with the understanding I'd be paying AP to rework them. His answer was NO- the coatings have to be ground off and the lens set refigured, at which point it is more work than making a new scope.

So, that's what to look for.

-Rich


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mgwhittle
Pooh-Bah
*****

Reged: 08/24/11

Loc: Chattanooga, TN
Re: Astro-Physics the Best Brand? [Re: Starhawk]
      #6069654 - 09/08/13 02:43 PM

But if we are talking about having an 180 or similar large AP refractor that needs to have the coatings ground off and lens refigured, then I would do that. The cost is certainly less than buying a used 180 in pristine, like new condition and you get the newest coatings and a refigured lens. Plus you probably will never be able to buy a brand new large AP refractor now that the 175 production is finished, so that might just be the next best option if you have a scope that needs that much work to bring it back to spec.

I know that Roland has done this in the past on several scopes, although all of them that I know of were on the larger end of the spectrum. It also must not be too cost prohibitive, based on the particular model needing the work, or people wouldn't have him do it.


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