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Ideal planet scope.

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#151 dag55

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Posted 15 June 2019 - 07:01 PM

In my mind, the ideal planet telescope is a 10 or 12" EQ Newt (split ring?) in a permanent location with a clear view of the south and overhead. Add a good binoviewer, pairs of long ZAOs, and an easy way to reach the EP, and I'd be all set. In reality, it would be too expensive and I have no place to set it up permanently. So-o-o-o, I've arranged to buy a used 8" f/8 EQ-mounted Newt. I'll need to have some servicing done on the mirrors. I'm thinking that within the realm of likely possibility, this may very well be my ideal set-up. Right now it has no fan and a tall R&P focuser, so I may change those things. And I'll built a cart for the Meade RG mount. I already have a tall adjustable chair and a Denk II with pairs of TV Ploessls.

 

Any thoughts? What's your ideal planet scope?

I had both a very good 8" Zambuto f-7.5 and a 10" Waite f-5.8 on an EQ mount, the 8" I had rotating rings but still a very big pain in the rear to use on an EQ mount. I am considering a slightly different set up 10" f-5.3 through f-5.5 for a shorter tube and mounted on an EQ-AZ mount, in AZ mode viewing will be far more easier as the EP will be on one side and accessible.  At the focal lengths mentioned as long as you get a premium mirror and build it well you can achieve 50x per inch with sharp image on the planets, and you can use a 1.83" secondary, CO 18.3%. good luck.

Dane


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#152 Deep13

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Posted 20 June 2019 - 12:48 AM

I had both a very good 8" Zambuto f-7.5 and a 10" Waite f-5.8 on an EQ mount, the 8" I had rotating rings but still a very big pain in the rear to use on an EQ mount. I am considering a slightly different set up 10" f-5.3 through f-5.5 for a shorter tube and mounted on an EQ-AZ mount, in AZ mode viewing will be far more easier as the EP will be on one side and accessible. At the focal lengths mentioned as long as you get a premium mirror and build it well you can achieve 50x per inch with sharp image on the planets, and you can use a 1.83" secondary, CO 18.3%. good luck.
Dane


Just waiting for the rain to end. I used a low profile focuser, so the secondary is 1.52" wide (minor axis).

#153 dag55

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Posted 21 June 2019 - 05:25 PM

I used a SilenX  80mm Effizio Quiet Case Fan in the 8" Newt. as I recall, small enough to mount in between the collimation screws and still provide good air flow for laminar removal. They are almost vibration free, what I did was use thin navcom rubber shims between the four mounting points to eliminate the vibration from transfering to the primary mirror. The fan was directly mounted to the mirror cell so this was an important detail of the design. I attached a pic of the rear of the Newt. good viewing and enjoy your new scope. One last detail, I used a piece of klydex for a baffle to the rear of the mirror cell to provide positive air up the tube. And a potentiometer or fan speed control.

Dane

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  • 8 inch newt-losmandy 004 (2).JPG

Edited by dag55, 21 June 2019 - 05:27 PM.

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#154 Deep13

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Posted 23 June 2019 - 06:39 AM

First light. Observed Jupiter and Saturn. Low in the sky and  a bit hazy.

Scope: 8" f/8. Edmund mirror with no aberrations and a new aluminum coating by Terry Ostahowski, Antares secondary, fan, gear reduction focuser, and a 10mm ZAO2. So, it worked as well as one would expect: sharp, high contrast, and no spikes.

Cart: I made it out of wood because the Meade RG mount is really heavy. I works pretty well.

Mount: It has an electric RA motor and an external electronic box that is supposed to give the user slow motion controls in RA and dec. I am still getting used to it.

 

 

Attached Thumbnails

  • Screen Shot 2019-06-23 at 6.45.31 AM.png

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#155 TareqPhoto

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Posted 24 June 2019 - 09:38 AM

Longf thread, didn't try to read all pages, but i don't know if it is about planetary imaging or planetary visual, if visual for me it doesn't matter at all, as i tried with my ST80 and 8" Newt and 7" Mak, all of them gave me nice view, i even look through C9.25 and Meade 10" SCT belong to others and the view was just nice as my Mak just a tad brighter, so i won't think too much about it to have a very ideal perfect ultimate scope, and i already started to get a large scope, 20" Dob, and this i can use for everything maybe, DSO visual and planets visual and planetary imaging.


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#156 Shorty Barlow

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Posted 24 June 2019 - 01:16 PM

gallery_249298_5348_183814.jpg

 

Ideal grab'n'go lunar/planetary Mak's. Above: 90mm Orion StarMax on SW AZ5 mount. Below: 127mm Sky-Watcher SkyMax on same mount.

 

gallery_249298_5348_902355.jpg


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#157 dag55

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Posted 28 June 2019 - 07:59 AM

First light. Observed Jupiter and Saturn. Low in the sky and  a bit hazy.

Scope: 8" f/8. Edmund mirror with no aberrations and a new aluminum coating by Terry Ostahowski, Antares secondary, fan, gear reduction focuser, and a 10mm ZAO2. So, it worked as well as one would expect: sharp, high contrast, and no spikes.

Cart: I made it out of wood because the Meade RG mount is really heavy. I works pretty well.

Mount: It has an electric RA motor and an external electronic box that is supposed to give the user slow motion controls in RA and dec. I am still getting used to it.

Looks good, you are making me miss my Newts.  more pics. please and have fun this summer with your observations.

Dane


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#158 CCD-Freak

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Posted 03 July 2019 - 11:52 AM

This makes me want to get my old 8" F8 (Edmund mirror) Dob out for a look.  I bought the mirror for $40 (in a mirror cell) at the TSP swap meet many years ago and it has delivered some of the best lunar and planetary images I have seen.   Great "bang for the buck" in a manageable size.  

 

8inF8-Dob-JL-xsm.jpg

 

 

John

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#159 CHASLX200

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Posted 03 July 2019 - 05:59 PM

This makes me want to get my old 8" F8 (Edmund mirror) Dob out for a look.  I bought the mirror for $40 (in a mirror cell) at the TSP swap meet many years ago and it has delivered some of the best lunar and planetary images I have seen.   Great "bang for the buck" in a manageable size.  

 

attachicon.gif 8inF8-Dob-JL-xsm.jpg

 

 

John

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My Edmund 8" F/8 was also a planet killer. Made around 1960.


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#160 tomjones

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Posted 07 July 2019 - 08:41 PM

My 5" apo 53-triple is outperforming my average 10" dob on Jupiter. The 10" looks like it is slightly out of focus. The 5" shows so much fine cloud details it is hard to draw.



#161 mic1970

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Posted 08 July 2019 - 07:52 AM

This is a Mr. Obvious question, but did you align the dob and/or was the mirror acclimated?  

My 5" apo 53-triple is outperforming my average 10" dob on Jupiter. The 10" looks like it is slightly out of focus. The 5" shows so much fine cloud details it is hard to draw.



#162 tomjones

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Posted 08 July 2019 - 12:03 PM

I noticed this difference between primo refractors and an average dob way back in 2010.

Had just got Takahashi TSA 102 and viewing alongside 8" f/7 1/8 waver that I had thought was pretty good, the Tak was clearly better on Jupiter.  Had my current 10" f/5.6 also out at same time and it was slightly better than the 4" Tak. The 10" could see that lineup of small white ovals in the band above the GRS while the 4" could only see two of the larger ones.

 

Now have new 5" f/7 53-triple and it is clearly better than 10" dob that has papers saying it is 1/10th wave. Don't have my 14" dob anymore, but the 5" frac is approaching the details it showed.  Yes all mirrors were clean and collimated.

 

Optical quality is what the apo's have at their enormous prices. A Zambuto type mirror would really enhance the dob's performance and still be a little cheaper than an equal viewing refractor.



#163 mic1970

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Posted 08 July 2019 - 12:53 PM

Interesting.  I wonder if it has do due with the contrast????  I don't think I will ever be able to afford a 5" triplet so I'll have to stick with my trustee dob. 

 

 

I noticed this difference between primo refractors and an average dob way back in 2010.

Had just got Takahashi TSA 102 and viewing alongside 8" f/7 1/8 waver that I had thought was pretty good, the Tak was clearly better on Jupiter.  Had my current 10" f/5.6 also out at same time and it was slightly better than the 4" Tak. The 10" could see that lineup of small white ovals in the band above the GRS while the 4" could only see two of the larger ones.

 

Now have new 5" f/7 53-triple and it is clearly better than 10" dob that has papers saying it is 1/10th wave. Don't have my 14" dob anymore, but the 5" frac is approaching the details it showed.  Yes all mirrors were clean and collimated.

 

Optical quality is what the apo's have at their enormous prices. A Zambuto type mirror would really enhance the dob's performance and still be a little cheaper than an equal viewing refractor.



#164 Darren Drake

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Posted 08 July 2019 - 01:16 PM

Aperture is everything.   Even a less than perfect big mirror will seriously outperform a much smaller apo as long as the newt is optimized. 


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#165 TareqPhoto

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Posted 08 July 2019 - 01:46 PM

Aperture is everything.   Even a less than perfect big mirror will seriously outperform a much smaller apo as long as the newt is optimized. 

Exactly, i try to find so so many results and images of planets done with larger APO compared to larger mirrors scopes, looking at big names and even ALPO i don't see big refractors results really, so i will use for example 14" or 20" scope with Zambuto mirrors, so which refractor can match this and how much it will cost?


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#166 nirvanix

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Posted 10 July 2019 - 11:37 AM

Agreed Darren and Tareq. If one wants to see more lunar/planetary detail, increase aperture while maintaining optical quality and success will follow.


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#167 TareqPhoto

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Posted 10 July 2019 - 11:39 AM

Agreed Darren and Tareq. If one wants to see more lunar/planetary detail, increase aperture while maintaining optical quality and success will follow.

Can't

Agree

More

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#168 Richard Whalen

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Posted 10 July 2019 - 06:54 PM

Agreed Darren and Tareq. If one wants to see more lunar/planetary detail, increase aperture while maintaining optical quality and success will follow.

Problem is maintaining optical quality. The larger the optics get the more difficult to get excellent optical quality. And above 8" or 10" seeing really comes into play at 95% of locations. Ive look through a lot of large dobs with premium mirrors from 12.5"to 42". With rare exceptions once above 16" its hard to get an excellent mirror, you can get a very good one though. Above 25" I have only seen a "good" mirror at best. Also the larger the mirror the longer the cooldown, I have seen many large dobs that never equalized all night long.

 

While large mirrors may seem excellent compared to other large mirrors, the are not compared to a smaller high end APO or MCT. A custom made 8" or 10" mirror can be though, just finding one may be tough. 



#169 Asbytec

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Posted 10 July 2019 - 07:37 PM

I noticed this difference between primo refractors and an average dob way back in 2010.

Had just got Takahashi TSA 102 and viewing alongside 8" f/7 1/8 waver that I had thought was pretty good, the Tak was clearly better on Jupiter.  Had my current 10" f/5.6 also out at same time and it was slightly better than the 4" Tak. The 10" could see that lineup of small white ovals in the band above the GRS while the 4" could only see two of the larger ones.

 

Now have new 5" f/7 53-triple and it is clearly better than 10" dob that has papers saying it is 1/10th wave. Don't have my 14" dob anymore, but the 5" frac is approaching the details it showed.  Yes all mirrors were clean and collimated.

 

Optical quality is what the apo's have at their enormous prices. A Zambuto type mirror would really enhance the dob's performance and still be a little cheaper than an equal viewing refractor.

That is an amazing report, quite likely the most amazing I've heard, and one that sparks much discussion. I did not see it through your eyes, but a 1/8 wave and a 1/10 wave Newt mirror are pretty darn near perfect as one might expect. No doubt the Tak 4" and the 5" triplet are absolutely the best, but they are not exactly perfect, either. So, there is some convergence in performance. Cooled and collimated, and especially in good seeing, the good 8" and 10" Newts (as stated) should blow the socks off a small refractor no matter how perfect. If they did not, something is wrong. Good quality optics count for a lot, especially in a larger aperture that has them as mentioned above. In addition to good figure, aperture brings a lot to the game, too. I've seen the beauty of an etched Jupiter in a smaller aperture conducive to the local seeing, so it's not like I do not understand the allure of a absolutely rock steady "etched" image of Jupiter. I cannot help wondering if the allure of a steady Jupiter actually trumped the performance of a larger well corrected aperture. Wondering if that is what makes the smaller one appear to out perform the (quality) larger one. 



#170 Richard Whalen

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Posted 10 July 2019 - 09:05 PM

That is an amazing report, quite likely the most amazing I've heard, and one that sparks much discussion. I did not see it through your eyes, but a 1/8 wave and a 1/10 wave Newt mirror are pretty darn near perfect as one might expect. No doubt the Tak 4" and the 5" triplet are absolutely the best, but they are not exactly perfect, either. So, there is some convergence in performance. Cooled and collimated, and especially in good seeing, the good 8" and 10" Newts (as stated) should blow the socks off a small refractor no matter how perfect. If they did not, something is wrong. Good quality optics count for a lot, especially in a larger aperture that has them as mentioned above. In addition to good figure, aperture brings a lot to the game, too. I've seen the beauty of an etched Jupiter in a smaller aperture conducive to the local seeing, so it's not like I do not understand the allure of a absolutely rock steady "etched" image of Jupiter. I cannot help wondering if the allure of a steady Jupiter actually trumped the performance of a larger well corrected aperture. Wondering if that is what makes the smaller one appear to out perform the (quality) larger one. 

Usually seeing. Many are not as lucky as we are to live in an area with good seeing. I have a friend who lives up north, under the jet stream most of the time. He says his seeing is usually worse than 2 arc seconds, sometimes 4 or 6.  He has downsized to a 140mm class APO from larger scopes, says on many nights even the 12.5" he used to own gave washed out views of dso's. Having better luck with his 140mm APO. 



#171 barbie

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Posted 10 July 2019 - 09:58 PM

I usually get only average seeing and transparency with an occasional above average to excellent night during the summer months so over the last 15 years, I've downsized to three and four inch apos as my primary instruments and have certainly not regretted the move.  Physical limitations also impose a strict size limit on the scopes so I now only have grab and go scopes and mounts.  I get out with these instruments far more often than I did when I had my big reflectors, which never did show the crisp, etched images of the planets that my two small Takahashi's always show me. For me, these small apos are the ideal planetary scopes.  YMMV.



#172 Asbytec

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Posted 10 July 2019 - 10:08 PM

Usually seeing. Many are not as lucky as we are to live in an area with good seeing. I have a friend who lives up north, under the jet stream most of the time. He says his seeing is usually worse than 2 arc seconds, sometimes 4 or 6. He has downsized to a 140mm class APO from larger scopes, says on many nights even the 12.5" he used to own gave washed out views of dso's. Having better luck with his 140mm APO.


That makes good sense. Once a large aperture begins speckling or bloated behavoir, all bets are off. Nothing wrong with tuning your aperture to prevailing local conditions.

#173 Redbetter

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Posted 11 July 2019 - 12:44 AM

I noticed this difference between primo refractors and an average dob way back in 2010.

Had just got Takahashi TSA 102 and viewing alongside 8" f/7 1/8 waver that I had thought was pretty good, the Tak was clearly better on Jupiter.  Had my current 10" f/5.6 also out at same time and it was slightly better than the 4" Tak. The 10" could see that lineup of small white ovals in the band above the GRS while the 4" could only see two of the larger ones.

 

Now have new 5" f/7 53-triple and it is clearly better than 10" dob that has papers saying it is 1/10th wave. Don't have my 14" dob anymore, but the 5" frac is approaching the details it showed.  Yes all mirrors were clean and collimated.

 

Optical quality is what the apo's have at their enormous prices. A Zambuto type mirror would really enhance the dob's performance and still be a little cheaper than an equal viewing refractor.

Assuming that you are referring to the ovals in the belt south of the GRS (below at present in the northern hemisphere in a refractor and below in a reflector) it is interesting that the Tak 102 is topping out about where my f/7 110ED (not apochromatic) and ES 127 Mak top out on resolved ovals, with the 110 being the slightly crisper of the two.  I confirm the ovals with a larger scope.  The old 8" SCT does better when the seeing supports it, and the stock 10" GSO dob can show the full string.  That 10" is sharp.  Most nights the ovals are not visible in any of the apertures because the seeing is just too poor.

 

The 20" buries the others, but rarely gets seeing that allows it out of "idle" mode around here and has never had a truly steady night locally.  It gives better views than the others in even mediocre conditions, but rarely even close to what I have seen with it from 32 N.  There I had frequent enough nights where Jupiter's moons were steady discs; here they never are, there is always some sort of moving flare(s) & undulation about them even on the best nights.    


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#174 TareqPhoto

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Posted 11 July 2019 - 06:17 AM

Problem is maintaining optical quality. The larger the optics get the more difficult to get excellent optical quality. And above 8" or 10" seeing really comes into play at 95% of locations. Ive look through a lot of large dobs with premium mirrors from 12.5"to 42". With rare exceptions once above 16" its hard to get an excellent mirror, you can get a very good one though. Above 25" I have only seen a "good" mirror at best. Also the larger the mirror the longer the cooldown, I have seen many large dobs that never equalized all night long.

 

While large mirrors may seem excellent compared to other large mirrors, the are not compared to a smaller high end APO or MCT. A custom made 8" or 10" mirror can be though, just finding one may be tough. 

People talk logic and i talk pictures, again, larger scopes will be worse in bad or poor seeing, but it will shine more in good to excellent seeing, now i don't based my decision on how poor is my sky is, instead, i based it how many nice nights i will get, and for that i don't mind going with largest i can, i may if i can get for example only 10% good/nice seeing every year then it is enough for me, and when i said pictures it is because i looked at all best great examples or mind blowing images of planets and it is likely 90% from larger scopes reflectors than 10", from different parts of the world, so no matter how many times we will talk about size or quality or seeing, there is always opportunities to use larger scopes for planets, in my yard i can see planets for longer than 4-5 months and in those months i see like 40-60 nights as amazing seeing, so it is unfair to make myself going with 6" or 8" only because i didn't have like 300 nights as exceptional, those 30-60 nights i can have results that lasts for many years.

 

I already asked about which mirror for larger scope, my plan was for 20", and i did get enough answers, and i have got about that "Zambuto" quartz mirror specially thin one, it says that it has better thermal performance, so there is something good then or high quality, i know about the price, but if someone can afford it then why?

 

What i feel about this kind of comments is "Hey people around the world, don't buy scopes above 10" or 14" because seeing will never be that excellent anywhere at all, so 16" and larger even 1 meter scopes are a waste or pointless", and when i look at images from 16" and 14" and 1 meter scopes the only thing in mind is how to afford those scopes regardless what people keep saying about seeing or "Size issues" matter



#175 CHASLX200

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Posted 11 July 2019 - 06:20 AM

My best planet views ever were with two 14.5" Zambuto and a 15" OMI all faster than F/5.  I had no problem using 500 to 800x and on the best nites over 1000x.  While i have had many great scopes nothing came close to the views with the smaller scopes as you run out light using very high powers.

 

Inch for inch nothing beats a refractor for the highest power cleaner views. My SW150ED and a super good 8" F/6 Newt are about dead even, but the ED shows Jupiters moons just a tad cleaner and sharper.




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