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Want a Planet killer-suggest some

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#126 Galicapernistein

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Posted 26 January 2020 - 09:30 AM

Absytec said.....planet killing is about seeing more than the other guy, right?.....     

  yes it is about seeing more ...detail...........it is about seeing more than I ever have before...

   Planet killing is a cool title    i like it   but as shown throughout the thread    so many variables are in play

    And I can tell you that for some of us it is just that magical night of excellent seeing when things all fell into place for whatever reason...................Like when I saw Jupiter and Saturn with my 1990 Tak FC-100  and got the best views  I had ever seen in my limited experience

 

  Of course   then when I was at Stellafane and looked through some of the big dobs for the first time  it was  a real   

eye opener..

A closed tube 10 inch Dob  f-8  would be a great step up for me     seeing more than I have before      I think at my level of experience      a good started Dob size

A closed tube 10” F8 would kill at just about everything.


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#127 Jon Isaacs

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Posted 26 January 2020 - 09:38 AM

Barlows may be useful with fast refractors, but I’ve never been satisfied with the views they provide in Newtonians.

I have good success with a good Barlow.  You mention a 3.5mm eyepiece, that could be a TV 3.5 mm Nagler.  Any 3.5 mm eyepiece with enough eye relief that it's usable will have some sort of Barlow-like section built in.

 

Jon


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#128 Galicapernistein

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Posted 26 January 2020 - 10:01 AM

I have good success with a good Barlow.  You mention a 3.5mm eyepiece, that could be a TV 3.5 mm Nagler.  Any 3.5 mm eyepiece with enough eye relief that it's usable will have some sort of Barlow-like section built in.

 

Jon

I guess you can call an eyepiece that uses a concave lens Barlow-like. I wouldn’t call it a Barlow though. But I have been looking for a simpler eyepiece design just to compare with my Naglers, just to see if it makes a difference.



#129 Asbytec

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Posted 26 January 2020 - 10:06 AM

"Planet killing is a cool title i like it but as shown throughout the thread so many variables are in play

And I can tell you that for some of us it is just that magical night of excellent seeing when things all fell into place for whatever reason..."

Great comment. I like the term, too, it has an impact when you say it. Like the impact we feel when we see it.

Though others have, I have never seen Jupiter so well as when it passed the zenith in Pickering 8/10 or better in a modest 6" aperture when everything was tuned and came together. My scope was mass produced and obstructed.

I have no doubt a premium 6" APO would have killed it a little better, but there was not one present on those many nights. Someone in Florida may have been observing Jove about that time and with a "real" planet killer, but does that rob me of my experience? Does a 12" premium Newt thus rob the guy in Florida of his title? And so on?

Can there be only one planet killer? If so, who is it this week? "The world wonders..."

We have to agree there are scopes or novice observers out there that cannot really "kill" planets due to poor optics or whatever. Not every scope or location is a planet killer. So how do we define what is or who is really killing it? Maybe there is a duct tape standard measured by how much is used keeping our jaw strapped to our face.

Edited by Asbytec, 26 January 2020 - 10:18 AM.

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#130 Galicapernistein

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Posted 26 January 2020 - 10:15 AM

"Planet killing is a cool title i like it but as shown throughout the thread so many variables are in play

And I can tell you that for some of us it is just that magical night of excellent seeing when things all fell into place for whatever reason..."

Great comment. I like the term, too, it has an impact when you say it. Like the impact we feel when we see it.

Though others have, I have never seen Jupiter so well as when it passed the zenith in Pickering 8/10 or better in a modest 6" aperture when everything was tuned and came together. My scope was mass produced and obstructed.

I have no doubt a premium 6" APO would have killed it a little better, but there was not one present on those many nights. Someone in Florida may have been observing Jove about that time and with a "real" planet killer, but does that rob me of my experience? Does a 12" premium Newt thus rob the guy in Florida of his title? And so on?

Can there be only one planet killer? If so, who is it this week? "The world wonders..."

The term planet killer has traditionally meant a slow Newtonian with a small secondary, whose performance characteristics provide good high power views of planets. It doesn’t say anything about the performance of someone else’s scope. 


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#131 Asbytec

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Posted 26 January 2020 - 10:19 AM

The term planet killer has traditionally meant a slow Newtonian with a small secondary, whose performance characteristics provide good high power views of planets. It doesn’t say anything about the performance of someone else’s scope.


Okay, your point is well taken. Thanks.
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#132 Jon Isaacs

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Posted 26 January 2020 - 11:06 AM

I guess you can call an eyepiece that uses a concave lens Barlow-like. I wouldn’t call it a Barlow though. But I have been looking for a simpler eyepiece design just to compare with my Naglers, just to see if it makes a difference.

 

A Barlow is a negative lens, it diverges the rays rather than converges them.

 

Short focal length eyepieces with a decent amount of eye relief are negative-positive eyepieces. With many such eyepieces, its posdible to safely remove the negative section and play around with it and see that it's basically a Barlow but one that's been tweaked, mostly because these are generally wide field eyepieces.

 

So what differences do you see when you compare a quality 7 mm eyepiece with a 2x Barlow to a 3.5 mm of equal quality?

 

Jon



#133 Asbytec

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Posted 26 January 2020 - 11:14 AM

The term planet killer has traditionally meant a slow Newtonian with a small secondary, whose performance characteristics provide good high power views of planets. It doesn’t say anything about the performance of someone else’s scope.


Your comment set me to thinking. It has to be slow Newts with small obstructions, and surely descent mirrors, are traditionally identified as planet killers based on their fine imaging properties. If "planet killer" still defines a certain class of scope, then that's the end of it.

If planet killers are identified by their imaging properties, then all bets are off. Imaging properties are dependent on more than a small (or lack of an) obstruction and long focal lengths. If it's about the view, then everything matters. However, if everything matters then "planet killer" becomes a grey area, including traditional slow Newts as 'potential' planet killers. Like most everything else.

I'm sure I violated a few logic rules talking in circles. lol.gif


Edited by Asbytec, 26 January 2020 - 06:50 PM.

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#134 Galicapernistein

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Posted 26 January 2020 - 03:23 PM

A Barlow is a negative lens, it diverges the rays rather than converges them.

 

Short focal length eyepieces with a decent amount of eye relief are negative-positive eyepieces. With many such eyepieces, its posdible to safely remove the negative section and play around with it and see that it's basically a Barlow but one that's been tweaked, mostly because these are generally wide field eyepieces.

 

So what differences do you see when you compare a quality 7 mm eyepiece with a 2x Barlow to a 3.5 mm of equal quality?

 

Jon

I have never had a good viewing experience with a barlow, so you’ll have to perform that experiment yourself.



#135 CHASLX200

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Posted 26 January 2020 - 03:36 PM

I have never had a good viewing experience with a barlow, so you’ll have to perform that experiment yourself.

I have many times with the older Circle NJ Barlows from Tele Vue made in the mid 1980's. Many times i have used a 3mm with a Barlow as well.



#136 Galicapernistein

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Posted 26 January 2020 - 06:16 PM

I have many times with the older Circle NJ Barlows from Tele Vue made in the mid 1980's. Many times i have used a 3mm with a Barlow as well.

Feel free to send your atmosphere up to the Midwest anytime.



#137 25585

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Posted 26 January 2020 - 06:26 PM

A closed tube 10” F8 would kill at just about everything.

My closed tube 10" F6 is very good.


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#138 25585

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Posted 26 January 2020 - 06:31 PM

I have never had a good viewing experience with a barlow, so you’ll have to perform that experiment yourself.

What Barlows - makes, powers & lengths, have you used, with which eyepieces and in which scopes?  Any other viewing accessories used at the same time?



#139 Galicapernistein

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Posted 26 January 2020 - 06:33 PM

What Barlows - makes, powers & lengths, have you used, with which eyepieces and in which scopes?  Any other viewing accessories used at the same time?

Just a 2x Televue on an Orion 8” F6. Not the best combination.



#140 hakann

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Posted 26 January 2020 - 08:17 PM

Out of topics but it shore would be nice see high mag star test on bigger/faster Newts ex in Pyrex.
Just say ; ’it would be nice’. Aka ’planet killer wievs.

I read a article before I got from Dream on test a 500 mm cellular in Zerodur in a high end lab ( not Dream ) at MRF and double diffraction ( told in nm RMS ) and it was not near even possible even at light weight good factor better than 6;1 in temperature room, no body heaat etc.
This was 20” and a space article.

OP, best way my guess has a decent scope and find/wait on good seeing.
I been at Roque/LaPalma ( +2.000 meter and one of the best places on Earth ( for 5 times and its dark 21.6-21.9 ) but seeing is tuff.

I was told, next time ; come see into the Starfire 175 mm ( at west side at 900 meter.

Edited by hakann, 26 January 2020 - 09:00 PM.

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#141 a__l

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Posted 26 January 2020 - 09:49 PM

And add a vertical tower to the room with stabilize the temperature. Interferometer above the machine with the manufactured mirror. Self-written software (LOMO).



#142 stubeeef

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Posted 26 January 2020 - 10:00 PM

I think I'll just wait till Hubble ends up in a government auction site.


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#143 MalVeauX

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Posted 26 January 2020 - 10:05 PM

Best optics and big aperture are great.... but not very useful under poor seeing.

 

How's the seeing where you are on average?

 

Very best,


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#144 stubeeef

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Posted 26 January 2020 - 10:27 PM

Best optics and big aperture are great.... but not very useful under poor seeing.

 

How's the seeing where you are on average?

 

Very best,

 

Varies greatly, but an hour way there is some nice dark sky on the Blue Ridge Parkway in Southern Va.
I'm moving to an area that will be quite cloudy but also borders Bortle Class 3 skies.
30min from my door will be this facility
https://www.pari.edu
Anyway, I'm retiring in about 6 years and will gladly take long journeys to where the dark clear skies are out west.


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#145 a__l

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Posted 26 January 2020 - 10:41 PM

I think I'll just wait till Hubble ends up in a government auction site.

There was a critical mistake even in making Hubble. I think that in the manufacture of optics for ATM there are many more such mistakes. For different reasons. Therefore, when someone write “kill” your telescope, let's at least a minimum of objectivity (video Star Test).


Edited by a__l, 27 January 2020 - 03:31 AM.


#146 stubeeef

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Posted 26 January 2020 - 11:02 PM

Huh?



#147 a__l

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Posted 26 January 2020 - 11:14 PM

Huh?

What? Hubble's critical mistake? This is common knowledge. And its correction cost a lot.

Was identified by the test by star lol.gif


Edited by a__l, 26 January 2020 - 11:21 PM.


#148 stubeeef

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Posted 26 January 2020 - 11:49 PM

im familiar with the issues and mission to fix it.

Don't understand where I was going to kill my telescope though.

 

Anyway, good night



#149 a__l

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Posted 27 January 2020 - 12:36 AM

Clear. The offer is not for you. You can read the posts above.

I wrote my post more correctly.
 


Edited by a__l, 27 January 2020 - 03:32 AM.


#150 Jon Isaacs

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Posted 27 January 2020 - 12:55 AM

The term planet killer has traditionally meant a slow Newtonian with a small secondary, whose performance characteristics provide good high power views of planets. It doesn’t say anything about the performance of someone else’s scope. 

 

I'm not so sure about that. 

 

I will say no more about that.

 

The issue in this thread is whether one wants a slow Newtonian or an excellent planetary scope..

 

Jon




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