134 replies to this topic

[starman876]

How would we define super planetary scopes. I always thought these scopes had longer focal ratios.  AP for one made the 5" and 6" F12 super planetary series.  These were APO's.  I thought the longer newts like F6 on up were considered super planetary scopes.    I would consider most maks F12 on up as super planetary.   Super planetary scopes would be good for planets and other bright objects, but not very good for deep space work.  Double stars would be another good objects to view with super planetary scopes.   I think another term I have seem for these longer focal ratio scopes is planet killer scopes.  

[J A VOLK]

I have a 5" AP Superplanetary (circa 1987) - it lives up to the reputation!  I think Roland made these because the faster 'APOs' he was making at the time still had some color, especially by modern standards.  Going to f/12 reduced the color substantially - still a small amount at high magnification, but pretty insignificant.

[starman876]

I have a 5" AP Superplanetary (circa 1987) - it lives up to the reputation!  I think Roland made these because the faster 'APOs' he was making at the time still had some color, especially by modern standards.  Going to f/12 reduced the color substantially - still a small amount at high magnification, but pretty insignificant.

I used to have the 5" F12 AP.  What a wonderful scope that was.  Never should have let that one go. 

[Jethro7]

How would we define super planetary scopes. I always thought these scopes had longer focal ratios.  AP for one made the 5" and 6" F12 super planetary series.  These were APO's.  I thought the longer newts like F6 on up were considered super planetary scopes.    I would consider most maks F12 on up as super planetary.   Super planetary scopes would be good for planets and other bright objects, but not very good for deep space work.  Double stars would be another good objects to view with super planetary scopes.   I think another term I have seem for these longer focal ratio scopes is planet killer scopes.  

Hello Starman876,

You have pretty much nailed it. With long focal ratio  refractor type scopes with their long light cones you can run the magnification up much higher before you start to lose resolution. I can clearly see that trait comparing the views between my Altair Starwave Ascent 102ED F/11 and my Astrotech AT102ED F/7. This is where the Long focal lengh refractors shine. I do not have much experience with MAKs but would assume this trait would also be true. The long focal ratio refractors excel for splitting double stars, for the exact same reason and you also get a very good dark contrast  at high magnifications between the double stars and background that allows the objects being viewed to stand out. These same traits that make the long focal ratio refractors Planet Killers inhibit their usefulness for observing many DSO's. This is where having other scopes come in handy. 

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

 

 

Edited by Jethro7, 08 February 2021 - 01:02 PM.

[clamchip]

I would define a super planetary as having a high focal ratio.

You need very high power, and to get it the telescope needs to provide a large image

for the eyepiece.

Almost all my planet observing is with a f/15 refractor.

I did do some with a f/8 fluorite + X5 Powermate but I prefer a f/15 achromat.

I have a f/13 6 inch Newtonian and it's a fabulous planetary scope, requires a ladder

though.

I suppose we can also arrive at this large image with aperture too.

Mr. Cave was a famous Mars observer and his telescope was a 12.5" f/6, 1828mm

focal length.

 

Robert

Edited by clamchip, 08 February 2021 - 01:38 PM.

[Justin Fuller]

In general "Planetary/ Super Planetary / Planet Killer" scopes are long focal length (1000mm+), long focal ratio (f/10+) with central obstructions less than 20% of the aperture diameter, with exceptionally smooth/well corrected optics, at least that's my understanding. My C14 with it's huge 32% obstruction "kills" planets better than any other scope I've owned before though, which included a slew of long focus achros and apos from 80mm to 5", an f/9 6" Newt and 16" Newt with a 24% central obstruction. It's a pretty subjective term. Good optics and a considerably larger aperture, no matter the central obstruction (within reason anyway) , will always outclass a smaller "planet killer" scope...and, of course, the seeing being excellent helps too.

Edited by Justin Fuller, 08 February 2021 - 01:09 PM.

[clamchip]

Here's a pretty good article on 'The recent Evolution of the Planetary Telescope' little mention of

refractors though:

http://www.alpo-astr...pe - Part 2.pdf

 

Robert

[clamchip]

Here is refractors, in part 1:

http://articles.adsa...JALPO..55a..15D

 

Robert

[Defenderslideguitar]

This is a helpful thread

 

 I had always assumed that super planetary meant   quite  long quality refractors  like the Roland Christian made older  AP     5  to 6  inch refractors..........................this thread is helping to expand the universe of that definition for me a bit.

 

Admittedly,  I was also confused in the past about  the term  " Planet Killer "   which was more subjective and more of a personal description..... but maybe that is a horse of a different false color .......

Edited by Defenderslideguitar, 08 February 2021 - 06:42 PM.

[Defenderslideguitar]

Here's a pretty good article on 'The recent Evolution of the Planetary Telescope' little mention of

refractors though:

http://www.alpo-astr...pe - Part 2.pdf

 

Robert

Love these strolling astronomers          newsletter reports    btw

[rathbaster]

 

 

 

 

Admittedly,  I was also confused in the past about  the term  " Planet Killer "   which was more subjective and more of a personal description..... but maybe that is a horse of a different false color .......

The first time I saw the term Planet Killer was in reference to a Burgess Optical scope (4" F/10 as I recall) about 12 years ago (?)

Does the term occur before that time?  

[DAVIDG]

 I have 4.25"  f/24 Schiefspegler  that I built  because it is a  super planetary scope ie Planet Killer  It has no chromatic aberration. It uses all spherical optics which are easy to test so I know when they are perfect. That results in the total POLYchromatic  wave front is  a true 1/8 wave. The scope is unobstructed so no issued with a secondary reducing contrast.   The OTA is less then 36"  long and weights under 10 lbs so  a CG5 Eq mount can easily handle it and I can also have out to observe in minutes and stored away in minutes so I use it   a fair amount. The slow f-ratio is easy on  eyepiece design so an  Orth works great. Because of the 114" focal length  I  can use medium focal length eyepieces with long eye relief to achieve high magnification needed to see detail on the planets. Best of all it cost me $75 to build the OTA.

   By the way the term "Planet Killer" comes from old Star Trek episode  were a robotic ancient spacecraft form another galaxy would blow up planets and consumer the material as fuel. 

 

                                    - Dave 

Edited by DAVIDG, 08 February 2021 - 07:23 PM.

[Defenderslideguitar]

In case anyone's is looking for Roland Christian's   article "What is the best planetary scope?"

posted here 16 years ago next month

 

https://www.cloudyni...-telescope-r402

Edited by Defenderslideguitar, 08 February 2021 - 06:33 PM.

[rathbaster]

 

   By the way the term "Planet Killer" comes from old Star Trek episode  were a robotic ancient spacecraft form another galaxy would blow up planets and consumer the material as fuel. 

 

                                    - Dave 

 

That use of the term I was well aware of 

Though trying to look through the 'Doomsday Machine' would be rather hazardous  

I recall a Star Trek novel that postulated that such machines had been developed to fight the Borg

[clamchip]

I Christened thee  'Hillbilly Super Planetary' when I built this telescope around a ancient

6 inch f/13 mirror I found on ebay.

It was really to be just a fun scope hence Hillbilly Super Planetary because I live in a 

rural area with stills in the hills, toilets in the front yards for them county fair prize winning

flowers.

Once first light the giggles quickly ceased when it was found to be a serious high power

planetary instrument and the name was changed to "AllenScope" after the name scribed

on the back of the mirror.

These long newts were what they used for planets back in the forties and fifties.

Robert

 

[John Huntley]

Would the LZOS 130mm F/9.2 triplet fit into this category ?

 

Mine is not old enough to be called a "classic" yet being a 2006 example but it's quite a slow focal ratio for a triplet.

 

 

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[Kokatha man]

....... My C14 with it's huge 32% obstruction "kills" planets better than any other scope I've owned before though, which included a slew of long focus achros and apos from 80mm to 5", an f/9 6" Newt and 16" Newt with a 24% central obstruction. It's a pretty subjective term. Good optics and a considerably larger aperture, no matter the central obstruction (within reason anyway) , will always outclass a smaller "planet killer" scope...and, of course, the seeing being excellent helps too.

     

[Kasmos]

The classic long refractor f/15-f/20 was indeed the traditional scope for viewing planets. I always associated Super Planetary with the ads, probably AP as mentioned in post #1. As for Planet Killer, I thought it was just slang, usually and again mostly in reference to a long refractor.

 

That said, I've heard several people state that the high power of a C14 is great for planets.

[CHASLX200]

My best views by far were with 11 to 18" Zambuto and OMI , Stamasters and Obsessions by a mile all F/5 and faster.  Don't need a scope to be slow and low for super good images of the planets. My Taks, AP's and 250+ other scopes never could come close to views at 700x to 1150x.  SCT's forget it, smaller fracts forget it, mass made newer Newts forget it. None could come close to much bigger perfect optics in my Dobs.

 

So F/5 and faster does the job if ya got the seeing and the optics and i have had it many times.

[starman876]

My best views by far were with 11 to 18" Zambuto and OMI , Stamasters and Obsessions by a mile all F/5 and faster.  Don't need a scope to be slow and low for super good images of the planets. My Taks, AP's and 250+ other scopes never could come close to views at 700x to 1150x.  SCT's forget it, smaller fracts forget it, mass made newer Newts forget it. None could come close to much bigger perfect optics in my Dobs.

 

So F/5 and faster does the job if ya got the seeing and the optics and i have had it many times.

and you keep letting them go why????

Edited by starman876, 08 February 2021 - 08:09 PM.

[CHASLX200]

I don't want a house full of scopes and junk. I hate clutter and like trying new stuff. Now have a 18" Obsession and soon hope to know if it is as good as my other Dobs in the past.

 

How many scopes do you have and how many have you sold?  Why do you sell scopes?

[starman876]

I don't want a house full of scopes and junk. I hate clutter and like trying new stuff. Now have a 18" Obsession and soon hope to know if it is as good as my other Dobs in the past.

 

How many scopes do you have and how many have you sold?  Why do you sell scopes?

I still have most of the scopes I have ever bought that were special to me.   That accounts for about 30 scopes that I use on and off that I have a hard time selling.    I probably hang onto the ones that I do not consider so special way to long.  Sometimes years before I let go of one.   Mostly all my scopes are classics.  I have about 40 Unitrons and hundreds of Unitron parts.   I have collected a bunch of Tak and zeiss scopes and other german and japanese classics.  I just love classic scopes.  I find it amazing that craftsman made these scopes with such detail before the computerized mills.  My scopes are all my friends.  It is hard to let go of a friend.  

 

did you try the Obsession before you bought it?

Edited by starman876, 08 February 2021 - 09:28 PM.

[Ben H]

What would you want, particularly, in a planetary scope? High resolution, high contrast, low/no chromatism, preferably long focal length for high magnifications with larger eyepieces providing better eye relief. 

 

The old f/15+ Fraunhofer refractors work well in this regard, though large examples are few and far between. The limitations of the crown and flint doublets were overcome by the extra long focal lengths. 

 

Modern glass provides the same low chromatic distortion in faster focal lengths but they're too expensive for me

Any slow refractor will do nearly equally as well, hence why f/8 6" reflectors hold their own. The old Edmund Space Conquerors and the Spacek reflectors which preceded are great starter scopes, performing well for the moon and plants for entry telescopes. 

On paper a Mak-Cass would also be a planet killer, though the Meade 125mm I tried was not nearly so impressive as the Edmund 150mm reflector. Haven't had a chance to use a Questar. The Meade 7" is certainly on my list of scopes I would buy if a fine opportunity dropped into my lap. The low surface to volume ratio of the Cassegrains and high thermal mass slows their thermal equilibration, so there's that as well. 

I think ideally, refractors would have the advantage as you can baffle the tubes for higher contrast vs only flocking with other scopes. 

My 'dream' planet killer would be a big old Clark.
 

Edited by Ben H, 08 February 2021 - 10:45 PM.

[RichA]

Here's a pretty good article on 'The recent Evolution of the Planetary Telescope' little mention of

refractors though:

http://www.alpo-astr...pe - Part 2.pdf

 

Robert

Refractors in the affordable category are too small to be considered top-flight planetary scopes.  A 10" f/8 Newtonian with a world-class mirror can be had for a couple thousand $$$.  A refractor of that size is $100,000.  Even a 7" refractor is $15,000-$23,000 or so.

[starman876]

Refractors in the affordable category are too small to be considered top-flight planetary scopes.  A 10" f/8 Newtonian with a world-class mirror can be had for a couple thousand $$$.  A refractor of that size is $100,000.  Even a 7" refractor is $15,000-$23,000 or so.

There is no denying that large refractors are expensive.  But then there is something magical about a large refractor that is hard to beat.