ahlberto
Pooh-Bah
Reged: 09/06/08
Loc: lisbon-portugal
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Re: AP Mak 10" what the next best thing
[Re: RodgerHouTex]
#5333035 - 07/24/12 12:35 PM
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Clearly Valerie has issues with C14s. To say that it wouldn't perform the best in "very good" to "excellent" seeing is ridiculous and defies the laws of physics.
Indeed.Its incredible how biased the "expert oppinions" can be...  Visualy is a no brainer and for phottografic work ive never saw a 10" mak or a 8" outperfotm a C14;-in fact they are not even close.A more expensive gear does not provive better views...they are waht they are...more expensive 
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bobhen
professor emeritus
Reged: 06/25/05
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Re: AP Mak 10" what the next best thing
[Re: RodgerHouTex]
#5333176 - 07/24/12 02:10 PM
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Clearly Valerie has issues with C14s. To say that it wouldn't perform the best in "very good" to "excellent" seeing is ridiculous and defies the laws of physics.
There is a review right here on CN between a 7-inch Apo and a C14. For planetary performance, it appears the scopes are very close with maybe a slight edge to the 7-inch Apo. The review was written by a C14 owner – he has owned his C14 for decades. I presume he has no issues with C14s.
There is also the list of “planetary” telescopes provided by
Mr. Yoshida. His list also puts 6-inch class Apos ahead of many larger reflector scopes. Although no 7-inch Apos and C14s are included, there are 5, 6-inch class Apo refractors ahead of the C11. I think it’s reasonable to assume a C14; 7-inch Apo comparison would yield similar results. I presume Mister Yoshida has no issues with SCTs.
(101 points) Takahashi μ-300
(96 points) ASTRO-PHYSICS 160EDF
(96 points) Zeiss APQ150
(96 points) Takahashi TOA-150
(95 points) TMB 152mm/F8-CNC-LW
(95 points) Takahashiμ-250
(93 points) ASTRO-PHYSICS 155EDFS
(90 points) INTES-MICRO ALTER
(90 points) ZEN250
(88 points) C-11
APM is planning on producing a 10-inch F14 Mak with specs close to the AP Mak. The original poster might want to consider this new offering.
Bob
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ahlberto
Pooh-Bah
Reged: 09/06/08
Loc: lisbon-portugal
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Re: AP Mak 10" what the next best thing
[Re: bobhen]
#5333210 - 07/24/12 02:32 PM
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Well,mr yoshida doesnt have a sigle newtonian so it doesnt count either.Well,refractor guys will allways see what they whant to see...active imagination plays a BIG ROLE but this are really old discutions with take us nowere.
Have a look at this thread .Its very well written and its an eye oppener 
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RodgerHouTex
scholastic sledgehammer
Reged: 06/02/09
Loc: Houston, Texas, USA
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Re: AP Mak 10" what the next best thing
[Re: bobhen]
#5333286 - 07/24/12 03:26 PM
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Once again, in very good to excellent seeing conditions where the atmosphere is NOT limiting the scopes a 7" APO will not show the same level of detail as a C14.
Resolving power of a 7" APO = 0.65 arcseconds
Resolving power of a C14 = 0.33 arcseconds
The C14 has twice the resolution of a 7" APO. It's simple physics and has nothing to do with the price of the scope or who made it.
Wait a minute - is this the "Refractor Forum"?
Edited by RodgerHouTex (07/24/12 03:28 PM)
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Alph
Pooh-Bah
Reged: 11/23/06
Loc: Melmac
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Re: AP Mak 10" what the next best thing
[Re: RodgerHouTex]
#5333316 - 07/24/12 03:43 PM
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Resolving power of a 7" APO = 0.65 arcseconds
Resolving power of a C14 = 0.33 arcseconds
You need to look at the actual 80% EE radii.
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RodgerHouTex
scholastic sledgehammer
Reged: 06/02/09
Loc: Houston, Texas, USA
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Re: AP Mak 10" what the next best thing
[Re: Alph]
#5333406 - 07/24/12 04:27 PM
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First you need to tell me what it is about the Dawe's criteria that does not apply, and then what "... the actual 80% EE radii." is that you are talking about. I'm not familiar with the term nor have I seen it used in any of the optical texts with which I am familiar.
But then again I've only been designing my own optics and manufacturing them by hand for around 44 years. The same with using and abusing my telescopes.
Edited by RodgerHouTex (07/24/12 04:28 PM)
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bobhen
professor emeritus
Reged: 06/25/05
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Re: AP Mak 10" what the next best thing
[Re: Alph]
#5333442 - 07/24/12 04:47 PM
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The .33 arc second resolution of a C14 is its “theoretical potential” – which it will “never” achieve unless you are located in the Keys or South Florida and even then it will take an rare extraordinary night to hit .33 arc seconds. And a quality 14-inch planetary Newtonian will best a C14 under those very rare conditions. In every other location, seeing will limit a C14’s performance. Where does the original poster live?
A quality optic will take 80x per inch on Saturn – any C14 owners ever use 1120x on Saturn? If not, then seeing is limiting the scope’s resolution, or the scope is not up to the challenge, or both. If you think 1120x is too much power, there is a poster here that uses a Starmaster and lives in Florida that has used 1100x to observe Saturn. Rolland took his Mak to Florida and used over 800x (80x per inch) to see the Enke division on Saturn. Anyone ever see the Enke division with a C14?
Seeing, optical quality, and optical design are (in almost every location) more important for lunar/planetary than raw aperture alone - you need all. Seeing, optical quality, and optical design, are also part of the ”laws of physics”.
Bob
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Alph
Pooh-Bah
Reged: 11/23/06
Loc: Melmac
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Re: AP Mak 10" what the next best thing
[Re: bobhen]
#5333479 - 07/24/12 05:11 PM
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Seeing, optical quality, and optical design, are also part of the "laws of physics".
That's right and that is one of the reasons why 80% EE (encircled energy) radius is used by professionals to quantify image/optics quality.
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Reef58
super member
Reged: 08/06/06
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Re: AP Mak 10" what the next best thing
[Re: bobhen]
#5333483 - 07/24/12 05:14 PM
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I compared my 160mm APO vs my C11, and the 160 did not blow the C11 away. The C11 allowed more detail to be seen, but the 160 had a sharper view. The only easy quote I can give is compared to the 160 the c11 appeared to be slightly out of focus, but more things to see in the eyepiece.
An interesting side note some low surface brightness objects pretty much invisible in the C11 popped into view in the 160, but this was from suburban backyards. At a dark site I am sure it would be different.
Richard
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RAKing
Postmaster
Reged: 12/28/07
Loc: West of the D.C. Nebula
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Re: AP Mak 10" what the next best thing
[Re: Reef58]
#5333499 - 07/24/12 05:30 PM
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I compared my 160mm APO vs my C11, and the 160 did not blow the C11 away. The C11 allowed more detail to be seen, but the 160 had a sharper view. The only easy quote I can give is compared to the 160 the c11 appeared to be slightly out of focus, but more things to see in the eyepiece.
An interesting side note some low surface brightness objects pretty much invisible in the C11 popped into view in the 160, but this was from suburban backyards. At a dark site I am sure it would be different.
Richard
I ran identical tests a few years ago and came up with the same answers. Interesting. I am 30 miles west of the DC area and face the Blue Ridge.
Ron
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rmollise
Postmaster
Reged: 07/06/07
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Re: AP Mak 10" what the next best thing
[Re: Alph]
#5333579 - 07/24/12 06:15 PM
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You need to look at the actual 80% EE radii.
Whatever gets looked at...well...not to break anybody's dreams, but an AP is a fine instrument, capable of world class wide field images, but it cannot defeat the laws of physics and will not show as much of _anything_ as a C14. 
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Alph
Pooh-Bah
Reged: 11/23/06
Loc: Melmac
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Re: AP Mak 10" what the next best thing
[Re: rmollise]
#5333609 - 07/24/12 06:38 PM
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You need to look at the actual 80% EE radii.
Whatever gets looked at...well...not to break anybody's dreams, but an AP is a fine instrument, capable of world class wide field images, but it cannot defeat the laws of physics and will not show as much of _anything_ as a C14.
As someone already said. Seeing, optical quality, and optical design, are also part of the "laws of physics".
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JimP
Pooh-Bah
Reged: 04/22/03
Loc: South Carolina
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Re: AP Mak 10" what the next best thing
[Re: rmollise]
#5333811 - 07/24/12 09:04 PM
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The Laws of Physics. Does that mean a 14" scope with a rough surface and 1/2 wave optics that will not cool down properly will outperform an 8" apo with smooth, 1/10 wave optics which easily reaches and maintains thermal equilibrium? Give me a break. If the Laws of Physics are to be quoted then the optical quality, thermal properties etc would also have to be the same. I don't believe they are. And, I have no association with Celestron or AP or TEC or TMB other than I have owned and used scopes made by them all.
JimP
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JJK
scholastic sledgehammer
Reged: 04/28/08
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Re: AP Mak 10" what the next best thing
[Re: RodgerHouTex]
#5334003 - 07/24/12 11:39 PM
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Once again, in very good to excellent seeing conditions where the atmosphere is NOT limiting the scopes a 7" APO will not show the same level of detail as a C14.
Resolving power of a 7" APO = 0.65 arcseconds
Resolving power of a C14 = 0.33 arcseconds
The C14 has twice the resolution of a 7" APO. It's simple physics and has nothing to do with the price of the scope or who made it.
Wait a minute - is this the "Refractor Forum"?
I'm not suggesting that a high end 7" apo will always outperform a C14 for planetary work, but the resolutions you cite are likely applicable to double star separation.
I have nothing against good C14s and hope to get a cherry one someday. However, I've been quite pleased with the AP Mak-Cass and Tak Mewlon 300CR.
And no, this is not the refractor forum. If it was, the discussion would be sensible. 
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Dan McConaughy
sage
Reged: 11/11/06
Loc: LA
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Re: AP Mak 10" what the next best thing
[Re: RodgerHouTex]
#5334009 - 07/24/12 11:45 PM
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If he is a vendor of Maks and Apos and not C14s, Valerie is likely biased.
For me, there is nothing wrong with value. My ego is not tied to high dollars per inch of aperture. I'm interested in what I can see through the eyepiece and the convenience of use, given my budget constraints.
If dollars per inch of aperture is the primary driver of one's telescope utility function, then get some kind of Zeiss scope - they have been the best for decades if not a century or more.
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JJK
scholastic sledgehammer
Reged: 04/28/08
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Re: AP Mak 10" what the next best thing
[Re: rmollise]
#5334010 - 07/24/12 11:46 PM
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You need to look at the actual 80% EE radii.
Whatever gets looked at...well...not to break anybody's dreams, but an AP is a fine instrument, capable of world class wide field images, but it cannot defeat the laws of physics and will not show as much of _anything_ as a C14.
Rod, have you ever looked through an AP 10" Mak-Cass?
I would suspect that C14 would go deeper on the faint fuzzies, but I would not assume it would be better for planetary/lunar views. The AP Mak-Cass is a fine optic and with decent seeing, it can tolerate very high magnification (which has its uses). I haven't yet seen a Celestron OTA that can do that. Perhaps they exist.
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JJK
scholastic sledgehammer
Reged: 04/28/08
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Re: AP Mak 10" what the next best thing
[Re: rmollise]
#5334045 - 07/25/12 12:20 AM
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You need to look at the actual 80% EE radii.
Whatever gets looked at...well...not to break anybody's dreams, but an AP is a fine instrument, capable of world class wide field images, but it cannot defeat the laws of physics and will not show as much of _anything_ as a C14.
Rod, at f/14.6, I wouldn't classify the AP10" Mak-Cass as a wide-field instrument. Also, the laws of physics include optical quality, thermal properties, etc., so I'm not sure your conjecture is always valid.
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brianb11213
Postmaster
Reged: 02/25/09
Loc: 55.215N 6.554W
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Re: AP Mak 10" what the next best thing
[Re: JimP]
#5334247 - 07/25/12 06:51 AM
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The Laws of Physics. Does that mean a 14" scope with a rough surface and 1/2 wave optics that will not cool down properly will outperform an 8" apo with smooth, 1/10 wave optics which easily reaches and maintains thermal equilibrium? Give me a break. If the Laws of Physics are to be quoted then the optical quality, thermal properties etc would also have to be the same. I don't believe they are. And, I have no association with Celestron or AP or TEC or TMB other than I have owned and used scopes made by them all.
Fact of the matter is, not all C14's have "1/2 wave optics and rough surfaces". As is well documented, some of the world's leading planetary imagers use C14s as their instrument of choice ... and they do produce some very nice images with them.
As for cooling, seeing etc ... well, clearly all scopes need to be properly acclimatised and to be at a site with good seeing in order to perform well. The difference is that a larger aperture scope - with its greater resolution potential - will outperform a smaller aperture scope, even one which has slightly better optical quality, whenever the conditions are good. SCTs and Maks depend on fan cooling, Maks actually rather more than commercial SCTs (thin corrector plate & thin wall tubes) ... if smaller refractors appear to need less cooling and/or tolerate bad seeing better than larger cats, maybe it's because their resolution potential isn't as great.
Having experience of all three, I would say that a good 180mm Mak shows about as much planetary detail as an average 200mm SCT, and both will outperform an excellent 150mm apo providing the seeing is even halfway reasonable and that all three scopes are allowed to stabilise in temperature.
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JimP
Pooh-Bah
Reged: 04/22/03
Loc: South Carolina
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Re: AP Mak 10" what the next best thing
[Re: brianb11213]
#5334265 - 07/25/12 07:19 AM
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Well, you guys who prefer the Celestrons have my blessings. I prefer apochromatic refractors and Maksutovs. I have been a lunar and planetary observer for about 47 years and have owned and used them all. To each his own. Just remember that optical theory and the laws of physics require laboratory conditions and perfect optics, something never encountered in the real world of lunar and planetary observing. With this post I bid you a fond goodbye. I have no interest in arguing. Have a great day!
best,
JimP
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RodgerHouTex
scholastic sledgehammer
Reged: 06/02/09
Loc: Houston, Texas, USA
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Re: AP Mak 10" what the next best thing
[Re: Alph]
#5334355 - 07/25/12 09:14 AM
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Let me preface this by saying that we are talking on this forum about amateur telescope optics. Two of the professionals who make these optics are Astro-physics and Zambuto Optical. Having perused their sites extensively, I have never seen a reference to an "80% encircled energy" criteria of which you speak. Nor have I seen it used in any of the telescope optics books I have. Who are the "professionals" that use this criteria?
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