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9.25 SCT, it ain't no planet scope

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#26 Starlease

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Posted 20 October 2018 - 06:57 PM

The only sct ever had was the 9.25. Mine was pretty good. Details on Jupiter were better than the above drawing. I saw Saturn's moon Titan as a reddish brown disk for the first time. Sure the images were dimmer because of all the glass the light had to pass thru. It has only has 3 collimating screws how hard can it be to get right.


 

#27 Deep13

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Posted 20 October 2018 - 08:19 PM

I went with the 9.25 because it is a nice size. I wasn't supposing it was better than other SCTs. I don't do astro photos, so, no camera. I do have a focusing mask. It really could be thermals.
 

#28 Deep13

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Posted 20 October 2018 - 09:53 PM

Read Celestron's collimation instructions. The odds that we will have a perfectly still night with a perfectly cooled scope in Akron, OH and that I will be available that night are about one in crapdillion.

 

Isn't there a way to do it with a sight tube and a cheshire?


 

#29 Starlease

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Posted 20 October 2018 - 10:05 PM

Make your own artificial star by covering a flashlight with aluminum foil and punching the tiniest hole you can in it. Put light across yard as far as you can and collimate on that. Out of focus star should be a concentric donut. Use an eyepiece around 10mm.


Edited by Starlease, 20 October 2018 - 10:05 PM.

 

#30 DMach

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Posted 20 October 2018 - 10:06 PM

You don't need a perfectly still night, fair to good seeing just makes things easier.

 

Alternatively, consider an artificial star? Plenty of options out there:

 

https://optcorp.com/...ant=44880199434

 

https://optcorp.com/...ant=44874948298


 

#31 gfstallin

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Posted 21 October 2018 - 05:28 AM

The only sct ever had was the 9.25. Mine was pretty good. Details on Jupiter were better than the above drawing. I saw Saturn's moon Titan as a reddish brown disk for the first time. Sure the images were dimmer because of all the glass the light had to pass thru. It has only has 3 collimating screws how hard can it be to get right.

 

Getting collimation right is easy, but getting the courage to make adjustments takes time for some folks. 

 

It's taken me a couple years to feel comfortable fussing with collimation using real stars. I had always depended upon my trusty artificial star from France (AKA "La Béquille" or "The Crutch" in English) for my C8 and C9.25, which had never steered me wrong. I even took to throwing collimation off purposely just to practice on rainy nights. Perfect collimation with the artificial star in a long indoor hallway (105 feet) always translated to a perfect airy disk in good seeing under real stars. When I acquired a C11, things changed. What was perfect collimation horizontally using the artificial star did not hold up when looking at stars at elevation. It was off in a way I had never experienced with the C8 and C9.25. Once I realized it was a collimation issue, I had two choices: I could pony up $85,000 to buy a truck crane for my artificial star so that I could lift it to 40-60 degrees apparent elevation, or I could just bite the bullet and learn to collimate on a real star. As useful as a truck crane can be for a person who has to say to himself "lefty loosie, righty tighty" literally every time he picks up a screwdriver (or "measure twice, cut your finger only once" with other tools), it just did not seem like the best purchase. After waiting for a night with good seeing, I went out and tried my hand at it. Within 15 minutes, I had a perfect airy disk at 800x, confirmed with a planetary camera, and it remained the same on stars in different parts of the sky. 

 

Here are images from that collimation effort: 

C11 Collimation 2
C11 Collimation

 

As simple as real-star collimation seems to me now, in my personal experience it was a longish road to get there. For some people who are more daring than I am, proper outdoor collimation will come quickly and easily. I needed more courage; however, the months of practice I had gained indoors was still invaluable. I understood very well which way to turn those screws ("lefty loosie..."). So while getting collimation right is always easy, some people are just not going to take to it as readily as others. The complexity of the task is not really the issue. The issue is the amount of time some people require before they are willing to fiddle with expensive stuff. 

 

George


Edited by gfstallin, 21 October 2018 - 05:39 AM.

 

#32 Billytk

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Posted 21 October 2018 - 09:58 AM

So far I have been pretty happy with my 9.25 on planetary AP. I'm still learning/getting comfortable with the collimation process, was much easier with my old reflector. Here is a video of my star test. I think it was close.  

 

https://www.youtube....h?v=Var-gd0EZ-U

Attached Thumbnails

  • X2018-02-17-1030_7-RGB_g4_ap73 R6 AI - Copy.jpg
  • 2018-02-17-0955_5-RGB_g4_ap1.jpg

 

#33 gfstallin

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Posted 21 October 2018 - 10:58 AM

So far I have been pretty happy with my 9.25 on planetary AP. I'm still learning/getting comfortable with the collimation process, was much easier with my old reflector. Here is a video of my star test. I think it was close.  

 

https://www.youtube....h?v=Var-gd0EZ-U

Nice Jupiter. 

 

17

 

I took this with my C9.25 last spring at 35 degrees apparent without an ADC. It isn't going in any magazines, but I think it attests to how well a C9.25 can perform. 

 

George


 

#34 mich_al

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Posted 21 October 2018 - 12:20 PM

The odds that we will have a perfectly still night with a perfectly cooled scope in Akron, OH and that I will be available that night are about one in crapdillion.



Which is likely the root of your problem! Big reflectors are not forgiving of temp changes or marginal seeing & that is why my refractors get more use than my big reflectors.
 

#35 coopman

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Posted 21 October 2018 - 12:37 PM

Have a go at collimating it with Metaguide, make sure it's properly acclimated and give it a night of good seeing. You will be surprised. I've owned 2x C9,25's one very good and one superb.

What is Metaguide?


 

#36 Jon Isaacs

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Posted 21 October 2018 - 01:28 PM

12" Is more limited.  I would say that I get 50 nights a year where I can fully exploit 12".   Most nights, this size is not working at its full potential.

 

 

In my mind,  it's not a question of working to it's full potential , it's a question of which scope is providing the "better" views.  On a night when the full potential of a 10 inch can be fully exploited,  a 12.5 inch (and in all likelihood a 16 inch or 22 inch) will provide more detailed, more colorful and cleaner views. 

 

Jon


 

#37 Cpk133

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Posted 21 October 2018 - 01:54 PM

Why don't you try to be more specific about what you can and can't observe with the 9.25?  What planets have you observed, what elevation, what kind of detail are you seeing?  "Smudgy" doesn't help very much.  What power are you observing at?  I remember reading a thread in the refractor forum where someone was chiming in about how awesome his premium refractor was on planets.  He went on to say how it's the first in a long line of scopes to definitively show the Great Red Spot! -give me a break.  The title of this thread is misleading.  The 9.25 is an excellent planetary scope  that's easily mounted on a tracking mount.  


Edited by Cpk133, 21 October 2018 - 06:17 PM.

 

#38 CHASLX200

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Posted 21 October 2018 - 01:59 PM

I bought a 9.25 about a year ago to supplement and eventually replace a DIY 5" f/12 refractor. I've had it out serveral times, always for several hours. Defocused, a bright star looks like a compact disk. In focus on a planet, it's always a smudgy. It's like a thermal problem, the scope is always out for hours. The 5" still delivers sharp, though not especially bright images. And the 8" Dob still gives remarkably sharp images.

No SCT's are  planet scopes. Always soft compared to a well built Newt.


Edited by CHASLX200, 21 October 2018 - 01:59 PM.

 

#39 SandyHouTex

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Posted 21 October 2018 - 02:13 PM

So far I have been pretty happy with my 9.25 on planetary AP. I'm still learning/getting comfortable with the collimation process, was much easier with my old reflector. Here is a video of my star test. I think it was close.  

 

https://www.youtube....h?v=Var-gd0EZ-U

Excellent pic in a typical, SCTs suck thread.  I wonder how long it will be until this one gets locked.  Now we just need CHASXL200 to come along and say how all SCTs suck compared to a good Newt..  Oh wait.  He just did.  And of course Eddgie to say how refractors, even an achromat are so much better.

 

By the way, the standard 9.25 in. SCT I have is diffraction limited.

 

All telescopes are excellent telescopes if you use them properly and allow for their limitations.  SCTs and Mak-Casses need extended cool down times due to being closed systems.  If you add vents and fans, you can speed it up.  They’re wonderful scopes if you allow for that.  No telescope can overcome poor seeing.


Edited by SandyHouTex, 21 October 2018 - 02:21 PM.

 

#40 CHASLX200

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Posted 21 October 2018 - 02:33 PM

Excellent pic in a typical, SCTs suck thread.  I wonder how long it will be until this one gets locked.  Now we just need CHASXL200 to come along and say how all SCTs suck compared to a good Newt..  Oh wait.  He just did.  And of course Eddgie to say how refractors, even an achromat are so much better.

 

By the way, the standard 9.25 in. SCT I have is diffraction limited.

 

All telescopes are excellent telescopes if you use them properly and allow for their limitations.  SCTs and Mak-Casses need extended cool down times due to being closed systems.  If you add vents and fans, you can speed it up.  They’re wonderful scopes if you allow for that.  No telescope can overcome poor seeing.

You are late to the gate nate, look above ya and wake up.  Images are dressed up and in no way look like it does with the eye ball. 5 OUT 60 THAT I OWNED I WOULD CALL GOOD. Plus i have better seeing than anyone on here 9 out of 10 times. Do a side by side with a Zambuto Newt and let the image do the talking.


Edited by CHASLX200, 21 October 2018 - 02:34 PM.

 

#41 Mike G.

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Posted 21 October 2018 - 05:01 PM

As another Ohio observer (20 minutes south of Lake Erie), a lot of your problem is likely seeing conditions. For me, conditions where I can exceed 150x are few and far between. Nights I can hit 200x or more can be counted on one hand (per calendar year) and usually not use a thumb. That said, there have been nights with the 12” on Jupiter at 320x that will stay in my mind forever. But most nights trying to use something shorter than my 12mm T4 results in soft and fuzzy planets. 


 

#42 Asbytec

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Posted 21 October 2018 - 06:53 PM

In my mind,  it's not a question of working to it's full potential , it's a question of which scope is providing the "better" views.  On a night when the full potential of a 10 inch can be fully exploited,  a 12.5 inch (and in all likelihood a 16 inch or 22 inch) will provide more detailed, more colorful and cleaner views. 

 

Jon

This is a great distinction to grasp. 


Edited by Asbytec, 21 October 2018 - 07:00 PM.

 

#43 Asbytec

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Posted 21 October 2018 - 07:25 PM

You are late to the gate nate, look above ya and wake up.  Images are dressed up and in no way look like it does with the eye ball. 5 OUT 60 THAT I OWNED I WOULD CALL GOOD. Plus i have better seeing than anyone on here 9 out of 10 times. Do a side by side with a Zambuto Newt and let the image do the talking.

I don't think anyone is saying a (9 inch?) Zambuto is not a nice view when compared to a C9. What I assert is, as Sandy said, even an SCT can be good on planets if it's tended to and prepped for observing. What I am really saying is, premium scopes are the best they can be, but the diffraction limit (including the obstruction) is not terrible. "Smudgy" "Mush Box" or whatever if they are prepped for observing and thermally stable. Which, by the way, the Zambuto needs to be, as well, and it is also obstructed (sometimes I think we forget that). Then, we hope for good seeing. I say that because I have seeing that equals yours on a regular basis and resolved 7 craterlets in the Plato challenge and seen albedo on Ganymede and a ton of other stuff that no "poor" scope in it's right mind has any business showing. With a largish obstruction and lesser optics, no doubt the SCT will lag the Zambuto to some extent. But, prep trumps optical quality in much the same way seeing does. Every scope needs a fighting chance to perform. And when they do, a C9 is quite capable even if it's not 'perfect.'


 

#44 TG

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Posted 21 October 2018 - 08:34 PM

Yes, I agree with @Eddgie and @CHASLX200 that the C9.25 is an absolute piece of garbage. In fact, if you own one, I entreat you to save yourself grief and throw it on the trash heap right now.

 

Here's how bad mine was:

 

post-19745-14073832457673.jpg


 

#45 nerich

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Posted 21 October 2018 - 09:57 PM

Yes, I agree with @Eddgie and @CHASLX200 that the C9.25 is an absolute piece of garbage. In fact, if you own one, I entreat you to save yourself grief and throw it on the trash heap right now.

 

Here's how bad mine was:

 

 

Man, what a shame. If you get tired of wrestling with that thing, let me know. I could use a good outreach beater. 


 

#46 Jon Isaacs

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Posted 22 October 2018 - 03:13 AM

I don't think anyone is saying a (9 inch?) Zambuto is not a nice view when compared to a C9. What I assert is, as Sandy said, even an SCT can be good on planets if it's tended to and prepped for observing. What I am really saying is, premium scopes are the best they can be, but the diffraction limit (including the obstruction) is not terrible. "Smudgy" "Mush Box" or whatever if they are prepped for observing and thermally stable. Which, by the way, the Zambuto needs to be, as well, and it is also obstructed (sometimes I think we forget that). Then, we hope for good seeing. I say that because I have seeing that equals yours on a regular basis and resolved 7 craterlets in the Plato challenge and seen albedo on Ganymede and a ton of other stuff that no "poor" scope in it's right mind has any business showing. With a largish obstruction and lesser optics, no doubt the SCT will lag the Zambuto to some extent. But, prep trumps optical quality in much the same way seeing does. Every scope needs a fighting chance to perform. And when they do, a C9 is quite capable even if it's not 'perfect.'

 

:waytogo:

 

I agree.  Getting good planetary views requires a decent scope and the C9.25 is a decent scope.  It requires care and attention to detail..  It requires stable seeing .

 

And then it requires a skilled and patient observer.  It is my belief that the biggest differences in what is seen is not in the optics but in the skill of the observer. I look at what others like Norme see with what they have and I know that I'm leaving something on the table. It's not my equipment that's lacking,  it's plenty good enough..  It's me, I have room to grow,  to improve,  to become a better observer. 

 

Jon


 

#47 Deep13

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Posted 22 October 2018 - 04:22 AM

As another Ohio observer (20 minutes south of Lake Erie), a lot of your problem is likely seeing conditions. For me, conditions where I can exceed 150x are few and far between. Nights I can hit 200x or more can be counted on one hand (per calendar year) and usually not use a thumb. That said, there have been nights with the 12” on Jupiter at 320x that will stay in my mind forever. But most nights trying to use something shorter than my 12mm T4 results in soft and fuzzy planets. 

It's not. I've tried it several times. I've also gotten very sharp views in my 8" f/6 Discovery (Terry O.) Dob and that 5" refractor. Unless I just happen to have bad seeing only on the SCT nights and good seeing only on the other scope nights, it's not the location.


 

#48 Deep13

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Posted 22 October 2018 - 04:23 AM

Excellent pic in a typical, SCTs suck thread. 

Uh-huh. I did not say that.


Edited by Deep13, 22 October 2018 - 04:39 AM.

 

#49 Deep13

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Posted 22 October 2018 - 04:33 AM

Why don't you try to be more specific about what you can and can't observe with the 9.25?  What planets have you observed, what elevation, what kind of detail are you seeing?  "Smudgy" doesn't help very much.  What power are you observing at?  I remember reading a thread in the refractor forum where someone was chiming in about how awesome his premium refractor was on planets.  He went on to say how it's the first in a long line of scopes to definitively show the Great Red Spot! -give me a break.  The title of this thread is misleading.  The 9.25 is an excellent planetary scope  that's easily mounted on a tracking mount.  

Since the beginning of summer: Jupiter, Saturn, Mars, Uranus.

I'm in Ohio, so it's the elevation they are from this location, pretty low.

The somewhat out of focus planet is surrounded by a wobbling--well--smudge the same color as the planet, like there is a semi-opaque filter of the same color as the planet over it. The smudge is about twice the with of Mars when I Iooked last week. I don't remember how big the smudges were on the other planets.
10mm, so 235x.
I've seen the GRS in my 8" Dob, my 5" refractor, and possibly my 12.5" Dob. It's not a difficult target when well-positioned.

No, it isn't. It describes my experience pretty well.

So far I have no evidence that this scope is an excellent planetary scope, though it does fit on the AVX mount which was a motivation for buying it.


Edited by Deep13, 22 October 2018 - 04:40 AM.

 

#50 Deep13

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Posted 22 October 2018 - 04:35 AM

Yes, I agree with @Eddgie and @CHASLX200 that the C9.25 is an absolute piece of garbage. In fact, if you own one, I entreat you to save yourself grief and throw it on the trash heap right now.

 

Here's how bad mine was:

 

post-19745-14073832457673.jpg

I'm not an optician. Will you tell me what I am looking at?


 


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