150 replies to this topic

[johnlind]

Imagine how long that would be lol

Imagine the difficulty with tube flexture? How long would that tube need to be?

John L

[Deep13]

The new spider doesn't work in the old one's drill holes. How do I lay out the drill holes for the new spider?

[scooke]

14.5" F4.3 Starmaster with Zambuto mirror or 18" F5 with Stabilite mirror.  Too close to call but incredible either way.  Stabilite reaches thermal equilibrium immediately so it has the best view fastest.

[HellsKitchen]

8" f/6 with a Lockwood or Zambuto. 

 

Or my 8" F/6. Nuff said. 

 

Nah, A solid tube 10" F/8 with a Lockwood or Zambuto.  That, IMO, would be the ultimate planet killer. 

 

That being said, my custom 8" F/6 eats planets for breakfast. 

Edited by HellsKitchen, 08 June 2019 - 07:34 AM.

[HoundDog]

Discovery 8" f7 looks like a good planetary scope. Wooden base, 1.25" between wall and mirror. Discovery fills the gap that Orion and Zhumel left open. They charge twice as much though.

Did someone mention a Discovery 8" F7 scope? This is my pea shooter 8" F7 Discovery dob which does a pretty good job with planetary views (others have told me it is an excellent planet scope after viewing through it). It also serves me well for many brighter DSO's too. 

I usually use either a Televue 11 plossl or Televue Nagler 13 T6 for most of my planetary viewing since I seem to live under a perpetual atmospheric jet stream. Every once and awhile, I'll use my Nagler 9 T6 when the viewing allows it. 

No, I do not transport the scope in the Hello Kitty car. That's for my granddaughter to blast up and down our dead end street... with supervision of course!

[scooke]

Slightly off topic but owning Stabilite mirrors (the original 18"F3.75 and my current 18"F5) taught me that so much bad seeing is local to the mirror.  In other words thermal issues.  The Stabilite mirrors showed pinpoint stars from the first moment while the 14.5" Zambuto is thin at 1.6" but still takes 30 minutes to an hour to show pinpoints.  The star test on the 14.5 is slightly better (1/16th vs. 1/10th) but at that point it is essentially perfect either way.  Thermal management is so important.

[scooke]

One other thing I've noticed and don't know why is that Jupiter can take less power than Saturn.  With the 14.5", I can go to 1056X fairly often on Saturn and Ganymede but at the same time Jupiter might only support 655X  before image breakdown.  Similar with the 18".  I've never understood this.  Any ideas?

[HellsKitchen]

One other thing I've noticed and don't know why is that Jupiter can take less power than Saturn.  With the 14.5", I can go to 1056X fairly often on Saturn and Ganymede but at the same time Jupiter might only support 655X  before image breakdown.  Similar with the 18".  I've never understood this.  Any ideas?

 

That's certainly not wrong. I think it is simply because Jupiter's features are low contrast gas on a very bright background, and increasing power just "spreads" that already low contrast out. I sometimes find that the Galilean moons are crisp disks, Jupiter's limb is sharp, but the detail on the planet gets washed out. 

Saturn doesn't have much detail on the globe, and the rings are hard edged, high contrast features so can take magnification. It certainly takes more power on the same night than Jupiter in my experience. 

 

Only 655x on Jupiter, do you have an atmospheric hole above your place? That is nuts I can't even begin to imagine what that would look like. 

Edited by HellsKitchen, 08 June 2019 - 10:55 PM.

[CHASLX200]

One other thing I've noticed and don't know why is that Jupiter can take less power than Saturn.  With the 14.5", I can go to 1056X fairly often on Saturn and Ganymede but at the same time Jupiter might only support 655X  before image breakdown.  Similar with the 18".  I've never understood this.  Any ideas?

I could use over 1150x on Jupiter with a 14.5" Zambuto and a 15" OMI on my best nites. Maybe it is too low for you now.

[25585]

Did someone mention a Discovery 8" F7 scope? This is my pea shooter 8" F7 Discovery dob which does a pretty good job with planetary views (others have told me it is an excellent planet scope after viewing through it). It also serves me well for many brighter DSO's too. 

I usually use either a Televue 11 plossl or Televue Nagler 13 T6 for most of my planetary viewing since I seem to live under a perpetual atmospheric jet stream. Every once and awhile, I'll use my Nagler 9 T6 when the viewing allows it. 

No, I do not transport the scope in the Hello Kitty car. That's for my granddaughter to blast up and down our dead end street... with supervision of course!

IMG_6359.JPG

You also need need one of these 

Attached Thumbnails

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[scooke]

That's certainly not wrong. I think it is simply because Jupiter's features are low contrast gas on a very bright background, and increasing power just "spreads" that already low contrast out. I sometimes find that the Galilean moons are crisp disks, Jupiter's limb is sharp, but the detail on the planet gets washed out. 

Saturn doesn't have much detail on the globe, and the rings are hard edged, high contrast features so can take magnification. It certainly takes more power on the same night than Jupiter in my experience. 

 

Only 655x on Jupiter, do you have an atmospheric hole above your place? That is nuts I can't even begin to imagine what that would look like. 

Move to the west coast of Florida.  Best decision I ever made.  I lived most of my life in the Kansas City area.  We got exceptional seeing late summer/early fall only.  North of Tampa, near the coast, we get exceptional seeing just about any time except the summer. Even the summer can have good seeing but the transparency sucks.  Any time the wind is blowing in from the gulf.  The best is late winter/early spring.

[Adun Toridas]

I plan on getting an Apetura AD 8 Dobsonian as my next upgrade from a second hand 4.5'' reflector that I purchased. I hear that 8" Dobs are perfect for beginners, but was hesitant as to the ability of planetary observation it could produce vs. a reflector. I've been told that the 8" dob can do both planetary and deep space observation and it suits a beginner like me.  

Actually, I had had the good fortune to view through 2 separate 8-inch f/8 reflectors. Each one had optics ground and polished by the owner. Unbelievable! These guys did an amazing on their respective mirrors. Jupiter at the Mount Kobau Star Party in Aug. 1985 I will never forget!

Neither will I forget the Oct. 1988 opposition of Mars through Lance Oklevic's 8-inch f/8 self fabricated newtonian reflector. It was a Sat. night, I believe, and Terence Dickinson gave a Mars lecture in the auditorium at the H.R. MacMillan planetarium. Afterwards many amateurs set up their scopes on the large concrete entrance to the Gordon Southam Observatory. A member's AP 6-inch f/8 Apo was also pointed towards Mars.

 

So yes, an 8-inch f/8 can make an ideal planet killer!

 

Clear Skies!

RalphMeisterTigerMan

[Deep13]

Did someone mention a Discovery 8" F7 scope? This is my pea shooter 8" F7 Discovery dob which does a pretty good job with planetary views (others have told me it is an excellent planet scope after viewing through it). It also serves me well for many brighter DSO's too.
I usually use either a Televue 11 plossl or Televue Nagler 13 T6 for most of my planetary viewing since I seem to live under a perpetual atmospheric jet stream. Every once and awhile, I'll use my Nagler 9 T6 when the viewing allows it.
No, I do not transport the scope in the Hello Kitty car. That's for my granddaughter to blast up and down our dead end street... with supervision of course!
IMG_6359.JPG

Do you have a bigger Hello Kitty car to move the scope around? My 8" Discovery Dob is f/6.

[mic1970]

The brown one is stunning.

 

A Cass with sufficient back focus & a rotating focuser (like the 4" F15 I built using a vintage Edmund/3B mirror set) is great for comfortable seated observing.  An 8" F7 Newtonian on a GEM is a good compromise for me, provided it has rotating rings, or is easier to turn in hinged rings than my RV-6 -- a shorter & cheaper scope, too than a Cass.

 

On nights when I have maybe an hour to observe, I'm not going to haul out my APM 152ED F8 APO + pedestal GEM, not while I have these two 6" Newtonians on Polaris mounts:

 

2x 150mm Newtonians on Polaris Mounts S05.jpg

 

As long as the views are good, practicality is a big factor for me.

 

[Mel M]

Have the people that think their refractors beat their reflectors held the competition when a breeze was in their face? The heat from our head is in a bad spot. When the wind is not strong enough a large fan blowing my heat away from my reflector makes the difference. Some nights it makes a lot of difference. I know there are a lot of other factors but blowing body heat away from the scope is a big one people do not do.

[HoundDog]

Do you have a bigger Hello Kitty car to move the scope around? My 8" Discovery Dob is f/6.

We don't have a bigger Hello Kitty car. That one was destined for a trash pile but Mrs. HoundDog rescued, cleaned, and restored it back to life. Even the in dash speakers work!

I took my scope out last weekend and sweated under the stars. Good times!

[Deep13]

I've installed the secondary in slots I drilled. I just have to collimate it. I've got the sight tube for the secondary, a Cheshire, Barlowed laser, and an auto-collimator.

[Shorty Barlow]

My ideal planetary/lunar scope is a 150mm, f/6 TS Optics (GSO) Newtonian.

 

 

It's ideal for me as it is mounted on a Sky-Watcher EQ5 at the north end of my garden to maximise the view into the plane of the ecliptic. The mount is covered with a tarpaulin when not in use which makes it relatively easy for me to carry the OTA out to it. Not having to set the EQ5 up every time I want to use it is a big asset. I'm physically disabled so any OTA bigger than 150mm could be problematical.

 

 

It's not a particularly expensive scope. The addition of a Baader helical focuser threaded onto a Baader 1.25" adapter gives a very fine tuning ability to the single speed Crayford. The rapid deployment is what makes it ideal. I caught a break in the weather on the Sunday night/Monday morning of the Jupiter opposition and decided to set up hoping the weather would hold. It was a quick decision around midnight as earlier I'd more or less given up hope of a session. I was rewarded with a bright sharp Jupiter at 180x. 

[Ed Jones]

Since the earth is the most ideal planet I'd say anything stronger than binoculars would be too much power!    

[Richard Whalen]

ideal planet scope is one without spider vanes, either unobstructed or 25% or less CO.

[areyoukiddingme]

My ideal planetary/lunar scope is a 150mm, f/6 TS Optics (GSO) Newtonian.

 

 

 

It's ideal for me as it is mounted on a Sky-Watcher EQ5 at the north end of my garden to maximise the view into the plane of the ecliptic. The mount is covered with a tarpaulin when not in use which makes it relatively easy for me to carry the OTA out to it. Not having to set the EQ5 up every time I want to use it is a big asset. I'm physically disabled so any OTA bigger than 150mm could be problematical.

 

 

 

It's not a particularly expensive scope. The addition of a Baader helical focuser threaded onto a Baader 1.25" adapter gives a very fine tuning ability to the single speed Crayford. The rapid deployment is what makes it ideal. I caught a break in the weather on the Sunday night/Monday morning of the Jupiter opposition and decided to set up hoping the weather would hold. It was a quick decision around midnight as earlier I'd more or less given up hope of a session. I was rewarded with a bright sharp Jupiter at 180x. 

I have a single speed focuser on my 8" F7, and have been thinking of upgrading to a dual-speed.

 

But it sounds like this might be a good solution for far less money. How do you like the fine-focus ability on the helical?

 

btw. is this the model? I assume these work like regular 2" to 1.25" adapters?

 

https://agenaastro.c...crofocuser.html

[Shorty Barlow]

I have a single speed focuser on my 8" F7, and have been thinking of upgrading to a dual-speed.

 

But it sounds like this might be a good solution for far less money. How do you like the fine-focus ability on the helical?

 

btw. is this the model? I assume these work like regular 2" to 1.25" adapters?

 

https://agenaastro.c...crofocuser.html

You'll need a Baader 2" to 1.25" adapter with a T-thread.

 

https://www.firstlig...er-adapter.html

 

There is a plate/ring on the adapter that screws off revealing the T-thread. The helical threads onto that. The helical is pretty good, in fact I miss it when it isn't on the focuser. One caveat though, it will change the in-focus distance slightly so some EP's or Barlow combinations may not achieve focus. 

Edited by Shorty Barlow, 14 June 2019 - 05:33 PM.

[Shorty Barlow]

ideal planet scope is one without spider vanes, either unobstructed or 25% or less CO.

My spider vanes are invisible lol.

 

 

OK, maybe not.

Edited by Shorty Barlow, 14 June 2019 - 05:41 PM.

[CHASLX200]

We don't have a bigger Hello Kitty car. That one was destined for a trash pile but Mrs. HoundDog rescued, cleaned, and restored it back to life. Even the in dash speakers work!

I took my scope out last weekend and sweated under the stars. Good times!

What is a hello kitty car?

[HoundDog]

https://www.amazon.c...e/dp/B01LYLBI9X
This describes a Hello Kitty car.