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dpwoos
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Re: Optimized Newts vs APOs new [Re: Pinbout]
      #5592548 - 12/28/12 11:49 AM

For me, it boils down to this. I don't think you would find anyone who makes top-notch APOs who would dispute that a Newtonion Reflector would, if properly optimized, produce views through the eyepiece that are equal to an APO. Whether this requires that an optical window be used to hold the secondary as opposed to a spider is an interesting question, but I bet that it doesn't. On the other hand, there are a bunch of reasons why newts cost a lot less than APOs of the same size, and why folks can make their own, and why APOs greater than 6" aren't readily available at all. These reasons all add up to compromise the performance of newts. Not a huge amount, but enough that folks still spend good money to own APOs.

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MKV
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Re: Optimized Newts vs APOs new [Re: Pinbout]
      #5592550 - 12/28/12 11:51 AM

Quote:

without the scope created first, there is no challenge at all cause there is nothing to compete against except for dreams and promises.



Oh, come on, Danny, that's just lame, imo. Ed was willing to make one for the challenge.

Mladen


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Pinbout
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Re: Optimized Newts vs APOs new [Re: MKV]
      #5592581 - 12/28/12 12:14 PM

Quote:



Quote:
--------------------------------------------------------------------------------

without the scope created first, there is no challenge at all cause there is nothing to compete against except for dreams and promises.


--------------------------------------------------------------------------------


Oh, come on, Danny, that's just lame, imo. Ed was willing to make one for the challenge.

Mladen




do you want to go there?

He really should make it first. I have no doubt he could. but until you do...

is the challenge about the scopes or is it about him.

Make the ##!@# scope first then present the challenge, you might actually get someone to take that challenge.

...but not without a scope first...and the proof is no one actually took the challenge.


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magic612
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Re: Optimized Newts vs APOs new [Re: Pinbout]
      #5592652 - 12/28/12 01:00 PM

Why are there no takers? I think basic psychology rules here. A telescope is not a need, it is a want. As such, it become an emotional purchase.

"Do I need a telescope? No. Do I want one? Yes. Do I want this expensive one that costs many thousands of dollars? Yes. Why? Performance, and it is ostensibly 'The Best.'"

So on one hand we have a 'best-performaning" APO refractor telescope, costing many thousands. If a similarly-sized reflector costing far less money is proven to be equal in performance (or of negligible difference), this severely hurts the rationalization that was required to make the many-thousand-of-dollars purchase. It is the equivalent of a souped-up-by-its-owner 1970's era Camaro matching the acceleration of a new Ferrari.

I don't' think even if the reflector with window was made there would be any takers from those who own similarly sized APO's. To me, the math says it would be equal in performance. It is the large cost difference that would hurt the owner of the large APO. "Ouch... I spent HOW MUCH on mine again?" Sure, they might justify it with "Well, the focuser is in a better position" or some mechanically-related rationalization. But performance-wise, why would they put themselves in such a position, knowing in advance what the (likely) result would be?

Unless they are an emotional masochist, they wouldn't. I don't blame them, to be frank about it. I wouldn't put myself in that position either.


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MKV
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Re: Optimized Newts vs APOs new [Re: Pinbout]
      #5592699 - 12/28/12 01:24 PM

Quote:

do you want to go there? He really should make it first. I have no doubt he could. but until you do...
is the challenge about the scopes or is it about him.



Yes I do want to go there, seeing that perhaps you need to think this trough a little bit more.

Ed would need to know which APO is to be compared, the size, the focal ratio, etc., so he could make a matching Newotnian counterpart. Otherwise you'd have to have someone make a custom-made APO to compare to Ed's Newotnian! Who's going to make an APO just to match his Newotnian?

Any owner of an already existing APO could have accepted Ed's challenge and have Ed make a Newotnian of the same size and focal ratio. But, understandably, no one did, and for a good reason! I'd feel pretty darn stupid if I bought a telescope that costs as much as a good used car only to discover a $250 Newotonian counterpart with an optical window that matches, let alone exceeds, its image quality.

Mladen

Edited by MKV (12/28/12 01:30 PM)


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MKV
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Re: Optimized Newts vs APOs new [Re: magic612]
      #5592705 - 12/28/12 01:32 PM

Quote:

Unless they are an emotional masochist, they wouldn't. I don't blame them, to be frank about it. I wouldn't put myself in that position either.



Spot on!

M


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Darren Drake
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Re: Optimized Newts vs APOs new [Re: magic612]
      #5592712 - 12/28/12 01:36 PM

I know it's not quite apples to apples but Napersky will soon acquire an AP Superplanetary 6 inch and one of the first things I wanna do is compare the Jupiter views to my high quality 8 inch f/6.9 newt. If the seeing is real good I think the results could be most interesting. Of course I will report back....

Edited by Darren Drake (12/29/12 07:54 AM)


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mikey cee
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Re: Optimized Newts vs APOs new [Re: MKV]
      #5592749 - 12/28/12 02:04 PM

Quote:

Quote:

do you want to go there? He really should make it first. I have no doubt he could. but until you do...
is the challenge about the scopes or is it about him.



Yes I do want to go there, seeing that perhaps you need to think this trough a little bit more.

Ed would need to know which APO is to be compared, the size, the focal ratio, etc., so he could make a matching Newotnian counterpart. Otherwise you'd have to have someone make a custom-made APO to compare to Ed's Newotnian! Who's going to make an APO just to match his Newotnian?

Any owner of an already existing APO could have accepted Ed's challenge and have Ed make a Newotnian of the same size and focal ratio. But, understandably, no one did, and for a good reason! I'd feel pretty darn stupid if I bought a telescope that costs as much as a good used car only to discover a $250 Newotonian counterpart with an optical window that matches, let alone exceeds, its image quality.

Mladen


Yeah you and me both! Mike

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kfrederick
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Re: Optimized Newts vs APOs new [Re: mikey cee]
      #5592826 - 12/28/12 02:57 PM

The APO will be better a 6 inch APO will have more light than a 6 newt . The image is formed by refraction so the surfaces need not as smooth . Feet of in focus . But sure for 1/5 the money for the newt .Also having no obstruction is very real even if some of it Might be in the brain .

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ed_turco
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Re: Optimized Newts vs APOs new [Re: MKV]
      #5592880 - 12/28/12 03:38 PM Attachment (19 downloads)

I did have a 4" windowed Newt of superlative quality that I recently donated to a youth ward of a certain hospital where I had multiple stays. So the telescope did exist and the challenge went unanswered. The telescope was listed in my signature, so don't anyone tell me that such a telescope didn't exist and that my challenge was a blast of hot air -- please.

Edited by ed_turco (12/28/12 03:55 PM)


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ed_turco
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Re: Optimized Newts vs APOs new [Re: ed_turco]
      #5592894 - 12/28/12 03:52 PM

At least one and I'll bet two of my students, who have surpassed me in their optical achievements, will carry forth this challenge in the future. One already has a windowed newt of extra superlative quality that he can stop down to the teeny aperture of the challenging APO, fit it with the appropriate diagonal, and once again say, "Bring it On!" But this will be his call. I should live so long to see a taker.

Doesn't it surprise anyone as to how few APOists have actually looked through an excellent Newt, even one that is not optimized? They'll give you all sorts of nonsense for not doing so, spider diffraction, CO, but NOT a look?

I have to doubt the sanity of people who broadcast gleefully about a new 50mm APO that has come out. What are they thinking? Are they thinking at all?

Final word for this posting. It is every teacher's dream that his students surpass him in their achievements. I have been doubly blessed.



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tim53
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Re: Optimized Newts vs APOs new [Re: magic612]
      #5592918 - 12/28/12 04:10 PM

Quote:

A telescope is not a need, it is a want. As such, it become an emotional purchase.




A telescope isn't a need?? I don't know about all ya'all, but I won't survive for long if there isnt at least one long focus newt around here. Like woody Allen might say if he were an amateur astronomer: "that's my second favorite organ!"

Tim


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magic612
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Re: Optimized Newts vs APOs new [Re: tim53]
      #5592960 - 12/28/12 04:49 PM

Quote:

Quote:

A telescope is not a need, it is a want. As such, it become an emotional purchase.




A telescope isn't a need?? I don't know about all ya'all, but I won't survive for long if there isnt at least one long focus newt around here. Like woody Allen might say if he were an amateur astronomer: "that's my second favorite organ!"

Tim




As my mom used to say, if it isn't food, shelter or clothing, it's a want.


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Pinbout
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Re: Optimized Newts vs APOs new [Re: MKV]
      #5592999 - 12/28/12 05:29 PM

Quote:

bought a telescope that costs as much as a good used car only to discover a $250 Newotonian counterpart with an optical window that matches, let alone exceeds, its image quality.





Perhaps you need to recalculate the cost/value of a hand figured windowed newt by a master mirror maker, the optics alone don't cost $250 and because he made them you can't omit the cost.


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gatorengineer
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Re: Optimized Newts vs APOs new [Re: Pinbout]
      #5593015 - 12/28/12 05:40 PM

I am also going to venture that on a given Northeast Night, you could take a Super Newt, a Super APO, and an 8"F6 GSO special out, and it would be tough to see the difference.

I will also tell you brightness aside there is no difference on the Average Night between my 25"F5 and my 8"F6 Mak Newt....

However, on the Extremely rare night,when I can turn the volume up to 11, and throw the Ethos 3.75 in the 25" then it is worth having every ounce of optical quality one can muster... But those nights are rare, and the cost goes expontential for that quality...

At the end of the day, seeing rules, and its supposed to be fun.....


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Datapanic
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Re: Optimized Newts vs APOs new [Re: Datapanic]
      #5593027 - 12/28/12 05:50 PM

Quote:

I found it! It's actually about an APO vs. Questar Funny and probably fitting for what this thread will turn out to.




So, who won!?


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azure1961p
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Re: Optimized Newts vs APOs new [Re: Datapanic]
      #5593197 - 12/28/12 07:31 PM

What seems to be taking a vacation here is the real physical effects of central obstruction - even 15%. Next are heat plumes off the primary. A window means nothing if you have to focus through a contrast killing thermal boundary layer . It can still be good, even amazing but its not going to match an apo if its still there . Frankly I think the whole optical window thing is getting over blown and not enough attention to treating the thermal issues which is of paramount importance if you want to do this apo versus newt thing.

Pete


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MKV
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Re: Optimized Newts vs APOs new [Re: Pinbout]
      #5593250 - 12/28/12 08:04 PM Attachment (10 downloads)

Quote:

Perhaps you need to recalculate the cost/value of a hand figured windowed newt by a master mirror maker, the optics alone don't cost $250 and because he made them you can't omit the cost.



If you can make a mirror you can make a window; it's just more work - two sides, and a central hole. No reason for the optics to cost more than $250 in 4 to 6 inch aperture.

But let's even double that and say it'd cost you $500 for optics, is it still worth paying 10 to 20 times more for the same or even inferior performance.

Mladen


Mladen


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ed_turco
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Re: Optimized Newts vs APOs new [Re: azure1961p]
      #5593383 - 12/28/12 09:35 PM

Pete,

Did you think


i wouldn't have thought of a small fan?

Ed


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azure1961p
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Re: Optimized Newts vs APOs [Re: ed_turco]
      #5593543 - 12/28/12 11:21 PM

LOL ok Ed,

didnt see it mentioned. Im happy as pie - my boundary layer fan finally has proper airflow across the face of the mirror. Just got it in.

I say one thing though that apo or refractor owners seem to have less issue with. Tonight for example Jupiter was way up near zenith and while I was contnually defocusing to check for proper cooling of the primary - evertyime I exhaled or had my hand on the edge of the tubes secondary end, this awful disruptive heat plume would enter the field.
For that Im doing the following...

1. Have a handle or knob of some sort farthjer down the tube so I dont have to grab the scopes open end to move it.

2. It seems odd but maybe somekind of fan intake to carry my breath elsewhere. When the scopes up at that angle my breath trail is like a smokestack. You could say the same for apo users but they arent exhaling inches from there objective opening.

Lower elevations like 45 degrees arent prob lem but 60 degrees and above it seems problematic.

Im all into the thermal thing right now so thats where my scope DIY concentration is.

Pete


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